Built 258?? to much?
Jimbos76cj
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- St.Cloud FL
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- 83 CJ-7.. 4" YJ springs front rear, J-10 44 front/AMC 20 rear,6 cy auto dana 300 35' bfg Done and gone!!
Ask me about my head light upgrade harness!!!
This is for my YJ (cj is on hold) I know this is a CJ forum but the AMC 258 i6 / 4.2l is the same.
So I picked up a motor last night thinking it was a 4.0 to build a stroker for my YJ with and come to find out it is a AMC 258 i6 / 4.2l . It was my fault for not properly reading the post correctly but thats anotehr story. Heres my question, the PO gave me the build sheet from the motor and WOW..
AMC 258 i6 / 4.2l block bored 60 over, KB 2227 pistons, comp 68-235-4 xtreme cam, balanced crank, every thing was turned and polished and resized. Clear water 4.0 7120 conversion head, block machined for ARP head bolts and studs .017 mopar head gasket. plus a bunch more. When I inputted all that info into a compression calculator its showing a little over 10:1 and roughly 4.66 cui. The only thing that seems wrong with the motor is a bad freeze plug and the PO says when he was running it, it was burning 1 quart of oil every 1000 miles. He thinks either a ring did not seat right or the shop who did the head work put the AMC 258 i6 / 4.2l valve seals on the 4.0 head causing them to leak around the valves. I got a ridiculously great deal on the motor so Im pretty stoked.
Am I close on the compression ratio? I know theres quite a few things that alter it but most places are showing the same numbers. Most 4.6 strokers thow out about 250hp, and reason this one should be any different? Im hoping to come up with either a offy or clifford intake for it.
So I picked up a motor last night thinking it was a 4.0 to build a stroker for my YJ with and come to find out it is a AMC 258 i6 / 4.2l . It was my fault for not properly reading the post correctly but thats anotehr story. Heres my question, the PO gave me the build sheet from the motor and WOW..
AMC 258 i6 / 4.2l block bored 60 over, KB 2227 pistons, comp 68-235-4 xtreme cam, balanced crank, every thing was turned and polished and resized. Clear water 4.0 7120 conversion head, block machined for ARP head bolts and studs .017 mopar head gasket. plus a bunch more. When I inputted all that info into a compression calculator its showing a little over 10:1 and roughly 4.66 cui. The only thing that seems wrong with the motor is a bad freeze plug and the PO says when he was running it, it was burning 1 quart of oil every 1000 miles. He thinks either a ring did not seat right or the shop who did the head work put the AMC 258 i6 / 4.2l valve seals on the 4.0 head causing them to leak around the valves. I got a ridiculously great deal on the motor so Im pretty stoked.
Am I close on the compression ratio? I know theres quite a few things that alter it but most places are showing the same numbers. Most 4.6 strokers thow out about 250hp, and reason this one should be any different? Im hoping to come up with either a offy or clifford intake for it.