left and middle came out during brake in and the bosses are cracked now. a real puzzle on the rod with the piston missing. pin looks in stock location. pins are tight on all three now and all looked good when installed. tops on remaining look good. head in that cylinder took a beating. started with a small tic like a hyd. lifter. new something was not good. after checking everything and everybody's suggestions and removing the pan it was still there. i run a crower solid cam so i knew it was not a lifter noise. started it up and it blew in about 2 seconds.
wrist pin education
- Thread starter denny
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don't know but i noticed that to. all the rods had the weight in grams, i think, written on them.
This why I let the shop do the short block assembly. That way if anything is amiss or needs adjustment- they can just do it rather than me dragging it back. I have assembled engines too but with what things cost these days I will let the experts do it- with a guarantee.
'came out during brake in process' - hmmm? How do you know that? Did you tear the engine down prior to it destroying itself?
'pins are tight now' - how tight? Press them out and measure the little end bore and pin to see the amount of interference. The fit has to be loose IMHO. Perhaps someone can help me out here, but IIRC there should be approx 750-900 lbs of pressure needed to press the pin into the rod. Also, how tight were the pins in the pistons? Did they pass the gravity check of holding the rod at 45 degrees and then rotating 180 degrees and the piston falls to the rod?
Lastly, if you didn't have piston to valve or head contact, then this is nothing that you did. Again, my opinion. But if what you're describing is 100% accurate and this happenned to me, then the guy/machinist I use would step up here.
Could really use some more pics to confirm - head surfaces, bearings - both rods and mains, bore (unless undamaged) and piston tops and skirts.
Jim
inspection of parts for was done before assembly was done by myself and a couple of my career mechanic friends. pin inspection was eyeballed and not taken apart to measure clearance. piston to valve clearance was good to go. was never a problem with dish pistons and not a real wild cam. engine was sent to scrap. when you gather all your parts up and have the machine shop do their thing and take your stuff home and assemble it yourself your on your own around here. like i said earlier this was about a five year process where i would buy parts when i could (eagle crank,resized gm rods,crower cam,summit pistons (kb),new valve train,summit intake, edl,carb). myself and my lifetime car friends have been doing this for 50 years and nobody can believe what happened here. this was my retirement project. crank,bearings,and rings looked perfect. this left a bad taste in my mouth, won't use this machine shop again. assembly was done about 2 years after work was done when i retired.
hindsight is always 20/20. i'm lucky to have some career mechanic friends around here and engine assembly was never a problem. but yes,warranty is always very good.
won't risk anything again,,,,that blueprint crate engine runs fantastic and it has a WARRANTY lol.
after all the smoke cleared (no pun intended) it looks to me like the small end on some of the resized rods were not good and the shop never verified this when they put the pistons on. when you have a shop do this work you assume they know what the clearances are on everything they do. had a few things done at this shop before and always did good work but never again. i'm sure other guys have had bad experiences from machine shops that was not discovered until something went to hell. still don' know why that piston blew and the pin is still there. will probably see the shop guy at the track sometime and i'll let him know what happened. i know what the symptoms of a loose wrist pin is now.
Total mess - obviously there was improper clearance for the pins to move - Thought you had new rods but who ever re-sized them is at fault. Were the piston bosses cracked?? Might be another problem and the reason for the piston hitting the head and blowing apart(cast pistons). Is there any contact with any of the other pistons?? Is there any witness marks of valves hitting the pistons?? Seems like something else going on besides the pins.
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