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Old 12-28-2022, 04:30 PM
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Default Cylinder bore thickness

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
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Old 12-28-2022, 06:22 PM
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Originally Posted by charlie66 View Post
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

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Old 12-28-2022, 06:27 PM
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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

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Old 01-03-2023, 04:16 PM
Joe-Touring Joe-Touring is online now
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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.

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Old 01-03-2023, 06:32 PM
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Originally Posted by Joe-Touring View Post
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 ....

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Old 01-03-2023, 11:32 PM
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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.

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Old 01-04-2023, 12:09 AM
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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.

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Old 01-04-2023, 08:51 AM
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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?

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Old 01-04-2023, 08:52 AM
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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 ?

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Old 01-04-2023, 12:08 PM
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.138 on a standard worn bore 400 is the thinnest reading I have seen. I have checked probably 12 stock blocks over the years. The 455 blocks seem to test a bit thicker than the 400s. I have a 400 block with xx in the casting that is well over .200 everywhere.

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Old 01-04-2023, 12:15 PM
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At least around me blocks are still around. I would invest in another one.

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Old 01-04-2023, 12:26 PM
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Originally Posted by charlie66 View Post
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.

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Old 01-04-2023, 02:44 PM
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Quote:
Originally Posted by Joe-Touring View Post
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.
‘59/‘60 389 blocks have thicker cylinder walls, webbing and bulkheads.

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Old 01-05-2023, 08:09 AM
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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..

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Old 01-05-2023, 08:22 AM
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Quote:
Originally Posted by Joe-Touring View Post
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.
A friend of mine got a aftermarket block sonic checked and had some .170 - .180 numbers . I was surprised . So to me if you can beef up a stock block it might not be so bad . Seems like you never know what you're going to get even if it is a aftermarket block as well..

If you get any numbers on this 400 please share them .. That's why i started this thread , so i could compare my numbers to other blocks but it seems like theirs not to many people besides you and bluleghost...

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Old 01-05-2023, 04:29 PM
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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.

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Old 01-05-2023, 05:21 PM
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.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

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Old 01-05-2023, 05:24 PM
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Troy , if you get it done please let me know what the results are .....

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Old 01-06-2023, 04:21 AM
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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.

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Old 01-06-2023, 09:49 AM
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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.

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