Hot Rods 265 SBC Maximum Overbore?

My '55 265 block is out for rebuild. It is currently .060 over. I need to overbore one more time but am having trouble finding piston bigger than .060?
Anyone know of a source or ideas?

 

.125" and use standard size 283 pistons.

It's an idea, probably not a good one, unless you have the block sonic checked and make sure the cylinder walls are thick enough

 

I think they will go 125. Wouldn't that put you in at a standard 283 piston?

 

Man he's fast.

 

Yep. Here you go. http://www.jalopyjournal.com/forum/threads/265-chev-125-bore-283-doable.373977/ Jack E/NJ

 

I'm told I can keep the .60 over as they honed it but it would not be as tight as a fresh .060 overbore.
This engine gets about 1000 miles a year and I'm not a lead foot.
So, I'm torn between just putting it back together as it (.060) or go the .125 with 283 pistons.

Also, I need a new cam. I have had info that I do not need that slot at the back ground into it as it was explained to me the oil is going down from the top end not up?
If that's the case....why did Chev put it there in the first place?
Anyone have info?

 

For only 1000 miles a year knurl the pistons put it together with new rings and it will last longer than you will.

 

I wouldn't even bother knurling the pistons, just roughen it up, new cast rings, and go.

But I am a known cheapskate.

 

Thanks

 

If you can get .065" rings which would be "file to ft" that would help too. Good luck.

 

I can probably find .080s for it but if all you are doing is freshening it and it is on the outer edge of being loose get a set of .060 forged pistons and hone to fit.

A lot of them got punched .125. The original 283 block was not a 283 speced block it was a punched 265 block.

 

beaner,
if you can find a source for .080's along with rings, I'd take them.

The engine shop thinks that the .060 over has already been honed as there was next to no ridge and they think someone already took care of it previously thus now leaving things loose!
I sure don't want to pull this thing apart shortly after doing a "fix".

 

Back in the day, when we didn't know better, we'd just bore them for 283 pistons and go ahead. Never had a problem.

 

>>>I'm told I can keep the .60 over as they honed it but it would not be as tight as a fresh .060 overbore.>>>

>>>The engine shop thinks that the .060 over has already been honed as there was next to no ridge and they think someone already took care of it previously thus now leaving things loose!>>>

Yeah, I think you said essentially the same thing before. So just throw the new rings in there and go. It'll be fine. Jack E/NJ'

 

you have to have agrove in the cam or yhe lifters wont get oil

 

rails32
that's the message I've been getting from everyone but this one older fella here who was a GM mechanic.
I think I go for the grove.

 

doesn't the machine shop have a dial bore gauge, so they can measure the size of the bores, and the taper?

If the taper is under 5 thou, it will last a long time, if it's under 10 thou, it should last long enough if you only drive it 1000 miles a year

 

I'd probably be more worried about the oblonginess measurement myself. 8^) Jack E/NJ

 

Yes, most are 2 with one cyl at 5.
I have all but one of the 60 over pistons as one had a very bad skirt crack and came apart when removed.

So, it seems my options are:
Purchase one 60 over piston, ring and reuse everything or.....
Find 80 over pistons/rings or.....
Get a set of stock bore 283 pistons/rings take it to 125 over

 

I would put in one new piston, and a new set of rings, and be done with it. But like you said, you have several options.

 

I'd think that with .005 or less wear in the cylinders, the engine would be a prime candidate for deglazing with a bead hone and a re-ring (maybe new pistons if you were worried about it). I'd be more worried about dropping into a water jacket with a .125 overbore than I would with a re-ring not holding up.

And on the camshaft/oiling deal, I think the early smallblocks had a flat machined in the back journal. It was the early big blocks that used a full groove. Although a fulling grooved journal on a small block cam would probably work. Might think about grooving the distributor housing while you're at it.

 

Well thanks everyone. I appreciate the help.
Sure can't beat this place for help!

I think I'm going with my option A.

 

Larry you are correct on the camshaft. Flat on the rear journal.

I have pulled grooved camshafts from small blocks but I am sure that they didn't come that way from the factory. There actually was an aftermarket cam that cam grooved and it was advertised grooved for better oiling.

I would check cylinder wear before I decided that an overbore was necessary. Bores straight and round gets you half way there, straight and round and within tolerance and you are golden. I have run more than one SBC with sloppy bores and file to fit rings, actually when that car was newish (into the later '60s) you could buy rings for them in increments of .001 up to about .005 over. You honed 'em and filed them to fit and drove them, it was common.

Another trick if you don't want to go to forged pistons is to coat your existing pistons. speed coating pistons adds a little to the overall size of the piston and is sometimes used by the low buck guys to freshen one without boring it. Its kid of like new millennium knurling.LOL