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Re: Continuing with the troubleshooting... distributor...
[Re: cal_gecko]
#1237665
05/24/12 01:58 AM
05/24/12 01:58 AM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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I'm wondering if you have something going on with the carb.
You're running an AFB style carb if I remember correctly. What kind of fuel pump do you have feeding it? I doubt that fuel pressure is the culprit here but those things want less than 6 psi. 5 psi of fuel pressure is usually the best place to be.
Did you have to turn the idle screw in very far to keep the car running? If so it will uncover too much of the transfer slot in the primaries.
Take a look in the front of the primary bores. With the throttle closed you should see a small vertical slot in each bore. They're way down at the bottom by the throttle plates. The boosters poking out into the bores will make it hard to look down that far.
The throttle blades should be completely below those slots. Some engine combinations want a little of the transfer slot open. Very little. Less than .060" of an inch.
I posted a pic of a carb upside down with the throttle open so you can see what I'm talking about.
The one round hole in each bore is where your idle mixture screw pokes through.
You can easily see the transfer slots running vertically in the bores.
There is a little horizontal slot in one bore but not the other. That's the full time vacuum port on the front of the carb.
The other bore has a horizontal slot even with the middle of the transfer slot. That's the "ported" vacuum slot on the front of the carb. If your throttle blades are open that far at idle you will definitely have a problem.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: Continuing with the troubleshooting... distributor...
[Re: feets]
#1237666
05/24/12 02:16 AM
05/24/12 02:16 AM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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In this pic you can see the throttle is closed. Quite a bit of the transfer slot is under the throttle blade (remember the carb is upside down here). I don't remember what I last had that carb on but that's a lot of throttle opening at idle.
Once you expose that much transfer slot to the intake vacuum you're going to have tuning difficulties.
Engine vacuum will pull lots of fuel through the slot and the adjustment screws on the front of the carb won't be able to control the idle.
Should you be right on the edge of too much slot exposed the idle can surge a bit. A good slug of vacuum will pull a bunch of fuel through the slot. If it gets too big of a gulp of fuel the engine rpm will drop. That means vacuum drops. It stops drawing that extra fuel. As the idle stabilizes the vacuum increases and starts the process over again.
It can yo-yo from there.
If you can't seen down the carb very well then fire the engine up and open the vacuum ports on the front of the carb.
The full time port will change your idle noticeably when opened.
The ported vacuum port should not impact idle much at all. If it does your throttle is open too far.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: Continuing with the troubleshooting... distributor...
[Re: feets]
#1237667
05/24/12 03:23 AM
05/24/12 03:23 AM
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Joined: Aug 2003
Posts: 12,589
Sacramento, CA
cal_gecko
OP
I Live Here
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OP
I Live Here
Joined: Aug 2003
Posts: 12,589
Sacramento, CA
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Feets- that's some great info, thanks. I'm using an Edelbrock Performer 1405 (600cfm) I feel like I may have made some progress tonight.. First off - I stopped by the auto parts store to picked up a new cap/rotor.. while I was there, ran into a nice guy with a sweet 440-powered Fury.. this thing was cool.  Anyways.... he and I chatted too long, and the parts store closed.. so I went across the street to Autozone and got my cap/rotor... Came home, swapped it out, no noticeable improvement. Next step: put markings on the harmonic balancer so I could avoid using the dial-back light .. I'm hearing that they don't always work well with MSD boxes. Adjusted idle timing to about 16 degrees advance, checking with both my dial-back light as well as a regular (non-dial) timing light to ensure they both read the same. I kept backing out the a/f screws until my vacuum started to increase, and it seemed to make an impact to how it ran. I had to back them out to about 2.5 turns out, but it seemed to start making a difference. I was able to get the idle speed screw backed off a bit. I am running a Holley blue fuel pump along with a Holley pressure regulator and a fuel pressure gauge .. no return line. At idle, the pressure does build up a bit .. it 'creeps'.. so I know I have to give it a few blasts of throttle to bring the pressure back down. Anyways, during the process tonight, I gave it some good blasts of throttle, and held it at a higher RPM range for a little bit... Next thing I know, it's holding an idle better than I've seen so far... Am I finally making progress? http://www.youtube.com/watch?v=UULdvZc8v...mp;feature=plcpKeep in mind - exhaust is total overkill - headers to 3" exhaust and turndowns.. .so exhaust is pretty loud.. I'll be getting a proper exhaust system installed when it's done.
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Re: Continuing with the troubleshooting... distributor...
