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Holley question - Idle
Posted By: 68Bullit
Holley question - Idle - 10/18/08 02:27 AM
Will adjustments of the AF mixture screws only affect the way the car runs at idle and not while the car is moving? Since the AF screws are on the idle circuit only? Experiencing a very rich condition while at idle with AED 750dp....Thanks
Posted By: mercman1
Re: Holley question - Idle - 10/18/08 02:47 AM
Where are your A/F mixture screws? Should be about 1.5 turns out. What is your idle RPM and vacuum at idle. I bet your power valve is open. If you have say 9 inches of vacuum you want a 7.5 power valve. Idle mixture will have a slight input off idle, but not enough to make a big difference.
Posted By: Lefty
Re: Holley question - Idle - 10/18/08 02:53 AM
It's my understanding that under light throttle cruise you are using the idle circuit.
Posted By: 68Bullit
Re: Holley question - Idle - 10/18/08 03:01 AM
Merc, is the power valve itself labeled with the number so you know which one you have? And where do I find the power valve?....Thanks
Posted By: mercman1
Re: Holley question - Idle - 10/18/08 03:39 AM
Yes and no...Holley powervalves are marked ie: 65 for a 6.5 inches of vacuum to open and 95 for a 9.5 inches of vacuum to open and so on. Most aftermarket powervalve are not marked. If you have a big cam and an automatic trans you may be idling in gear at 4 inches of vacuum (like my old cuda with a 590 solid) so I used a 2.5 powervalve.Warm the engine up, put it in drive with parking brake on and observe vacuum reading. Then purchase a powervalve 1.5 - 2 inches below this number and you'll be fine.
Posted By: 68Bullit
Re: Holley question - Idle - 10/18/08 04:04 AM
Dumb question here, but help me to check the vacuum. haven't done that before. What guage, and where to hook it up, also, exact location of the power valve in the Holley carb?....Thanks
Posted By: 70AARcuda
Re: Holley question - Idle - 10/18/08 04:20 AM
you need a vacuum guage and hook it up to the manifold vacuum... like where the power brakes are hooked too...
you do now want ported vacuum...like what the vacuum advance on the distributor is hooked up too..
Posted By: FurryStump
Re: Holley question - Idle - 10/18/08 12:02 PM
Holley recommends cut the vacuum number in half to get the power valve number. If they don't make that exact power valve number round down to the next one.
Posted By: CJK440
Re: Holley question - Idle - 10/18/08 01:00 PM
The power valve being open will not contribute to rich idle mixtures.
If you have a rich idle mixture, your screws simply are too far out or your manifold vacuum requires the idle stop screw to be cranked in so far that you are drawing too much fuel from the transfer slots. This is a common problem.
Take the carb off and look at the primary throttle plates and look at how much of the transfer slots are exposed. Or take a pic and post it.
http://www.carcraft.com/howto/77958/photo_05.html
Posted By: JimG
Re: Holley question - Idle - 10/18/08 01:22 PM
Quote:
The power valve being open will not contribute to rich idle mixtures.
If you have a rich idle mixture, your screws simply are too far out or your manifold vacuum requires the idle stop screw to be cranked in so far that you are drawing too much fuel from the transfer slots. This is a common problem.
Take the carb off and look at the primary throttle plates and look at how much of the transfer slots are exposed. Or take a pic and post it.
http://www.carcraft.com/howto/77958/photo_05.html
Good advice all around.
Bullit, once you confirm your float levels and make sure your idle mixture screws aren't screwed out too far, look at what CKJ440 said, and re-read what I wrote about transfer slot/throttle plate relationship in your other thread. There's a good chance it'll fix your problem.
Jim
Posted By: JimG
Re: Holley question - Idle - 10/18/08 03:47 PM
We might be getting ahead of ourselves. Let's check the basics before we fix the carb.
How many cubic inches is this engine? Camshaft duration @ .050"?
What's going on with the ignition timing? What's your static timing and what's the total advance?
Jim
Posted By: 68Bullit
Re: Holley question - Idle - 10/18/08 04:29 PM
Quote:
We might be getting ahead of ourselves. Let's check the basics before we fix the carb.
How many cubic inches is this engine? Camshaft duration @ .050"?
What's going on with the ignition timing? What's your static timing and what's the total advance?
Jim
Mild 360 with CompCams XE-268 224 @.050 approx. 10:6:1 compression with box-stock Edelbrock Heads. not sure what the timing is, balancer is marked withe the timing tape, I just need to get a timing light to see exactly where it is. Engine is basically a fairly mild 360 with a good MP convertor and gears. Carb is just VERY rich, more so than it should be, even after re-jetting. Thanks for all the help guys....
Posted By: GomangoCuda
Re: Holley question - Idle - 10/18/08 05:09 PM
Don't "fix" anything until you know where the timing is.
Posted By: JimG
Re: Holley question - Idle - 10/18/08 08:31 PM
Quote:
Mild 360 with CompCams XE-268 224 @.050 approx. 10:6:1 compression with box-stock Edelbrock Heads. not sure what the timing is, balancer is marked withe the timing tape, I just need to get a timing light to see exactly where it is. Engine is basically a fairly mild 360 with a good MP convertor and gears. Carb is just VERY rich, more so than it should be, even after re-jetting. Thanks for all the help guys....
Bullit:
OK, for some reason I thought this was a 440 we were discussing. Glad I asked. And you're right, that's a fairly mild cam.
At the risk of explaining something you already know, here's the Reader's Digest condensed version of what I'm thinking: your cam, while mild, still has more valve overlap than a stocker. As such, you have lower cylinder pressure at idle than a stocker. That makes the engine want more initial ignition timing than a stock 360. If the timing is set per stock specifications, you'll probably need to advance it. And when you do, the idle speed will increase, allowing you to back off the curb idle screw, and (I suspect) bring the throttle plates into a much happier relationship with the transfer slots, which has just GOT to help your rich idle condition.
