Aluminum Rods How Many Runs

We run a 526 BAE (Brad 5) in Top Dragster. 1471 Rootes @ 34% over, 23 degrees timing, & turn it to 7800. Car runs easy 6.50s @ 215. What would be an acceptable rod change interval.

 

I'd say no more than 35. We run a Brad 6 motor with an 8-71 PSI H.H. and we change them at 30-35.

Brandon

 

23deg @ 7800 should live a LONG time! But rods are cheap insurance and VERY expensive when they exit the block!

 

That seems like a pretty mello tune.I would go atleast 50 passes inspecting them every 5 passes.I run a dart big m block with c&a rods with a 1471hh at 45% and 32 * of timming at 8300 rpm's and go 75 and have had real good luck.It sucks to throw away $1000 when they still look perfect but,its what you have to do. What kind of rods do you use?I had bad luck with Brooks.

 

RPM and recipricating weight (pistons, rods etc) are the 2 big contributors to rod life. The rest has its effect also but it's not as substantial.

My experience, theirs definitely a difference between Chevy and Hemi in rod life. Piston weight is what I think it is.

 

gregl...........Rods are Brooks.
SoDak..........Are you saying Hemis are harder on Rods than Chevs

 

If you run a 526 with a 14-71..and you run brooks run the b2 rods..we cycle ours out every 20 to 25 passes.Dave

 

Racer 360
I do. In tractorpulling a run lasts about 12 seconds and the RPM is pretty well maintained, for instance, if I could make every run at 7500 RPM I would.(track conditions vary this) So basically thats 12 secs at 7500 RPM.
With that being said I think our "run" is probably equal to 2 runs on the dragstrip.
The #'s posted here back that up. The hemis we run against change rods every 15-25 runs, but the chevys go way longer. I change them at about 75 runs and the last time we broke one was in '95, and that was from an oiling problem/brg failure.
What is a typical bobweight for a modern day hemi?

 

Does anyone manually check the rods anymore? We always do a teardown after a meet and check little end, big end, and center to center. If it's out more than .0018 on the big or .0010 on the small or crushed/stretched more than .003 we take them out. Haven't lost a rod since 1995. I wish we could find a cheaper rod checker that I could afford:$1200 for a fixture is a little steep when you need lots of other parts.

 

We run our GRP rods 20 runs, check them, and then put 10 more on them. After that they become souvenirs. This is in a 510 ci hemi, 8-71 at 65 over, 20% nitro motor around 8400 RPM.

 

Hey JT, are you running a F6 injection hat from Jeff Fagala?

For the record, we've run Childs&Albert and BRC but Howards are definitely our #1 choice. Don't have beef with any of them, but have never had a problem with Howards so why change.

 

That is one of Jeff's hats. I'm trying to talk him out of a new carbon fiber one for this year.

 

Why does GRP and BME tell everyone 50-60 passes?
I just pulled my BBC down today and everything looks good after 25 passes.
I'm going to put fresh bearings in it and run it on the dyno then put in a new set of GRP's so I'm fresh for this season. What do you guys think?

470ci BBC,11.5:1,BME rods,hemi pin,14-71 Littlefield@25 over.shift @ 8000rpm

I was thinking 30-40 passes tops out of a set?

 

we had a set of rods in our 526 BAE/TFX 8-71 turning 8200 56% overdrive and was changing them about every 35-45 runs. Last set we had in it, found a crack on the rod cap where its machined out for the bolt head. (brooks b2 rods). This was after 18-20 runs. clean runs at that (no pedal or shake) anyone ran into that before??

 

2700 bob hemi b2 brooks 40 pulls and out what about heat ,say pulloffs play a role in rod life?? thoughts ??or does the rod only get so hot?

 

I was wondering the same thing. MGP told me at 50 to send the rods in for inspection, then put another 25 passes on them and use them for clock holders.

 

How many runs?

I get asked this question more than any other. The answer is "it depends".
It depends on RPM, stroke, bob weight, tune-up, oil supply, and proper installation among other things. Typical NHRA TAFC should get 15-20 passes. TAD (blown) 20-30 passes. TAD (nitro) 50+. NHRA Blown Pro-mod 40-50 passes.

Brian Scollon
GRP Connecting Rods

 

Brian's rods, TAFC NHRA, 10,500, usually 20 passes, take 'em out and give them to kids at track, no holes in block(knock on wood).

 

You guys are going to think Ive lost my marbles, but back in 1979 I ran a set of BME aluminum rods 250 runs in a 531 Arias Hemi Chevy in my altered. I don't remember the bob weight but it was plenty heavy. I raced Top Gas West and bracket one at OCIR and everywhere else with it.

It was carbureted (two Holley Dominators) and ran 170 miles per hour shifting it at 8,100 (3 speed turbo 400). Compression ratio was around 11:1. The engine was put together to make a lot of laps in an effort to test Nick Arias new hemi's Chevy valve train life

Don't believe me? Ask Dave Calvert at CP Pistons. It was his engine. At that time he was the piston engineer for Arias. Steve Montrelli's "Bomb Shop" put it together.

Some day I'll post a picture.

Randy