Ok I just bought a new crate motor a few weeks ago and it has been running fine up until a few days ago when it puttered out and died on me in my driveway. Now it will try to turn over but wont make it. I checked to make sure that it was getting fuel and now know that isnt the problem. Ok this is where it starts to get bad.

Ok I'm pretty much a backyard mechanic so I dont really get to do everything the "correct" way. So to check to make sure there was some juice getting to the plugs, I pulled the wire off of the number one cylinder and stuck a screwdiver in it, and placed it up against the headers to see if it would spark when the motor was turned over. I've done this before many times and never had a problem, except this time.

When my buddy turned it over it took a few revolutions then there was a loud BOOM like a shotgun going off. There was a bright light and I could feel a small amount a force blowing back. After my ears stopped ringing I noticed some smoke coming from the valve cover breather. When I pulled it off I noticed the cover was full of white smoke. So was the other valve cover aswell leading me to believe the whole crankcase was.

The motor still tries to turn over like before but i havent got it started yet. I'm not worried about that so much. I just cant stop worrying about what kind of damage I caused from that explosion. If anybody has had this or even heard about this kind of thing happening, could you let me know what caused this and what am I probably going to have to replace inside the motor now.

Thanks in advance for any replies.

 

never in my live have a heard of something exploding inside the crank case...


sure it wasn't just a back fire from the carb and the smoke just went thru the pvc hose and vent?

if your car even has those...

 

I havent ever heard of it either and thats the same way I check for spark.... interesting. Ill ponder this one

 

Maybe you're getting too much gas and ignited some that leaked out of the carburetor and onto the headers? The engine sure as hell won't turn over if it's rich, but it'll definitely blow up if you put spark to it

 

Does the engine turn over like it wants to start and doesn't or does it struggle to turn over. If it turns over fine and just won't start check your timing. The distributor might have moved and your timing could be off. That would also cause the backfire. If the backfire was as bad as you say, I would also check the powervalves and floats if you run a carb.

 

the powervalves shouldnt be an issue, holleys have had the protecters since like 84 i believe?

now i think the carb backfire is the best estimate..check your timing...make sure its dead on, sounds like its so far off that itll crank and the backfire you got possibly pushed the smoke through the pcv system back to the valve covers...the heads are closed off, there really is no other way for smoke to get in there besides the burnin oil off the valvetrain or stuff working its way up from the crank case. and there is really no way to explode something in the crank case other than a hole in the piston and fuel gets down there and something catastrophic like that.

 

u might want to check the power valve after u get it running.i had to redue mine on my old setup when i was going from race gas to pump gas and playing with the timing to get it right and mine back fired threw the carb and took mine out.is your distr. holder on tight i've seen them be on lose and seen them jump and reseat them selfs down on the wrong timing point.does it just turn over like its nothing or is it hard to turn over?