Backfire turned bad day

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charger/tse

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I made a nitrous pass car left very hard toted wheels further than ever hit 2nd still strong from 2 to 3rd shift hit the rev limiter and boom nothing came out the bottom but now pops through exhaust and will not start looks ok under the valve covers its a drag car 318 stroked to 390 any ideas what to look for ?
 
Sometimes you can just have a nitrous explosion. Maybe it's something simple. First thing I would do is a compression test. Quick, simple and will rule out a few things.
 
Does it pop or try to fire? Pull dust cap off and make sure the distributor spins when cranking, then do the compression test. Check to make sure balancer still lines up at red. Maybe shucked timing chain. Could be anything but start with the basics
 
I'm with Rusty on this one, do a compression check first. it will point you in the right direction and you can peek at the plugs while you are at it.
 
They always run best right before they blow up.

Since you're running nitrous, I suspect you ran lean and cooked the pistons. That will usually mess up your valves too.
Take the heads off. I doubt by some miracle that it is something that doesn't require taking the heads off.

If you want to tip toe into this, do as already suggested, compression test. Pull all the spark plugs, have a look at your freshly roasted aluminum.

Power adders have a bad habit of burning aluminum when they don't get what they want, fuel. I hope it is something simple but that's wishful thinking. It's normal to have oil in your intake runners and air cleaner when the magic smoke goes out the exhaust.
 
Thats why I say d spark plugs first. Could have killed the electrode tip.
AKA No spark...

The compression test was a great idea.
If he has the tool. Cheap to rent or purchase and borrow.
 
Compression is good 190 on all passenger side and 220 210 220 215 on driver side distributer is turning plugs look good so I pulled the heads every thing looks good no marks on pistons from valves no damage to piston tops or cylinder walls .push rods good so I put gas in intake ports 2 valves leak per head and 1 exhaust per head but Idk why it wouldnt start with that much compression no viable sign of valves bent
 
I'm surprised, really surprised. Glad for you that there's not much wrong.
 
Compression is good 190 on all passenger side and 220 210 220 215 on driver side distributer is turning plugs look good so I pulled the heads every thing looks good no marks on pistons from valves no damage to piston tops or cylinder walls .push rods good so I put gas in intake ports 2 valves leak per head and 1 exhaust per head but Idk why it wouldnt start with that much compression no viable sign of valves bent
id check the timing chain...
 
I'd be inclined to bet the timing chain jumped unless you've already checked it
 
with a big cam, if the chain jumped valves would have kissed pistons. something wrong with ignition
 
Well golly jeepers Beave, whaddya know?

One of these days, all you guys who argue with me about simple diagnosis will learn that is the right way to do it. This guy listened and how bout that? His **** isn't torn all to hell either. I didn't spend 40 plus years in the field to be somebody's forum *****.
 
His shot isn't all torn to hell, but wasn't the original question why it wasn't starting and just popping through exhaust? Pretty easy to suggest a compression test. Bout the first thing ANYONE would do! Still dont explain why it doesn't start though does it? All these engines you build and all the stuff you do, how do you have time to be on here running your mouth about how stupid every one else is on EVERY SINGLE thread and how no one else's stuff is worth a shot and you know EVERYTHING? Seems pretty childish and arrogant to a bunch of guys just looking to share ideas and info!
 
Just another modest guess here... s'thing electrically happened when he hit the rev limiter.
What could it be... I have no idea.
 
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Just another modest guess here... s'thing electrically happened when you hit the rev limiter.
What could it be... I have no idea.

That's what I was thinking after he posted that the pistons look good. Maybe had a spark box crap out or maybe a short in the limiter chip.

Jack
 
OP, what ignition system and rev limiter do you have? Has it ever backfired before at the limiter? Some limiters act by randomly cutting out firing cylinders and will build up unburned fuel in the exhaust that often gets lit off. (Hence the popping.... ) It almost sounds like the ignition and limiter failed when it went into rev limit mode this time.

What is different between the driver's and passenger side? The compression readings are around 25 psi different between the 2 sides; that normally indicates a compression ratio difference of over 1 point, which is a lot. Did you take the compression readings with the carb in place and the throttle closed? While you have the heads off, it would be good to measure the piston's deck height on both sides to see if they are maybe .010"-.020" different.

You can do a spark check with the heads off. Put the distributor back in and hook all the ignition up. Take the spark wire from the coil and place it so the distributor end of that wire is about 1/4" to 3/8" from metal, crank the engine, and see if it jumps a good blue spark over that wide gap in open air. (BTW, it is NOT a good test to look for spark across a spark plug gap in open air. That small gap can be jumped in open air by a 5000V spark, but 25000v or more is needed to jump that same small gap in a compressed fuel/air mixture.)
 
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