Engine Rebuild Specs

[55 Fargo]

Hi all, was looking tat the engine re-build specs on my stcuk spare 251 full flow oil pressure engine.

Here are the specs,

Remanufactured at Winnipeg Manitoba using the Chrysler Method.

11-02-1956

Mains Std

Bore 3-7/16, .030

Rods Std

I am seriously thinking of rebuilding this engine in the future, I have the head off it now, there is no cyl ridge, or scores.

If it was taken to .030, would that mean it was bored or oversiszed rings.

Just trying to see what I have here............Fred

[martybose]

It means that it was bored 0.030" larger than the standard 3-7/16" bore.

Marty

[Don Coatney]

That would make it a 255 CI engine same as the one I have in my Plymouth.

[Plymouthy Adams]

[quote name=

If it was taken to .030, would that mean it was bored or oversiszed rings.

Just trying to see what I have here............Fred[/quote]

boring the block .030 requires taking .015 of metal alway leaving you with a .030 larger hole..then you have to have a piston also .030 oversize and matching rings..most shops will require the pistons as the last few thousanths should be honed and have the correct piston to wall clearance to ensure that when hot will not sieze when at full expansion..don't ever take a block to the shop without your pistons already in hand..well. lets say take it for a check for what oversize you may need and then get them before the shop does the actual bore..

[Norm's Coupe]

boring the block .030 requires taking .015 of metal alway leaving you with a .030 larger hole..then you have to have a piston also .030 oversize and matching rings..most shops will require the pistons as the last few thousanths should be honed and have the correct piston to wall clearance to ensure that when hot will not sieze when at full expansion..don't ever take a block to the shop without your pistons already in hand..well. lets say take it for a check for what oversize you may need and then get them before the shop does the actual bore..

Tim,

I'll agree with taking the old pistons into the shop for checking what the bore is currently. However, I think it's best to let the shop supply the pistons after they finish boring. That way you are sure you have the right size because they bought them to fit the bore they had to take it to. If you buy them before they bore it, they may be too large or too small and then you'd have to buy another set. I let the machine shop supply my pistons and rings when I had my engine bored.

[Plymouthy Adams]

that my friend will be a mistake you will have to live with..the machine shops I deal with WOULD never bore without the slug in hand...that is the difference of throwing together a an engine or taking the time to build it at the specs designed for a longer life and non scuff on breakin..but hey again it is your block..fine line between break in and break down...sometimes Norm you need to do a bit of research prior to answering...read up on balance and blueprint..this will at least give you the idea behind hone finsish on re-bore..not saying you have to blue print an engine..and by the way that only means returning the block to the original tolerances (fit) from the factory..

[Young Ed]

Tim I imagine doing it norms way would work out fine as long as you had a competent shop. Afterall if you let them supply the pistons they would more then likely buy them and then bore the block to match when they arrived.

[Norm's Coupe]

Tim,

I was going to buy the pistons and rings myself first. After all, I had already bought all the other parts needed, except those parts and the valves. But...............following the advise of my mechanic friend who has worked at it since the 60's, building many engines in his time and working on many old cars, plus owning his own shop for a living, I'd be better off following his advise. He also picked the shop for boring the engine, shaving the deck and milling the head. That shop had also been around since before he I was even born. Something tells me those people along with the professional mechanic, knows a little more than I do or any of us backyard part-time mechanics do about building engines. So.........I let the shop supply the pistons, rings and wrist pin bushings like he told me to do. We did the install ourselves, except for the wrist pin bushings. They did that at the machine shop also. So........when you have competent people working with you and for you, you should listen to what they say. Plus, by doing so, I saved quite a bit of money because I also got his discount on those parts, and the machine shop work. FWIW, the shop only bored it 30 over.

Also FWIW, I never make any decisions like this or any other important decision without first checking it out with professionals in what ever field we are talking about. Especially when it's out of my professional field of experience. That's better than just going by a book that I may have read on the subject, which I also do. Only then is a decision made. So........I do my research when needed.

Not saying the back yard mechanics don't know anything, just that I wouldn't do something a back yard mechanic suggested unless I first checked it out with professionals, especially on an engine rebuild.

Maybe you need to find better machine shops that you can trust.

[55 Fargo]

So getting back to my questions, do you guys think that this engine could be rebuilt again, even though it was bored .030 already. I have no idea how many miles have been put on this engine after the rebuild.

The only thing I do know is the cyls have no ridges, the valve chamber had no sludge, the engine is eized, no doubt from sitting a long time.

There is oil in the engine, it has the full flow oil filter, that may have helped with engine wear.

Of all my engines, I think this may be a good choice to use for a future rebuild, as it is the 251, and has the full-flow oil filtration.

Maybe make a bit of flattie high perf out of this engine

[Tony WestOZ]

Strip the engine and find out why it`s seized.

Measure everything.

If the bores are OK. A quick hone will be all you need.

Pistons might be allright as well so a new set of rings might be all you need.

Back in their day 60th finished pistons were available as well as 90th semi finished ones, so you have a long way to go before the block becomes unusable.

[Norm's Coupe]

Fred,

Tony is correct. Sounds like you have a long way to go before you max that engine out with boring. Not sure I'd want to, but someone on the board mentioned something about going about 120 over.

That said, before you rebuild that engine you should have it checked for any small cracks in the block by a shop. I wouldn't trust it simply by just looking. Some cracks may be hidden or not visible to the naked eye. It's worth the extra few bucks to have it checked first. Otherwise you could spend all that time and money rebuilding it, only to find out the block wasn't any good to start with.