can a motor backfire if you overwind it???

[billlsbird]

Hello everyone, Can a motor backfire if you overwind it? I have blown 392 hemi in a '32 ford & it's been backfiring. I just found out today that I've been overwinding it.... Thanks! Bill

[Mike P]

Yes it can. It's usually caused by the valves floating or the mixture leaning out because the fuel system can't keep up with demand (in the old days point float could also be a problem).

If it startsd backfiring all the time at lower RPM after it's been over reved chances are you have bent a valve or pushrod.

[shoprat]

A blown mtr will also backfire when too lean

[pro70z28]

Backfiring with a blower is a bad combination.

[jerry clayton]

They usually only do it ONCE!!!!!!!

I think I still hold the altitude record for a 6:71

[pat mccarthy]

when i over rev my 548 past 7000rpm it,s on the rev chip cuts out the cylinders and then i get off it.it will un seat the pop off valve on intake and pop then i put my foot back in it

[gassersrule_196]

Originally Posted by jerry clayton

They usually only do it ONCE!!!!!!!

I think I still hold the altitude record for a 6:71

i remember reading about a somebody who had a brand new pink blower and backfired it thru the O in the champion sparkplug sign on the top end i belive it was riverside?

[billlsbird]

Thank you Mike, Shoprat, Pro70, Jerry, Pat & Gassersrule, Then I think this is why my motor is backfiring at high RPM's. I've been overwinding it. I looked at the paperwork that came with my motor & redline is 6000 RPM. I've been winding it over 6000. I'm sending away tonight for a 6000 chip for my rev-limiter. I don't think it's running too lean cuz the motor was professionally built & tunned. And the guy who put the motor in set the fuel pressure regulator at what he said was the right pressure {6 pounds?}. It also backfires when I'm turning it over to start it but not once it's running {at lower RPM's}. So maybe the timming is also off? In fact, I think I read where blower motors should start in an instant. Why does mine turn over & over? Thanks again! Bill

[R Pope]

Check the intake valve springs. If they are ok, do a comp. test, may have a bent intake valve. Backfire when cranking means something is allowing combustion into the intake. Not good with a blower!