[drewm]

Originally Posted by steve25

The motor has 60 psi thick bottom plate oil pump which I do not think it would have been built with from the factory, also the motor should have had a full lenght windage try, did it?

It did have a full length windage tray, removed for pictures.

I do think that I am going to sell this one. Maybe find someone with a B body looking for a correct stamping. I know with a stroker kit, this motor could be built nicely. My guess based on my busted transmission and chipped up pinion gear is that it is already a runner. And I really cannot get over how clean this thing is.

[Schurkey]

Originally Posted by 77 TRASHCAN

The top of that piston sure looks ugly, to me! I wonder what’s going on there?

Originally Posted by dirtybird400

Yeah, Oil burning in that cylinder. Wonder what the plug looked like?

Bore scopes are not known for color fidelity or image detail. Sad, but true.

I originally thought the piston was showing erosion, perhaps from detonation. Later, I considered that it might be carbon build-up.

"I" would pull a head or two, (after testing for cylinder leakdown) to inspect for bore wear and piston condition with "my own eyes" instead of the 'scope. It's not like you're specifically trying to save the head gaskets.

[geeteeohguy]

That's a '66 big car 389. '66's used the Arma Steel crank as well. Looking at your block's lifter bosses, I see all are centered, which means this block had no core shift, which is a great asset. Many of the '66 blocks have off-center bosses indicating casting core shift and resulting thin cylinder walls on one side of the cylinder. As clean and solid as this 389 is, it is an excellent candidate for a build. You would be hard-pressed to find a nicer core 400-455 anywhere these days. I say build it! The 76 heads are 68 cc 'big car' heads with slightly less compression than the 77 GTO and 421 heads, which usually go 64cc. Not a bad thing with today's fuels. You can use a bit less dish on the pistons. Helped a friend build this same exact motor (66 big car 389 with '65 76 heads) about 12-15 years ago with Ross dished pistons and the thing is a powerhouse and runs on 89 octane without issue. 389's are great engines.

[drewm]

Originally Posted by geeteeohguy

That's a '66 big car 389. '66's used the Arma Steel crank as well. Looking at your block's lifter bosses, I see all are centered, which means this block had no core shift, which is a great asset. Many of the '66 blocks have off-center bosses indicating casting core shift and resulting thin cylinder walls on one side of the cylinder. As clean and solid as this 389 is, it is an excellent candidate for a build. You would be hard-pressed to find a nicer core 400-455 anywhere these days. I say build it! The 76 heads are 68 cc 'big car' heads with slightly less compression than the 77 GTO and 421 heads, which usually go 64cc. Not a bad thing with today's fuels. You can use a bit less dish on the pistons. Helped a friend build this same exact motor (66 big car 389 with '65 76 heads) about 12-15 years ago with Ross dished pistons and the thing is a powerhouse and runs on 89 octane without issue. 389's are great engines.

Ugh, this decision is killing me. If it were the original motor, it would be a no-brainer. Part of the issue is this car is me reliving my youth and thinking that I want to do to this GTO what I wasnt able to do to my first one. Psychological issues...

What do you think this motor is worth if I sold it? Considering that I have no idea if it is standard bore or not. And that it hasnt run in 25 years.

[1968GTO421]

If you sell this relatively mint block, what are you planning to purchase for your GTO? (Perhaps a MR-1 or MR-1A and go big time with the displacement and power?)

[drewm]

Originally Posted by 1968GTO421

If you sell this relatively mint block, what are you planning to purchase for your GTO? (Perhaps a MR-1 or MR-1A and go big time with the displacement and power?)

Thats a good question. I dont know. I think I would look for either a standard bore 400 or 455 and base my decision off which block I end up with.