You must, must, must figure out how much ignition timing your engine wants at idle before changing stuff on the carb.
If you have to advance your timing very much to get the idle right, you might end up with too much advance at higher RPM. That's OK, you can deal with that next. Just find how much initial timing makes the engine the happiest at idle and off idle.
You're gonna need a timing light. You've already got a timing tape installed - that's good. You won't need a timing light with dialback.
Shout back if this doesn't make sense. This is basic stuff, and there are lots of people here who can walk you through it.
Jim
Posted By: 68Bullit
Re: Holley question - Idle - 10/18/08 10:29 PM
Thanks Jim, I'm pretty sure the timing is right, or VERY close to where it needs to be. I had a good engine builder/tuner put everything together and I know for sure that the timing has been advanced (hence the tape in place, etc). I'll get a reading on it either way and report back. So, just a basic timing light right? Just hook it up and check it while idling normally in park?....Thanks
Posted By: JimG
Re: Holley question - Idle - 10/19/08 12:25 AM
Hello Bullit.
Yes, just check it in park. Be sure to disconnect the vacuum advance, if it's connected.
If you reconnect the vacuum advance and the timing advances at idle (assuming it's plugged into ported vacuum, on the passenger side of the primary metering block), that's another clue that the throttle plates are too far open at idle.
And just for future reference, since you have a timing tape, rev the engine while checking the timing (vacuum advance still disconnected) and see how far it advances. Should be in the 35 degree neighborhood, I think. The guys running Edelbrock heads on small blocks can give you the generally agreed-upon number.
I also never asked - if you screw the idle mixture screws all the way in, will the engine stumble and perhaps stall out? It should if things are as they should be. Don't screw them in too tight (just enough to gently seat them), or you can damage the needles on the end.
Jim
Posted By: moparmarks
Re: Holley question - Idle - 10/19/08 04:15 PM
Like said above, get the time set first. Timing is set at 800rpm.
Is the carb new? Rebuilt? Used? Is an older style or newer?
Does the A/F screws make a difference when turned in?
Posted By: fox
Re: Holley question - Idle - 10/19/08 04:34 PM
Also, are the primary venturies dripping fuel at idle?
You have been given good advice.
Posted By: 68Bullit
Re: Holley question - Idle - 10/19/08 10:41 PM
Okay. Sorry for all the confusion. The Holley appears to be fine. Here's what I found today when I started looking around some. This is a picture of the breather and I've got a moderate amount of smoke coming from the small opening of this breather. That is the smell that I've been experiencing. I had no idea it was coming from the breather obviously, and it really resembled a rich burning odor. I do have a pcv valve on the opposite valve cover, and both valve covers have baffles. Every time the engine gets up to temp and I come to a stop immediately after driving, the smoke odor is all but overwhelming. Given my setup, is there anywhere to route a hose from this breather so it won't puff smoke, even while the pcv is hooked up to the carb?......Thanks
Posted By: 68Bullit
Re: Holley question - Idle - 10/23/08 10:35 PM
No wait! I take that back. Just fixex the PCV problem and got the smoke out of the engine bay, but to no surprise, the Holley is definitely still rich! Still smelling it at idle pretty bad. Just wanted to post the update
Posted By: 68Bullit
Re: Holley question - Idle - 10/23/08 10:37 PM
And if this Holley is burning excessively rich at idle, would that have a negative effect on the fuel economy as well?
Posted By: JimG
Re: Holley question - Idle - 10/24/08 12:55 AM
Quote:
And if this Holley is burning excessively rich at idle, would that have a negative effect on the fuel economy as well?
heck yeah!
OK, we're back where we started with the Holley...which was checking your timing and being sure that retarded ignition timing wasn't causing excessive curb idle throttle plate opening...
Check the timing and let's be sure that's where it should be before we decide the carb is the culprit.
Jim
Posted By: 68Bullit
Re: Holley question - Idle - 10/24/08 01:19 AM
Okay. Haven't put a light on there yet, but I'm almost certain the timing is good. I know that it HAS been advanced, just after it's recent build, and about every other time when starting the engine, there is a little clunk in there (slow skip for a lack of better description), that indicates the timing has been advanced. If I don't put the light on there now, what's the next step? OR, am I hearing that I need to put the light on there anyway?
If so, I gotta order one.
Posted By: dgc333
Re: Holley question - Idle - 10/24/08 12:13 PM
I have a 10.6:1 compression 360 with the same Comp XE268H cam. The engine wants about 17 degress BTDC for intial timing. I have the mechancal advance set for 16 degrees for a total mechanical of 33 (magnum heads like less total than open chamber heads). The vacuum advance is adjusted so its all in at 14"Hg of vacuum.
You have to get the timing right before you can even think about messing with the carb.
FWIW, I am running a Holley 670 Street Avenger on my engine and it was just about perfect out of the box. I tried larger carbs and the low rpm throttle response was not what i wanted for a car that is driven approx 7500 miles a year on the street. The 670 gives up nothing to the 750 I had on it on the top end either.
Posted By: JimG
Re: Holley question - Idle - 10/24/08 12:55 PM
Bullit;
It might seem like a pain, but doing things out of order, or taking something for granted can send you down the wrong path and waste lots of time and money. Please resist the urge to assume anything! Almost everyone on this board who has EVER had their hands dirty working on a car can tell you their tale of woe that resulted from taking a shortcut. Heck, I've got plenty of those stories myself!
