Upon further inspection of the pistons, it appears that the compression would likely be the same between pistons since the older ones are flat, and the newer ones are dished in the middle, but domed on the outside to make up for it. the problem is that the pistons in the avls motor have a deeper dish in them to allow the higher lift valves to clear the pistons, so im almost certain that the valves would end up hitting the pistons when avls engaged if I just swap the heads over.
In further news, I think the heads off the car i picked up are likely trash as the oil pump has a lot of pitting in it which I didn't notice until I cleaned it up, so I either need to swap the entire ej251 which I dont think is possible due to the missing avls, or pick up a complete motor.
the other option is to buy ej253 pistons and heads, swap those into the ej251 short block and re-assemble. I dont really think its worthwile though, I would probably be better off just selling the old motor and buying a complete ej253.
In further news, I think the heads off the car i picked up are likely trash as the oil pump has a lot of pitting in it which I didn't notice until I cleaned it up, so I either need to swap the entire ej251 which I dont think is possible due to the missing avls, or pick up a complete motor.
the other option is to buy ej253 pistons and heads, swap those into the ej251 short block and re-assemble. I dont really think its worthwile though, I would probably be better off just selling the old motor and buying a complete ej253.
