bottom end swap

[jxnkyle]

this is my first post as a new member so please don't flame me too hard. i have a 91 ka24de that had a massive rod knock due to a spun bearing. for parts, i've aquired a 90 ka24e. i don't want to head swap if i can avoid it bc of the timing cover gap. so my question is, will i have any problems swapping the crank, rods, and pistons from the e block into the de block? are the internals identical?

[rogoman]

The crank and rods are the same, however the pistons are different. Early 1990 pistons will net you about 11.6:1 compression on a DOHC motor. Also the combustion chamber area in the head is MUCH different from SOHC to DOHC, DOHC pistons have a very large dish, whereas SOHC pistons are nearly flat top. Early SOHC pistons in a DOHC will give you ~11.6:1 compression.Later SOHC pistons in a DOHC will give you ~11.1:1 compression.

Why not just stay with the DOHC components with your rebuild.

[jxnkyle]

the dohc motor i have has a rod that is pretty well destroyed from the previous owner still running the car hard after he spun a bearing. i bought the car with several parts missing intending to put it all back together and drive it. recently i picked up a 90 f/b for parts. it had a blown head gasket, so i wanted to use the bottom end parts to replace mine. 11.1 to 1 doesn't sound so bad though either. colder plugs and 93 octane would keep it together i think. maybe a little ignition timing adjustment. thanks for the post. all help is appreciated.

[180fan]

it's gonna be some work. Matching up the sohc bottom end and a dohc top end won't match up like you expect. Have some thin sheet metal around and be ready to make an adapter piece that'd fill up the gap.

Although, I'd still suggest picking up a dohc, it'll be much less work, and also 93 might not be enough...