Timing Chain Jumped?
 

Just got done reapiring my port engine. 454/420HP. I bought the boat last season and since I bought it, the port engine ran crappy. Was really hard to start. It would crank over, fire for a secong then immeditaly stall. Didnt have much power, kinda sluggish and the exhaust just dint sound healthy compared to the other engine I just had the heads done, all new valves, etc. New distributor, cap rotor, plugs, wires, cam, lifters. Now the chain has jumped, and it wont even start. It cranks over like no compression, like when the plugs are out. Im guessing this thing had a loose chain from the get go. It ran the smoothest idle at about 30 degrees on the crank right before it jumped. DO you think this was my problem all along??

Re: Timing Chain Jumped?
 

Being that the chain jumped, the valves are out of time with the pistons. There is a good chance the valves are now bent.

Re: Timing Chain Jumped?
 

I thought chevy motors were ok if the chain jumps a tooth? If my valves got ruined after a 1200 dollar valve job, Im gonna light a match to this boat for sure

Re: Timing Chain Jumped?
 

what makes you think the chain jumped ?????????


very rare on bb chev mtr, possible dist off after all you did just have it out ??????

Re: Timing Chain Jumped?
 

It was running poorly, sluggish, no power, made it out the harbor, chopped the throttles a bit then it just died wouldnt restart. Returned on one engine. At the dock, tried to start it, cranks fine but sounds just like it has no compression, like cranking without the plugs in, spins fast.

Re: Timing Chain Jumped?
 

Depends on the motor. Clearances can get tight. Is the motor stock?

Re: Timing Chain Jumped?
 

Its a stock 420HP 454 with stock GM pistons. I think the compression ratio is 8.8:1

Re: Timing Chain Jumped?
 

no pops or backfires when cranking ??????

Re: Timing Chain Jumped?
 

nope. Just cranks over. I know the chain didnt break cuz the rockers still move when I rotated it by hand.

Re: Timing Chain Jumped?
 

You should be able to tell if the chain jumped pretty easily with the valve covers off. Bring #1 to TDC and see what the timing mark shows.