Need some motor help
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Joined: Jan 2001
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Car: 99 Formula
Engine: LS1
Transmission: T56
Axle/Gears: 342
Need some motor help
This is for my brother.
It's a '74 Chevelle 350 that's in his thirdgen.
There's several problems.
He just added a Summit cam 488/488 lift about 1 month ago. Stock springs ( I know I know, he should have changed them, but this wasn't my doing)
It's also has a Holley 600 VS carb.
I haven't had a chance to listen to it, but he says it idles real rough now. It will cut out and an occasional backfire thru the intake. At first I was thinking maybe a choke adjustment problem, but then he said they didn't change the springs, so I told him tomorrow pull the valve covers and check the springs.
Also, there is a lot of soot on the exhaust pipes and he also said there was gas in the pipes.
Can anyone shed some light?
I know a busted spring would cause a poorly running engine, but what about the other symptoms?
Thanks for any help.
It's a '74 Chevelle 350 that's in his thirdgen.
There's several problems.
He just added a Summit cam 488/488 lift about 1 month ago. Stock springs ( I know I know, he should have changed them, but this wasn't my doing)
It's also has a Holley 600 VS carb.
I haven't had a chance to listen to it, but he says it idles real rough now. It will cut out and an occasional backfire thru the intake. At first I was thinking maybe a choke adjustment problem, but then he said they didn't change the springs, so I told him tomorrow pull the valve covers and check the springs.
Also, there is a lot of soot on the exhaust pipes and he also said there was gas in the pipes.
Can anyone shed some light?
I know a busted spring would cause a poorly running engine, but what about the other symptoms?
Thanks for any help.
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From: Readsboro, VT
Car: 85 IROC-Z / 88 GTA
Engine: 403 LSx (Pending) / 355 Tuned Port
Transmission: T56 Magnum (Pending) / T5
Axle/Gears: 3.42 / ?
he probably pulled out a rocker stud and has a valve that won't shut.
If he doesn't, he will. That's too much lift for a stock spring... especially one from an old smogger head. Hell, that's WAY too much cam for those heads, but that's another battle all together...
If he doesn't, he will. That's too much lift for a stock spring... especially one from an old smogger head. Hell, that's WAY too much cam for those heads, but that's another battle all together...
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From: Jackson County
it's never ran right since the cam swap? did he/you degree the cam? if not you really don't know where it's at? did he install it straight up? check timing, valve adjustment, look for bent push rods, coil bind, pulled out stud, but i doubt that happened, vacuum leaks.
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Car: 1982 Z28
Engine: LS1
Transmission: T56
Originally posted by Jim85IROC
he probably pulled out a rocker stud and has a valve that won't shut.
he probably pulled out a rocker stud and has a valve that won't shut.
The stud locates the rocker fulcrum...raising it would limit the amount of valve opening, not closing.
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MAS,
Was anything done to the heads? 0.488" is just about beyond the interference point for those "lovely" little exhaust valve rotators and the tops of the valve guides on those mid-'70s heads. I'd be looking for valve train damage before running it again.
BTW - When you get the rocker covers off, check the head casting numbers.
Was anything done to the heads? 0.488" is just about beyond the interference point for those "lovely" little exhaust valve rotators and the tops of the valve guides on those mid-'70s heads. I'd be looking for valve train damage before running it again.
BTW - When you get the rocker covers off, check the head casting numbers.
Last edited by Vader; Apr 12, 2003 at 12:18 PM.
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