Expected Piston wear?

Rubatoguy

Rubatoguy

Member
This piston probably has about 4 hours of use. Are the marks that look like scratches on the piston a normal wear pattern? The engine had been overheating to the point the starter could not turn it over.


Thanks,
Todd
 
Sorry - the photo did not post on the first try.
 

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How fast have you driven the car with this engine rebuild?
What was happening just before the engine got too tight to start? Car drivng, engine speed, etc.
 
Piston wear should be nil at only 4 hours of running.
As i mentioned in your other post take it back to the rebuilder if still in business and get it straightened out or money cheerfully refunded.
 
I'm certainly no expert on the subject, but opinions are like...well you know, so I have one.

If the engine overheats to the point of not turning over, there's been damage done. Maybe not catastrophic, but damage and any wear showing is probably not normal.
 
The story is that when the engine was received from the rebuilder - back in the 1980's it had a knock. Taken to a local shop who found the main bearings too loose and a rag in one of the oil passages. Also the oil pump shaft cracked. This was repaired, and after that the car would run for about 1/2 a mile before overheating. When you stopped. The engine would not turn over. After cooling it would start. I would guess it has been driven no more than 10-15 miles in total. Then left to sit for 25 years. I am tearing it down to see the condition before I have it correctly rebuild. I did have the radiator cleaned out, and the company reported there were lots of bits that looked like rubber in the radiator. All of the pistons have vertical scratches, but I am not sure if this is normal wear. (See other post with the JBWeld on the crank end bearing.) I do not know how to check, but it is possible that the crank is not centered within the bores of the cylinders.

Todd
 
"All of the pistons have vertical scratches, but I am not sure if this is normal wear."

it is not.

It was not clearanced properly
 
I would begin by accurately miking the pistons and cylinders, each piston for it's cyl. What do the bearings (Babbitt) look like?? If it's overheating and seizing I'm going with clearances rather than the cooling system at this point. JMO
Paul in CT
 
I read that the original specs was .002 clearance piston skirt to cylinder. This was with original split skirt pistons. Solid skirt pistons usually need .001 clearance per inch of piston skirt diameter. I'm sure that somebody will disagree but thats the way that I do mine.I've never seen a too tight engine last very long or run very fast.
 
Purdy, I agree with you on the piston/cylinder clearances. I don't think any of the old clearance specs should be even considered because the metallurgy and design of today's parts is so much different. Piston alloys are different as are the grinds, valves are alloys not plain steel as the originals were so original specs won't work with either. With this engine being built 25 years ago, I don't think any problems are going to be addressed by the original builder if he is still in business. Most warranties are to the original purchaser and for a specific length of time. Looks like a competent rebuild is in order. Unfortunately seems like the west coast is lacking in that anymore.
 
James Rogers said:
Purdy, I agree with you on the piston/cylinder clearances. I don't think any of the old clearance specs should be even considered because the metallurgy and design of today's parts is so much different. Piston alloys are different as are the grinds, valves are alloys not plain steel as the originals were so original specs won't work with either. With this engine being built 25 years ago, I don't think any problems are going to be addressed by the original builder if he is still in business. Most warranties are to the original purchaser and for a specific length of time. Looks like a competent rebuild is in order. Unfortunately seems like the west coast is lacking in that anymore.
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James, we have some good rebuilders in our area. Scheduling is a problem, and most are getting to an age where they want to quit schlepping engines around. But with patience one can still get a good engine rebuild.
 
700rpm said:
James, we have some good rebuilders in our area. Scheduling is a problem, and most are getting to an age where they want to quit schlepping engines around. But with patience one can still get a good engine rebuild.
Click to expand...
I will concede there are some good ones in the north west.
 
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