1955 Olds piston cracks
#1
1955 Olds piston cracks
My 1955 Olds has 5 out of 8 cracked pistons on the vertical side of side of the skirt, at the height of the wrist pin, One of the cracked pistons had previously been replaced. all of the cracked pistons are cracked in the same area.
What is causing these pistons to crack? I am purchasing pistons from Egge,
Will i have the same problem? Are the pistons from Egge more durable?
Any information would be very appreciated. Thanks
What is causing these pistons to crack? I am purchasing pistons from Egge,
Will i have the same problem? Are the pistons from Egge more durable?
Any information would be very appreciated. Thanks
#2
Do you have pictures you can post? Have you or your machinist considered other piston mfg's? Pre-ignition is a piston killer, deposits or wrong spark plug heat range can be causes. Todays gas may require rejetting. A good race engine builder should be able to tell just by looking at your pistons what caused the cracks. Let us know if you find the cause. Good luck
http://www.enginelabs.com/engine-tec...tails-pistons/
http://www.enginelabs.com/engine-tec...tails-pistons/
#3
Dave,the 324 Olds engines were. Bad about that problem. We owned a used car lot and sold many '54-'56 Olds, and rebuilt several . It was my job to clean the ring grooves and inspect the Pistons for cracks going down from the wrist pin holes. You could pull pressure on the skirt of the Pistons on each side,and the crack would open up and be easily seen.
If they were cracked they would make a clicking noise when put in a strain on a hill.
At that time we never found any other Pistons that were designed differently. Best of luck, .The car I sold less than 2 years ago never had the problem ,but only had 51,000 miles when I sold it . Call Tony at Ross Racing. Good luck, Larry
If they were cracked they would make a clicking noise when put in a strain on a hill.
At that time we never found any other Pistons that were designed differently. Best of luck, .The car I sold less than 2 years ago never had the problem ,but only had 51,000 miles when I sold it . Call Tony at Ross Racing. Good luck, Larry
Last edited by Rocketowner; March 11th, 2018 at 01:37 PM. Reason: Add
#5
You are very welcome that I could identify the problems you are experiencing. I will say,that we closely inspected each piston for possible cracks,replaced the damaged ones ,but I can't recall any that didn't hold up well after putting new Pistons where the damaged ones were cracked. I am surprised that you saw the cracks,if you weren't accustomed to them giving a problem. Hope everything works out well . I searched online and was only find either 20 thousandths over, 30 over or 60 over,but didn't see Any standard size Pistons. Good luck, these were great cars. Larry
#8
To me it would be doubtful that a stock 324 with 8-1 compression would suffer from pre ignation with out having issues with the balancer or someone messing with the distributor. I would think probably a design issue or instillation problem at the factory would be more likely.
https://rossracingengines.oursafeserver.com
You might give Tony at Ross Racing Engines a call if anyone would know about this being a common problem he would know, he works on them daily...Tedd
https://rossracingengines.oursafeserver.com
You might give Tony at Ross Racing Engines a call if anyone would know about this being a common problem he would know, he works on them daily...Tedd
#9
Dave, you just might have hit on what your problem is if your engine is still standard bore size and you are just replacing pistons. If the cylinders haven’t been bored they are likely tapered from wear and the majority of the wear is always at the top of the ring travel where the pressure is the greatest. The same thing could happen if the engine was bored and honed a little too large. What has happened is that you likely have too much piston to bore clearance which is allowing the piston rock in the cylinder. This could very likely cause a piston to crack. I would suggest you have a machinist check the cylinders for taper and bore size then measure the piston for the clearance. Cast pistons are supposed to run very tight in the bore, some engines have an allowable clearance of slightly less than a thousandth of an inch, .001”. I would bore the engine to .020” oversize and get eight new pistons. Usually if you bore the engine to the exact twenty over standard size, the clearance will be correct as it is built into the piston. I’ll bet you won’t have any more problems if you do this. Also make sure your distributor is in good condition and the timing is set to spec. I would have the distributor run on a Sun machine and check the centrifugal and vacuum advance for proper operation. Too much advance can cause detonation which is really hard on cast pistons. I think someone above mentioned this also. Sometimes you have to spend more money to save it. Good luck.
Last edited by Fpcopo; March 13th, 2018 at 04:46 PM.
#10
I just found an article from Olds V-8's taken from an article from Wikipedia about the problem with piston skirts cracking on the early '55 Olds 324 engines. (Quote) For engines built during the first part of 1955 , the 324 skirted Pistons had a reputation for failing due to the cast aluminum skirt separating from thr steel interior braces .This problem did not appear until the engine had around 50 K miles. Sounds like the problem did not occur in the '54's, but the compression was increased in the '55 model. Larry
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