The Stovebolt Site Forums The Shop Area Engine Shop Need Your Help Yet Again - Engine

You may remember my sad story. I bought this 20,000 mile 57 truck a few years ago. It ran great until I wore it out driving 80 mph on the highway. She was actually running ok when I took her apart but I wanted a hot rod and I wanted to get rid of those solid lifters.

I bought a 62 235 that had a powerglide tranny attached. I was told that it ran when removed but it smoked. I've had a few of those before. I took the engine to a professional (debatable) engine builder who replaced everything in the motor. He was suppose to have replaced the valve guides and hardened the valve seats too.

I had nothing but trouble with that engine. I could never get it tuned right and it had a violent vibration at take-off. I assumed there was oil on the clutch. Within a 100 miles or so, the mains and rod bearings were shot and I had no oil pressure.

I pulled the engine again, but the builder wouldn't honor his work because it had been over a year since he built it. (I took my time detailing the engine compartment and then it took a little time to blow.) I finally convinced them they should repair the engine.

I got the new build back (they weren't happy) a few weeks later and installed the engine. Since I wasn't sure what was up with the clutch, I installed a NOS flywheel and another clutch and pressure plate. I went from 9" to 11" (at least I think that's what it was). I had both flywheels turned before they were installed.

In less than another 100 miles the engine blew again. Again, I had vibration issues.

I took the truck and all to a different shop where it's been for nearly 3 months. I decided to have them diagnose/fix the engine and add a Tremec 5-speed tranny. Since they've had it, I've gotten 3 different stories about what happened to the motor. The first story was that the thrust bearings were wrong and that tore up the bearings. The second story was that the crank was warped. This week's story is that the engine is internally balanced and the flywheel is also balanced. The flywheel has to be fixed to make it neutral. The reason he claims the flywheel is wrong is that when the put the engine back in the truck, they had a bad vibration too.

Here's where you folks come in. What's up? What are your ideas about what's going on here? This guy builds pretty strong high-horse motors so we know he knows something about what he's doing.

Thanks for your help. I sure long for those days when I could jump in the ole girl and just cruise across town. It's been over 2 years since I could do that. Bummer!

So you say 'what do you mean hot rod?' It has an Offy 2x intake with Holley/Weber carbs, Fenton headers, and HEI. I did not do anything to the cam but she's getting a RV-like cam in this build.

Jerry,

I would be real worried with this new guy too! Until he lays the bum part on the bench and shows you exactly what is wrong with it, he is blowing smoke.

Stuart the Pessimist

How about the front pulley being out of balance? Did the engine vibrate just sitting still idling or did you have to be on the highway?

I'm not talking about a backyard mechanic that thinks he's building 500 hp engines. This guy holds drag racing records and frequently builds >1000 hp engines. I watched him dyno a 1500 hp hemi.

I suggested the harmonic balancer to him too. We'll see what he comes back with. I did bend the pulley hauling it and I straightened it as much as I could. The truck seems to idle pretty smooth. It's on take-off and highway speeds that I feel the vibration. I'm starting to like the harmonic balancer more and more as we discuss it.

yup once the balancer is messed up it'll never be right!

The balancer itself wasn't hurt. It was the pulley that was bent and I straightened it best I could.

I'm skeptical about the whole crank/flywheel thing. ALL 235 are internally balanced, and the flywheels are neutral balanced on these engines. If it had been a smallblock, I could see that error hapenning, as there are both internal and external balance smallblocks, but not with the 235. Also, the crank out of a 235 is pretty heavy chunk of forged steel (78 pounds, to be exact), and while I suppose it could get warped, I think that would show up pretty fast during assembly. I don't want to sound like I'm knocking the guy, he probably does know his way around a late model engine, but it just seems like he doesn't know the older engines very well.
I'm inclined to say balancer, too. There might be an issue with the crank as well, seeing as it did trash 2 bearings.

Well; it seems my NOS flywheel was out of balance by 6 ounces. It was re-balanced and I picked up my truck yesterday. I drove 30 miles home in traffic and a short bit on the highway. She did great. I think I could get to like this truck again.

6 ounces?! What did it have, a tumor? I'm not a mechanic but 6 ounces sounds like a lot to me.

No wonder it was vibrating.

"New" is not necessarily good, since you don't have any history of prior performance. Too bad you had to learn that the expensive way! Yes, all inline 6-cylinder engines are inherently balanced, although harmonic balancers and flywheels can change that situation. Good luck on the latest buildup!
Jerry

I was wrong; it was 8 ounces.

Maybe it was new defective. A mechanic installed it 50 years ago and it shook the whole car so he put a different one. 50 years years later someone finds it and sells it for NOS. We have stuff around our shop that was new defective and someone put it back on the shelf. Thank goodness we don't have anything they fit any more. 20 years from now someone might have hell trying to restore a 220 cummins with parts he found shoved in back of our place.