conrod replacement time?

ClayGlover · Jul 10, 2003

what would you consider the out-of-round limit for rod bushings? specifically i'm checking a mac 21 rod and the lower bushing ID is .199 wide and .202 tall. about .003" taller than it is wide from use. not sure of the history of the motor, i got it second hand. is it ok? the crankpin measures little, if any wear.

also, is it safe to re-use wristpin clips after removal or no?

Ian Inverarity · Jul 11, 2003

Clay,

I have read somewhere that if you have more than 0.001" out of round it is time to replace the rod!

As for wrintpin clips, I personally re-use them, but have heard that I shouldn't!! :- They are generally not that expensive, it may be good insurance to use new ones.

Ian.

missbudpilot55 · Jul 12, 2003

Clay, Ian is correct anything past .001 is considered excessive wear and it should be replaced, don't put it off til later as you will be junking what could have been a very good motor. Conrods are inexpensive compared to a new motor, conrod will usually crack the case, bend the crankpin, not to mention the piston and sleeve. "Replace the wrist pin clips every time you remove them, cheap insurance that one will never fail."

"BEEN THERE DONE THAT" 8)

Bill D.

paul heuston · Jul 13, 2003

just to help. not that i am an engineer.

if you think it needs replacing change it or show it to a boater you can trust..

i have snaped 3 picco rods 2 from not running properly and the other from not loking after it ...

paul

deatroyer racing.

picco destroyer

p.s. i have a blown picco 90 w/out. piston.liner and rod.

EatMyShortsRacing · Jul 13, 2003

If in doubt replace it!!!!

And dont look at my Rossi 21 coz I reckon it has 5 thou movement in almost every direction...

Guess what I am replacing when I get home???

EMS Racing is that a Picco Rod on my key chain???

nitrotoys · Jul 14, 2003

YES Replace the wristpin clips, there a couple of bucks, and if you loose one cause you didnt do it in a new rblt engine, it may damage engine again.

you'll kick yourself if that happens to you, we have all cut corners once or twice and have learned.

TimD · Jul 14, 2003

I always replace the wrist pin and clips if I'm replacing a rod. I also check the pin boss in the piston at the same time. Not essential I guess but I know they are all OK.