Just remember that sometimes, the cure to the problem you're describing is drilling holes in the throttle plates of your carb. Drilling holes that you cannot easily undrill is the very last resort - we need to be sure the basics are coverd first. Hence checking the timing and knowing what you've got.
Do you have any "car buddies" from whom you can borrow a timing light? If not, look on eBay. You don't need anything fancy due to the fact that you have a timing tape installed. A used timing light will be more than sufficient.
Did you ever try screwing the idle mixture screws in to see if the engine would stumble or stall from a lean misfire? If it will, that's a good indication that you can get rid of some of the excessive rich condition with idle mixture adjustment. If not, it's yet another indication that the throttle plates are too far open at idle.
The previous poster gave you some good info for timing setup.
Does that AED carb have 4 idle misture screws or 2?
Jim
Posted By: 68Bullit
Re: Holley question - Idle - 10/28/08 05:18 PM
4 Idle mixture screws
Posted By: Anonymous
Re: Holley question - Idle - 10/28/08 05:28 PM
Quote:
Bullit;
It might seem like a pain, but doing things out of order, or taking something for granted can send you down the wrong path and waste lots of time and money. Please resist the urge to assume anything! Almost everyone on this board who has EVER had their hands dirty working on a car can tell you their tale of woe that resulted from taking a shortcut. Heck, I've got plenty of those stories myself!
Just remember that sometimes, the cure to the problem you're describing is drilling holes in the throttle plates of your carb. Drilling holes that you cannot easily undrill is the very last resort - we need to be sure the basics are coverd first. Hence checking the timing and knowing what you've got.
Do you have any "car buddies" from whom you can borrow a timing light? If not, look on eBay. You don't need anything fancy due to the fact that you have a timing tape installed. A used timing light will be more than sufficient.
Did you ever try screwing the idle mixture screws in to see if the engine would stumble or stall from a lean misfire? If it will, that's a good indication that you can get rid of some of the excessive rich condition with idle mixture adjustment. If not, it's yet another indication that the throttle plates are too far open at idle.
The previous poster gave you some good info for timing setup.
Does that AED carb have 4 idle misture screws or 2?
Jim
CHECK YOUR TIMING. You probably dont have what you think you have OR what you need- ESPECIALLY IF ITS A STOCK DISTRIBUTOR
With the timing advancedto 17 degrees at idle wit hte total at 34 or so, you'll have better idle quality cause your odle speed would have picked up- allowing you to close down the idle screw and throttle plates a bit. that gives you better control over the mixture.
Trust me, Im going through the same thing right now (see my post about epoxying mechical advance slots). I had a rich idle too. timing was SUPER LOW. I adjust it higher, idle speed picked up allowing me to slow it down by closing the throttle a bit. now the mixture screws work and idle is better.
The slot adjustment I just did on the advance plate will allow me to set the initial where I need it and still have the total advance I want (without going TOO HIGH).
my distributor fooled me. it fooled me for about a month or so as I was getting this motor togehter..... CHECK IT
Posted By: 68Bullit
Re: Holley question - Idle - 10/28/08 06:10 PM
Thanks Guys. Looking at a couple of timing lights now. I know for sure the timing has been advanced but I still need to know the numbers anyway, and for future use, etc. BTW, currently using an MSD distributor with 8mm plug wires, and a MP electronic box. Should have a light shipped to me within a couple of days.
Posted By: 71383beep
Re: Holley question - Idle - 10/28/08 10:24 PM
Posted By: 68Bullit
Re: Holley question - Idle - 10/29/08 10:43 PM
Quote:
Like said above, get the time set first. Timing is set at 800rpm.
Is the carb new? Rebuilt? Used? Is an older style or newer?
Does the A/F screws make a difference when turned in?
Update.
Okay. Still waiting on the timing light. Just recently started the car and tried turning the A/F screws and it DID affect the idle of the car. After turning in the screws just 1/4 turn each (all 4 of them), the rpms went waaay down and the engine would stall.
Posted By: JimG
Re: Holley question - Idle - 10/30/08 12:15 AM
Quote:
Just recently started the car and tried turning the A/F screws and it DID affect the idle of the car. After turning in the screws just 1/4 turn each (all 4 of them), the rpms went waaay down and the engine would stall.
OK, that's good.
Your entire problem might just be the idle mixture set up too rich. If you can turn any of those 4 screws in (clockwise) and not negatively affect the idle quality of your engine, you've probably helped the situation.
Go around to all 4 screws (after the engine is fully warmed up, and if you don't have intake manifold heat we could be talking 20-30 minutes) and try turning each idle mixture screw in, maybe 1/8 revolution or less at a time, then stop and give the engine time to respond. Blip the throttle now and then. As soon as the engine begins to stumble, you went a little too far with that particular screw. Back it out to the last spot where the engine idled OK, then move on to the next screw.
What I'm trying to get you to do is set the idle mixture at the leanest possible setting where you still have acceptable idle. If you do the above and still have that rich carb stench, it's a sign we need to look elsewhere for the problem.
Still check the timing when the light comes in and let us know what's going on. In the meantime, doing the above won't hurt a thing.
Jim
ETA: You know, no one has mentioned the float levels. Duh! Have you checked them?
Posted By: 68Bullit
Re: Holley question - Idle - 10/30/08 01:53 AM
Quote:
ETA: You know, no one has mentioned the float levels. Duh! Have you checked them?
Yeah, both levels appeared okay as far as I know. I checked them on level ground and fuel appeared to be level with the bottom of the sight opening for the FRONT, and then SOME (very little oozing) from the REAR float bowl sight opening once the screw was removed. Sound good?
Posted By: JimG
Re: Holley question - Idle - 10/30/08 11:56 AM
Quote:
I checked them on level ground and fuel appeared to be level with the bottom of the sight opening for the FRONT, and then SOME (very little oozing) from the REAR float bowl sight opening once the screw was removed. Sound good?
