361 to poly 318.

[barbee6043]

That's 'mis-info' right there. You had better sonic test any block that you plan on taking +.100 out of or you could end up with a home made 'thin wall' block. The last 400 block that I had sonic checked had a pretty good amount of core shift in it and it wasn't to the good side either.

Maybe he meant the poly could maybe go that much over?? Dunno but like said, a sonic test is always smart.

 

[Cranky]

Maybe he meant the poly could maybe go that much over?? Dunno but like said, a sonic test is always smart.

Maybe....his exact text was...."All Mopar blocks can go +100 overbore they is super thick in the cylinder area!" Maybe he meant to say all poly blocks could go that far but that's not what was typed. Can all poly blocks go that far? I dunno.

 

[polyjohn]

Yes all Mopar blocks can go +100.

I did ‘not’ say for racing purposes, unless it’s been sonic tested...

Every block is slightly different and the core shift may be ‘good shift’ towards the compression/thrust side.

Some are that bad they are only Ok for +30.

440 source sonic tested hundreds of Mopar blocks and found they were all perfect for maximum overboring.

The Hinckley’s 426 Poly build was 0.130 over stock in a 318 block!
It made 550hp and that is mental.
They should have used a 340 block, but trusted their own knowledge to use a very underrated 318 garden variety block...

“Who knew”...

 

[polyjohn]

I just re-read my fantastic ‘Chrysler engines’ hipo book.
The first chapter being a 1959 361ci Plymouth Hot rod lol.
Bill Laroy had faith in his lowly 361 engine and went on a personal mission to prove everyone wrong.
No one would grind him a race cam, as they said in 1959 “it just ain’t worth the trouble”...
Then the mighty Iskenderian stepped up, and the rest is history...

“Why waste your time on that no hoper” was the cry!
So he proved them all wrong with a 150mph run at Bonneville lol...

But even more fun is the “half mile” Riverside dragstrip...
120mph @ 22.80 seconds.
My friends 273 Dart, could only do 22 seconds in the Quarter lol...

 

[Don Frelier]

That's 'mis-info' right there. You had better sonic test any block that you plan on taking +.100 out of or you could end up with a home made 'thin wall' block. The last 400 block that I had sonic checked had a pretty good amount of core shift in it and it wasn't to the good side either.

My brother has an industrial 413 block that was bored to a .060' over 440.
So that one was bored .100" and it sonic tested just fine.
But it was an industrial block if that makes any difference I think he has the heads with the water jacket connections on his shelf.

 

[33 IMP]

My brother has an industrial 413 block that was bored to a .060' over 440.
So that one was bored .100" and it sonic tested just fine.
But it was an industrial block if that makes any difference I think he has the heads with the water jacket connections on his shelf.

No offense Don, but j think your memory is faulty, or the jnfo you were told is.
413 bore is 4.187, .060 over 440 would be 4.380. I doubt many blocks will go .193 over (more than 3/16ths).

 

[Don Frelier]

No offense Don, but j think your memory is faulty, or the jnfo you were told is.
413 bore is 4.187, .060 over 440 would be 4.380. I doubt many blocks will go .193 over (more than 3/16ths).

I'll check with him but I believe what I said is correct total bore of .193" or something close to that.
I didn't believe him when he first told me that.

Here's what he texted me when I asked him:
413 truck block bored to 4.35. Sonic checked at 4 locations on each bore for thickness on all 8 cylinders.

 

[oldkimmer]

That’s a .030 over 440. Still a stretch imo. I have gas the LA 318s bored to 4.04. That’s .130 over 318 to make a 340. Kim

 

[polyjohn]

Quite common to over bore the 413 to fit stock bore 440 pistons!

But 0.130 over bore is a bit too much for my liking...

But if you have seen a 1963 427ci Ford block, then you know what ''thin-wall'' means lol...
They say +20 on those engine was a disaster waiting to happen?

But then we all know they were bored out 406's for the first few years of production...