Delayed 2024 racing season for the 43 Dragster.
This is what happens when you don't check, double check, triple check your own work and others.
Never made it to the track. This happened with just one hit in front of the house.
Two rods and one main bearing suffered damage.

Block and rods are saved. Crank maybe...

Yikes!
Sorry to see that Jeff.

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Hyper_pak

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Official Cookie and Mater Tormentor.

Dang, sorry to see that, Jeff. Best of luck on repairs.
Lou

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Home of Slant6-powered fun machines since 1988

Sorry to see that! What was the cause?

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Sorry, Jeff,

I have been there with that one in Ruster a few times.

Is that a Cast Crank engine?

Best of luck getting it sorted out.

Greg

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http://www.youtube.com/hyperpack

Greg: Yes, it's a cast crank.
Last year I built the cast crank version short block. Same pistons, a little bigger cam, same rods but narrowed to fit the cast crank, everything else the same as my earlier forged crank engine. I picked up almost 0.20 in the 60ft times. Yes, the cast vs. the forged made that big of a difference. That's almost 30 pounds less rotating mass. The energy to accelerate the 30 lbs. rotating weight can now be spent accelerating the car. The crank is an 84 version, the very lightest I think. Defiantly way lighter than an 83 I recently acquired. In my lightweight dragster, this weight difference is huge. Most dragster owners would have to spend thousands to shave off 30 pounds, little lone rotating weight. 60ft times are 1.40.

I ran that engine last year and made some of the best passes the car has ever made. I was running in the very low 10s. My goal has always been to be in the 9s naturally asperated. Late last year I lost oil pressure and found a wiped out #2 main. Bearing did not spin, but main cap got hot and shrank. Crank was now bent and would only clean up at 0.040 under, and those bearings are not available. Luckily I had yet another crank and acquired another main cap. I put my old forged crank short block back in the car and finished out the season. Block was fixed and new crank was ground 0.020. Put it all back together, added Ricks windage tray over the winter, and then this happened. (Lots of other stuff done to the car like full disassembly to powder coat chassis, reconfigured front end, shaved weight here and there, new steering box and shifter). Note, I never made it to the track. After getting the car running, I made a test hit on the street in front of my house. Fortunately, my neighbors love it. They are all gear heads. One hit and then lots of smoke out the breather, and 20 psi oil pressure.

Other specs. I am running methanol. Slightly higher oil pressure with a shim under spring at 60 psi. Valvoline VR-1 10W-30. Engine ran great and made some awesome passes, even winning at Bandimere before the #2 let go last year.

So, I'm doing something wrong. Wrong oil? Cast crank can't take it? My guess is bearing clearance. I never checked that. I'm a Manufacturing Engineering Manager in a machine shop. We just spent 1.3 million on a horizontal mill. I know better. I even have access to very high dollar gauges. But i never checked the clearance. And neither did my machine shop guy that outsourced the crank grinding. This is engine #4 for me and never had a bearing issue. In fact, that forged crank backup engine is now in dads car. Bearing look like new.

Some other issues: I've been asked by three people if I put the #2 main bearing in wrong. I sure hope I'm better than that, but I didn't film or take pictures, so I guess I could have. If I did, that's pretty amazing that the assembly lube lasted that long. Then there are the rods... As some of you may have noticed, these are Molnar rods, narrowed to fit the cast crank because only the forged crank version is available. No big deal for someone that has access to some nice equipment right? My machine shop guy noticed that the rod caps were not on the right rods. I never noticed, but each rod is actually serialized. I take great care to keep the caps with the respective rods. But during the narrowing process, each cap had to be notch for the bearing tang. I think this is when the caps got mixed. Three rods had the wrong caps, and two of those were the burned bearings.

Now, block is fixed with yet another new #2 main cap (lots of work on the block, so didn't want to start over with another block), rods are fixed with all big ends re-sized. 0.030 under bearings have been bought. We now know what the crank should be ground to in order to have 0.003 clearance. Changing oil to full synthetic designed to be run with methanol. May add an oil heater, defiantly adding an oil temp gauge. I probably could have caught the issue if I had monitored oil temp. Something that just came to mind. The blow-by on this build seemed more than what I'm used to. That was probably the hot rods and main cap burning oil.

So Rick: Cause? Hell if I know! But what I do know is this guy don't give up. I may have to go back to a forged crank, but I'll give it all I got.

Shoot me some ideas or comments. I don't know it all that's for sure.

Hope you got it figured out Jeff.

The motor in my car at Jeffers was a light cast crank. Mike loved them.

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Official Cookie and Mater Tormentor.

Maybe obvious question, but did you have the replacement main cap line bored/honed to the block?

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Charrlie: Yes. Did that. Both times very little material had to be removed. Thankfully the main did not spin.

Update: At machine shop now. Found a crack letting water into oil. People kept telling me the methanol was getting into the oil. It didn’t run long enough to get that much “milking”. That would explain the previous failure that transferred to second build. I pressure tested but didn’t do a coolant system leak down. Hate to start all over with a new block, but at least I have one if need be.

I might need to have an admin move this post to the engine page. Sorry about that. Kinda figured this is a racing engine topic and not so much regular street or stock rebuild.

Been there done that with Ruster too.
What is your bore size?

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http://www.youtube.com/hyperpack

Jeft I have inside and outside micrometers.
Not the best, but they work.
I check stuff going together.
But as a last check I use plastigage on rods and mains.
Cavemen I know but it helps me sleep at night.
You will get it fixed.

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Hyper_pak

Greg:
I'm running 3.485 bore size.

I have always done that too. But after purchasing a $50 dial bore gauge I will probably not go back to that. Why you ask. It is probably fine for 95% of the time. But the last crank I put in an engine I found that when I torqued down my mains the crank got tight and would barely turn. I had plasti-guaged all of them and they were all in the .002-.0025 range. In the mean time I got my dial bore gauge in the mail. I pulled the crank back out and reinstalled the bearings without crank. What I found was one main cap at the parting line had a tiny ding on the edge. It looked like someone dropped it on something hard and caused a tiny ding. But when the crank is bolted in that tiny ding which may have been .003 or .004 deep was enough to pinch the crank in that one spot. I took a small file and ground that tiny bit off and the crank spins like a dream. Truth of the matter is that no one puts plasti-guage in the parting line so it would never be picked up.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Another block acquired today. My plan is to build it back and make the best of what i can of the racing season. I had a schedule planned out, and I'll just jump right in wherever in that schedule I land once I get the engine back in the car. Best guess is a few weeks from now. Certainly want to make the Knoxville race.