Yeah, sounds good! I was worried that the levels were way high, but you're OK.
OK, back to the idle mixture screws.
Jim
Posted By: 68Bullit
Re: Holley question - Idle - 10/31/08 08:17 PM
Quote:
Hello Bullit.
Yes, just check it in park. Be sure to disconnect the vacuum advance, if it's connected.
If you reconnect the vacuum advance and the timing advances at idle (assuming it's plugged into ported vacuum, on the passenger side of the primary metering block), that's another clue that the throttle plates are too far open at idle.
Nothing is hooked into my carb except a PCV from both valve covers. I have a T-fitting to accept both hoses from the valve covers and it is routed into the single fitting at the back of the carb. The carb is a mechanical secondary. When I check the timing, Do I just unhook the hose at the back (where both valves run into the carb)? Still waiting on the light but thought to ask about this anyway. Getting ready to go outside and check the A/F screws........
Posted By: Anonymous
Re: Holley question - Idle - 10/31/08 08:20 PM
well thats a problem. you are sucking from BOTH valve covers.... where is the inlet to the crankcase.
you want 1 PCV valve on one side valve cover and a breather on the other....
Posted By: 68Bullit
Re: Holley question - Idle - 10/31/08 08:27 PM
Quote:
well thats a problem. you are sucking from BOTH valve covers.... where is the inlet to the crankcase.
you want 1 PCV valve on one side valve cover and a breather on the other....
I've done both. Had the PCV on the passenger side with a breather on the driver's side, then just recently hooked up both PCV's. I can set it back to the PCV/breather setup, but it's really rich either way. BTW, the only reason I did both PCV's was because the breather was putting out a little bit of smoke.
Posted By: Anonymous
Re: Holley question - Idle - 10/31/08 08:54 PM
put the pcv on the side opposite the fill cap.make sure there is suction at the pcv, else find out why. make sure the vlave cover is tight.
to check the pcv system, let the car idle with pcv in VC. remove breather and hold a stiff piece of paper up against the grommet. it should be sucked up against it (albeit lightly). if it doesnt, you dont have enough vacuum or too much blowby or the oil fil or VC is leaky
Posted By: Mark340A66
Re: Holley question - Idle - 10/31/08 09:00 PM
Quote:
Quote:
well thats a problem. you are sucking from BOTH valve covers.... where is the inlet to the crankcase.
you want 1 PCV valve on one side valve cover and a breather on the other....
I've done both. Had the PCV on the passenger side with a breather on the driver's side, then just recently hooked up both PCV's. I can set it back to the PCV/breather setup, but it's really rich either way. BTW, the only reason I did both PCV's was because the breather was putting out a little bit of smoke.
The breather hose should be connected to your air cleaner which would stop the smoke. What kind of air cleaner do you have? It should hvae al least one fitting that mates to the breater hose.
Posted By: 68Bullit
Re: Holley question - Idle - 11/01/08 01:26 AM
I've got an aftermarket cleaner and there doesn't appear to be a place for the breather hose to fit into.
Posted By: 68Bullit
Re: Holley question - Idle - 11/19/08 10:17 PM
Okay, best I can tell, I've got 18 initial, and 33 total. I went as far as I could go on the rpm tgo make sure the 33 didn't continue to climb higher and it stopped at 33.
Posted By: CokeBottleKid
Re: Holley question - Idle - 11/20/08 12:08 AM
Sounds alright, did you get a dial-back light? Sometimes it's hard to read those timing tapes...
You checked with the vacuum advance disconnected yes?
Posted By: 68Bullit
Re: Holley question - Idle - 11/20/08 01:06 AM
Yeah I got a dialback light but I didn't use that feature, I just read the tape. My engine builder also marked the timing at 33 so I know for sure that the full advanced timing is 33. I'm interested in learning though, so how would I use the dialback feature?
Posted By: Anonymous
Re: Holley question - Idle - 11/20/08 01:23 AM
whatever you dial back the light to, thats what the zero mark on the balancer is.
Posted By: 68Bullit
Re: Holley question - Idle - 11/20/08 01:34 AM
Quote:
whatever you dial back the light to, thats what the zero mark on the balancer is
Correct. But how much do you dial the light back? What are the actual steps to take when doing it this way? And what do you read if there is no tape there? Sorry that I'm so literal just not sure how 
Also thre is no vacuum advance on the distributor. It's an MSD dist.
Posted By: Anonymous
Re: Holley question - Idle - 11/20/08 01:46 AM
say yo want to check or set for 33 degrees advance. dial the light until it reads 33 btdc. look at the balancer and when the 0 line on the balncer lines up with the 0 mark on the timing chain cover, you are at 33 degrees advance.
if the 10 btdc mark on the balancer lines up with the 0 mark on the cover, youre at 43 degrees advance
Posted By: JimG
Re: Holley question - Idle - 11/20/08 02:04 AM
Bullit:
The timing seems about right. Sorry you had to go through all that to find out, but it had to be done.
You're sure you can't lean the idle out with the mixture screws, right? First, check that again. Just as a test, screw them in until the engine starts to stumble, then back them out ONLY until it smooths out, and no more. This isn't the preferred way to set the idle mixture, but it will determine if perhaps the idle mixture screws can fix the problem. If it can, we can work on that. If not, we know to look elsewhere.
Next, go back to post 8 or 9. CKJ440 posted a good picture of where the throttle plates are supposed to be in relation to the transfer slots at idle. Pull the carb, be sure the choke is all the way off (so the fast idle is not set) and be sure the throttle plates only leave enough of the transfer slots exposed so that what you see looks like a square. If it looks like a rectangle, that could be part of the problem. Check the secondaries for the same problem. This is usually a problem on larger/more radically cammed engines, but like the timing, the basics must be covered first.
