We were putting together my buddies SB Ford stroker yesterday. He has a brand new set of GRP aluminum rods, bought directly from them. We both think they are messed up. Measuring the big end, with the bolts down we got a variation of 0.0007" between the smallest and largest big end diameter. We even installed them and used Plastigage to confirm our measurements. This seems way off to me. Obviously, it's not possible to get the bearing clearance right with the rods that are way out of spec. Shouldn't the tolerance be ~0.0002"? We are calling GRP tomorrow. Just wondering what people thought.

BTW: they f'ed these rods up already once by sending us rods with a Chevy big end bore. I have never heard of a problem with GRP, but two bad sets out of two???

Rich

 

Ya - .0002" is the accepted value. Did you measure for taper or bellmouthing?

With sunnen's diamond hone system you can keep .00001" straight and .00015" roundness tolerances...I want one lol.

 

Yah, I was thinking it was .0002". We only got so far as measuring the bore with a bore gauge. It seemed so far off that we re-checked with inside mics and then Plastigage. I think I am just gonna say "send me a new set and check them beofre you send them out this time". Kind of dissapointing in a $900 set of rods, to say the least.

Rich

 

Ya need to have the correct crush on an aluminum rod to keep the bearing in or ya need pins which isn't a bad idea.
They distort more than a steel rod(ya probably know that) and need the proper dimensions.

 

Talked to GRP yesterday. They make these rods on CNC machines and check them with a "go-no go" type of gauge. Guy was incredulous, more or less said "impossible" but they are paying for shipping for them to go back and be inspected/made right. Having had experiences like these in the past, I have made a "secret mark" on the bad rod. That way, if they decide to send a replacement but won't admit the first one was wrong, at least I will know that I can measure rod bore/bearing clearance and was not hallucinating.

Rich

 

Well, was my face red. We found the answer, which was a mismarked cap!!!

Rich

 

GRP will be glad to hear that, I'll bet.

I'm impressed that you fessed up here in front of everyone. Not everyone whould be so forthcoming.

Thanks, Rich.

 

I will say, in my defense, that 'twas my buddy, not me, who marked the caps! GRP's incredulity was warranted! We were appropriately contrite on the phone with them.

Like "oops, sorry, must have taken an extra stupid pill this AM".

Rich

 

Better safe than sorry, and it never hurts to eat a little crow once in a while. I'm glad everything worked out for you and your friend. That's all from the peanut gallery for now.