sjv328

Hello everyone,
Im new to the group and any and all advice or input would be welcomed. I am currently building a 362 for a 77 cutlass supreme. my machine shop messed up and bored my 1970 350 block 40 over and the whole goal was to up the compression. due to the shortage of 40 over pistons I had to improvise and use 425 pistons from egge. the block was later bored to .68 over to fit the 4.125 piston. my question is has anyone ever run this before I cant seem to find much literature on this topic?

joe_padavano

Not very different from building one that's 0.060 over, which isn't very unusual. Egge pistons will be cast, not forged, so there's that problem. Otherwise, should be no issue. You might want to verify balance, however.

sjv328

thank you for the reply ive read many of your posts. I guess I should have explained my entire build plans I was just concerned if .68 over was too much. I have freshly rebuilt 3a heads, comp cam dual energy kit Duration 275/282, Lift .476/.508, stock tranny and rear 2.43 posi, 7111 intake, not sure on carb yet. any suggestions

joe_padavano

3A heads would be from a 1977-1980 350 motor. Are you sure that's a 1970 block? I'm not worried about going 0.068 over on a 1970 block, but I would be concerned if it's really a 77-80 block. Also, the 3A heads have 75 cc chambers, vs the 60-64 cc chambers on earlier SBO heads. If you really want to run the large chambers, you had better do the math to figure out what CR you really end up with. I'm a little concerned that you appear to have somewhat mismatched parts - cast pistons, low CR, high lift cam, etc. The 2.43 gears will make the car a dog off the line (or is that a typo and the gears are really 3.42).

sjv328

The block is a 68-76 from the casting number. I had the 3a heads available until I can afford aluminum. The pistons are the high compression flat top 425 pistons which with a 75cc should give me around 9.3 9.5 ish from what the machine shop told me. If I used a 5-6 or head the compression would be over 10.5 correct??? I'm going off reputable shops opinion when I brought It to them. Do you think the cam is to hig?

sjv328

http://egge.com/part/egg-t100-l2214-8/

Fun71

That info shows the Egge pistons are .006" shorter than factory piston, so take that into account when doing compression ratio calculations. That's a lot better than most cast pistons that are .020" short. Looks like those have a shallow dish as well but the volume isn't listed.