Hex-a-just timing set failure

[Krooser]

My friend's DLM laid down last night...dropped power then locked up.

He pulled the timing cover today and found the chain wadded up .

Comments?

[BillK]

Same thing happened to good friend of mine. Turned out the roller cam button had come apart and one of the little rollers ended up in the chain It does not take much of anything in there to break the chain. I would be doing some real careful examining.

[Baprace]

My friend's DLM laid down last night...dropped power then locked up.

He pulled the timing cover today and found the chain wadded up .

Comments?

Krooser , Two things seem to show up in that picture, where is the roller button and second it appears that the rear set of teeth are shiny on the front side of the gear, it looks like the cam gear is running forward and the front of the gear seems to show the same thing to me. It's a little hard to tell in that picture, first thing I would check is the crankshaft snout still straight ? Then I would check the camshaft for straightness. JMO

[Krooser]

Good points...

I may be able to run over there Monday night and get a bird's eye view of things.

After two crank bearing failures last season he needed some good luck this year. But the engine was down on power from my point of view but what do I know?

Loosing a cam button would trigger this whole deal. I think he will pull the heads again.

Last night after the failure the engine was locked up. Broke the starter and bellhousing, too. May have been cracked after a ujoint broke last week and took out the high dollar carbon fiber driveshaft.

Film at 11....

[tenxal]

Posting this as 'Hex-a-just timing set failure' is pretty misleading.

[pdq67]

I figure that it is a failure after viewing the wrapped chain.

Wasn't it Smokey that used Chevy's plastic toothed timing sets because they dampened better than other sets?

BUT he said to watch them because the nylon teeth do wear out/come off over time.

pdq67

[Alaskaracer]

Two crank bearing failures? Is the crank bent? Lots to look at before putting it back together.....

He has no choice but to pull the heads...there are bent valves, I'll assure you. Timing chain break = bent valves every time....

I'd just pull the whole thing down and recheck EVERYTHING.....something isn't right because timing chains aren't the easiest things in the world to break....Going back together I'd get one of these if you're sticking with a chain:

http://www.progearweb.com/index.htm

[Krooser]

It's likely he already has the engine torn down.

This was a "pro" built engine...I believe the shop redid the damage once last year and my buddy redid the last set of bearings himself.

IIRC the bearing issues last season was related to problems in the dry sump system.

[Krooser]

Posting this as 'Hex-a-just timing set failure' is pretty misleading.

Maybe I should have used a question mark...

[falcongeorge]

I figure that it is a failure after viewing the wrapped chain.

Wasn't it Smokey that used Chevy's plastic toothed timing sets because they dampened better than other sets?

BUT he said to watch them because the nylon teeth do wear out/come off over time.

pdq67

think that was the Grump

[Krooser]

I believe you are correct.

I sold my copy of Jenkins first book... Kinda wish I hadn't .

[Krooser]

I believe you are correct.

I sold my copy of Jenkins first book... Kinda wish I hadn't .

I just spoke with my friend Adam... I'm going to try to get over to his place Tuesday night to help him pull the motor and do an inspection. He's thinking bent valves, too. With an 8,500 rpm chip bad stuff happens fast.

[BlitzA64]

I just spoke with my friend Adam... I'm going to try to get over to his place Tuesday night to help him pull the motor and do an inspection. He's thinking bent valves, too. With an 8,500 rpm chip bad stuff happens fast.

Guaranteed some bent valves, likely some valves, push rods and maybe a lifter or two. I had a cam pin come out and the cam retarded, got exhaust valves, and pushrods, piston damage and tore up a head pretty good too

[Krooser]

Preliminary inspection...12 bent pushrods!

[Truckedup]

My vintage land speed race bike uses a dual strand # 35 roller chain to transmit power from the engine to transmission..I believe those timing chains are the same pitch and width? The bike engine makes about 65 Hp at the crankshaft, 2 cylinder engine. Two primary factors in my situation affect chain life, the sprockets out of alignment or harmonics caused by crankshaft flex.
The first sign is the links seizing , the second sign is a broken chain....