piston problems - need advice

[Ray Stewart]

1957 Silver Hawk partial flow 289 block 535801-P53824. Car has set for years but did start. Restoring. Pulled heads and found marks on block & some pistons:
piston 40 block 45 #1
piston no mark block 35
piston 35 block 35
piston 35 block 40
piston 35 block 35
piston no mark block 35
piston no mark block 35
piston 35 block 40
Does this mean the block has been bored? If so, is the mismatch typical? One cylinder is marked 35 and has pitting. Is it typical to have this mismatch piston oversize to block bore? Note that the very bottom of the oil pan & valleys between lifters have a thick gray paste which I am assuming is metal. SI catalog shows up to .080 over pistons but only .060 over rings. Based on the gray paste (there is a lot of it) should I try to find another engine-I do want to stay with the 289 Stude? If another engine is the way to go, any idea on who to contact to get one? I have looked at TW and vendors...haven't had much luck.
Thanks for the help.

Ray Stewart SDC
51 pick-up
57 silver hawk
62 lark

[jclary]

Ray, If you are active in your local state SDC chapter, how about getting some of your fellow members with rebuilding experience look at it with you? Nothing like being able to touch, feel, and smell it in order to form an opinion as to the status and evaluate the engine. As to the gray residue...it could be from some additive that has settled, moisture, etc. If you have dropped the crank, look at the main bearings. If metal shearing or other debris has occurred, you should be able to see some embedded in those soft bearings. Barring some untoward damage, like cracked cylinder walls, or maxed out bore, the block should be worth saving. Just be sure, if you do a rebuild, to replace the cam bearings and install a new fiber timing gear. You might get a lot of opinions on the forum, but experienced eyeballs on the engine would be best. Good luck with it.

John Clary
Greer, SC

Life... is what happens as you are making plans.
SDC member since 1975

[r1lark]

Ray,

Studebaker select-fit the pistons to the blocks. The numbers stamped in the block deck next to each cylinder indicate the piston size (in 1/10,000's IIRC) to be used during assembly. I believe the shop manual discusses this in the engine section.

Best thing to do is make a quick check of the bore diameters with a snap gage and micrometer to determine if it has been bored before.

The grey 'paste' may be lead deposits, which I think were common back in the old days when lead was used in the gas. One of the old-timers <G> like StudeRich will probably weigh in on this.

Paul
Winston-Salem, NC
Visit The NEW Studebaker Skytop Registry website at: www.studebakerskytop.com

[Mike Van Veghten]

Just fix what you have and don't be concerned about its past. Kinda like a girlfriend...leave her past as the past..!
.035 overbore isn't a problem.

Also, as far as parts availibility, pistons and rings are available from several sources in from .030" to .090" overbore.
Though I'd stop at .060" or .062" overbore.

Another thing to verify is if the crank has been ground too far undersize. Depending on the amount, there are fixes for that too.

This grey "paste" is just residue from old oil and moisture. Most likely nothing to worry about.
When you start to actually rebuild the engine, have the block and heads pressure checked for cracks. A few additional dollars, but well worth the effort on an engine with an unknown past.

You are doing what a million others have done, nothing to worry about.

Mike

Mike

[StudeRich]

Ray, everything you have said points to an ORIGINAL never disassembled engine!

The gray (ash) deposits are normal, and from 50's Oil and Gasoline.

The factory fractional over/undersize markings are also normal.

I would bet it turns out to be a STANDARD bore, possibly needing only honing and re-ringing.

One of the old-timers <G> eh Paul? [8]

StudeRich

[r1lark]

quote:Originally posted by StudeRich
One of the old-timers <G> eh Paul? [8]

StudeRich

I meant that in a respectful sort of way Rich!!

Paul
Winston-Salem, NC
Visit The NEW Studebaker Skytop Registry website at: www.studebakerskytop.com

[Ray Stewart]

Thanks for all your help! I feel much better about the engine now...it will go to the machine shop next week. Wife says I'm in a better mood now too!

I would belong to an SDC chapter but haven't found one in my area. I am near the TN line in Breeding, KY half way between I75 and I65...extreme rural and not near a large city. The SDC and forum does make me feel connected! Have met some good people at Shelbyville, TN last spring and Nashville, IN back in May.

Ray Stewart SDC
51 pick-up
57 silver hawk
62 lark

[StudeRich]

quote:Originally posted by r1lark

I meant that in a respectful sort of way Rich!!
Paul

I know you did Paul, but it still sounds...well OLD!

StudeRich