[i82much]

Originally Posted by i82much

From what I remember, the BBC engines need to get into a tall deck before you get the huge displacement advantage over an aftermarket Pontiac, something like a 535 Pontiac vs. a 555 BBC. I'm not sure for street use there is a huge advantage for the BBC. But if you want to deal with the tall block stuff and build a 632 BBC, I don't know how on a dollar-for-dollar basis a Pontiac can compete with that.

Actually google is telling me you can do a 572 standard deck BBC. I'm not gonna lie, I love my Pontiac, but that is pretty tough to beat.

[Formulajones]

Originally Posted by i82much

Actually google is telling me you can do a 572 standard deck BBC. I'm not gonna lie, I love my Pontiac, but that is pretty tough to beat.

Yeah the Siamese bore BBC stuff with standard decks can be built pretty large. I have a GM 502 here that I'm going to do something with soon. With it's 4.470 stock bore and a little 4" crank it's already a 502. 540 is easy to accomplish with a 4.250 crank and that falls right in. Can even go slightly bigger on bore or crank or both and reach 565 or so without much effort. You start getting the wrist pin up into the ring package which bothers some people but that's been going on for decades with all brand engines and proven to be fine.

What dad did with his Pontiac was sort of the extreme on the other end. Since Pontiacs typically have small bores, and the MR1 is no different. He went with a 4.350" bore on his MR1 to leave some meat for future builds, but those things accept an enormous crank without trouble. So he bought a 4.750" crank and stuffed it in there for 571 cubes in a standard deck block.

[i82much]

Originally Posted by Formulajones

Yeah the Siamese bore BBC stuff with standard decks can be built pretty large. I have a GM 502 here that I'm going to do something with soon. With it's 4.470 stock bore and a little 4" crank it's already a 502. 540 is easy to accomplish with a 4.250 crank and that falls right in. Can even go slightly bigger on bore or crank or both and reach 565 or so without much effort. You start getting the wrist pin up into the ring package which bothers some people but that's been going on for decades with all brand engines and proven to be fine.

What dad did with his Pontiac was sort of the extreme on the other end. Since Pontiacs typically have small bores, and the MR1 is no different. He went with a 4.350" bore on his MR1 to leave some meat for future builds, but those things accept an enormous crank without trouble. So he bought a 4.750" crank and stuffed it in there for 571 cubes in a standard deck block.

will that 571 live with extended street driving? I heard those long strokes can be tough on side loading. It will be a long time before I have to pull my 505 but a 571 sure is fun to think about ...

[Formulajones]

Originally Posted by i82much

will that 571 live with extended street driving? I heard those long strokes can be tough on side loading. It will be a long time before I have to pull my 505 but a 571 sure is fun to think about ...

So far it's been perfect. I think it's been together going on 6 years now, maybe more like 7? Time flies. I'm not sure on the exact mileage on it currently but we go on 2-300 mile round trips with it fairly often and it doesn't complain, starts with a blip of the key, runs cool, and overall generally seems to be a pretty happy engine.

[i82much]

Originally Posted by Formulajones

So far it's been perfect. I think it's been together going on 6 years now, maybe more like 7? Time flies. I'm not sure on the exact mileage on it currently but we go on 2-300 mile round trips with it fairly often and it doesn't complain, starts with a blip of the key, runs cool, and overall generally seems to be a pretty happy engine.

That's awesome. Nothing like a sweet hot rod.