On a SBC 350 that is in the car? I've had intake fitting issues in the past that I sqeaked by on with double gaskets that are holding (cross yer fingers). So is there anyway I can accurately determine deck height- or at the least how much I should have the intake trimmed to fit correctly?

The previous owner of the block doesn't have a clue, and these markings were on the deck surface:

"ON-IT PERF"
"V0508TRJ"

I figure there's a good bet the deck was taken down to 9" even, given how much play there was when I sat the intake on the block for a test fit. I also have aftermarket trickflow 23* heads on there. Any suggestions before I have my expensive replacement intake machined down? How much to take off???

:cheers:

 

Oh wow, this is a toughie. First off I'm unclear if the heads are on or off right now cause you said you test fit something on the block.........that may be a typo, so I'll figure the heads are still on and you don't have info on compression height, rod length, etc, etc,

If the heads are currently still on, maybe you could use a cheapo intake as sort of a test piece and have the shop machine it in increments while you ran back and forth to test fit and eyeball it. I would think you could get close enough the first or second time around to get it OK. Heck, the intake's tolerance is probably the least critical of the entire engine.............all you really need to do is get it airtight (and leakproof :lol: ). And, I really doubt the thing has .025 off it unless it's been used and abused a bunch of times. You'd probably hit paydirt the first or second try since it sounds OK right now by doubling up the gaskets. I'd start off by assuming (there's that word) an average .005 mill for each time you know the motor has been rebuilt, and go from there.
Now, if you had the heads off (or one of them) and knew the specs on the rotating assembly, you could just bring one of the pistons up to TDC, check for zero in the hole, and do the math back down from there. There's no guessing that way. Good luck to you! :cheers:

 

thanks for the reply. Actually what happened was I built up the motor (on a 70's era casting) after being told that it had not been taken down any (the seller was... 'assuming'), but when I put the stock crossfire intake on, it would sit too low- meaning for the bolts to thread into the cylinder heads, there would be too much space under the 'china' surfaces of the intake! But I was in a time crunch and HAD to get the car running, so I quick-fixed it with double gaskets and bolted it down. Put everything together and have been driving it for two months now. But I am planning a TPI conversion and want to solve the problem this time around.

Come to think of it... what would trimming the intake do to fix that (having space under the manifold when the bolts are threaded into the cylinder heads??? Perhaps I have a more serious problem? aaahhh! OK looks like I need some more input on this one.

help?

TTT
[Modified by Ramanstud, 1:21 AM 3/2/2003]


[Modified by Ramanstud, 5:25 AM 3/2/2003]

 

TTT

 

If the deck was machined down to 9inchs the intake would be tight not loose. Sounds like the intake has been machined off. Try another intake to see if it fits.

 

yeah, but we haven't machined the intake (had the car since 1986). Frankly this is the first time the intake has been off. Could it be inter-year differences in spec, or the block?

If the new intake still appears too short, what are my options?

 

Something doesn't add up, here. The block is a "vee". If it has been decked, the tops of the vee, are closer together. Since the heads mount on top of the block, the manifold mounting surfaces, also get closer together. You say yours are too far apart. When the heads or block have sufficient material removed from the deck, the manifold side of the heads are often milled to retain manifold fit. Possibly you have heads that were milled for a decked block, going onto an undecked block. This is the only way *I* can think of that would spread the heads further apart than spec. Another possibility, would be if the heads were done as described above, and your stock manifold is hitting the block, end rails, and preventing the manifold from dropping far enough down into the "vee". Significant milling of the block and/or heads, require that all three surfaces be addressed.

There were no intermediate year alteration of deck height or manifold specs. Aside from some internal "balance" holes between intake runners, all, 1982-1984 (only years used) Camaro, Firebird, and Corvette, either 305 or 350 Crossfire manifolds are the same and interchangeable. Good luck, and...

RACE ON!!!

 

That precisely why I'm stupified! The trickflow heads are fresh out of the box (not milled), the intake is untouched, and the block (only thing I'm not sure of) is apparently not the issue- since the 'V' appears too wide. Arg. I ought to give trickflow a call- but I cannot believe they would change the dimensions in any way since the heads are a direct replacement.

But to recap: if I place the crossfire manifold on the 'v,' it sits too low to line up with the bolt holes in the cylinder heads. It almost suggests I OUGHT to get the block decked... But I'm not pulling the whole motor out for that- I'll just keep using double gaskets....

:banghead:

 

Okay! The manifold sits too low.
That wasn't clear, until now. Maybe the heads aren't "finished". Trick Flow ought to be able to help. If the combustion chambers are larger than spec, possibly, these heads slipped past quality control. Probably milling the heads will solve the problem. Good luck, and...

RACE ON!!!