[hurryinhoosier62]

Originally Posted by 25stevem

Scott, why don’t you open up your wallet nice a wide and sleeve a whole Pontiac block and report back after 2 full ( ( complete ) seasons of racing?
Oh and the motor must make at least 800 hp by the way.

WHY are you participating in public pecker measuring in the STREET section? The OP asked a valid question. A few of us( myself and Mike G.) are professional engine machinists. Our goal is to help people with their STREET engine questions. If you are running an 800hp STREET Pontiac, good for you! If you are only being a contrarian take it somewhere else.

[tom s]

Virtually all deals in the street sections end up in how much HP is being made or lost when street ability is way important in my mind.I deify someone to tell me the diff in 25HP peak HP from the ass dyno in a car that is 90% of the time driven from off idle to 3000.Just another day.Tom

[hurryinhoosier62]

Originally Posted by Joe-Touring

What is the consensus for minimums on thrust and non thrust surfaces? The machinist recommended 0.150” on the thrusts, and 0.100” everywhere else.

I noticed that, I am slightly apprehensive about the shop. The owner/main machinist was not the guy doing the sonic check or the sleeve removal.

The rule of thumb I was taught was .135 MINIMUM on the primary thrust wall and .100-.110 MINIMUM on the other walls. This assumes you are using the engine for street use ONLY, are utilizing the lightest piston/pin/ rod combination you can afford and are keeping the RPMs down. The lighter the reciprocal mass the less stress on the cylinder walls.

[Dragncar]

Originally Posted by hurryinhoosier62

I know of two ‘66 389 blocks that had cylinder walls less than .090 thick.

Whitmore told me the 66 398s had thin bore and a lot of comebacks.
It was one of the reasons the 67 400s are said to have thick cylinder walls.
I have a 2 bolt 67 400 that is .060 over. I would like to get is sonic checked just out of curiosity. But I do not think anyone does it around here.

[PAUL K]

Originally Posted by 25stevem

Scott, why don’t you open up your wallet nice a wide and sleeve a whole Pontiac block and report back after 2 full ( ( complete ) seasons of racing?
Oh and the motor must make at least 800 hp by the way.

Why do all the Internet providers of false information always want someone else to step to the plate "and do something"?

Fact; you can sleeve all eight cylinders on a Pontiac block. Your second hand information was false and I tried to correct it as politely as I could.

As long as you are in the know, please tell us IF Scott stepped to the plate and built this engine for "your" test would his theoretical 800 horsepower stock block Pontiac engine with eight sleeves make more power compared to a block with no sleeves and thin cylinders?

[PAUL K]

FWIW we have built a LOT (comparatively) of Pontiac engines using an SD455 block as the foundation. They have consistently had the thinnest cylinder walls of all the 455 engines we have checked. So any folks looking to get rid of those junk thin wall blocks, I would be happy to take them off your hands, I'll supply with a nice 455 block with thicker cylinders and even set up the freight on my end.

[hurryinhoosier62]

Originally Posted by tom s

Virtually all deals in the street sections end up in how much HP is being made or lost when street ability is way important in my mind.I deify someone to tell me the diff in 25HP peak HP from the ass dyno in a car that is 90% of the time driven from off idle to 3000.Just another day.Tom

Well said, Tom! Most people cannot tell the difference. What people SHOULD be obsessed with is does their street engine idle at a stoplight and NOT overheat, does it get reasonable fuel economy, and do you have to wear a gas mask to keep from suffocating from the unspent fuel fumes from the tailpipe.

[hurryinhoosier62]

Originally Posted by PAUL K

FWIW we have built a LOT (comparatively) of Pontiac engines using an SD455 block as the foundation. They have consistently had the thinnest cylinder walls of all the 455 engines we have checked. So any folks looking to get rid of those junk thin wall blocks, I would be happy to take them off your hands, I'll supply with a nice 455 block with thicker cylinders and even set up the freight on my end.

I sure you would, Paul! The idiocy of some knows no bounds. BTW....no disrespect toward you as an engine machinist and builder. Your omission was a brain fart on my part.

[highway star]

I'd first confirm the cylinder numbers on that sheet are correct, because they are switched sides?

