I pulled my 350 motor from the 68 today in order to do a head/cam change. I bought trick flow heads and crane energizer 278 cam.
(222/222 467/467. I planned on using fel pro 1094 .015 head gaskets to get my .040 quench.
When I pulled the stock heads off I noticed the pistons have 4 valve reliefs, but they are recessed in the piston with a raised ring on the outer edge. The casting number on the piston is 6271096 and has a letter "H" on the top of the piston. Is this going to mess up my quench calculations? Am I looking at new pistons? I need some help.

Thanks!
Mike

http://www.kb-silvolite.com/slvpg29.htm

7th one down... you need to find out how many cc's the relief is to determine your compression ratio accuratly. my guess would be about... opps they give it to you as about 11.5cc.

I'm not sure what happens to the quench cause that relief is already .07" down.
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1968 Coupe (http://www.eden.rutgers.edu/~vath/Camaro/), 327/210hp project in process. PS/PB, Factory AC, adding camelhumps and a CompCam XE262
1986 Chevy Stepside (http://www.eden.rutgers.edu/~vath/Stepside/), dying 4.3L, TH-400, no A/C, 2wd, 1/4 million miles.

[This message has been edited by JIM68 (edited 01-12-2003).]

I guess I didn't know that a '68 motor had dished pistons in it but rather f/t's like my stock, 350 L-48..

You are probably looking at a low compression engine unless you get a set of at least 64 cc heads for your motor.. pdq67

Jim, thanks thats it. The short block is a 78 or 79 4 bolt truck block. Again, my main concern is what happens to my quench area?
I think I'm probably going to end up with replacing the pistons. One thing leads to another!

Mike

Mike,

With that type of piston you really don't have any quench area. To get the quench effect you need a fairly large flat portion on the piston to match up with the flat portion of the head. If you need a dished piston to achieve your desired CR, you can use a piston with a D-shaped dish to maintain a good quench area.

Chris

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Chris Avery
'69 Nova, 355 (soon to be 383), 9.3:1, Keith Black 12 cc D-cup hypereutectic pistons, 180 cc Dart Iron Eagles w/64 cc chambers, Comp XE-262, Crane Energizer 1.6 ratio roller rockers, Performer RPM, Holley 650 DP, TH350 w/B&M shift kit, B&M 2400 RPM Torkmaster converter, 4.10 10-bolt posi. Best 1/4: 13.098@103.41, 1.949 60'

If you have the 64cc Trick Flow Heads and that dish is 11cc then your static compresison ratio drops to about 9.5:1. that is not ideal but isn't too bad with your cam choice. Another 1/2 point higher would be best, but as is you will probably be able to run 87 octane and still make 350-375 HP.

If you go to a -6cc flat top (without the recess) your static compression ratio goes up to 10.0:1. A little better for your cam and an extra 10 HP. With a good quench type flat top piston and aluminum heads you should still be able to run midgrade gas, maybe even 87.

Thanks for the help, I really want to do this right, so while I have it out I will change the pistons. Not having done an engine rebuild myself, a friend of mine is going to help me out. I am going to get a bore gauge and see if I have to go .030 over. I hope just a hone will do. Can anyone recommend a decent hypereutectic piston to get me to 10.25 with the 64cc trick flows?

Thanks!
Mike

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=6770&item=1876636902

Just loking through Competition Products website and found these Dynagear/Badger pistons. Are they any good?
http://www.competitionproducts.com/page73.html

Thanks!
Mike