Awesome and sad ride report

[sonny]

Hard to imagine a cam chain breaking like that. Hoping everything is OK with the motor.

 

[Mike188]

S***, talk about unlucky, but looks like you got out of the correct side of the bed if you've missed damaging the rest of it

 

[warp9.9]

Do you suspect the APE cam tensioner?

I see your going Lush now and giving it a thumb's up!

APE from Carpenter

Neville Lush's version.

No its not the APE unless the chain needed adjustment. The same would happen if you used Nevs and didn't adjust it. Remember they are both manual and only adjust if they are adusted. The real difference is the ease of adjusting. For instance the APE tensioner you have to hold the stud while backing the lock nut out so you can take a pick and pull back the O-ring so you can feel the movement and restriction when adjusting. Thats because there is no groove for the O-ring to sit in and seal it just binds in tge V of the threads. Where Nevs has a spot machined for the O-ring so it acts like a seal yet adds no drag to the tensioner disrupting your adjustment. I believe he used the APE also but from that designed a much better one.

 

[BillB]

Well that sux Rob.

On the other hand you can consider yourself lucky in one way.

If that chain turned loose in the middle of a 9000 rpm high gear dyno pull, there might not have been enough of the motor left to put back together.

 

[BigNorm]

I hope you get it back together soon Rob

 

[Claviger]

Well that sux Rob.

On the other hand you can consider yourself lucky in one way.

If that chain turned loose in the middle of a 9000 rpm high gear dyno pull, there might not have been enough of the motor left to put back together.

Yeah I was already thankful while sitting on the side of the road yesterday that it let go when and how it did, aside from being at idle, this was about optimal. Thinking back, I think I was in 3rd at 40 MPH, so like 2k at very low throttle, 3% ish.

Regarding cam chain tension, it was screwed in gently by fingers till it bottomed, them backed out a SMIDGE. It's better/safer a little loose than a little tight, so no, I don't think this was my error. The chain guide looks pretty good except for one line where it was scored. Both guide halves still in 1 piece and both move freely and easily.

Putting a scope on order today.

 

[Claviger]

On a plus note, that extra engine I have will be donating it's very good condition chain guides and I'll order up a new chain, I already have the new tensioner, cam cover seal, and cam, so currently I'm only out $80... Lol.

 

[Penner]

Thanks to pistons with good valve pockets.

 

[Claviger]

Spoke with my father, who's built an untold number of very high strung race engines.

In his 45 years as a mechanic, and 20 building race engines he's only seen 1 chain break the way mine did, and it was a result of the chain being scored by a customer during assembly.

Going to file this under "random manufacturing flaw" and go on with life.

He also agrees, if valves are sealing (they are) and move smoothly, it's fairly certain they're not bent since the valve to guide tolerance is so small, any binding would be immediately apparent.

 

[Kevin frazier]

Spoke with my father, who's built an untold number of very high strung race engines.

In his 45 years as a mechanic, and 20 building race engines he's only seen 1 chain break the way mine did, and it was a result of the chain being scored by a customer during assembly.

Going to file this under "random manufacturing flaw" and go on with life.

He also agrees, if valves are sealing (they are) and move smoothly, it's fairly certain they're not bent since the valve to guide tolerance is so small, any binding would be immediately apparent.

Dads know stuff, that’s what I’m talking about, even our very smart sons we raised call us for opinion, cool stuff there, but now we know where rob gets it from