[Re: cal_gecko]
#1237670
05/24/12 04:59 AM
05/24/12 04:59 AM
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Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
Striving for excellence
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Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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It looks like you are doing well. The engine has a decent lope and idles well. The exhaust tone from the rear sound like a cammy engine with mild compression. More squeeze would change the somewhat muted exhaust note to a crisper one. No offense meant on that though. I like it. Your idle vacuum numbers look better than I expected. I thought that I once saw 18" at one point? If so, thats great! I have between 7-9" in the Charger, and I have power brakes! I still need to add in that vacuum tank to supplement the booster. The color on that car is TANGY ! Wow... that car is going to be great! It reminds me of abodyjoe's car. Glad to see you're making progress, Greg 
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Re: Continuing with the troubleshooting... distributor...
[Re: Kern Dog]
#1237671
05/24/12 06:35 AM
05/24/12 06:35 AM
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Joined: Aug 2003
Posts: 12,291
Kent, Wa
340SHORTY
Truck Nut
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Truck Nut
Joined: Aug 2003
Posts: 12,291
Kent, Wa
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I have the MSD 6 on my 340 with a factory elec dist and I cannot check the timing with a dialback light. It has to be a regular light.
I still say you have a carb or vacumn problem.. Try another carb that is being offered. Anything for a test is basicly fine..
I am truckless..
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Re: Continuing with the troubleshooting... distributor...
[Re: Kern Dog]
#1237672
05/24/12 12:19 PM
05/24/12 12:19 PM
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Joined: Aug 2003
Posts: 12,589
Sacramento, CA
cal_gecko
OP
I Live Here
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OP
I Live Here
Joined: Aug 2003
Posts: 12,589
Sacramento, CA
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OK .. I am excited that things may be getting better... I know I've read that if the Edelbrock Performer is getting too much gas, that the gas will be visible coming out the 'boosters'.. I am not aware of where the 'boosters' are, but after reading Feets response above, I'm wondering if the boosters are these air horn s sticking out into the venturi... If they are, there was a fair amount of gas coming out of them at idle... I just thought that was normal. You can kind of see it in the video I did of it running last night.. http://www.youtube.com/watch?v=v-ucCl8KX...mp;feature=plcp
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Re: Continuing with the troubleshooting... distributor...
[Re: Kern Dog]
#1237673
05/24/12 12:26 PM
05/24/12 12:26 PM
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Joined: Aug 2003
Posts: 12,589
Sacramento, CA
cal_gecko
OP
I Live Here
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OP
I Live Here
Joined: Aug 2003
Posts: 12,589
Sacramento, CA
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Quote:
It looks like you are doing well. The engine has a decent lope and idles well. The exhaust tone from the rear sound like a cammy engine with mild compression. More squeeze would change the somewhat muted exhaust note to a crisper one. No offense meant on that though. I like it.
No offense taken, at all. I would LOVE to have higher compression, but I just don't have the ability (money) to do the things necessary to increase compression to where I'd like to have it (probably close to 10:1 would be great....) Quote:
Your idle vacuum numbers look better than I expected. I thought that I once saw 18" at one point?
I think it was settling around 10-12" when I was getting things closer to where I think it should be - hoping that will be good enough for my power brakes  Quote:
If so, thats great! I have between 7-9" in the Charger, and I have power brakes! I still need to add in that vacuum tank to supplement the booster.
The color on that car is TANGY ! Wow... that car is going to be great! It reminds me of abodyjoe's car. Glad to see you're making progress, Greg
Thanks man - I appreciate the encouragement, and all the help, tips and suggestions from everyone so far.. there's no way I would have been able to do this without all the help.
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Re: Continuing with the troubleshooting... distributor...
[Re: feets]
#1237676
05/24/12 01:21 PM
05/24/12 01:21 PM
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Joined: Sep 2005
Posts: 406
California City, CA
dart440
mopar
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mopar
Joined: Sep 2005
Posts: 406
California City, CA
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There shouldn't be a any fuel coming out of the boosters at idle. Air flowing through the venturi should be the only thing that draws fuel out from the boosters.
That is a sign of too high a float level, dirt in the needle/seat hanging them open, defective needle/seat or excessive fuel pressure forcing fuel past the needle/seat.
Looks like you may have found your problem...or at least one of them!!!
When you work on Spaceships for a living, how bad can a workday be?
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Re: Continuing with the troubleshooting... distributor...
[Re: feets]
#1237677
05/24/12 01:24 PM
05/24/12 01:24 PM
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Joined: Aug 2003
Posts: 12,589
Sacramento, CA
cal_gecko
OP
I Live Here
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OP
I Live Here
Joined: Aug 2003
Posts: 12,589
Sacramento, CA
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Quote:
Quote:
I'm wondering if the boosters are these air horn s sticking out into the venturi...
