[charlie66]

I recently had a 1970 400ci block Sonic tested. Is there anyone here that can tell me what the common cylinder thickness numbers would be on a block of this year typically would be.? I attached a picture of the results to compare. Any input on this will really appreciated.

Thanks

[blueghoast]

Originally Posted by charlie66

I recently had a 1970 400ci block Sonic tested. Is there anyone here that can tell me what the common cylinder thickness numbers would be on a block of this year typically would be.? I attached a picture of the results to compare. Any input on this will really appreciated.

Thanks

I've seen better but for a .040 over already it's not real bad,I would like
to see more between the bores. Maybe some one else with more knowledge
might chime in.

GT

[charlie66]

Originally Posted by blueghoast

I've seen better but for a .040 over already it's not real bad,I would like
to see more between the bores. Maybe some one else with more knowledge
might chime in.

GT

What worries me is the front of a couple of the bores . How thick have you seen them?

Thanks for your input

[Joe-Touring]

My (limited experience) opinion is depends on what you’re doing with it. Since this is the race section, probably a strong build? From what I’ve seen those numbers would be just fine on most street builds. If you want some other opinions, here’s a thread I started on the same topic:

https://forums.maxperformanceinc.com...d.php?t=857000

My numbers were quite a bit worse, and I think it was about 50/50 go/no go. The most important part is the thrust side, and yours are plenty thick.

[charlie66]

Originally Posted by Joe-Touring

My (limited experience) opinion is depends on what you’re doing with it. Since this is the race section, probably a strong build? From what I’ve seen those numbers would be just fine on most street builds. If you want some other opinions, here’s a thread I started on the same topic:

https://forums.maxperformanceinc.com...d.php?t=857000

My numbers were quite a bit worse, and I think it was about 50/50 go/no go. The most important part is the thrust side, and yours are plenty thick.

Thanks for the link . I wasn't aware of that thread . You got a lot of opinions . What did you wind up doing with the block ?

Mine will be a street motor. We have no tracks over here ....

[Joe-Touring]

Originally Posted by charlie66

Thanks for the link . I wasn't aware of that thread . You got a lot of opinions . What did you wind up doing with the block ?

Mine will be a street motor. We have no tracks over here ....

It’s still hung up at a machine shop. I think he’s putting it off since it has a cracked sleeve and needs to be re-resleeved haha. I just had a 400 done at another nearby shop so I’m in no rush. If the resleeve turns out good, my plan is to make it a low comp 87 octane truck engine. I’m thinkin a short fill with block filler and I’ll be a-ok.

[chiefbigb]

That's worse than any I have tested. The shop I do business with doesn't like to see anything under .125 at finish bore size. The block is your foundation. Starting with a weak one is probably not a good idea.

[charlie66]

Originally Posted by chiefbigb

That's worse than any I have tested. The shop I do business with doesn't like to see anything under .125 at finish bore size. The block is your foundation. Starting with a weak one is probably not a good idea.

Are you taking about Joes block or mine ?

[charlie66]

Originally Posted by Joe-Touring

It’s still hung up at a machine shop. I think he’s putting it off since it has a cracked sleeve and needs to be re-resleeved haha. I just had a 400 done at another nearby shop so I’m in no rush. If the resleeve turns out good, my plan is to make it a low comp 87 octane truck engine. I’m thinkin a short fill with block filler and I’ll be a-ok.

Do they make thick sleeves for racing like they do for the Honda blocks. You interlock them . I like that idea.. Did you sonic test the new block?

[Joe-Touring]

Originally Posted by charlie66

Do they make thick sleeves for racing like they do for the Honda blocks. You interlock them . I like that idea.. Did you sonic test the new block?

You can absolutely pop some big sleeves in your block, properly done, it should be much stronger than a stock block. I believe the interlocking sleeves on Hondas are because those blocks are open deck, whereas Pontiacs are closed deck. Main issue with sleeving is cost, if you do all 8 cylinders, you’ve probably sunk more on that block than if you bought an aftermarket block.

I’m sure the shop did sonic the 400, but I’ll need to look for the paperwork. Would be interesting, I’ve seen people say on here that 67 400 blocks have the thickest walls and webbing.

[chiefbigb]

At least around me blocks are still around. I would invest in another one.

[charlie66]

One thing i forgot to mention is that this block has a 4.160 bore. I think that's .035 over ..

I did this last minute after having it machined . Not the way to go about i know. But at least i know where the blocks at for cylinder thickness..

[Dragncar]

Originally Posted by charlie66

One thing i forgot to mention is that this block has a 4.160 bore. I think that's .035 over ..

I did this last minute after having it machined . Not the way to go about i know. But at least i know where the blocks at for cylinder thickness..

.040 over.
How much did this cost Charlie ? I have a .060 over 67 400 that I would like to get checked out.

[charlie66]

Originally Posted by Dragncar

.040 over.
How much did this cost Charlie ? I have a .060 over 67 400 that I would like to get checked out.

125.00

[charlie66]

Troy , if you get it done please let me know what the results are .....

[Dragncar]

Originally Posted by charlie66

Troy , if you get it done please let me know what the results are .....

No problem but I am not sure anyone around here does it. I will make some calls.

[Half-Inch Stud]

Odd thinness at the For/aft CYL clock positions. Nice sonic measure awareness.
Hard-block up to the water pump hole edges and freeze plug edges out to reduce CYL worries.

[chiefbigb]

Sonic testers are more affordable than they once were.

[25stevem]

I would much sooner do a half fill on a block for added support such as that with some questionable areas before putting in even a thin wall sleeve.

The main issue is that in hindsight that block should have been sonic check before the first bore job done to it and then the over bore could have been off set to maximize what was left for wall thickness.

[hurryinhoosier62]

Originally Posted by 25stevem

I would much sooner do a half fill on a block for added support such as that with some questionable areas before putting in even a thin wall sleeve.

The main issue is that in hindsight that block should have been sonic check before the first bore job done to it and then the over bore could have been off set to maximize what was left for wall thickness.

Steve, you don’t want thin wall sleeves, period! The thinnest wall sleeves we used were 9/32” wall (just over a quarter of an inch). Thin wall (3/32”to 1/8”) sleeves simply do not hold up. My basic block prep routine starts with a good cleaning, followed by NDT then an ultrasonic check of the cylinder walls. It’s always best to spend $125-150 on an ultrasonic check of the cylinder walls to ensure you have a useable block.