Thread: 402 (.030 over)

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Got a good deal on a BBC 402 .30 over. Bore is 4.155 and stroke is 3.766. The compression ratio on the build sheet for the pistons (TRW L2383 .030) is 9:1 @ 102 cc head. I'm looking to put this in my 70 Nova and would like to get at least 450 hp on pump gas. Any recomendations on what heads would be a good fit? I'd rather not change out the pistons to get the compression ratio up, but I will if necessary. Cam is Comp .556 with hydraulic lifters. I was looking at the ProComp 2.25 intake/1.88 exhaust. Single plane manifold with 800 cfm carb.

well you will need the 102 cc to keep the 9.1 to run any kind of cam .if you use a big chamber head with more cc you will lose steam CR and have a pig. them old heads i would say could make 400 hp with a small roller cam that is were you should put your money not in the heads that will not work. i am not up to speed on the procomp heads i do not use them.they make a 102cc head? and a small valve them396/402 bores are small you very well could be cutting the deck for the intakes valves to clear as well as cutting them pistons for the bigger intake valves . get me the casting numbers of the old heads with some work could get you were you want or very close

I have a 402 .030 over with 292 casting heads. The heads are 113cc and with the kb hyper pistons (.180 dome), and .039 gasket, I am getting 8.8to 1 static compression. I would find some heads like casting 292, or 840 with a 113 chamber and clean up the bowls. I put 1.88 exhaust valves in mine. Go with a small roller cam. Look at Howards cams 222/234 .577/.579 112 lsa. This would be a good choice and it is $500 with roller lifters. I'm running a crane power max flat tappet 216/228 .520/.515 112 lsa. it pushes a 4000 lb car through the traps at 14 flat spinning the tires. I have run several roller cams on the desktop dyno and the howards cam above surpassed all with amazing torque figures and horsepower. Save your money and get the roller!!! It will be worth it. Also listen to Pat, he has helped me many times.

yep hi lift short dur them bbc O ports like that to a point :>) did i give you bad cam numbers? did you run any ERSON numbers ? well the TRW pistons number could be off? but the L2383f30 would be 8.29 at 100.9 and 7.78 at 109.4 ? shows piston as a 030 over on a 402 i am sure i used that piston but i did look it up on flat lander so them are the number s look low ? . you can not go any bigger on the chamber if the numbers hold water

Thanks guys. The casting # on the heads is 3993820 - '71 402 heads. Heads were milled .010 flat. Stock size valves 2.06/1.72. What about installing a set of Probe dome top pistons - 9.6 @ 118cc with the procomp head set up and a properly sized cam?

I have no personal expereince with Pro Comp heads personally. But i will tell you if you go over to the Team Chevelle, Team Camaro and Team Nova sites your gonna hear more bad expereinces about those heads more than any other aftermarket part I have ever read about. No opinion with no experience..just telling you what i have read.