I have a '77 360, machinist is boring it now.
He told me .040 is not cleaning up one of the cylinder walls that got rusty.
Is it safe to take these blocked to .060 over?
I've heard bad stories about it.
Thanks all!

Wally.

77 , not without a sonic check.

What are the others cleaning at? .040 would be max on that from what I have read, if the others clean at less then sleeve that one hole.

My 76 360 has been .060" since the early 90s. Make about 450. Sonic is never a bad idea.
Doug

A better question would be how bad is the bad cylinder. If we're talking about small rust pits I'd say live with them. I've done it with no noticeable effects.

Also it is quite unnecessary to take the entire block out to 60 over if it only needs one hole to be that big. We're not building Formula One engines here, or Pro Stock. The casting quality of Mopar blocks is such that one hole may be quite satisfactory at 60 but others may not.

Don't remove more metal than you have to.

I know that pistons usually come in sets but singles can usually be had for off-the-shelf items. For example, Sealed Power pistons become singletons if there is a W in front of the part number. A set, H843CP becomes a single piston numbered WH843CP.

But the first thing to determine is whether you can live with the cylinder at 40 over.

R.

If you had a early block, I understood that they were cast with 340 molds and the cylinder walls were much thicker than the later ones, so a .060 bore could be used. I had a '77 360 that had been rebuilt and was .040 already. When I took it apart, I found one cylinder had been scored by a loose pin. It was easy to tell it would not clean at .060 and rather than spend the money to have the block sonic tested or sleeved, I scrapped it and salvaged the crank and heads for friends. There are lots of core motors out there to choose from.

Not worth ruining a block just to make it look new.

Me too. I ran a 2.2 Turbo engine with enough pits my machinist wouldn't guarantee his bore job. 100K later when I sold it that hole still had comparable compression to the other three.

My suggestion is that you weigh your cost options if this is not a race-only motor. If it is, get a new block.

Assuming this is mainly a street engine, these guys are all correct. Option #1 If you want to go all cylinders at 0.060" oversized, then you should at least check the cylinder walls (sonic test I think) to see exactly how much metal you have to work with.

Option #2 would be to just sleeve that one cylinder & run 0.040" oversized in all the holes. I know you could make just ONE cylinder 0.060" oversized and probably still get the balance right on the motor, but I'm inclined not to do that....maybe for no good reason.... but I'd always be worried about that one cylinder running a little hotter and putting out 5 horsepower more than the other cylinders....maybe it's just me.

Option #3 is find another block. If you get lucky, you might be able to run the stock-bore pistons you already have???

In all cases, you should bore the cylinders the least you can get away with, but all the same in my opinion. For all options, figure out what each would cost and go for it.

You guys have been sold a bill of goods by all the magazine writers and so-called "tech" guys over the years since you first picked up a Car Craft or Popular Hot Rodding or whatever. For most of them, the first requirement is to be able to write a simple declarative statement. No education of engine physics or mechanical design is required.

The engine is just a big stupid lump of cast iron. Well at least, most of them, including all of them we're talking about here. Yes, of course, taking pains to do things the right way will almost always result in a "better" end product. But where's the line between "good" and "good enough"? Chrysler engineers worked hard to figure out where the line was and that's why their balance jobs were the worst of the Big Three aned why they're the only ones to use cranks, lifters, etc with undersizes or oversizes.

Long long ago I met a guy Vern from Fergus Falls who had a dirt track racer. He'd blown his good motor and put together another out of all sorts of leftover parts. The pistons had come from three different engines and they were for three different compression ratios. The engine powered him to something like Third place. I was shocked that the engine would run at all. Somewhere in the back of my mind I didn't expect the engine to run at all, much less for a whole race.

NASCAR teams experimented with differences for individual cylinders. Dunnick has done some really interesting work with ignitions and can show that even the best distributor has around 4 degrees of spark scatter at high speeds. Lower quality systems can have 9 degrees of spark scatter. That's huge. Comp builds camshafts with different events for the outer four cylinders.

What I'm getting at is that pro engine builders don't feel the need to have everything identical.

R.

Rrrrrrrr! (new pirate movie).