Those are the boosters.
Quote:
If they are, there was a fair amount of gas coming out of them at idle... I just thought that was normal. You can kind of see it in the video I did of it running last night..
http://www.youtube.com/watch?v=v-ucCl8KX...mp;feature=plcp
I don't recall how much fuel comes out of my boosters when it's at idle.
If it's tuned properly there shouldn't be much fuel coming through there.
If your fuel pressure is too high it will push fuel past the floats and flood the carb through the boosters.
You need to make sure the pressure is below 6 psi and stays there.
Just pulled the top of the carb off, and checked floats... float drop was right around 15/16" to 1" at the end of the float, and float height was nearly dead-on at 7/16".
I'm thinking that the pressure regulator I have is not working properly.. I have dialed it way down, so when it's running at 2000rpm or so, it's set to about 3.5psi, but when it idles for about 30 seconds or so, it's going up to 6 or 7. It's a Holley blue fuel pump with a Holley pressure regulator and Autometer pressure gauge. Is there a way to stop that pressure creep?
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Re: Continuing with the troubleshooting... distributor...
[Re: dart440]
#1237679
05/24/12 01:33 PM
05/24/12 01:33 PM
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Joined: Aug 2003
Posts: 12,589
Sacramento, CA
cal_gecko
OP
I Live Here
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OP
I Live Here
Joined: Aug 2003
Posts: 12,589
Sacramento, CA
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Quote:
There shouldn't be a any fuel coming out of the boosters at idle. Air flowing through the venturi should be the only thing that draws fuel out from the boosters.
That is a sign of too high a float level, dirt in the needle/seat hanging them open, defective needle/seat or excessive fuel pressure forcing fuel past the needle/seat.
Looks like you may have found your problem...or at least one of them!!!
If I want to check the needle/seat - do I need to take the carb off, or can I do that while it's on the car?
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Re: Continuing with the troubleshooting... distributor...
[Re: cal_gecko]
#1237680
05/24/12 01:38 PM
05/24/12 01:38 PM
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Joined: Sep 2005
Posts: 406
California City, CA
dart440
mopar
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mopar
Joined: Sep 2005
Posts: 406
California City, CA
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Check the needle for a groove (wear) and also blow through them with some carb cleaner to be sure there is nothing hanging them open (dirt, teflon tape, etc). I try blowing air through the fuel inlet (by mouth, not air compressor) while moving the float to see it the needles seat properly. If they shut off the flow of air in the seated position they are okay.
If the needle/seat is good and the float level checks also, replace the pressure regulator as it is not working properly.
One other thing, check to see if the floats have fuel in them (if brass) or if they weigh too much if the black plastic (the black plastic floats will sometimes absorb fuel like a sponge) and they will sink, causing the fuel level to be too high also.
When you work on Spaceships for a living, how bad can a workday be?
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Re: Continuing with the troubleshooting... distributor...
[Re: dart440]
#1237682
05/24/12 01:52 PM
05/24/12 01:52 PM
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Joined: Aug 2003
Posts: 12,589
Sacramento, CA
cal_gecko
OP
I Live Here
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OP
I Live Here
Joined: Aug 2003
Posts: 12,589
Sacramento, CA
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Quote:
Check the needle for a groove (wear) and also blow through them with some carb cleaner to be sure there is nothing hanging them open (dirt, teflon tape, etc). I try blowing air through the fuel inlet (by mouth, not air compressor) while moving the float to see it the needles seat properly. If they shut off the flow of air in the seated position they are okay.
If the needle/seat is good and the float level checks also, replace the pressure regulator as it is not working properly.
One other thing, check to see if the floats have fuel in them (if brass) or if they weigh too much if the black plastic (the black plastic floats will sometimes absorb fuel like a sponge) and they will sink, causing the fuel level to be too high also.
I tried blowing in through the fuel inlet,.. while floats were in 'down' position, air went in easily.. when I moved floats to the 'up' position, I was unable to blow any air in.. floats are brass, do not seem to have any fuel in them
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Re: Continuing with the troubleshooting... distributor...
[Re: cal_gecko]
#1237683
05/24/12 02:04 PM
05/24/12 02:04 PM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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You've been blowing a lot of fuel through those primaries. Perhaps blowing it up too. You can tell by the color. Your fuel pressure is probably the cause of this whole mess. Aren't you glad you did all that other stuff? 
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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