How old is this carb? Is it fairly new, or has it been sitting around for a long time? Is it time for a rebuild?
Is the carb clean? Spray some carb cleaner down all 4 idle air bleeds. If they're blocked it can cause a rich idle. If you don't know where they are, and if no one else comes to the rescue with a good picture (hint hint), I'll find one and post it tomorrow.
Jim
Posted By: CokeBottleKid
Re: Holley question - Idle - 11/20/08 03:18 AM
I'd like to know what an AED carb is and what they've done to it.
Second can you get us some general info?
Could you go around to each idle screw and turn them all the way in lightly and count the turns? Bring them back to where they were after...
Could you do the same for the curb idle screw (the front blade stop screw on the drivers side)? Back the screw off until the throttle blade stops moving and count the turns while doing so. Make sure the choke isn't connected in any way shape or form...
Posted By: 68Bullit
Re: Holley question - Idle - 11/20/08 04:37 AM
AED does performance fuel systems of various kinds and also custom built carbs like mine. I think they are out of Virginia.
http://www.aedperformance.comHere are some pictures of the carb. It might be 2 years old now. There is no choke. This carb is a 750 dp with 71 fronts and 82 rear. Engine is mild 360 with CompCam's
224@.050, box stock eddy heads, headers, 4.30 gears behind a FMVB 904 and 2500 stall. Could this be too much carb for my application???
Posted By: JimG
Re: Holley question - Idle - 11/20/08 12:36 PM
Coke Bottle Kid:
After I had him check a couple more basics, I was going to have him pull the metering blocks off and measure the idle feed restrictions, if he's comfortable doing that and if he has/can borrow some gauge pins or a set of numbered drill bits. Like you, I had wondered what AED did to modify that Holley carb, specifically the idle circuit.
Bullit:
In your first picture, as you're looking down into the top of the carb, the idle air bleeds are the things that look like miniature jets, and the ones for idle are the 4 outboard bleeds with larger orfices. I'm pleasantly surprised that your carb has screw in air bleeds. Can you read the numbers on them? If not pull one from the front and one from the back and tell me the number on it.
Jim
Posted By: 68Bullit
Re: Holley question - Idle - 11/20/08 05:23 PM
The outer bleeds are 75 and the openings appear to be way larger than the inner ones. Couldn't see the reading on the inner bleeds but if I need to pull them to get a better look just let me know.. BTW, I've got more jets from where I've done some rejetting on this carb. Will these jets interchange with these bleeds? I've got 70's, 72's, and 73's I believe.
Posted By: JimG
Re: Holley question - Idle - 11/20/08 06:15 PM
Quote:
The outer bleeds are 75 and the openings appear to be way larger than the inner ones. Couldn't see the reading on the inner bleeds but if I need to pull them to get a better look just let me know.. BTW, I've got more jets from where I've done some rejetting on this carb. Will these jets interchange with these bleeds? I've got 70's, 72's, and 73's I believe.
Wow! Your idle air bleeds are already large at .075". I was hoping they were around .060" so an increase to .070" or .075" would lean things out. Usually, if you're running an IAB larger than you've got, there's something else going on. You MIGHT lean it it out with an even larger air bleed, but again you might run up against a wall where increased bleed size won't help.
No, main jets do not interchange with air bleeds.
You still need to look at the throttle plates vs. the transition slot and make sure that's OK. In fact, I looked at the link you posted to the AED site, and it was near the top of the "troubleshooting"(?) page.
You said the float level wasn't too high, but triple check it - primary and secondary.
Assuming the carb has a defective component (as opposed to just needing tuning) it's possible that the power valve has a tiny rupture in the diaphragm, and it's possible the gasket between the main body and the metering block is leaking and engine vacuum is sucking fuel from the accelerator pump passage. There are probably other possibilities that I'm not thinking of.
Why don't you call AED and see what they have to say. They have a nice looking website - perhaps they have nice customer service to match. Also, ask them if they think your idle feed restrictions are too large for an engine as mild as yours. See if they'll tell you what size the idle feed restrictions are, and if they increase them over the standard Holley size, which will probably be somewhere between .032" and .036". See if they'll log onto this site and read this discussion.
Jim
Posted By: 68Bullit
Re: Holley question - Idle - 11/20/08 07:35 PM
Okay, I read the tuning page there again and if I'm reading it correctly, it states to check the throttle plate relationship if you have a lean condition causing a stumble and off-idle hesitation. Then it recommends checking the float levels and then the power valve for an excessive rich idle situation. I've been wondering if that could have anything to do with my power brakes not feeling exactly right??? How do I vacuum check the power valve?.....Thanks
Posted By: JimG
Re: Holley question - Idle - 11/20/08 07:48 PM
Quote:
Okay, I read the tuning page there again and if I'm reading it correctly, it states to check the throttle plate relationship if you have a lean condition causing a stumble and off-idle hesitation. Then it recommends checking the float levels and then the power valve for an excessive rich idle situation. I've been wondering if that could have anything to do with my power brakes not feeling exactly right??? How do I vacuum check the power valve?.....Thanks
Bullit:
While the throttle plate/T-slot thing will certainly cause an off-idle stumble, it can also cause pig-rich idle because the the mains start flowing at idle. Most people won't complain as long as the car seems to run right, no matter how bad the exhaust stinks (and they have to clean their back bumper every time they drive, and replace the plugs...) Kudos to you for being willing to go the extra mile.
As far as checking the power valve...if you have (or know anyone who has) a Mityvac vacuum pump, you can check the power valve with a suction cup that comes with the kit, and although it's a hit-and-miss proposition, it can be done. I have a power valve tester from Moroso that is used with the Mityvac that works much better.
