Jvette73

My 350 in my truck. I reved it for my kid. He didnt ask, I just did it. Wuuuummmmm....wuummm...wuuummmbaaaaa...P OW!!!! Big backfire thru the exhaust!!!! Motor stalled. Wont start back up. Sounds like it jumped time on the timing chain. Is this possible? I hope so. I know I can fix that. Its not knocking on crank. Just cranking faster and then slower and spitting from the carb with a slight flumping from the exhaust. It almost want to run. Any idea what might have broke? Other than my common sense. Im hoping timing chain.

88'Cubka

Ouch.....

shoptek

I think your on the right track. It sounds to me like the nylon gears on the timing set are gone. Probably a new chain and gear set will get her back up and running.

Jvette73

Nylon gears are no longer on there. I changed them years ago. I hope its the chain. I think its a stock single style steel gear on there. Pray for me.


[Modified by Jvette73, 6:11 PM 1/16/2003]

Darkness

Check your distributor, and timing also check the spark plugs and see if the gap was closed. It happened once to me.

Later :cheers:

dlw

I did a similiar thing to my 350 and it turned out to be a spun cam bearing.

jackson

I too think it may be the chain. Easy to check to see if broken. Remove power wire at dist. Remove cap. Spin motor w/ starter. If dist rotor does not turn when motor spins ... the chain is broke (or cam is broke but NOT likely). When cam does not turn then there will be no oil pressure ... no op when cranking another indication chain is broke.

dogboy

Check the simple stuff first wires, plugs, etc. pull the valve covers and check each rocker to see if they aren't loose(BENT pushrod) than see if they open and close in time with the timing marks for the #1 cyl. . Check your fuel pump and see if its pumping gas right. Than check your timing chain. Also check if you are getting compression for each cylinder when you have the plugs out.

fauxrs

Check and see if your distributor is loose - it may have turned under the revving if the bolt was loose. I dont see you jumping a tooth on the chain - the chain would have to have a ton of slack such that it would barely run before - if it popped off the chain - weell you know what that would mean.

Willing to bet you either had the distributor turn or you blew a power valve or something in the carb. Sounds like distributor to me.

Larry B.

Check the distributor rotor. I had one that broke out of the plastic and was pointing off at a 30 deg. angle. It had all of the symtoms of a jumped timing chain. A lot easier to fix.





[Modified by silvervetteman, 5:38 AM 1/17/2003]

Jvette73

Thanks everyone, all great suggestions. Im pretty sure the dist housing didnt move. I recently put a new summit HEI in it and im sure I tightened the hold down bolt real good. I suppose the shear pin holding the dist gear could have sheared off. The first thing I was gonna do was connect my timing light and have someone crank it for me so I can see where the mark is. I know I set it to 14degrees initial when I installed the new dist. So well see if thats moved any. After that I will pull the dist cap and crank again and look for rotation of the rotor. Even if it is the timing chain, its not a hard job on this truck.

Murphys Law here is: its a 4WD truck, and as usual I broke it the day before we got snow. Ive done this several other times before. So next time I break my truck, you can count on snow shortly thereafter.

When I figure it out, Ill be sure and post back and let you all know what I find. :smash:

Alwyn678

Well at least it wasn't the vette

Jvette73

Yes im glad it wasnt the vette. The good thing too is, it broke in my driveway. So it didnt strand me or leave me with a towing bill. At least I had some luck :crazy:

NHvette

Sooo ....
The kids were playing in the truck, and the BIG kid blew the engine ? :yesnod:
Sounds like something I would do. :rolleyes:

I hope it is something simple. Even though the dist is new - maybe it jump a tooth or two from the cam. Not likely, but I'm hoping it's something simple.

Good luck. Guess we know where you'll be this weekend.

:seeya

Jvette73

Im probably gonna wait till the weather warms up a bit before I dig into it. A little snow out there now and its kinda cold. Just hope my other POS hold up meanwhile. I got 4 cars but the wife takes the new van and the vette is covered cause the salt on the road. Guess im gonna rely on my 86 pont 6000 for now. This weekend is too busy anyway with our 15 year old testing for blackbelt in Tae Kwon Do on sat and a celebration with family on sun. Keep you posted when I figure it out. Im guessin its most likely the timing chain.

MIDNIGHT BLUE

i hope you were watching your tech when this happend!
because now you know your red line :banghead:

Jvette73

Nope...wasnt watchin the tach. I was playin it by ear....listinin for that awsome crackle sound from the flowmasters you get when its backin down from high r's. I got the crackle sound alright...but it was followed by the big "Bang" Im doubt i took it over 5k. But I could be wrong. Silly me :banghead:

Jvette73

Whoo Hooo got it runnin again!!! Heres the skinny. I had my son crank the engine while I shot the timing light and looked for the mark. Couldnt find the mark anywhere near the scale. I took the dist cap off and rotated the crank by hand untill the mark on the balancer was lined up with the 0 pointer on the scale. I noted the position of the rotor and realized it was pointing not at #1 on the cap, but at #8. I put the cap back on and rotated the dist counter clockwise to bring the rotor closer to #1 position on the cap. Turned the key and it fired up instantly. Reset the ignition timing and done. Runs as good as ever and still maintaining great oil pressure.

I assume that if the timing chain had jumped a tooth then it would still not be running quite right. Since it seems as good as ever, I guess it was the dist gear thah must have jumped. I know for sure that the dist housing didnt rotate on its own cause it was thightened down very good.

So what do you think? Was it the dist gear or the timing chain that jumped? Any of you ever heard of a dist gear jumping a tooth? I havnt...untill now maybe.

Thanks to everyone for the input in this matter. Glad I got it goin again without spendin a dime, although I hope this oil stain comes out of these warm up pants my wife just bought me. :chevy :cheers:

Steve Straus

I think it's time to get a new distributor gear.

What kind of cam is in the engine? If you have a solid or a roller cam, you need a melonized distributor gear, or the cam gear will wear it out.

Otherwise, something sounds really fishy. I'd start inspecting timing chain gears and taking some measurements on the cam gear and distributor gear before I did anything else.

Jvette73

Its a hydraulic flat tappet cam in the motor. Not sure of the grind but its very torquey but way mild. Higher lift but low duration. I got the cam from a street rod builder who said he took it out of a stock 350 chev marine engine. The cam is great for a 4x4. I can turn the idle way down to 200 rpm no bull. It wont quit. Blee blee blee blaa blaa blee blaa....you can practically count the revolutions of the crank it will run so slow. put yur hand on the valve cover...no vibration.. balanced motor. Sweet. Runnin like a top:cheers:

I am still at a miss as to what actually happened. it seems all good again now.