Gurus Needed
Thread Starter
Pro
Joined: Feb 2005
Posts: 616
Likes: 2
From: Sedalia MO
Gurus Needed
If you have seen my other thread, you may know i am having issues tuning my carb. I did what I was told and capped off all vacuum ports. I also went a step further and bought some gasket seal and sealed both sides of the gasket and reinstalled the carb. The car starts fine, and idles @1000 rpm and pulls between 15 and 17 inches of vacuum (high lobe cam). The problem is, if I let it sit and idle, the RPMs go down and then stalls out. When it stalls out the compression spits a little fuel up through the carb. I have ruled out vacuum leak since everything is sealed or capped off. Or, it could be a vacuum leak is coming from the intake manifold itself? The only other option is timing, which would really suck, because Bubba didn't bother marking TDC or the degree to which he set it at. I set it to the max vacuum I can get, is this a good idea, or bad? Any help would greatly be appreciated.
Thread Starter
Pro
Joined: Feb 2005
Posts: 616
Likes: 2
From: Sedalia MO
Not when the Holley was on, but it wasn't running great either. I thought it was the cam lobe, but now I am not so sure. It was running really rich, but I thought it was the Holley 750. Also, when it stalls there is a little smoke venting from the breather tube, and pcv tube.
Thread Starter
Pro
Joined: Feb 2005
Posts: 616
Likes: 2
From: Sedalia MO
When I started the car it was idling around 500-600. I just turned the idle screw up to 900-1000. Also when adjusting the idle screws, I connected the vacuum gauge and turned until I go the best possible vacuum, which still ended up being approx. 1.5 turns each. Then readjusted the idle to 1000 RPM.
Drifting
Joined: Jul 2011
Posts: 1,697
Likes: 139
From: Syracuse NY
When I started the car it was idling around 500-600. I just turned the idle screw up to 900-1000. Also when adjusting the idle screws, I connected the vacuum gauge and turned until I go the best possible vacuum, which still ended up being approx. 1.5 turns each. Then readjusted the idle to 1000 RPM.
Thread Starter
Pro
Joined: Feb 2005
Posts: 616
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From: Sedalia MO
for awhile then it stumbles and dies. When it dies it spits a bit of gas (tiny bit) up through the carb, and a bit or smoke comes through the breather tube and PCV valve. The smoke may be normal, but i have never noticed it before. Could just be the angle of the sun through the window of my garage, I dunno? Also, when I connect the vacuum advance, the car's vacuum reduces to around 10 and stumbles again. Can I buy just a new advance, or does it need a new distributor?
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Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
Something is really not right. That the engine dies after ideling for a few minutes makes me wonder if your carb is running out of gas. When it starts to stall, can you work the throttle and keep it running? I think you said no to that question. So when it dies, have you tried working the throttle while looking down the primaries to see if the carb is squirting fuel. If not, the float bowl is probably empty. In that case, check fuel pressure when running, and/or test the fuel pump for volume of output. The Chassis Service Manual instructs how. BE VERY CAREFUL!
The fact that the vacuum goes down when you connect the vacuum advance can tells me it is leaking and must be replaced. Get Lars' paper on ignition problems. Check the stickys or search for Lars. Don't run out and buy a new distributor, figure out what, if anything, is wrong and correct it. Even if you buy a new one, you will still have to dial that one in, so dial in yours.
SBCs, and I suppose BBs too, like a lot of vacuum at idle. If your complete ignition system and carb are dialed in correctly, assuming no mechanical problems, your engine should purr and go like he££ when you gas it.
Pete
The fact that the vacuum goes down when you connect the vacuum advance can tells me it is leaking and must be replaced. Get Lars' paper on ignition problems. Check the stickys or search for Lars. Don't run out and buy a new distributor, figure out what, if anything, is wrong and correct it. Even if you buy a new one, you will still have to dial that one in, so dial in yours.
SBCs, and I suppose BBs too, like a lot of vacuum at idle. If your complete ignition system and carb are dialed in correctly, assuming no mechanical problems, your engine should purr and go like he££ when you gas it.
Pete
Racer
Joined: Sep 2009
Posts: 437
Likes: 3
From: Alvin Texas
The brass float may have a leak allowing gas to leak in. this makes the float heavy and lets the carb flood. Usually you can shake it and hear the fluid sloshing. Another way to check is to hold the float under hot water (really hot) and if it has a leak bubbles will come from the leak.
Thread Starter
Pro
Joined: Feb 2005
Posts: 616
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From: Sedalia MO
Thanks Pete! Yes, I can mess with the throttle and keep it running. I let it die because the engine acted like it wanted to catch up with itself, so I let it go to see what it would do...it died. I will check the fuel bowl, and I had already decided to purchase a fuel pressure regulator. I mean, it can't hurt. I will keep you posted. If anyone has anything further to offer, please feel free.
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
As a life-long trouble shooter in various environments, I can tell you there is more satisfaction in figuring out what is wrong and fixing THAT instead of throwing parts at a problem. Usually costs less too.
Pete