I had 460ish miles on the 383 when the timing chain broke last time and bent 5 valves. Well, the performance shop fixed it all for free. Got ~700 miles on the motor again, ran good at the track two weeks ago(11.78 at 115.6 on drag radials on shakedown passes). Well, tonight I was on the highway, went wot, hit about 4k rpms and the car just shut off. Pulled over and cranked the motor over and watched a rocker through the hole in the valve cover and it didn't move at all, but the accessories turned over.

So....why in the world would it happen again????

 

Is the chain itself snapping? are you breaking teeth off?

 

chain snapped last time, not sure this time, will have it apart on Monday or Tuesday. We replaced both the sprockets and chain last time with new ones.

 

Do you have an electric water pump? If so the same thing happened to me (on the freeway story). When you install the WP there is an optional shaft (water pump gear in side the timing cover) I didnt take it out because it was optional....but maybe since it doesnt have the stress or pull on it now it snagged the chain somehow....

 

What kind are you using?

 

Csi

 

try timing gears, they can handle a bit more HP and sound cool.

 

Im pretty sure there are no timing gears available for our cars do to optisparks fitiment on the timing cover.

 

Get the Cloyes HD LT-4 CHAIN and make sure the two plugs in the end of the lifter galleys have the tiny oil holes in them to lube the chain and water pump gear if you have one.A lot of shops overlook this and The General put them in there for a reason. I think you have found the reason.Also make sure the sprockets are in line,looking from the side.Put a streight edge across the face of both to check.

 

First chain that broke was a cloyes HD, 2nd one was a stock one from the dealership and sprockets from the dealership. I'm still running a stock WP, and the machine shop assembled everything the 1st time and the 2nd time. I'll have them check the plugs to make sure they have the tiny holes in them. The machine shop is very reputable, and I even mentioned to them about the sprockets not being lined up and he said he doublechecked them and they were.

This sucks, I got to pull the motor again. At least we've got it down now, this will be the 6th motor pull I've done in ~2 months.

Could something be "locking" and causing the crank or cam to stop spinning thus causing the chain to break?

 

Not likely to be locking up.What spring pressure are you running? Remember get the set without the "oversize" crank gear.Check again the cam end play.

 

I used to hear reports of broken timing chains back in the mid 90s.

Most of the high reving guys are running a electric water pump and a true double roller TC now

Then again I was twisting my stock timing chain to 6,600 for four years.

 

You might want to make sure that you didnt break the key-way on the end of the crank.. That is what happened to mine with 7k miles on a brand new setup which broke my HD Cloyes chain and bent 10 ferra 6000 valves, 11 moly pushrods, etc..

 

Any chance you have too much lift for the valve springs causing them to bind up?

Tom Piper

 

Sorry to hear that Justin! Hopefully the shop will take care of you again, and fix the problem! It's gotta be something small that's being overlooked.

Good luck!