Hi guys, im new to the whole compression ratio thing and I need a little help with my setup, I want to know what my compression ration may be at this point and what I may need to change or add to get 9.5:1without going too far into the bank (I only make 8.00hr) here is my setup so far:

-79 olds vin R 350 .30 over
-Comp Cams XE262H 262/274, Lift .475/.480,
-Federal Mogul pistons(stock) 4.087 bore, Recessed head 0.215 deep x 2.920 diameter yields 7.91:1 compression.
-72 olds 350 heads 409147 7A
-Performer RPM Intake
-Standard Felpro head gasket (summit part#FEL-8506PT) I dont know the thickness.

I hope thats all the info that is needed. Please help!

 

Standard fel pro head gaskets will probably have dropped your compression ratio, because they may be thicker than stock.

Where's the block that you took the 7A 's off of?
You should be building that one instead of a 79.

 

If you get thinner piston rings it may free up some horses too.

 

You can not get to 9.5 to 1 with those pistons. The 22 cc dish would require a 55 cc head and zero deck to make it work. I posted this in another thread recently, and of course was insulted by Norm. Imagine that. But it is the problem I alluded to as far as the lack of piston choice. If those pistons sit .040 down, with a .045 gasket and 68 cc heads, your cr is 7.7 to 1. There is no making up for that dish. Can you afford $700 for new pistons, honing, and decking? If so, the 6cc Speed Pros, and milling the deck .015 should give you right at 9.5 to 1. If the heads cc out a little lower, better yet.

 

I hope this is still a paper project. Did you order all of this stuff and install it already?
I'm doing a 7A headed 350 project right now too. I'll let you know later on this month what I end up doing. Keep an eye on my thread in Small block forum.

 

Thanks for your help I really appreciate it. Sadly this isnt a paper project I already ordered the parts.........but thats when receipts come in handy, back to Summit for exchanges!!

 

There are still some Badger pistons around. They do sit down in the hole but were available in the small dish (10cc IIRC) and are inexpensive like the Sealed Power pistons. Contact info, http://www.badgerpistons.com/

 

And of course, captjim cannot find the source and the quote, because the insult was in his imagination.


Re: The link he posted. Near the top of the page, click the "Warehouse" button, then scroll down, to find the one closest to you. It is where your local machine shop can get the correct "Badger" pistons for your particular application. Your cost should be less than you paid at Summit.

Or, you can get them from any of the following "Badger" distributors: Augusta Engine, Hepburn Enterprises, or Performance Enterprises, who just happen to be, machine shops.

In addition, any of the above machine shops can help you, to get the most "bang for your buck".

Norm

 

Originally Posted by 72CUTTY
........ i only understand about 25% of what captjim said ........
Don't feel bad. I know what he's talking about, and I still don't understand most of it.

Sounds like an insult to me.

 

Read what is actually there. The insult is in your imagination.

Norm