Right now I have a 383 with home ported 882 heads not sure how much
good the porting is going to do. Thinking about going with 64cc with 190 cc runners but i am concern with compression. I have flattop 2 valve relief pistons with 6in rods.Any opinions for compression with the 64 cc want to stay using pump gas.

Thanks

 

I just did a iron Vortec swap on my 78 L82 with stock flattop single valve relief pistons with no issues. I'm around 10:1 compression.

 

Really it depends on what cam you're running. Do a search for a DCR calculator, this is where you really need to look.

 

Man, if you really wanna know what your compression ratio is, you need to know the combustion chamber volume, compressed gasket thickness, the width of the cylinder hole in the gasket (most are 4.1 inches), the deck hieght (distance from the piston to the block deck at TDC), and the volume of the valve reliefs or dish in the piston, the actual bore diameter, and the stroke. Then, with some complicated math, (or a handy-dandy CR calculator) you can figure out the static compression ratio. Then, if you know the valve timing of the cam, you can figure out the dynamic compression ratio, which, inorder to run 87 octane gas, needs to be around 8:1 or less, depending on even more factors. You need to find out all of that info, (unless you already know it, and just didn't want to get to technical) download a free DCR (Dynamic Compression Ratio) calculator, and do the math, or you won't REALLY know. And since the engine is already built, the only variables you really have to play with are combustion chamber volume and gasket thickness. (maybe cam timing, if you want to get that involved)
Now, if you insist on an educated guess, I'd say with a 383, depending on the deck hieght, gasket thickness, and valve relief volume, If you want to run cheap gas, you should probably stay with a 76cc combustion chamber, a 64cc might put you up well over 10:1 static, and unless you've got a HUGE cam, your dynamic CR might be too high to support pump gas. The longer stroke aggravates the whole problem of keeping CR down, also, BTW. Sorry I couldn't be of more help, and I hope I am not coming off as preachy, but, man, it ain't guesswork.


Scott

 

383 with 5cc flat tops, zero deck and .041 gasket with a 4.125 bore and 6" rods is right at 11 to 1. Need a pretty big cam to run 93 octane. Headers, low 1st gear final ratio and.with an auto at least a 3000 stall convertor. Unless everything is spacifically designed for the build streetability will probably suffer.

 

Why not go to 75ccs? I'm sure Mako would love to tell you about some AFRs

 

It all depends on your budget and power expectations

 

Ask yourself ... is gas quality and/or octane likely to improve.

Keep the 882's ... with 64cc chambers & a "regular" gasket your static will be at least 10.25:1.

If block has NOT been decked, use felpro #1094 head gaskets along w/ your 882's ... static will be about 9.6:1 with great quench height.

 

These would be perfect for your engine. 72 CC chambers 190 ports. Fresh. Not mine but just showing you a possible option. Will run on pump gas.
http://cgi.ebay.com/ebaymotors/AFR-A...QQcmdZViewItem

 

Thanks guys for the info I think I will keep what I got for awhile .
I have not even drove car yet.Right now I am figuring how to put front clip back what a pain!