400 block 383 bore

[racingsnake440]

My friend has a block with casting number 3698630-400 that has a 4.25” bore. Anyone ever see this before? Is is a service replacement block for a 383? I'm guessing it should be ok to bore to 400 size?

 

[dano]

Any factory stamps on the pan rail or ID pad? There should be notes for things like over/under bore, plus sized bearing(s), etc.

 

[Desoto291hemi]

That is not a 400 block I believe
Or check your mic a little bit closer .
That is a casting number for a 73-78 400 engine
But I can’t imagine that Chrysler made a 383 with a 400 mold
Check your casting number again also

Tommy

 

[Swingn’71]

For starters, what is the casting date ??

 

[YY1]

.030 over from 4.00 bore?

 

[PRH]

I'm guessing it should be ok to bore to 400 size?

Always a smart move to get the block sonic checked before boring it that far.

 

[Oldmanmopar]

I sold replacement warranty block in the crate for a 383 71 road runner. It is a 400 steel crank short block. Sold it to member 69383valiant. I believe it is still at the shop.

 

[Desoto291hemi]

It was a 400 block with 383 crank from the factory ?

sounds good to me

Tommy

 

[Garrett Ellison]

It wouldn't surprise me if there weren't a later military or industrial application that used a 4.25 inch bore.

 

[Desoto291hemi]

It wouldn't surprise me if there weren't a later military or industrial application that used a 4.25 inch bore.

That’s very possible

Tommy

 

[69383valiant]

I sold replacement warranty block in the crate for a 383 71 road runner. It is a 400 steel crank short block. Sold it to member 69383valiant. I believe it is still at the shop.

Yup still there somewhere. Here's the tag that was on it.

I sold replacement warranty block in the crate for a 383 71 road runner. It is a 400 steel crank short block. Sold it to member 69383valiant. I believe it is still at the shop.

 

[racingsnake440]

I checked the casting number and bore measurements multiple times because they didn't make sense. Think it was a '73 casting date. It has the 'hourglass' or infinity symbol looking coolant ports in the deck. I didn’t get any other numbers off the block, will have a look next time I’m there.
Didn't think of industrial stuff being different, that sounds plausible

 

[YY1]

Yup still there somewhere. Here's the tag that was on it.


View attachment 1716441512

Someone on FBBO is creating an archive of warranty block tags, hopefully to see if the tag numbers can be deciphered.

I've got two-1968 318 and 1976 318