[mkube396]

I have had my block in storage and was bored one day and started to look at it. Well they said they line honed it and I went to take the caps off to look at something. They didn’t mill the caps I was reading that when they line hone the mains u need to mill the cap or it will just be making the bore bigger. Could they have been just small to begin with?
butt i here that the mains for the factory are big to begin with. is this right?
it is a BBC 402
I am going to borrow a bore gage what should the size be +/-

 

[Tom Mobley]

the mating surfaces of the caps should show to have been machined. The block won't. Personally, if the caps have not been surfaced I'd have a hard time believing it was align-honed. What do the surfaces of the saddles look like? should be fresh honed, not old bored.

 

[BillK]

MK,
If it was align honed, the surface where the bearing goes should look like the cylinder wall, with a crosshatch. They are bored at the factory and do not have a crosshatch finish.

 

[mkube396]

it does i put a pic up... it dus look crosshatch where the bearing would go but the caps have not been surfaced

 

[BillK]

mk,
I looked at your picture and its hard to tell. There are cap grinders that cut in the direction like yours looks, but most of them leave a curved pattern, like on the block deck. The main bearing bore should measure between 2.937" and 2.938" I prefer them on the small side of the spec.

 

[CNC BLOCKS N/E]

I would say they did not cut the caps and just line honed the block as it should be checked to make sure its no over size.

At our shop we line hone to the high side because if you don't some times they won't clean up at the parting line causing a complaint from the customer as we have found that 90% of the GM blocks are on the high side from the factory.

If the caps were cut they should have been cut on the sides as we lay the cap down and cut the side first and stand the cap up cut the bottom as it will be cutting 90 degrees. And if this is not done on the rear main it could put the thrust out of square the main line.

 

[mkube396]

well i dont have a bore gage yet but i was playing around with my calipers and i was geting 2.938 all the way around