39 B block

[36 A]

I scored a like new set of 4 11/16 +.045 pistons at the leseur swap meet . Has anybody ever bored a 39 B block that far ?

 

[Husker44A]

.045 isn't very much over. About two fingernails stacked. Now if you bore a block. 090 or. 125 over that's a lot. Yes the blocks can handle it with no troubles at all. A lot of times the machinist doesn't have to cut the full. 045 from the bore unless its a new bore. Only removes maybe .010 tho that's only. 005 off each side. With some elbow grease you can do that with a hone. Patience included. Good luck.

 

[teddy52food]

That block is only 4 & 1/2 standard. Not sure if you can go that far. The skirt may get too thin. And where would you get .010 pistons? They were only made in .045, .090 & .125 over .

 

[36 A]

4.5 bore vs 4 11/16 is 3/16 of an inch bigger + the .045 . I'll have to check it out .

 

[Anonymous-0]

Go to a shop that can sonic test a block. This will probably be a shop that does some hi-preformance work.

 

[[email protected]]

Contact Josh Blackburn, on the pulling forum. Or Ray at Extreme Tractor parts. They know the answer for certain, just takes a phone call. Im pretty sure you CAN do it, no need to sonic test. Im 100% sure you can do the 4,11/16" just not sure with 45 over.

 

[jd b puller]

Answered you on the pulling page.

 

[Supercharged 3800]

BULL$HIT no need to sonic test!!! Every block will be slightly different due to core shift, AND 70+ years of corrosion in the water jacket. I know of a early styled (1946) B that is 4.687+.045 and is fine. A sonic test is an absolute MUST on a block before boring that much. Even then, sonic testing won't be 100% certain because you could hit a small rust pit and run water into the cylinder.

If the block is nice on the water jacket side, 4.687+.045 will be fine. But if the block is really rusty crusty on the water jacket side, bad things might happen at that over bore. BUT YOU CAN NOT JUST BLINDLY SAY TO BORE IT TO THAT SIZE WITHOUT CHECKING IT OUT FIRST!!!!

But like Ray mentioned on the pulling board, the block is 1/2" longer so some math will be needed to make sure the compression will come out as desired.

 

[[email protected]]

Well as you've stated yourself- sonic test is NO gaurantee (I.E. a waste of time & $ in my mind). Around here it would need to be shipped off somewhere (more $ & time). He already has the pistons. So to me its faster , sensible, & cheaper to bore, pressure test & move on. "Bad things" would only be water in the cylinder or the oil. Not a catastrophe, & another block can be had for $100-150 all the time.


J