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Old 10-02-2009, 03:49 PM
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Intake manifold not sealing?

So apparently i have lost the ability to install and seal an intake manifold the right way...

So i have a 327 sbc with: forged crank, forged pistons, calculated 10.7:1 scr, ported 462 heads, 2.02/1.60 stainless valves.

Crane cams #111411 mechanical flat tappet cam, 292/300 adv. dur., 256/264 @ .050, .545/.563 lift, 1.5 full roller rockers, 4200-7200 operating range.
short tube headers and dual 2.5" exhaust dumps before the rear tires, 5 speed manual+4.10's.

This is all in my 1988 camaro, and was my daily driver until now.

I did what many people here said; get a performer rpm air gap intake manifold.

So back to the beginning: What are signs of a bad intake seal??

I keep losing oil, and my plugs are always black. My valve guides and seal are all fine (learned the hard way thinking the machine shop messed up those), my pcv valve is not the cause.

My symptoms are: horrible idle - either it will idle at 1200+ or it will die, i can adjust the air speed screw and the rpm won't change (unless i go to far than it just strait up dies)

I had a vacuum gauge hooked up and it is always fluxuating between 3-5"hg

I would like the most performance possible, but i would still like to have a suitable idle and not have black plugs all the time.

I currenlty have two intakes: the rpm air gap #7501, and a weiand single plane #7546. For some reason, the weiand single plane is listed at 1500-6500 operating range??? Would i see any noticeable change with a victor jr?

When i swithched from the weiand single plane to the RPM air gap, my idle didn't seam to change much, and i could really tell anything different cruising around town.

The block has not been decked, but the heads were milled once .007"

I need some suggestions for intake manifold gaskets and proper sealants to use. Any other tips would be appreciated! I am 19 and i do take the time to clean both surfaces really good and clean and the bolt holes. What am i forgetting about???

Thanks again!

Josh

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Old 10-02-2009, 03:59 PM
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If the heads were not properly milled. You could be sucking air on the bottom side of the intake runners. I have seen this a bit on SBC engines. This will cause your symptoms.
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Old 10-02-2009, 04:04 PM
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they were milled right, i just need some advise on some proper tools and procedures to properly seal an intake manifold. The heads are ported so i imagine i can't uses stock replacement type gaskets. Probably some aftermarket performance oriented type gaskets with not exhaust crossover???
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Old 10-02-2009, 04:06 PM
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But for sure the was a leak when i pulled of the wieand single plane. the intake runners were covered in oil, as well as the first few inches of the intake manifold runners.
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Old 10-02-2009, 04:07 PM
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Intake Mainfold Leak

Leak Info here. >> http://www.crankshaftcoalition.com/w...ak%2C_internal
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Old 10-02-2009, 04:20 PM
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Interesting...

So it looks like im going to remove the intake manifold right now, and clean everything up again.

What intake manifold gaskets should i use?
Sealer? Copper seal spray-a-gasket??

Looking forward to replies!

josh
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Old 10-02-2009, 05:36 PM
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So i just finished taking the intake manifold off, and here is what i found:

All the intake valves are covered in crusty looking oil, but the stems on the open valves are nice and shiny. The intake manifold gasket seamed to have sealed right, but then again... When i removed the weiand single plane, the gasket looked like it hadn't sealed right - causing everything to be coated in oil. I put the performer rpm on it and ran it for a whole 10 minutes, and then took it back off. Does the oily residue on the runners and valves ever self clean??? Or did i just waste a bunch of time???

Like i said before, the heads were redone when i first got the motor, new everything. I had this problem before, and i took off the heads. I took them to the machine shop just to determine that everything was like new. The shop even gave me new head gaskets and intake manifold gaskets just because of the trouble i went through.

I am really confuse as to why there is so much oil in the intake runners, and also as to why i keep loosing oil??
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Old 10-02-2009, 06:20 PM
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Are you saying the oily substance is in the intake manifold runners....or in the head passages?...If in the intake, it has to be getting in before where the intake meets the heads.

Just a thought.....where is your PCV connected to, the bottom of the carb?
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Old 10-02-2009, 06:45 PM
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the oily stuff is in the entire intake runner on the head, and the first inch or so on the intake. The plenum of the intake manifold has no oily substance. The pcv is hooked to the bottom of the carb (holley 650 dp), to the passenger side valve cover and there IS a baffle. I even got a braided cleave pvc tube just to see if that is where i am getting my oil form. Tube remains clean.
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Old 10-02-2009, 06:54 PM
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Blows that theory........

Has to be the intake gaskets leaking then
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Old 10-02-2009, 07:02 PM
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Any suggestions on a gasket to use??

Considering fel pro 1206.

???
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Old 10-02-2009, 07:26 PM
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Quote:
Originally Posted by Biscuit6447
the oily stuff is in the entire intake runner on the head, and the first inch or so on the intake. The plenum of the intake manifold has no oily substance. The pcv is hooked to the bottom of the carb (holley 650 dp), to the passenger side valve cover and there IS a baffle. I even got a braided cleave pvc tube just to see if that is where i am getting my oil form. Tube remains clean.
If you are talking alot of oil in the runners, I would say that there is too much oil being pumped to the lifter valley. Did you install any oil restrictors? It would seem that because there is oil in the intake runners of the head and 1" in the intake itself, that the gasket is not sealing completely OR, the gaskets are being saturated with oil because of excess top end oiling. While I don't use it for sealing many gaskets, you may try to seal the gaskets with High Temp RTV silicone or my favorite that I use alot, Permatex Aviation Form-A-Gasket. If you use the RTV, just make sure that you don't over do it as it will squeeze out into the runners when the intake is torqued down. That is another idea, make sure you are torquing the intake instead of just tightening and always torque in increments from the center out to each end. You can Google the tightening sequence for that. I would start with 8lbs. of torque the first round, 16lbs. the second and 9lbs. the last time for a total of 25lbs. with an aluminum intake. I'm sure other people will differ with me on this but it has always worked for me.
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Old 10-02-2009, 07:38 PM
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I have not modified the oiling system since ive had the motor. I assume that the oil pump is high volume and/or high pressure because i get 75psi on cold start, and 50+psi from 2000rpm and up. usually 30psi at idle and warm.

No lifter valley baffles or anything.

This is what i mean:

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Old 10-02-2009, 09:05 PM
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Has anyone heard or used these intake manifold gaskets?

http://www.summitracing.com/parts/FPP-1245/
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