Holley question - Idle - Moparts Forums

Register Log In Moparts Forums Moparts Question and Answer Holley question - Idle

Print Thread

Page 1 of 4

1

2

3

4

Holley question - Idle #138158 10/17/08 10:27 PM 10/17/08 10:27 PM
Joined: Mar 2008 Posts: 571 Western NC 68Bullit OP mopar
68Bullit OP mopar Joined: Mar 2008 Posts: 571 Western NC	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 Last edited by 68Bullit; 10/17/08 10:41 PM.

Re: Holley question - Idle [Re: 68Bullit] #138159 10/17/08 10:47 PM 10/17/08 10:47 PM
Joined: Mar 2005 Posts: 553 Stuart FL M mercman1 mopar
mercman1 mopar M Joined: Mar 2005 Posts: 553 Stuart FL	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.

Re: Holley question - Idle [Re: 68Bullit] #138160 10/17/08 10:53 PM 10/17/08 10:53 PM
Joined: Sep 2005 Posts: 6,516 Santa Cruz, California L Lefty master
Lefty master L Joined: Sep 2005 Posts: 6,516 Santa Cruz, California	It's my understanding that under light throttle cruise you are using the idle circuit.

Re: Holley question - Idle [Re: mercman1] #138161 10/17/08 11:01 PM 10/17/08 11:01 PM
Joined: Mar 2008 Posts: 571 Western NC 68Bullit OP mopar
68Bullit OP mopar Joined: Mar 2008 Posts: 571 Western NC	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

Re: Holley question - Idle [Re: 68Bullit] #138162 10/17/08 11:39 PM 10/17/08 11:39 PM
Joined: Mar 2005 Posts: 553 Stuart FL M mercman1 mopar
mercman1 mopar M Joined: Mar 2005 Posts: 553 Stuart FL	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.

Re: Holley question - Idle [Re: mercman1] #138163 10/18/08 12:04 AM 10/18/08 12:04 AM
Joined: Mar 2008 Posts: 571 Western NC 68Bullit OP mopar
68Bullit OP mopar Joined: Mar 2008 Posts: 571 Western NC	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

Re: Holley question - Idle [Re: 68Bullit] #138164 10/18/08 12:20 AM 10/18/08 12:20 AM
Joined: Jan 2003 Posts: 9,826 las vegas 70AARcuda master
70AARcuda master Joined: Jan 2003 Posts: 9,826 las vegas	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.. Tony 70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)

Re: Holley question - Idle [Re: 70AARcuda] #138165 10/18/08 08:02 AM 10/18/08 08:02 AM
Joined: Oct 2004 Posts: 2,843 Connecticut FurryStump master
FurryStump master Joined: Oct 2004 Posts: 2,843 Connecticut	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. best of 11.24 at 119 mph 1.60 60’. 68 340 S Barracuda Fastback F.A.S.T [IMG]http://i67.tinypic.com/2mnnnnt.jpg[/IMG]

Re: Holley question - Idle [Re: FurryStump] #138166 10/18/08 09:00 AM 10/18/08 09:00 AM
Joined: Jan 2003 Posts: 9,982 Ansonia, CT C CJK440 master
CJK440 master C Joined: Jan 2003 Posts: 9,982 Ansonia, CT	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 2017 Contusion Blue Challenger T/A 392 M6 "BLKNBLU"

Re: Holley question - Idle [Re: CJK440] #138167 10/18/08 09:22 AM 10/18/08 09:22 AM
Joined: Jul 2007 Posts: 531 Virginia J JimG mopar
JimG mopar J Joined: Jul 2007 Posts: 531 Virginia	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 Last edited by JimG; 10/18/08 10:03 AM.

Re: Holley question - Idle [Re: JimG] #138168 10/18/08 11:47 AM 10/18/08 11:47 AM
Joined: Jul 2007 Posts: 531 Virginia J JimG mopar
JimG mopar J Joined: Jul 2007 Posts: 531 Virginia	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

Re: Holley question - Idle [Re: JimG] #138169 10/18/08 12:29 PM 10/18/08 12:29 PM
Joined: Mar 2008 Posts: 571 Western NC 68Bullit OP mopar
68Bullit OP mopar Joined: Mar 2008 Posts: 571 Western NC	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.... Last edited by 68Bullit; 10/18/08 12:33 PM.

Re: Holley question - Idle [Re: 68Bullit] #138170 10/18/08 01:09 PM 10/18/08 01:09 PM
Joined: Jan 2003 Posts: 4,760 Moved to N.E. Tennessee GomangoCuda master
GomangoCuda master Joined: Jan 2003 Posts: 4,760 Moved to N.E. Tennessee	Don't "fix" anything until you know where the timing is. In theory, there is no difference between theory and practice. In practice, there is.

Re: Holley question - Idle [Re: 68Bullit] #138171 10/18/08 04:31 PM 10/18/08 04:31 PM
Joined: Jul 2007 Posts: 531 Virginia J JimG mopar
JimG mopar J Joined: Jul 2007 Posts: 531 Virginia	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 Last edited by JimG; 10/18/08 04:38 PM.

Re: Holley question - Idle [Re: JimG] #138172 10/18/08 06:29 PM 10/18/08 06:29 PM
Joined: Mar 2008 Posts: 571 Western NC 68Bullit OP mopar
68Bullit OP mopar Joined: Mar 2008 Posts: 571 Western NC	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

Re: Holley question - Idle [Re: 68Bullit] #138173 10/18/08 08:25 PM 10/18/08 08:25 PM
Joined: Jul 2007 Posts: 531 Virginia J JimG mopar
JimG mopar J Joined: Jul 2007 Posts: 531 Virginia	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

Re: Holley question - Idle [Re: JimG] #138174 10/19/08 12:15 PM 10/19/08 12:15 PM
Joined: Nov 2003 Posts: 12,494 Western Colorado High Desert moparmarks I Live Here
moparmarks I Live Here Joined: Nov 2003 Posts: 12,494 Western Colorado High Desert	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? 72 Satellite Sebring Plus 440, 72 Dart 5.9 4-spd, 68 Valiant, 73 W200, 78 D100 sb, 78 D200, 98 DAKOTA, . Moparmarks Parts & Restorations Desert Mopar Metal Grand Jct. CO 970-261-7039 http://moparmark.com/ motormangj@gmail.com

Re: Holley question - Idle [Re: moparmarks] #138175 10/19/08 12:34 PM 10/19/08 12:34 PM
Joined: Jan 2003 Posts: 541 chatham, Ilinois F fox super street
fox super street F Joined: Jan 2003 Posts: 541 chatham, Ilinois	Also, are the primary venturies dripping fuel at idle? You have been given good advice.

Re: Holley question - Idle [Re: 68Bullit] #138176 10/19/08 06:41 PM 10/19/08 06:41 PM
Joined: Mar 2008 Posts: 571 Western NC 68Bullit OP mopar
68Bullit OP mopar Joined: Mar 2008 Posts: 571 Western NC	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 Last edited by 68Bullit; 10/19/08 08:11 PM.

Re: Holley question - Idle [Re: 68Bullit] #138177 10/23/08 06:35 PM 10/23/08 06:35 PM
Joined: Mar 2008 Posts: 571 Western NC 68Bullit OP mopar
68Bullit OP mopar Joined: Mar 2008 Posts: 571 Western NC	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

Page 1 of 4

1

2

3

4

Moderated by Al_Alguire, Hotwheelsjr, moparts, not_a_charger, RangerDan440, tboomer

Hop To

Powered by UBB.threads™ PHP Forum Software 7.7.1