Thread: broken starter bolt

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A freind of mine has a 350 bored and stroked to 385ci and he recently went to start it and some how the engine backfired or something of that sort and busted the bolts of the engine that holds the starter on. What may cause something like this. The timing or maybe somthing else. Any help would be very great.

We see this all the time at our Marina, on small block Chevys. Two things can cause it. Bolts that aren't torqued tight enough (or are the wrong ones....some use metric, some sae) or a backfire while cranking. There is a lot of force on those bolts while the engine is starting, trying to shove the starter sideways.

Buy brand new bolts, and torque them to the manufacturers specs, which generally is 50 ft lbs.

If the starter had a brace on the backside originally, reinstall it. Some do, some don't. People leave them off when replacing starters to take a shortcut.


Don

New GRADE 8 bolts at 25 ftlbs.

Well I the backfireing caused it was the timing not right. This is the first time the engine was fired and has not been timed but it still shouldnt be that far off, or could it.

You could be 180 out. Easy to do, I used to do it practically on every motor I built until I learned the thumb over number one cylinder trick.


Don

I know that and I dont know how he timed it but on all my engines which are small block chevys they have also been 180 out and never backfired that hard. But I am not saying it is not possible. I guess I will have to go check it out and thanks for all your guys's help.

So backfiring is a good indication that the timing is off?

Originally Posted by Damien_63

So backfiring is a good indication that the timing is off?

Yep. The valves are supposed to be closed on the piston being fired (when the engine is in time) but when you are out of time, the spark is hitting that cylinder when one or both of the valves are open to some degree, and the exposion escapes the cylinder. If the intake valve is open, it backfires through the carb. If the exhaust valve is open, it backfires through the exhaust.


Don