I took the pistons off of the rods tonight. The first thing that caught my eye is that the pin bore didn't have a bushing. I'm no expert, but everything I've seen so far has had one? I have no idea what the pin material is. I then removed the cap to inspect the bearings. The date on the bearings is 1-85. So I'm assuming the motor was built in the mid-late '80s. My question is, how long could these rods have ran before going bad without a bushing? I have the tooling to bush it, but I'm thinking I'm probably better off buying a new set. The make of the rods is Waterman(Mech. fuel pump manufacturer). Someone told me that Waterman used to make rods along time ago.
I've made 2 stroke rods out of 7068 aluminum that ran over 20,000 rpm that had no bearings on either end. .
alot of modern OHC cars dont use cam bearings in alloy heads and they dont seem to wear out unless theres an oil flow problem. never seen an alloy rod but i imagine itd be ok
In case anyone is wondering what motor I'm talking about, I'm building a 331 sbc injected nitro motor for my slingshot.
Full floating pins don't have bushings in the pistons. Why are you worried about the rods? Are you going to run this engine on the street? .
If you don't know the history of the engine, maybe you are better off replacing them anyway? [Edit] Even more so, now you mention you are building a nitro engine!
get new oners, aluminum rods only have so many passes in them, if you dont know the history of them make wall hangers out of them for sure.
I feel pretty dumb now. I have an old set of top fuel rods. I was watching TV and looked down and saw them. No bushings. I don't know what I was thinking when I was worried that mine didn't have any. The car won't be ran but 3 or 4 times a year. The parts that I have for it won't last to long either. I'm using a stock 327 block (lrg. journal) and a stock forged crank. It's going to be on a lose dose of nitro (40%).
makes sense i guess. aluminum is obviously "soft" and acts as it's own bushing or sorts. probably why a steel rod needs a bronze bushing. you don't want to hard materials wearing on each other. and i concur on the new ohc engines not having cam bushings. it's just cast iron on cast aluminum now-a-days.
ive heard in the early 60's of people running bonniville with alum rods and NO bearings, summers brothers siezed and engine running that way
Alum rods never had pin bushings. The question will always be: how many cycles have the rods been run. To trust a used alum rod is akin to Russian Roulette. If you know exactly the life history, then you have info for a good decision. If it's a maybe, what is all you're parts worth? So you have several of us that agree on not taking the risk.
Another vote for hanging them on the wall. I ran a set too many passes and turned a nice engine into scrap. A chunk of the rod got jammed into the cam and stripped out the timing chain. Bent 14 of the 16 valves. Piston came up and put a huge divot into the aluminum head, $400 to repair, ruined the crank, block and oil pan. Bent the cam and ruined the roller lifters. Huge window in the block. Lots of aftermarket rods for sale cheap these days. Buy some!!!!!!!
Somewhere I've got the remains of a Howards aluminum rod that came out of an old A/Fuel motor. The big end had failed but the pin end looked like new. Seem to recall the pin bore still showing the finish from being honed and don't believe there was any oil hole drilled in it. Do some of the T/F and F/C guys still change the rods after every pass like some of them did several years ago?
Are those the stock 5.700" length rods??? I'd build a length checker but I don't own a bridgeport.. Have them checked for stretch... If they still check in @ 5.700" in length, I'd run them... Also have them checked for hair line cracks using what I believe is called the "ziglow" method...
The Jalopy Journal
