Intake gaskets for a zero decked block?
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Intake gaskets for a zero decked block?
When you have a block that has been zero-decked, does that affect what intake gaskets you use? Should thicker gaskets be used? I am asking because I am trying to figure out why I am burning oil on high rpm deceleration only; not at start up (usually valve stem seals) and not on acceleration (usually rings). Just to make sure, I did compression and leak down tests, both of which showed my rings and valve seats were fine. I don't really know how to check the valve guides for leakes, but I do have new teflon seals. I removed my intake, and although I couldn't see traces of any oil leaks on the gaskets, the intake valves do look a little oily, as well as a couple of the plugs. The only other thing I can think of is oil being sucked through the PCV valve. I believe that on high rpm decel, there is a high vacuum created when the throttle blades snap shut, which could possibly go throught the PCV or any minute intake gasket leaks. BTW, I was using Fel Pro 1205 gaskets with a Performer RPM intake on Performer RPM heads. TIA.
Last edited by 7t2vette; May 17, 2007 at 09:38 PM.
Le Mans Master
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From: Gladstone MO
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The block being zero decked should not have any effect on the intake, If the heads have been cut, then there may be a slight misalignment. Other than that, how is the baffle system under the PCV in the rocker cover? You are correct, there will be a high vacuum when you let off at high speed.
Thread Starter
The ORIGINAL and bestest
Joined: Oct 2000
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From: Toronto Ontario
Toronto Events Coordinator
The block being zero decked should not have any effect on the intake, If the heads have been cut, then there may be a slight misalignment. Other than that, how is the baffle system under the PCV in the rocker cover? You are correct, there will be a high vacuum when you let off at high speed.
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
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The guy that did the block should have done the china walls too, but who knows? Just the fact that your gaskets look good sort of takes that out of the equation IMHO.
Le Mans Master
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From: Unreconstructed, South Carolina
Decked block ... angles do Not change ... but depth of "V" does ... heads are now deeper in the V ... where the V isn't as wide as stock location ... same intake width must fit into that slightly narrower V. You may ... MAY need thinner intake gaskets ... BUT probably not.
However, if the machinist erroneously did NOT square the deck surface(s) to crank centerline & bank-to-bank & bores ... the angle(s) will change. There should be 90 degrees between sbc/BBC deck surfaces.
However, if the machinist erroneously did NOT square the deck surface(s) to crank centerline & bank-to-bank & bores ... the angle(s) will change. There should be 90 degrees between sbc/BBC deck surfaces.
Thread Starter
The ORIGINAL and bestest
Joined: Oct 2000
Posts: 10,009
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From: Toronto Ontario
Toronto Events Coordinator
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Run a bead of silicone all the way around a 1205 gasket and you should be OK, that's what I did before I got my intake milled to match my milled heads and stiil do after the intake was matched, never had any problems doing it this way 
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