Old School vs Magnum on 86 Dodge W100

nm9stheham said

You might want to ask about the cracks in detail from the shop, and then inquire here. How deep and long and numerous are the cracks?

If those are 302 heads, then that is supposedly common.... Some guys here will refuse to touch them, and some guys here will run them all day with the cracks. I don't know enough about the 302 crack situation to be of much help, except what I have just reported.

Those Magnum heads have smaller combustion chambers, nominally 62 cc versus 68 cc's for the LA318 heads. So the compression is better for low RPM torque, which is an attribute to pursue for a street truck IMHO. The chronic issue with smog-era 318's was low compression ratio and it takes pistons like KB167's to really correct that.

Are you planning to cam up this engine at all?

BTW, I would expect more wear in the LA318 block, but you gotta measure to be sure. The Magnum block is .015" shorter so has a bout .25 point better compression from that alone. Seems like the block is OK...yes?

Click to expand...

I wish I were more experienced on whether my cracked heads were a problem or not. The machinist seemed to feel they were unusable. I don't know whether they are 302 heads - if someone tells me how to check, I will.
Regarding "camming up" I had planned to go back stock to save my son money. The truck would be used as a second vehicle and we weren't looking for a "performance" engine. Not that I would mind some performance but the truck is geared so low, I don't see where its worth the additional cost. We really just want a good running engine that's dependable and get rid of the old 2bbl carburetor that's such a dog. My son is disheartened (as you can imagine) after hearing about the heads so I'm looking for a way to help keep him going forward best I can. My options at the moment seem to be A) commit to re-manufactured heads for the magnum (another 450 on top of the rebuild kit) or B) tear into the LA and start over; that may lead to more bad news depending on the shape of the block, heads, crank, and cam. Since my magnum block is in good shape, I may could use it with the LA heads. I guess there are other options like buying another 5.2 magnum from the salvage yard but they we're taking more risk by not knowing it's condition. Not sure what the next step is yet....