Fuel Rods And Pistons

What do you guys usually do w/ rods and pistons that have 10-20 passes on them. Is it worth sending them back to GRP and getting checked then running again? I have a couple sets of GRP fuel rods and JE Pistons. One set has 8 passes, the others have 20.

Josh

 

When you say "fuel rods" are you talking A/Fuel or Top Fuel. Top fuel aren't getting "10-20" passes on them. More like 1 or 2. A/Fuel are getting, what 50 or more runs? If they were run with blown alky 25 would be about it for GRP's. A few more as long as you are watching the diameter of the ends and have a rod bolt stretch gauge.

 

Cracks in the pistons are just one thing. The only true way to tell the condition is with a hardness tester. Most forged pistons start at 72 to 80 on the "B" scale. From that point on, they will drop to about 50 to 55 on the "B" scale. This is where they will take a set and they're still good. When they drop below 50 is when you need to pitch them. I've seen many pistons without cracks, the skirts look good, but they were soft as butter. I realize a hardness tester isn't on everybodies bench, I'm just saying beware. 20 to 30 runs and I would change them out.

 

Tony,
Where do you take your measurement? Dome, flat part, skirt?
Thanks
Dave Koehler

 

What material are they made from ?

 

Anywhere on the top of the piston, the dome or the deck. Make sure it's flat, level and clean. Otherwise you'll get false readings. Take measurements on various parts of the top and you will see a trend. You can then compare the readings to your computer downloads (EGT's). Rockwell testers tell no lies. We always had guys telling us that the piston just blew up for no reason. We would have them mark which cylinder they came out of so we could translate back to the customer what the problem was. Before you knew it, they came back saying, "Oh yeah, I found the problem".

 

I believe they're "top fuel" rods, they're monsters. However this guy was running them in his pro mod on alky. Isn't that common to run the fuel rods in an alcohol car?

 

What are you planning on putting them in? Also, I'd ask why he changed a set after 8 runs. Most people (IMO) will go around 15 runs (at least) before changing rods unless something happened during run, but didn't result in rod failure, like hitting the rev limiter. In those cases, or others like that, they might get changed just to be on the safe side.

 

Maybe I should back up a little. Bought a 526 hemi w/ brad fuel heads from a guy. It came w/ new rods still in the box, and another set of rods w/ 20 passes that were sent and ck'ed by GRP. And the set that was in the motor (bought it assembled) has 8 passes on them.