Vinny P

Lets start with the basics... I have an NA 540 that I built last year. It as 104 hours on it. I run it hard but , thats what its made for, right. I am very anal. I always maintain everything above and beyond. I am running an RM Builder solid roller cam, nothing to big, 200 lbs on the seat and 575 lbs open.
Earlier this season, I had an oil pressure issue. I posted it here, dont know of anyone remembers it. I found a small chip of metal in my check valve, for my ESP preluber. It was hanging the valve open, causing oil to flow back into the pan, when the engine was running, thereby creating a lower than normal oil pressure. I chalked that piece of metal up to.. I have no clue what the hell this is, the filter is clean, I'll watch it carefully. Then a few weeks ago, came the bombshell !! I hit the switch for my preluber, after a few seconds of priming, the pump stops with a huge clunk. I take the pump apart to find a another chip of metal in there. I clear it out and try the pump again. I lean on the switch for a longer than normal time, all worked fine for about 1 minute, then clunk, the pump stops again. This time, the chip was pretty big, looked to me like a tip of the timing gear. So, my season was over..
Today, I tore down the engine to find 20 teeth chipped off the cam gear. The crank gear is perfect. I am running a Dart Big M block. I have alway been concerned about the fact that there is no direct oiling to the cam gear in this block. I remember a post Smitty started here on just that subject. That is what made me think, the mystery chunks were cam gear pieces. The cam roller button is perfect, I had the timing chain cover backed up to the water pump with epoxy, no chance of cam walk. I ran a straight edge against the gears while they were mounted on the engine, no issues.
There is no blueing on the gears or the chain. Apparently, there is no oiling issue?? So, what the hell caused this gear to fail? Its an Isky gear set, maybe just a bad gear?
In any case, I ordered a Jesel belt drive today. At least I can see if the belt is about to take a crap on me.

Next.. take a look at the broken ARP oil pump drive.. I have never seen a failure like that. I called Teague today. I wanted a new oil pump pick up. Since I am running ther pan, I figured get it from them. I was told that they have seen several ARP drives fail. Bob had found something with the way ARP is cutting the groove. Bob had ARP cut the groove somehow differently for him. So, I ordered the drive from him.

So, after a lengthy post, any clue on what is going on here?

Vinny P

more pictures

Linster

You need to completly rebuild the motor. There will be metal in the bearings. Not sure what caused the timing failure but I would not do the belt. I like the rollmaster timing chains. In the cam sprocket area make sure you have the block plugs with the very small holes for oiling the timing set. Most engine builders throw them away for new plugs not realizing they have holes. Check the cam spocket to crank spoket alignment. Never seen a problem there but something is breaking the teeth. Something is off for that to happen or you just got a bad casting

DMOORE

I've never seen that in cam gears. But on a motorcycle, if the chain stretches too much, it will do exactly the same to the sprokets. Busts the teeth right off. Just a thought.





Darrell.

Vinny P

The pieces seemed too big to go through the pick up. I took the oil pump apart, there is a minor scratche or 2, nothing too bad. Hopefully, teh filter caught anything that made its way through. Tomorrow I will pull off the rod and main caps to check the bearings.

Vinny P

I thought of that. However, my thought was even though I know these HV pumps can pump alot of oil , arent you taking oil from somewhere else that needs it? Like the lifters?

BenPerfected

I have run the Jesel belt drives for about 10 yrs. Sterling also uses the Jessel belt drive as do may others. I don't know what caused your gear issues, but in a BBC marine application the Jesel belt drive is a reliable system. This could be a lot worse...like the first run in 2009.

BillK

The purpose of the holes in the front plugs is to prevent air lock in the lifter oil galleys. It has nothing to do with lubricating the timing chain. Not all big blocks came with them from the factory.

As far as this particular failure goes, the timing set looks like a stock cast iron truck set, nothing special. I would go with a Cloyes True Roller set myself. They are pretty bulletproof and have been around for a long time. The belt drive would be ok also if you want to go that route, even though I would not think it was needed in this case.

I also have got to agree with the others that with that much metal floating around, it is time for a complete disassembly and a good cleaning

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

ezstriper

Vinny, I have been messing with these things for many years, in race cars and boats and have never seen a timing gear break !! but from what I see I would change the oil pump for sure...not matter how it looks...looks to me something was trying to lock up in that area...how does the dist/cam gears look ?..yes I do remeber your other post...good luck..Rob

Linster

I understand why it was done, but it definatly adds oil to the backside of the timing set I like that with a timing set rhat uses a bearing