Before I pick up the phone and begin laying out my hard earned jack to the parts people, I have a question that has seemingly everyone baffled. I'm planning on the Canfield 197s 65cc and a Crower stick (519/540 lift, 226/236 @ 50, 286/294 adv. ).....ya...it's a mini-rammed motor...My question...I'm wanting to have the heads milled to ...say....58 or 60 cc, to increase my compression. Can I expect possible valve/piston clearance problems If the're milled, or am I going to be OK? Anyone out there running 58 or 60 cc heads and a fairly nasty cam with the stock lower end. If so, post your head cc's and your cam's lift. Thanks in advance.

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bottlejunkie,
You didn't mention your pistons, deck-height, or compressed gasket thickness. If you run a thick gasket with .010+ deck-height, and your pistons have good sized valve reliefs, then no you probably will not have to worry about clearance problems as long as the cam-timing is correct (chain install).
However, in the end there are no promises and you really just have to assemble it and see.
There are too many variables for anyone to know for sure. Personally I would not expect a problem unless you're running a domed piston, or you advance your camshaft a large amount.

good luck
ODB

 

most SBCs i've ever checked with flat top pistons would take a .650 lift cam to come with in .1 valve to piston clearance. that said remember all engines are differant and it depends on what parts you use.

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ICON Motorsports

1st & 3rd

 

ODB.....this is a bone stock L98 shortblock..that's kinda why i figured people have already been down this road. As far as my head gasket...thickness is yet TBD...if I'm not 100% sure about my piston/valve clearance....I'll probably just go with the 65 cc and run a thinner (.029) gasket to net me around 9.8-1. If I can get away with milling the heads, I'll try to have them milled to yield me a compression ratio of around 10.5 with a standard head gasket. Hopefully this 2nd post clarified any confusion...Thanks

 

I second ede, that's a really moderate amount of lift, can't imagine any kind of performance heads having trouble with that. But anyway, isn't that a flat-top motor? If so, 65cc will put you at about 10¼:1 anyway with no milling.

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"So many Mustangs, so little time..."
ICON Motorsports

 

I have a 224/232 cam with .497/.517 lift and pistons that have the same relief as stock, but my block is zero decked. The heads are 58cc. The minimum clearance I measured was .186.

 

Madmax......based on your response, I'm led to believe that my combo should work without any clearance problems. My only concern is that your block was zero decked whereas mine isn't. So what's your take, should I be OK?

 

So were you going to deck your block too?
I have measured many stock engines to have .025+ deck heights, so there would go your compression. There are really too many variables that you'd have to open the engine up to find out for sure. Take a look at your pistons. If you are over .010 deck height and the pistons have valve reliefs then there should be no problem with the pistons. You may also want to check clearance up top between the retainer & valveguide though.
Sorry there is no simple yes or no answer, but we're all in the same boat. We all have to do the checks to be sure.
ODB

 

RB83L69....yes it is a flat top motor. If memory serves me right the stock compression of my '88 L98 with stock heads is 9.3-1. Stock heads are 64cc, so I can't possibly see how 65cc heads could net me over 10-1. Am I missing something here?

 

Duration affects piston to valve clearance more than lift. I would check it anyway. It should clear noprob

 

Blue: you should recalculate...

Compression ratio in that motor combo, allowing 64cc chambers, 6cc for valve reliefs, 9cc for head gasket (.040") and 6cc for deck height (.025"), works out to 883 total volume ÷ 86 minmum volume, which is something like 10.28:1.

Somewhere on the net there's a CR calculator, or you can do it by hand like I do (did that come out right?), I think you'll find that you're in pretty good shape with the heads just as they are.

In any case that's a pretty mild cam as such things go, less than I run even, you shouldn't have any problems. And my bottom end is mostly stock, I have stock rods and a cast crank anyway, although I do have forged pistons and ARP rod & main bolts.

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"So many Mustangs, so little time..."
ICON Motorsports

[This message has been edited by RB83L69 (edited February 08, 2001).]