My heads are 3993820's and have not been touched. I originally was going to punch them out to 2.19/1.88 and clean them up a bit. The documentation I have says they are open 105 or 113 chambers. My quesion is, for a mild buildup, should I stick with these? There is a swap meet this weekend and wasn't sure if I should scout around for others. I planned on a dual plane intake, modified Rochester carb, a cam with .500'ish lift and 220'ish duration, headers, etc. If I were to look for some heads, what do you recommend? What do I look for on the heads? For example cracks, is there a common place that heads crack? Thanks for the help. As always, much appreciated.

I run the 820 heads on my 70ss,the exhaust valve is laid back a little so exhaust is unshrouded,with the 2.19 intake I had to lay back the edge of the chamber 1/16" bringing my chambers to 115cc.They are open chamber large oval port heads and if there's nothing wrong with them I would use them. graemlins/waving.gif

Like JRS70LS5 said...... graemlins/thumbsup.gif

Thanks for the info, it's good to hear. Any "tricks of the trade" with these heads? I tried posting a picture of the stock piston to get someone to give me a guestimate of the compression ratio I would see with the combination of the head and piston. The block appears to be stock, and i believe to be a 70 or 71. The pistons have a raised area across the middle of around a 1/4" high, with one valve relief. The piston also has a hole(on purpose)on the top facing the outside of the block. Sorry to ramble, I just see alot of these flat-top pistons being installed and was thinking these domes would cause too much compression for 91-92 octane. Thanks again!

Look closely to see if there are any numbers on the top of the piston. It sounds like a .095 -.133+/- dome but can't be sure of course. The hole in the piston is for orienting the piston during installation I believe, but again, the pros on this site will validate my assumptions one way or another..... graemlins/waving.gif

Double check the dome. A .250" dome is fairly big. I would bet the dome is closer to .095. Either way if you have a .095 dome, unless the block is zero decked and/or set up with a .035 - .040 quench {highly unlikely unless it has an original style .020" steel head gasket }, the compression is way under what you think you have.

My guess - open chambers 8.2 - 8.4 /1
closed chambers 9.5 - 9.7 /1

Thanks guys. The only number I can see is a large 6 or possible 9 by itself along with an R by itself.

As you stated, I was over on my view of the dome hieght. It appears to be over and 1/8" but under a 1/4".

Make a clay impression of the piston top and CC it. That should tell you everything you need to know. As long as you are within a CC or two, it will be good enough for a street motor. Use Pat's program to figure compression after that.

Good luck,

Troy.

Your either going to need a part # or cc the pistons to figure out your compression and cc the heads because there all different no two are the same.Pistons come in different heights I use a .340 piston for compression of 10.7 goodluck! graemlins/thumbsup.gif

In a 402 based engine, you probably have the TRW 2354 {or equivalent} .169" Dome 19.8CC piston. Make sure of the deck ht of the piston. These are supposed to be 9.3 ratio w/ 106.9 CC head, assuming a zero deck ht and a .039 head gasket. I would tell you to validate the CC of your heads. If you have 115+ cc heads, you are way down 8's for a comp ratio. On a 402 based motor, every CC is worth approx .10 point.