Just what you wanted to hear...after buying a timing light only to find out that your timing was fine, now there's something else to buy. Do you have any car buddies who might at least have a Mityvac kit you could borrow?
Jim
Posted By: Anonymous
Re: Holley question - Idle - 11/20/08 08:36 PM
ive used the mityvac aspter to test PVs before. it can be tricky. make sure you have a good seal to the cup or it will look like you have a leaker. maybe use a little grease around the rim to seal it better when testing
Posted By: BSB67
Re: Holley question - Idle - 11/20/08 11:44 PM
Bullit - Based on the info that you have shared so far, I cannot help but to think we're missing something. Someplace in this thread you may have already answered these questions and I just missed them.
1. When was the engine built.
2. Was it run on a dyno?
3. When was the engine first run in the car?
4. What carb was on it then?, and how did it run?
5. Has it ever run correct with this carb?
6. Did you buy the carb new from AED?
7. Why do you believe that the smell is from being rich?
8. Does it smell idling in neutral as well as when its in gear?
9. What is the neutral idle rpm?
10. What is the idle rpm in gear?
11. 1/4 turn in and the idle deteriorates, but how many turns out (from being seated) are each of the mixture screws (I think someone asked this)?
Also, check the ignition timing while the car is idling in gear (obviously you'll need someone to help.) and report that back to us.
Finally, your throttle cable should be hooked up on the carburetor side of the carb throttle extension bracket.
Posted By: CokeBottleKid
Re: Holley question - Idle - 11/21/08 02:23 AM
Ya just like Jim says I was going to suggest going right to the IFRs (idle feed restrictors) in the metering blocks. Obviously that carbs been played with a bit, good chance the IFRs are too big. Do be sure your throttle plates are right tho, please do as I described earlier and give us a count on all the idle screws and the throttle stop...
Posted By: 68Bullit
Re: Holley question - Idle - 11/21/08 03:37 AM
Not sure about the throttle stop but all four corners are exactly 4 turns out each
Posted By: CokeBottleKid
Re: Holley question - Idle - 11/21/08 09:36 AM
You sure you weren't counting half turns? 4 is extreme....
Posted By: Anonymous
Re: Holley question - Idle - 11/21/08 12:16 PM
set the mixture screws to get the best vacuum at idle. 4 does seem like a lot
Posted By: 68Bullit
Re: Holley question - Idle - 11/24/08 02:52 AM
Four quarter turns out = one complete turn out on each idle mixture screw. Is the throttle stop the same as the idle adjustor?
Posted By: JimG
Re: Holley question - Idle - 11/25/08 12:58 PM
Quote:
Four quarter turns out = one complete turn out on each idle mixture screw.
Bullit:
If I understand correctly each of the four idle mixture screws is one complete turn (360 degrees of rotation) counter-clockwise from being lightly seated, correct?
Quote:
Is the throttle stop the same as the idle adjustor?
If I understand your question correctly, the curb idle screw (also might be called the idle speed screw) is on the drivers side, and points up at a about a 45 degree angle.
The term "throttle stop" more commonly is used to describe a similar screw on the secondary (rear) of the carb. Most point straight up, requiring you to remove the carb to access it.
BSB67 asks some valid questions, including "how do you know it's rich?". Since most Holleys are too rich, especially at lower loads/RPM, when you asked about "rich", I began answering about "rich". Seemed reasonable to me. An engine that is idling lean also makes a smell, but it's entirely different. Are you familiar with the difference? If I was a betting man, I'd still have money on "rich", but since none of us are there to take in the sights, sounds, and smells as you try to tune this carb, we have to ask questions that may seem over the top to you.
It would be easy to verify whether it's too lean. Just get some 60 or 65 air bleeds and swap 'em for those 75's in the carb now. If the problem gets worse...it was rich to begin with.
I'd really like you to pull the metering blocks and measure some holes. To measure them, you'd need a set of numbered drill bits. You use the shank end of the bit (the end that normally would insert into the drill) and find out which bit fits the hole the best. I can post pics of the holes you'd need to measure. How comfortable would you be doing that? Do you know anyone from whom you can borrow a set of numbered drills?
Jim
Posted By: tampacuda69
Re: Holley question - Idle - 11/25/08 09:33 PM
Regarding the air bleeds:
I have a similar setup as Bullit on my 340.
When I was using a 750cfm Proform main body on my double pumper It ran rich and throtle response was not as sharp as my 650dp. I called Quick Fuel Technologies and they suggested I change my Primary screw in air bleeds. Original bleeds were #75 outboard and #36 inboard, Sugested change is
#70 outboard and #30 inboard.
All secondary air bleeds are #36 (no sec. mixture screws.)no changes being made.
Coast is $4.00 per set. I am waiting for delivery.
Posted By: BSB67
Re: Holley question - Idle - 11/25/08 10:06 PM
Quote:
Regarding the air bleeds:
I have a similar setup as Bullit on my 340.
When I was using a 750cfm Proform main body on my double pumper It ran rich and throtle response was not as sharp as my 650dp. I called Quick Fuel Technologies and they suggested I change my Primary screw in air bleeds. Original bleeds were #75 outboard and #36 inboard, Sugested change is
#70 outboard and #30 inboard.
All secondary air bleeds are #36 (no sec. mixture screws.)no changes being made.
Coast is $4.00 per set. I am waiting for delivery.
Smaller air bleeds will make it richer.
Posted By: JimG
Re: Holley question - Idle - 11/25/08 10:15 PM
Quote:
Regarding the air bleeds:
I have a similar setup as Bullit on my 340.
