85 & 86 T1 block and head question

[moparbob]

Today I had some time to do some research on my 85 SC. I have a 85 parts car also. My silver SC is a 85 with an 86 block and motor. My parts car has all the 85 drivetrain still intact, But motor is bad. Upon finding this out, I began to read on all the info about G Head and Fast Burn Heads and how the 85 and 86s had differant distributers. Anyhow, can a 86 block with a g head work with the 85 electronics and what would this do to the compression ratio?

[cordes]

If I'm not mistaken the G head will lower the compression with the 85 block, and the computer won't give you near enough spark advance.

[turbovanman²]

Look at the head, the number is by the thermostat housing. Swirl is 782, the g-heads are 287, 655.

G-head on swirl pistons will lower the compression aprox 1/2 a point, you will need a cal for this as it makes the car very sluggish.

Swirl head on G-head pistons, will probably raise the compression aprox 1/2 point, thats not good.

[moparbob]

Thanks for responding. After reading all day on the subject, I was going to try to return the head and distributer back to 85 on the 86 engine. I also have a 11psi mopar comp for the 85. But finding out the compression ratio will be off makes me return to the drawing board. The bad part is , when I got the silver 85 sc, the owner told me it had the motor replaced but they could never get it to run correctly. When I bought my parts car, the motor had the plugs out and that owner had no idea if the car ran previously. I think this will turn into a money hole if I keep trying to go 85 "original" T1. It is looking better to intercool this thing and forget about these pre-commonblocks.

[cordes]

Never mind. I didn't realize that the 85s still had the G head. If your head is bad you can probably get a new swirl head at the JY for $30.