I took my engine apart to change bearings and the rear main seal and I noticed that the rods are a little tight at the pistons. now there stock rods and J.E. piston the pins are pressed on the rods. With the piston flat the rod won't just fall to the side you have to push on it to get it to move is this normal or is there something wrong last year I tore the motor apart and they didn't seem to be that tight before maybe one was a little tight but now they all are o No: o No:
Once I bougtht a set of used pistons with the rods attached.......3 or 4 of them were just as you described. When I pressed the pins out, only on the "tight" ones the bores in the pistons where the pins go through were galled..........needless to say I didn't use those pistons, I sprung for a complete set of new ones. I'm no engine rebuilding expert, but I would presume yours are galled also. :bglasses:
Assuming cold weather...What happens if you take one in the house? By warming the piston,I'd bet the pin slide freely.
If they weren't that tight last year you may have collapsed the piston skirts or bent the pins.There may have been some detonation on those cylinders.I would measure the skirts on the pistons and see if they have collapsed.Either that or like 10sec 350 said your pins were to tight and now they have galled the pistons.
I had 1 wristpin in an engine before that was too tight. In that cylinder there was wear on the side of the bore when the piston would smack the block, as the piston broke loose from the pin. When I took the engine apart it took some effort to move the piston on the rod, not good. I think your better off floating those rods then press fit. Jeff
With a floating pin I ran .0008" clearance. I agree to check the pistons closely for any skirt collapse issues and for galling in the pin bores. With a pressed pin you'd want somewhere in the .0008" to .001" clearance range, so I've been told. I like the floating pin set-up as it is friction free and easier for me to do install without access to a rod heater or press. I also used the double spiral locks over the snap ring set up. Of course with the floating pin you'll need to bush your rods, and not all stock rods will accept a bushing, need to check them carefully first. Which is one reason I went with the Crower billet rods. Gran Sport Garage
Take them apart. With any conclusion you come to, I would definitely take them apart and inspect them. There is something wrong and it won't last long if you try and put it back together like that. At least your catching it before you end up with a bunch of broke junk. :blast:
Yea i'm gonna look in to this more...the seem very hard to turn over even with the plugs out and i have been having problems with it at idle it wouldn't stay running under 1500 I thought it was the carb but starting to think it has to do with the tight pins.....I was going to bush the rods but that kinda sounds like your weaking them...so I haven't had any time to look at it more but going to pull the pistons out and check them over... If I get a new set of after maket rods what would be the best ones to go with??
I went with the Crower steel billet rods. I don't know how they compare as I didn't look at other brands. It was one of those parts swap things. But they are labeled their "mid-weight" versions. Good for 850 hp, they claim in their advertising. They are the stock Buick big end dimensions with a bushed small end. The quality of construction and finish is top notch, really a purty piece. 7/16" capscrews. 6.615" long. I'm happy with them and with my hp levels and intended use they shouldn't be stressed. But will allow me to build up from its current level, if I lose just a few more brain cells and decide to throw some more cash at it. :laugh:
Dubuick, The first thing you need to do is get that piston, pin and rod assembly out of your cold shop and into a nice warm area that will stay at 72*. Whenever a wrist pin is checked in a piston, the piston must be at room temp (72*) for atleast 48 hours. I have had pins that were extremely tight when I kept my pistons with my basement which is around 68*. The same goes for checking a rob bearing clearances on aluminum rods. If you still have a problem then you must find out WHY this happened. Was it detonation? Poor Oiling? Inspect the rod bearings for any issues. Good Luck