When I was using a 750cfm Proform main body on my double pumper It ran rich and throtle response was not as sharp as my 650dp. I called Quick Fuel Technologies and they suggested I change my Primary screw in air bleeds. Original bleeds were #75 outboard and #36 inboard, Sugested change is
#70 outboard and #30 inboard.
All secondary air bleeds are #36 (no sec. mixture screws.)no changes being made.
Coast is $4.00 per set. I am waiting for delivery.
Hi Tampacuda:
That would make perfect sense. Changing your main air bleeds from 36 to 30 will delay the start of the mains, essentially leaning out the bottom end. 30 is more in the neighborhood of what you'd expect to see after a Holley has been tuned on a mild street engine. 36 is rather largish.
Perhaps the Quickfuel folks thought that after you'd delayed the start of the mains, you'd need a richer idle to compensate, and hence the change of the idle bleeds from 75 to 70. If it was me, I'd swap the main air bleeds first and leave the 75's in the idle. If it doesn't exhibit lean symptoms, I'd stop there. If it does, you can always change the idle bleeds next.
It is generally agreed that the idle air bleeds should come in between 50 and 75, and if you need to go outside that range you probably need to look at something else. Bullit's problem is that he's already maxed out as far as idle air bleeds are concerned. He could possibly go larger but eventually he'll reach the point where additional air bleed size won't make any diference.
Bullit possibly has the same problem as you're working on - rich low end (including idle). Problem is, once the car is moving, you no longer smell the foul stench and assume everything is OK. Ignorance is bliss, eh?
Jim
Posted By: 68Bullit
Re: Holley question - Idle - 11/25/08 11:44 PM
Jim,
I can pull the metering blocks and get a measure for you. Can you diagram which holes you're referring to?
Also, would it be a good idea for me to try the #70 and #30 first and see how that works?
Posted By: Cudahlr
Re: Holley question - Idle - 11/26/08 12:51 AM
Im going to go out on a limb.... but try adjusting the secondary blade angle, it should be open just a very small amount, if its not the front blades will open the transfer slot too much, causing a very rich condition.
Turn the secondary idle screw till it just opens the blades, which in turn will raise the idle speed, allowing you to back off the front idle screw, decreasing the transfer slot opening.
Posted By: 68Bullit
Re: Holley question - Idle - 11/26/08 01:04 AM
Cuda, Can you help me locate the secondary idle screw?.....Thanks
Posted By: Cudahlr
Re: Holley question - Idle - 11/26/08 01:21 AM
Quote:
Cuda, Can you help me locate the secondary idle screw?.....Thanks
You will have to take the carb off to find this, it is a small screw accessible only from the bottom, directly behind the throttle shaft on the passenger side of the carb, you will need a small flat blade screwdriver to turn it. Remember where you started to return back to the same position if needed.
Look at figure 5 in this link.
http://www.holley.com/data/Products/Technical/199R10016-2.pdf
Posted By: 68Bullit
Re: Holley question - Idle - 11/26/08 01:35 AM
Excellent. Thanks for the link. One last question before I try this. If the engine is running and up to temp, would I be able to look straight down on the top of the carb and see if the secondary plates are open the same amount as the front, or be able to see if they're open at all????
Posted By: Cudahlr
Re: Holley question - Idle - 11/26/08 01:53 AM
The engine does not have to be running, you can look down but it is kinda hard to see how much they are open in relation to the transfer slots which are easily more visible from the bottom.
Quick fuel makes this nice bracket so you dont have to take the carb off every time to make a small adjustment.
http://www.jegs.com/p/Quick+Fuel/743841/10002/-1
Posted By: JimG
Re: Holley question - Idle - 11/26/08 01:04 PM
Quote:
I can pull the metering blocks and get a measure for you. Can you diagram which holes you're referring to?
Yes, later today, if necessary. See below.
Quote:
Also, would it be a good idea for me to try the #70 and #30 first and see how that works?
Probably not. If indeed your idle is rich, dropping your IABs to 70 from 75 would make it richer. The only reason you'd want to do that would be if you weren't sure it was lean. See BSB67's previous question.
Changing the MABs (Main Air Bleeds) will have no effect at idle because you've already checked and your throttle plate/transfer slot relationship is correct, and viewing the T-slot with the carb at idle (with carb upside down, off the car) the only exposed T-slot looks like a square. The mains (and hence the Main Air Bleed) would not be working with the throttles closed to this point, which is how the carb is supposed to work. We KNOW this is the case, because you checked, right? If not, disregard everything else that's been said until the throttle plate/T-slot thing is checked and corrected.
CUDAHLR describes one of the methods for correcting the throttle plate/T-slot relationship. Don't touch that screw unless you've got more than a square of T-slot exposed at idle - it will accomplish nothing under these conditions. I was under the impression that we put that issue to bed a few weeks ago, so either confirm that the throttle plates have been checked against the T-slot at idle, or let's fix it and move on.
I'll wait to post the metering block pics until you get back us that the throttle plates are correct at idle.
Tell you what - I'll post some pictures of correct and incorrect throttle plate postions at idle and you can confirm yours is correct. All this renewed discussion of transfer slots make me nervous.
Check back for photos later today.
Jim
Posted By: JimG
Re: Holley question - Idle - 11/26/08 01:27 PM
Quote:
...would I be able to look straight down on the top of the carb and see if the secondary plates are open the same amount as the front, or be able to see if they're open at all????
Yes, but that's not what's important.
This is a picture of a baseplate that's taken off a carb, and I'm holding open the primary throttle plates. You can clearly see the transfer slots.
Posted By: JimG
Re: Holley question - Idle - 11/26/08 01:42 PM
Here's a photo showing correct relationship between the T-slots and the plates at idle. The exposed T-slot looks like a square.
