NEEDED:Valve guide advice
Thread Starter
Racer
Joined: Feb 2004
Posts: 253
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From: Athol NY
NEEDED:Valve guide advice
Could worn valve guides be bad enough to keep a steady vacuum from forming? All other vacuum lines and manifold/carb mount, etc. seem O.K. Car runs sort of good, but sure not great! Breaks up under hard acceleration, not good. Carb has been rebuilt, as well as all ignition components. Plugs 4 and 6 are fouling on regular basis. I should have worked on this before the snow melted! :bs
Tech Contributor
Joined: Aug 1999
Posts: 14,370
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From: At my Bar drinking and wrenching in Lafayette Colorado
Re: NEEDED:Valve guide advice (R 73 454)
Doubtful. If the guides are severely worn, you'll be sucking lots of oil down the intake valve stems and laying down a good cloud of smoke every time you start the engine. If you're not smoking or consuming excessive oil, the guides aren't sloppy enough to affect vacuum.
If you're breaking up on acceleration and having low vacuum problems, you might want to verify your timing and total timing setup. But first, verify that your timing marks really do coincide with TDC and make sure that your balancer outer ring has not slipped. Once you have the timing marks verified for accuracy, be sure to verify that you're getting 36 degrees total timing. Once this is done, you can then start a troubleshooting procedure if you're still having problems.
[Modified by lars, 10:03 AM 4/1/2004]
If you're breaking up on acceleration and having low vacuum problems, you might want to verify your timing and total timing setup. But first, verify that your timing marks really do coincide with TDC and make sure that your balancer outer ring has not slipped. Once you have the timing marks verified for accuracy, be sure to verify that you're getting 36 degrees total timing. Once this is done, you can then start a troubleshooting procedure if you're still having problems.
[Modified by lars, 10:03 AM 4/1/2004]
Pro
Joined: Jan 2004
Posts: 535
Likes: 1
From: Darwin, Australia NT
Re: NEEDED:Valve guide advice (R 73 454)
You should do a leakdown test to see what is going on in cylinders 4 & 6 plus all the others. Worn guide are a common problem and usually appear before the rings go. Oiled up plugs will help a motor break down. Try hotter plugs in the short term.
Thread Starter
Racer
Joined: Feb 2004
Posts: 253
Likes: 0
From: Athol NY
Re: NEEDED:Valve guide advice (Simmo)
Harmonic balancer is new, timing has been O.K. Vacuum is not really low. It just flickers VERY quickly. I just don't understand this #6 cylinder. The cam lost it's lobes on that cylinder several years ago, so I rebuilt engine. Started running rough again, brought it to Jughead supposed "corvette specilist" to check valve adjustment, ape promptly overtightened lash, on guess what #6 cylinder. Cam 2 disintegrated on way home! Rebuilt engine again. I'm not cutting corners here, I use all GM or TRW parts and a reputable machine shop! I just thought the guides might have been overlooked at machine shop. This is a stock spec 454 by the way. I think a leakdown test may be in order. :banghead: :U :bs
Melting Slicks
Joined: Feb 2003
Posts: 3,053
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St. Jude Donor '03,'11
Re: NEEDED:Valve guide advice (R 73 454)
Vacuum is not really low. It just flickers VERY quickly. I just don't understand this #6 cylinder.
that would explain the rough running and poor acceleration.
run a compression check.
[Modified by turtlevette, 11:01 PM 4/1/2004]
