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Discussion Starter · #1 ·
I waited a long time for my 496 build only to have it fail. It is a 496 with 13-1 compression. Rotating assembly was new except for crank. It was std on mains .010 on rods.New ud harold/lunati solid roller with new comp lifters.Heads fresh from machine shop.After bringing it home clean,i rewashed everything myself to be absolutely sure.When i cranked it,it had 60 lbs oil pressure idling 25 when hot.Thats exactly what the old 454 was with no problem for several years. I ran it some in the shop and drove it a few miles. Every thing seemed ok.Took it to the track,done my burn out,staged and left the line and my shift light never came on. Looked at my tach-5800 and not moving then to my oil pressure 10. Loaded up ,came home,tore engine down.It had a spun rod bearing,all the other crank bearings just fell out of the block with no tension.Three spun cam bearings and a ruined 400 dollar cam.Lobes are perfect as are the lifters.Plenty of oil up top.One very peculiar sight is the combustion chambers and exhaust ports which were polished when assembled.They are so rough and it feels so gritty almost like pool sand.Tops of pistons same way.No damage to any of this ,it just scrapes off with fingernail.Can anybody help diagnose these multiple problems?I got one good thing out of this and that was the feel of the holeshot with the left front wheel up 8 inches,but it wasnt worth what i spent!
 

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Can you post some pics?
 

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66 El Camino 57 Chevy pickup 2004 Tahoe
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What Gary said. What fuel were you running? Fresh stuff? Total timing? 13:1 doesn't leave the margin for error that lower compression does.

Probably it detonated, killed the bearings, trashed pumped through the system got in the cam bearings.

The sandpaper type texture on the tops of the pistons is the giveaway.

Need to do a detailed analysis of the cam and ignition timing. What distributor are you running?
 

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Did someone, maybe the machine shop, glass-bead the intake manifold and not wash the runners out thoroughly with brushes and blow them out with compressed air?

I've seen that happen before. Abrasive glass beads through the entire top end of the engine. Not good.



Randy
 

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Discussion Starter · #7 · (Edited)
Initial advance is 20 total 36 in by 3000.108 octane fuel cam was a 107 set up at 103 charging my camara batteries now trying to get some pictures up. The fuel in question came from our local speed shop
 

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66 El Camino 57 Chevy pickup 2004 Tahoe
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what type of damper and timing pointer are you using?

And what pistons?
 

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Discussion Starter · #9 · (Edited)
I was afraid this was gonna come up. It's a cat sfi approved 6 inch damper.Pistons are srp pointer is homemede but i found tdc with a dial indicator so i feel ok about that
 

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66 El Camino 57 Chevy pickup 2004 Tahoe
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you shouldn't feel ok about that, there's likely error there but probably not enough to cause the problem you have. There's several degrees rotation near TDC where the piston barely moves but the crank does.

Have you torn down the short block already? It would be worthwhile to re-check the timing marks using a positive stop type deal. You can use a real short bolt in a head bolt hole with a large diameter washer that will stop the piston. From some of your responses so far I have a feeling you already know about this, but a guy has to cover all bases when there's a catastrophic failure.
 

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BTW, you $400 cam is not ruined. The journals can be spray welded and ground back to size or just welded and ground. There's ways to save the journals, it's the lobes and gear that count.
 

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BTW, you $400 cam is not ruined. The journals can be spray welded and ground back to size or just welded and ground. There's ways to save the journals, it's the lobes and gear that count.
Talk to Delta Cams (Google them).

They can fix damn near anything, and they're reasonable. Good folks, too.

They even cut the whole back journal and gear off a couple of my older billet rollers, and installed the cast gear and last journal from a cast iron cam, so I could run stock distributor gears. You can hardly tell where the cut was made. Beautiful work, and only $65.00!

Randy
 

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Just wondering if in the end this looks to be a detonation issue his ign timing wasnt that agressive at 20 deg base with 36 total all in by 3k rpm to detonate on race fuel unless the race fuel he thought was 108 octane wasnt race fuel and was 93 junk pump fuel or they are playing games mixing it with lower grade 93 fuel to make more money and they possibly mixed to much 93 fuel with race fuel lowering the octane too much for your setup to handle.

If you find its detonation and your cam had enough duration to properly work with the hi comp you have i would have the race fuel tested you bought to see if it in fact is the 108 octane lvl you paid for and were told it was,hope you have a reciept for it.

Becasue if you have a bill for the fuel and it turns out to be lower grade fuel by a sig amount then you have grounds for a " justified lawsuit " IMHO with repect to the person that sold it to you and also the person/mfg/comp that supplied it to the person that sold it to you because you know they will be pointing fingers at eachother if thats case,you could bet on that so you want both parties in the same place at same time so they can duke it out n front of a judge in small claimes court which is generally up to $5,000 which should hopefully cover your rbld.

Let us know how this all pans out.

Good luck.

Scott
 

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Well, I wasn't going to say anything about the possibility of bum/doctored/diluted fuel since I have no knowledge of the shop in question.

How can a guy get fuel tested for octane in a timely fashion anyway? If the timing marks check out and the fuel pressure and carb are OK then suspicion could fall on the fuel. That's the reason I was asking if it was fresh. Poorly stored race gas can lose several points of octane quickly.
 

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Holy moly, it seems a bit scary to build a high comp engine knowing that there is the possibility of some fool selling you bogus fuel.

You simply cant run normal fuel in a high comp engine therefore solely rely on perfect fuel...

10.5 comp would feel safer in my opinion.

Good luck with your findings dude.
 

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Discussion Starter · #18 ·
Well,guys, thanks for all the info. You don't know how much help ya'll have been. I've built several engines through the years and have never seen anything like this. My first really hipo engine was for a friend's car in 1988. We were just kids and threw everything together-never checked clearances-nothing balanced.It was a 12-1 solid flat tappet 427, tunnel rammed 7 grand engine.All we had around here back then was aviation fuel. Run it for 2 years and tore it down to refresh it and had it balanced.I'll never forget what the man that balanced said about it. He laughed and said that he didn't know how we could see the tach, that it should have been vibrating badly because it was 30 something grams out of balance. But at that there was no bearing damage after bunches of 1/8 mile races.There will be no high compression after this. I hated that i had done the compression before i got through with the build. I pulled the pan first and saw the bearing failure. The bearings is where the damage is.The crank does not look like it had trash or grit on it. The bearings are what took the abuse. And until i pulled the heads,i could not for the life of me figure out what happened.When i saw the piston heads,combustion chambers,and exhaust ports,i had a very bad feeling.It just feels sandy.
 

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jerry detination may have very well played in it.but also check to see if the oil screen was far enough off the bottom of pan.my 454 did same thing almost and all i could find wrong was the screen was to close to pan .when you turned it up it couldnt get the oil it needed.
 
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