[Joe-Touring]

Originally Posted by tom s

Virtually all deals in the street sections end up in how much HP is being made or lost when street ability is way important in my mind.I deify someone to tell me the diff in 25HP peak HP from the ass dyno in a car that is 90% of the time driven from off idle to 3000.Just another day.Tom

Absolutely, everything is a compromise. You have to take all your drivetrain components into account, and determine what trade offs are worth it to you. And you’re right, most people won’t notice an extra 25hp at 5000 RPM, but they most definitely will notice if it doesn’t idle below 1000 or get better than 12 mpg.

[Joe-Touring]

Originally Posted by hurryinhoosier62

The rule of thumb I was taught was .135 MINIMUM on the primary thrust wall and .100-.110 MINIMUM on the other walls. This assumes you are using the engine for street use ONLY, are utilizing the lightest piston/pin/ rod combination you can afford and are keeping the RPMs down. The lighter the reciprocal mass the less stress on the cylinder walls.

Thanks hoosier, using those numbers, looks like boring out another 0.030” would cause issues in most of the cylinders. Thrust sides on Cyls 5 and 6 being the most affected. I was hoping to reuse the OE cast rods that came with the block, they’ve already been redone with ARP studs. I know Eagle h beams would be lighter, but if I’m springing for forged pistons/rods, it doesn’t make sense to not build a stout 455 with 9.5 or so compression and a RAIV cam. And it seems the vibe is that this block would be the weak link in that setup.

[Joe-Touring]

Originally Posted by Dragncar

Whitmore told me the 66 398s had thin bore and a lot of comebacks.
It was one of the reasons the 67 400s are said to have thick cylinder walls.
I have a 2 bolt 67 400 that is .060 over. I would like to get is sonic checked just out of curiosity. But I do not think anyone does it around here.

Heard this as well. I have a 67 400 in work at another machine shop that will be my “nice” engine. I’ll post the sonic numbers up when I get em. Hopefully that block is good or I’ll have to start searching again…

[Joe-Touring]

Originally Posted by PAUL K

would his theoretical 800 horsepower stock block Pontiac engine with eight sleeves make more power compared to a block with no sleeves and thin cylinders?

I’ll take a crack at this. I’d say it would make more power due to the higher cyl rigidity resulting in better ring seal and less piston friction.

Originally Posted by PAUL K

FWIW we have built a LOT (comparatively) of Pontiac engines using an SD455 block as the foundation. They have consistently had the thinnest cylinder walls of all the 455 engines we have checked. So any folks looking to get rid of those junk thin wall blocks, I would be happy to take them off your hands, I'll supply with a nice 455 block with thicker cylinders and even set up the freight on my end.

Interesting, do the SD’s have design characteristics that would make the thin cyl walls a non issue? If I did a short fill w/ hardblok and got lighter forged pistons/rods, would it hold up to 9.5 comp and a RAIV cam? Otherwise, it seems dropping the coin on good pistons/rods would be a waste.

[Joe-Touring]

Originally Posted by hurryinhoosier62

Well said, Tom! Most people cannot tell the difference. What people SHOULD be obsessed with is does their street engine idle at a stoplight and NOT overheat, does it get reasonable fuel economy, and do you have to wear a gas mask to keep from suffocating from the unspent fuel fumes from the tailpipe.

Definitely, I wanna drive the hell out of my car this summer. I’ve spent more than enough time wrenching on it, it’s turned out great, but I would like to take some big trips without any issues. And perhaps after enough seat time and tuning experience, make some more aggressive changes.

[Joe-Touring]

Originally Posted by highway star

I'd first confirm the cylinder numbers on that sheet are correct, because they are switched sides?

The sleeve is at least marked in the right place, driver side rear, but other than that, I can’t say. The thin spots are all over the place, and at this point I can’t say that I want to sleeve the whole block and make a fire breather.

[tom s]

If doing custom pistons you can bore just what is necessary,dont have to do 30-60.Tom

[74Grandville]

I’ve looked at the gap between the cylinders between a 400 vs 455 and there didn’t seem to be much different. Yet the STD bore on a 455 is larger. This does not take core shift into account.

I’ve heard 400’s going .060 with out to much issue, but I’m not sure I’d trust a 455 at .060. I think of a 455 as a 400 already .030 over.


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