Posted By: JimG
Re: Holley question - Idle - 11/26/08 01:49 PM
Here's a photo showing too much T-slot exposed at idle.
Bullit, either check this or confirm that it's A-OK before we do anything else. You've checked your timing and it's where it'll stay, so this is the next thing to do before changing anything else.
Your engine is small enough and mild enough that I don't expect this to be a problem in your case, but we can't assume it's correct. There's an old saying about what happens when wee assume...let's see, how does it go...hmmmm?
Posted By: 68Bullit
Re: Holley question - Idle - 11/28/08 05:41 PM
Okay. I've checked the underside of the Carburetor and here's what I found. The fronts look okay, in fact, they almost appear to have the majority of the slot that is covered by the throttle plates, in other words, there appears to be less that is open, than there is covered. Not much at all, but maybe a small amount. This means there isn't too much exposed anyway (Looks like a good square and definitely not rectangular). The secondaries have none, absolutely none of the transfer slots exposed. Is this the problem? Do I open them up to have the square exposed, then make an idle adjustment when I get the carb back on the car????
Posted By: 68Bullit
Re: Holley question - Idle - 11/28/08 09:17 PM
I'm starting to think that the primaries are the only throttle plates to check for throttle plate/slot relationship correct? Here are some pictures of the throttle plates. I could be wrong, but it appears this carb MAY NOT need to be adjusted. I was told that AED custom builds their carbs to match each customer's application. It smells rich to me, but maybe that's the way it's supposed to be (like other rich Holleys). Look closely and you will see where the main plates have been drilled. Other thing that I wanted to point out is the burnt look coming from the transfer slots, and the eyelets near the transfer slots???? Looks even more burnt up close and in person. Is this normal????
While I'm here, I wanted to see if this is the correct setup for the birchwood spacer and gaskets (base gasket, spacer, and another gasket between the spacer and carb????)
Posted By: JimG
Re: Holley question - Idle - 11/28/08 09:59 PM
Eric:
That looks perfect - don't mess with it. Yes, I see they already drilled holes in the primary throttle plates for you.
The pics look good - what kind of camera are you using?
And yes, the black is normal at the T-slot discharge. You can see a little of it on the baseplate I took pictures of a few days ago, and I even wiped it down with a paper towel sprayed with carb cleaner before I took the picture.
It's just fine that there's little to no T-slot showing on the secondary.
You said it smells rich to you, but you don't seem 100% sure. Is there anyone from whom you can get a second opinion?
Here's the next thing to do if indeed it is rich. I'll give you a brief synopsis and you can tell me if it's something you wish to pursue. If you do, I can go into more detail and walk you through it.
What I'd want you to do is pull off the metering blocks and take some pictures of them. I'd identify the Idle Feed Restrictors for you. They're tiny holes, and they are the "jets" for the idle circuit (and the transfer slots) but unlike your main jets, you can't just screw in new ones. I'd get you to measure them using the shank end of numbered drill bits. Then you'd find some wire with a diameter that would make the hole about 25% smaller (remember Pi R squared) depending on how big the hole is, and use the wire to restrict the hole, then put the carb back together and try it. That will lean out your idle circuit - possibly not enough, possibly too much. After you find out, you'd juggle the wire size to get it right.
The good news is, there's no drilling involved to find out if this is the problem. If the wire doesn't fix it, you yank it back out and go on about your business.
If you want to try it, I'll help you. And there are other people here who have done this as well, and I'm sure they'll help too.
Jim
Posted By: 68Bullit
Re: Holley question - Idle - 11/28/08 10:39 PM
Jim:
Yes, I'll venture into the metering blocks and give this a shot.
Let me go back briefly to your questions.
- Camera is a Canon SD850 IS. It's a good camera for the money, and Thanks for the complements.
- My wife is the only other witness, and she tells me the same thing, that it smells bad. I asked her if she thought it smelled rich and she said yes. We both agree that my clothes smell everytime I get out of the car. If she was the only one complaining then it would be different, but I notice the odor also. There is no odor making it's way into the car unless I am stationary and idling with the driver/passenger windows down. Literally though, as soon as I pull into the garage, and then get out of the car, even after shutting the engine down immediately, the smell has made it's way into my clothes, and into the garage area.
I'm beginning to think that because I have a Holley, that this is normal? This car runs exceptionally well, and is broad throughout the rpms. It's no power house of course, but it runs really smooth, and well!
- You say the black is normal at the T-slot area, but again, mine looks a little white-ish, as if it's burnt some. That's not camera glare either, it looks burnt, and also burnt around the eyelet area just up and to the right from the T-slot. If you say it's okay, then it's okay.
Thanks again for all your help thus far, and to everyone else who has replied
Posted By: JimG
Re: Holley question - Idle - 11/28/08 10:59 PM
Hi Eric:
I'm still betting it's rich. When performance carbs such as Holleys are made, they must run on a variety of engines with varying specifications. If there is a lean spot, it will manifest itself as a stumble and make the telephone ring at the tech support center for the carb manufacturer. If it's a little too rich across the board, spark plugs don't last as long, you need to continually clean the rear of the car and your clothes stink, as you observed - but the engine still runs OK. No time wasted at the tech support center talking to some p!$$ed off guy who thinks he just paid good money for a junk carb
Despite the fact that I'm betting rich, it's still not a 100% certain thing.
But the wire thing will confirm or refute that fact really fast.
Do you have a set of numbered drills? If not, do you know anyone you could borrow them from? If not, do you have a Harbor Freight store near you? They sell a decent set. I bought a set at Big Lots recently too. They were junk as far as drill bits are concerned, but you could still use them to measure orfices and such.
Whenever you're ready, pull the metering blocks and post some pics and we'll get started.
I'm off to work.
Jim
