Engine Running stock plugs in my aluminum heads
- Thread starter rockyracoon
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Cheapskate207
The left one hangs a little lower
I hope it cures my problem. If not it's remove the heads time to check for core shift. The only other theory I have is vacuum leak into the crankcase but smoke test was inconclusive. I'm running a TFS stage 1 cam and I'm only pulling around 11-13 pounds but a lot of guys running that cam are getting around the same.
Cheapskate207
The left one hangs a little lower
It’s a long ways from wrong plugs to pulling the heads to check for core shift. You can check the alignment of the heads and intake manifold by pulling the upper intake and a snake/inspection cam. The inner ports are easy enough to check with a flashlight and dental mirror.
I’m curious. If it also passes compression check and leak down checks, and a cooling system pressure test, what would you need to pull the heads for?
I would suspect a bad intake manifold gasket if it passes compression and leak down tests and a smoke test was not helpful.
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I’d hate to have you go the work of pulling everything to get the heads off and the heads for an easier to fix problem.
Please let us know how the plug change goes.
Well I've been chasing the low vacuum for over 2 years. I've replaced the intake gaskets probably 4 times. Intake is new, (Edelbrock) heads are new (pro comp) I've pulled the intake 4 times with the same results fel pro 1250. TFS cam. Motor pulling around 12 pounds vacuum. This is a 95 gt. Car has good low end power but dies up top. I did use an endoscope and appears there is moderate port mismatch. Just changed spark plugs to 3924s issue got a little better but car will still stall at idle when turning the steering wheel. At this point I feel the port mismatch is the culprit, possibly leaking vacuum into the crankcase. Motor was completely built. Good compression but haven't performed leakdown.
@Mustang5L5 @jrichker @MustangIIMatt
What test do you suggest for testing this before Rocky pulls it apart again???
@rockyracoon are those steel core Felpros? (I would have to search for the right numbers.) It would be unusual to have that many paper gasket failures that quickly, but if the mating surfaces are not quite parallel etc., it’s possible.
Yes they are steel core. I've even tried stock gaskets I believe 9334s.
One other thing is that once the car gets to operating temperature the idle gets worse. Btw no codes whatsoever. Passes cylinder balance test. So since the car idles worse when warmed up I really believe it's vacuum related.
One other thing is that once the car gets to operating temperature the idle gets worse. Btw no codes whatsoever. Passes cylinder balance test. So since the car idles worse when warmed up I really believe it's vacuum related.
For the sake of completeness, I’d do a compression test to see if a valve is hanging open, and then smoke test for leaks.
What are the aluminum heads anyway?
What are the aluminum heads anyway?
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Makes sense. A bigger fire/spark is going to suck more air. If the electrode isn’t down far enough and burning right, it won’t be pulling as much air.
Mustang 5L5 have done numerous compression tests all cylinders are close to each other and around 150 psi. And as stated have performed smoke test which was inconclusive.
The car pulls nice down low to the point she'll go sideways and all squirrelly shifting into second if I don't let up but something just isn't right and I keep coming back to vacuum leak. I'll have to see how much vacuum she's pulling with the right plugs I just installed. Oh the heads are pro comp 64cc 2.02/160.
The car pulls nice down low to the point she'll go sideways and all squirrelly shifting into second if I don't let up but something just isn't right and I keep coming back to vacuum leak. I'll have to see how much vacuum she's pulling with the right plugs I just installed. Oh the heads are pro comp 64cc 2.02/160.
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I don't remember if you posted already but what is your timing set at?
Timing can have an affect on vacuum.
Timing can have an affect on vacuum.
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