gapimpin

I was manually shifting my built 700r4 and didnt get it out of 1st till the tach was pegged at 6k. im guessing i got up in the 6.5-7k area and heard a pop.
the car shut off quick and my friend that was in a car next too me said he heard a loud rattling noise.

We pushed it off the road and started looking at it. the rotor had come off the dizzy and was knocking around inside the cap. we also found that the dizzy doesent turn with the motor.

I took off a valve cover and cranked it again. none of the rockers moved so the cam isnt spinning.
Is it possible i broke the double roller timing chain or would the cam sproket maybe come off?

what do you guys think happend with those symptoms?

Comp788

Anything is possible... You might have sheared the keyway in the crank, had the bolts cole loose/out of the timing chain sprocket, or had the timing chain break...

Apeiron

Does your belt turn when you crank it?

AlkyIROC

The chance of breaking a double roller chain is possible but slim. As mentioned above, the keyway could have broke. The crank gear could have split and broke. The cam gear bolts could have fallen out. The camshaft could have broke. The front of the crank could have broke preventing the timing chain from rotating. Is the balancer rotating while cranking over the engine?

If the cam stopped rotating for any reason and the engine died, then the pistons were still going up and down while the valves were open. There's a good chance you have some bent valves.

You're going to need to do a complete tear down to inspect for damage. Start by pulling the spark plugs to check for damage. Pull the oil pan and see if there's anything sitting in the bottom.

dayton's Z

get ahold of a pressure tester make sure you have compression in you cylinders to check for bent valves.

and good luck hope its something minor as minor can be in this situation

gapimpin

ok so a little more info....
It wasnt a double roller just a stock roller chain. we found the chain lodged in the top of the timing cover and all the teeth on the crank sprocket had been sheared off. we replaced the timing set and the motor turned over first try but it was running rough like it was running on 4cyl. I didnt hear any rod knock but the motor stopped and wont turn over now. when i hit the starter it moves a little but not much and goes back when i let off the starter. could i possibly have bent a valve and its keeping the piston from going to tdc?
we didnt see anything in the oil when we drained it. Ill pull the heads sometime this week just havent had a chance to yet cause the car is down in austin and i live 120miles away in waco.

Damon

Yeah, you probably dinged some valves crooked the first time you lost the chain. Then when you fired it again with the new chain something got wedged and stopped it from turning any further. When you lose a timing chain at high RPMs bent valves are a practical certainty.

AlkyIROC

Well a factory chain is a different story. Normally the plastic teeth on the cam sprocket fail first.

As mentioned above, you'll have bent valves. Price out some replacement heads. They may be cheaper than getting the ones you have repaired. Don't buy anything until you pull the heads to asses the damage. If a piston is damaged, you might as well price out a rebuilt engine.

ibmtech

iTrader: (1)

You will have to look at the top of your pistons for damage. I had a 3.1 Regal engine that some idiot (ME!!!) accidently swapped the push rods on.. I got the blue and the orange rods mixed up on 1 cylinder.. After I started it up.. I thought I had dropped a rod so after a few more hours, I pulled the motor to inspect for damage. Once I got the heads off again, I found the mistake and had to do a little grinding on the piston and it worked ok.. I was extremely lucky and sold the car and it never had another problem.. You don't sound like you can be that lucky.

gapimpin

well we pulled the heads and it did have some bent valves. all the walls looked fine and the pistons looked fine. it got dark and cold out though so we didnt have time to try and turn it over again. only one of the valves was bent bad enough to keep it open a little all the rest looked closed. im betting when i take off the springs though its gonna be hard to get them to move. i really hope i didnt damage a bearing. thats what the guy at the local speed shop said probably happend. we will see when i try to crank it by hand though.