'65 396 Engine Cylinder Over-bore Max Size?

[James W.]

What is the maximum over-bore size for a '65 396 cubic inch cylinder bores. This is the original 962 block that the car was bore with.

Why I ask is that "Bubba" performed a .030" over-bore on the block back in the 1980's but all of the bores are not the same size for the pistons that were installed at that time. The engine uses a large quantity oil and I'd like to go to the next larger over-bore size or have custom sized set of pistons made based on the amount of material that needs to be removed to get all the cylinder bores to the same approximate size.

More info to follow on the approximate cylinder bore sizes currently.

Any advice help would be greatly appreciated.


Best Regards,

James West

[Guest]

Re: '65 396 Engine Cylinder Over-bore Max Size?

James,

1965 962 396's and very early 942 427's have plenty wall thickness. Those blocks can be identified by the ribs in front (right above timing chain cover) and on back. Also, you could get block sonic tested for wall thickness. This is where a reputable machine shop comes in handy. I would order custom pistons and bore block as little as possible.

[Patrick B.]

Re: '65 396 Engine Cylinder Over-bore Max Size?

You will have no problems. A 962 block cast no later than June or July 1965 (with ribs) has the same inner water jacket mold as a 427. It can be bored to at least 4.310.

[Richard G.]

Re: '65 396 Engine Cylinder Over-bore Max Size?

Bore the block and then order the pistons.
I did it the other way around and one cylinder didn't clean up.

[Dick W.]

Re: '65 396 Engine Cylinder Over-bore Max Size?

Seen quite a few bored .125 for drag racing. But then there is always the block that the casting core shifted. Like was posted, have it sonic tested.

[Joe R.]

Re: '65 396 Engine Cylinder Over-bore Max Size?

If it's bored at .030 now there would be no problem going to .060 but make sure that the machine shop has the pistons you want to use so they can be fitted during the honing process.
Remember the block can be sleeved if there is a problem.

JR

[Gene M.]

Re: '65 396 Engine Cylinder Over-bore Max Size?

I've never had anything bored and honed without having the pistons in my hand to make sure the fit was right. Any good machine shop will want the actual pistons that are going in.

[Joe R.]

Re: '65 396 Engine Cylinder Over-bore Max Size?

I've never had anything bored and honed without having the pistons in my hand to make sure the fit was right. Any good machine shop will want the actual pistons that are going in.

In total agreement with Gene!!!!!!

JR

[Richard G.]

Re: '65 396 Engine Cylinder Over-bore Max Size?

Ok, I get it....
My reference was to be sure the block will bore to the piston size. Especially a expensive custom size.
I would rough bore the block then order the pistons and then finish hone to size with the pistons in hand.
Ill take my wet noodle beating like a man....
The whole exercise was to bore the block as little as possible.

I would consider going to the next standard overbore if sonic testing proved the wall thickness adequate.
As many miles as these Corvettes get on them one might have to convert them to an electric drive before it requires re-boring again.
Rick

[Patrick B.]

Re: '65 396 Engine Cylinder Over-bore Max Size?

Ok, I get it....
My reference was to be sure the block will bore to the piston size. Especially a expensive custom size.
I would rough bore the block then order the pistons and then finish hone to size with the pistons in hand.
Ill take my wet noodle beating like a man....
The whole exercise was to bore the block as little as possible.

I would consider going to the next standard overbore if sonic testing proved the wall thickness adequate.
As many miles as these Corvettes get on them one might have to convert them to an electric drive before it requires re-boring again.
Rick

The Sealed Power or Federal Mogel 11:1 forged pistons are nearly identical to the TRW pistons that were original equipment. They are available in .030 and .060.