351W brain teazer
Old School Hot Rodder
Joined: Feb 2006
Posts: 6,472
Likes: 11
From: Exmore, VA
Ok, well crap, can you get it to show the lean condition without a load, say just bring up the RPM to the same area it pings at? If so, you can try gradually pushing the choke blade closed and see if the RPM goes up or the engine seems to run smoother. Once you get the answer to that, there is another, more difficult check. With the engine running at the lean point, look down the primary barrels of the carburetor and see if the booster venturiis are feeding any fuel. If they are not, then you are still on the idle transition circuit. If they are then you are running on the main jets. From there I may have another suggestion. One question, do you know if the primary throttle plates have a bleed hole in them? Some carburetors do, some don't.
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Joined: Feb 2005
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I had an idea last night and just got a chance to check it out.
I hooked a vacuum gauge to the dipstick tube and plugged both valve covers which means that there was no normal way to have vacuum in the crankcase. If there had been then that would mean a manifold leak. Sad to say that there was only pressure (about 1/2)".
Next step is to eliminate the EGR adapter as a source of a vacuum leak.
I hooked a vacuum gauge to the dipstick tube and plugged both valve covers which means that there was no normal way to have vacuum in the crankcase. If there had been then that would mean a manifold leak. Sad to say that there was only pressure (about 1/2)".
Next step is to eliminate the EGR adapter as a source of a vacuum leak.
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New User
Joined: Feb 2005
Posts: 11
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Well guess what guys?
I decided to run the garden hose over the intake manifold in case there was a pinhole leak I hadn't seen. When I got near #8 intake, I heard this sound like water had just hit the headers. I couldn't see that part of the manifold because of the throttle linkage so I removed it and there it was. The intake gasket was somehow up about 3/16" and I could see the blue permaseal.
I laid a bead of high temp silicone then fired it up for about 1 second and it sucked it right in. I patched it 2 more times then let it set up good.
The idle dropped had 200 RPM so I brought it back up and leaned out the idle screws 3/4 turn.
I'm not sure that it has cured the problem but it must be part of it and I now have to do the one job I didn't want to have to do.
You may all call me a bonehead now.
Thank you all for your input. It gave me the drive to go after the problem.
I decided to run the garden hose over the intake manifold in case there was a pinhole leak I hadn't seen. When I got near #8 intake, I heard this sound like water had just hit the headers. I couldn't see that part of the manifold because of the throttle linkage so I removed it and there it was. The intake gasket was somehow up about 3/16" and I could see the blue permaseal.
I laid a bead of high temp silicone then fired it up for about 1 second and it sucked it right in. I patched it 2 more times then let it set up good.
The idle dropped had 200 RPM so I brought it back up and leaned out the idle screws 3/4 turn.
I'm not sure that it has cured the problem but it must be part of it and I now have to do the one job I didn't want to have to do.
You may all call me a bonehead now.
Thank you all for your input. It gave me the drive to go after the problem.
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