Big Boys Toys

Twin 502 Crate motors,
Both installed at the same time with the exact same equipment.
One motor had a catastrophic ring failure throughout all cylinders.
Had three different engine people look at and got three different opinions.
1) Looks like ring failure due to contamination according to one guy.
I asked contamination from what, he said just plain dirt, did not make sense to me I change my oil faithfully every 15 to 20 hours.

2) Second guy says looks like ring failure possibly from excessive fuel, cylinder wash down.
This did make some sense but why would one motor fail and not the other, and he commented it could be the powers valve in your holley that failed. This could be a possiblity ???

3) Third guy who has done some work for me in the past and done a fine job, was somewhat stumped, but drew up a little sketch of what the compression ring looked like and forwarded it to his ring tech guy and they came back and said the failure was caused by bad fuel and the motor failed because of detonation.

My response was, why didnt the other motor fail, is has great compression, and is burning the typical amount that any 502 does with forged pisions. Both motors run on the same fuel tank???

Motor condition after tear down was all cylinders had suffered ring failure and scratched all the cylinder walls bad enough that a basic hone job may not clean them up.
Does anyone know how much you can typically remove by honing???

Thanks Brian

Dave F

Most engine builders like to bore well with in .010 of final bore berfore they start to hone.
Usually .005 to .007.

As far as one motor failing and not the other. It could be the too much fuel thing or maybe you had a leak in the intake and leaned it out. Just trying to throw something at you. It obviously is in that motor, and not a common thing like bad fuel.

Maybe those particular rings could have been installed incorrectly from the factory.?

Let's see what the others have to say.

DAVE

liquid lounge

Since all 8 holes were stuck....let's narrow it down a bit...
what did the chambers look like? Piston tops? Where did the pistons score the cylinder wall; ring lands I assume...what about the piston skirts? A long shot bet at this point would be a ring butting or clearance [piston to wall] issue...not that unusual for an automotive "crate engine"...not that unusual for a typical automotive hi-perf machine shop!!

Vinny P

Can you post a few pictures of the damaged parts?? A picture is worth a thousand words.

Big Boys Toys

Liquid Lounge
The chambers or cylinders had scratches in all, may need to bore the block.
The piston tops looked fine no skuffing at all, but the skirts did show signs of very slight skuffing.
The cylinder walls had scratches in each cylinder.
The bores measured 4.665 and were all the same. The cyllinders were pretty round top to bottom.
Crankshaft had a few minor scratches, so I had the machine shop polish the crank, I figure I should toss in a fresh set of main bearings and rod bearings with a new oil pump while I am at it.
I have not way to post any pictures.
I have a sneaky feeling that I may have run the boat too hard for approximately ten minutes before I really had the motors broken in. I may have heated the rings up enough to cause them to loose there tension and from that day on my oil consumption did nothing but get worse.

Thanks for posting.