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Discussion Starter · #1 ·
How much valve clearance should i have without head gaskets. Right now im owing about .005. I just put my e7s on my 86 shortblock with no valve reliefed flat tops and puttyied the pistons to check and without a head gasket they hit the piston. I tried again on another cylinder but with my original head gasket with the heads bolted down but not torqed and i had about .03 clearance. My new felpro head gaskets are thicker then the original ones but im not sure how much they will compress and im also unsure about how much the lifters will pump up when the motor is running. Just wondering how much clearance i need so i can decide if i can run it or do i need to get some thicker head gaskets or shim my rocker arms. Im going to check tomorow to see how much clearance i had with my e6s(boat anchors). Just wanting to do it right so i dont tear anything up after rebuilding it. Thanks
 

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You want min .080 once all is finished min. .100 is better if your gonna spin it hard.

Which Felpro gasket are you using? They have CV specs on them. There is no way your gonna make up .085" with any gasket dude. You can either "eyebrow" the stockers or your gonna have to switch pistons or forget the heads.
 

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You will def need to flycut your pistons. .03 Clearance in nothing. YOU WILL HAVE CONTACT!
 

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E6/E7

Just curious... Have the heads been milled? Is the cam stock and installed straight up? If so, wow - just shows how different clearances can be motor-to-motor.

Anyway - agree with others here. No way you have enough. I got about .090" on my intake - exhaust had plenty.

I'll be interested to see what your clearance are when you measure the stock E6's. From what I could tell, the valves sit at least 1/8" deeper in the head giving you that much more.

Good luck! Mark
 

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.080" intake, .100" exhaust. Be sure you use a converted solid lifter when you take the measurements so that the plunger isn't depressed throwing off the measurements.
 

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Discussion Starter · #6 ·
Sounds like i have problems. Im not to sure about the cam i think that it is stock though. It had no makings or part numbers on it and it ran just fine with the e6's. The heads are off a 95 and have never been touched. As for what felpro gasket im using im not sure of the part number but its the one that came in my full kit for an 86. What would you guys recomend to fix this problem. New pistons is out of the question, ive heard there is a tool i can get to put reliefs in with the motor together not sure about that though. Would you shim the rockers, stock 1.6s, or maybe get some shorter pushrods. Also how much could the rockers throw off my measurements if they are depressed? Thanks for the help guys.
 

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Michael Yount said:
.080" intake, .100" exhaust. Be sure you use a converted solid lifter when you take the measurements so that the plunger isn't depressed throwing off the measurements.
Also, personal experience suggests that if you going to try and run as tight as .080 you need to check EVERY cylinder and do it with an actual gasket of the brand that you're going to use installed. BTDT, luckily it wasn't mine :D

The guy was just going to check one cyl and wanted to "calculate in" the published head gasket clearance. We did it his way (and truth be told I was pretty much fine with it at the time) but I did talk him into doing a cyl on each side just to satisfy my own, (inadequate in this case, paranoia.

It looked OK by the numbers we saw and calculated but the next weekend was a cylinder head R&R for bent valves. After that, I feel that "calculating in" the head gasket clearance can be too inaccurate to play on the edgeunless you have lots of experience with a particular gasket (as in you've measured multiple sets and they've been consistently the same thickness each time). I mean do you REALLY know that the published crush is correct?
 

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I always buy head gaskets in 3's - one to sacrifice for p to v measurement with a head torqued to about 50 ft-lbs. Capri, I suspect your parts-bending episode had more to do with the calculation fiasco than the tolerances mentioned above being on 'edge'. Of course, they assume that the engine revs are under 6500 rpm -- more revs = more clearance. Local builder who assembles racing engines that see 7500-8500 rpm likes to have .125", even .150" for his more ham-fisted customers that love to bounce the motor off the rev-limiter lap after lap. They also assume that the engine has a properly matched set of valve springs for the camshaft and train that's being used. There's also the matter of valve edge to relief edge clearance - .06"-.08" is ok for engines like these.

hotrdlx - your comments about shimming rockers and shorter pushrods lead me to believe that you might have a fundamental misunderstanding about what causes p to v interference. Go to the link listed below - it offers a pretty good primer on what the issues are. Cutting valve reliefs is one option. Different pistons is another option. A camshaft with later opening intake valve timing and/or earlier closing exhaust valve timing is another option. Going back to your E6 heads is another option. If you're going to run the E7's with the bigger valves, you have to gain the clerance you need somehow. Replacing the pistons or notching the pistons you have with valve reliefs are the most common approaches.

http://www.geocities.com/jjonibones/PVC.html
 
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