i have a 383 stroker in a 95' pont. firebird. it makes 400+rwhp. and i gave a lunati chain and gear set to the shop that built the motor. i cant tell if that is what went on the car or not, but the crank gear completely stripped and the chain broke. im not sure what happened first. but the car shut down in an istant, w/ out a sound. so what im asking is, how does something like this happen??? who is at fault? is it the shops fault because of maby something was done wrong? or did the part just fail? any ideas???

 

Sorry about your misfortune.
Did the lunati chain come with the cam and crank gear or it was just the chain. If it didn't, did you replace the crank gear?

 

Good question. Everything should have been changed, not just the chain. I have never heard of that before. i've heard of chains breaking but not stripping the crank gear. Does the crank rotate at all?

 

Actually, cam gear failure is very common.

Never heard of crank gear failure before though. I wonder if the untested Lunati may be the culprit....

When you change a chain or even need to remove it for some reason, it is very wise to change BOTH crank AND cam gear, especially if you're running stock parts and high HP numbers.

 

Mine broke because I floated a valve. A couple of the factory springs were 1/2 the pressure of what it should be when the head guy tested it.

I am sorry to hear of your issue. GL and I hope it is only a chain.

Ben

 

What about the proverbial align bore problem of taking out too much material from the block instead of the caps and the chain has too much slack in it. Did you get new caps when it was stroked? You could have the distance checked from the top of the block mains to the deck.

 

the lunati set came w/ the chain, and noth gears. we havent checked yet to see if the cam is spinning but i think if it wasent, than that would make sence on why it would strip the gear instantly. i was worried that maby the original gear got put on by mistake, but i founf the original is still on my stock crank. so that is not the case. im not sure on the whole new cap thing, but i wouldent think that is the case because i think i remember a distance check and belive it or not the guy who built my motor is supposed to be one of the best. any ideas on what kind of set to go w/ now, i want a strong chain, but i dont want to have to run an electric water pump, so that kind of narrows my options. ?i was thinking maby an lt4 set?

 

miss print "the lunati set came w/ the chain, and noth gears", the lunati set DID come w/ BOTH the chain and the gears! i have had this motor like 3 months!

 

Excess slack would be a contributing factor. Rapid acceleration/deceleration (like sitting and revving the engine) causes the slack to transfer back and forth from one side of the gears to the other. Excess slack would cause the chain to want to ride on the outside portion of the gear teeth. If one tooth failed under a significant stress situation, it might cause it to take the other teeth with it, as the teeth are weaker the farther they are from the center of the gear.

It might just have been a bad gear, too.

 

StrkdFormula383 - is the lunati chain a roller or not??? I considered it when I installed a new cam eariler in the year, but all Summit and Lunati tech told me was that it was a "linked belt" . I couldnt get a definite answer with specifics as to why it was even better than the stock chain - no one , including the lunati tech could give me any specs on it. So I decided to go double roller instead of taking my chances with the unknown.

So if you dont mind, give us some details on the Lunti chain set.

 

no the lunati is not a roller. it is a stock replacement piece of ****! whitch i wish summit or lunati could have told me when i bought the damn thing. i dont want to run electric water pump so i am going to go w/ a lt4 extreme duty set this time! my cam is spinning so that is good, i just hope i didnt bend valves!

 

Well, hopefully you wont find anymore damage and it was just the chainset. Good luck...

 

If your going with an electric water pump why dont you go with the Cloyes Double Roller. As far as the LT4 extreme duty, you don't need a electric water pump to use it.

I'm just worried about a what happened to the teeth that stripped off.

 

i am going w/ the lt4 extreme duty, that way i dont have to use eletric water pump, i should order it today. i was also worried about the teeth that got stripped. we got alot of them from the bottom of the timing cover, but not all. so we have dropped the k-member and about to get the oil pan off so we can clean it out and make sure there ane no teeth in my bottom end!

 

Just a thought, you are using a harmonic balancer, right? Some of the aftermarket underdrive pulleys require that you put the smaller pulley between the stock balancer and the mounting flange. I have heard of some people breaking their timing chains because they left the stock balancer off and just used the underdrive pulley. You probably already know this, just though I would bring it up.