i have a 72 duster with a 318 the stock timing gear teeth striped of the cam gear so i put a double roller in it and put some new push rods cus some was a tad bent now i went to fire it up and its backfiring the gas through the the carb and popin through the exhaust can anyone help

 

When your timing gear stripped and jump time, your pistons hit your valves. That is what bend your push rods. It also bent your valves. You will have to remove your head, replace the bent valves and have a valve job done. Or just replace the heads with another set with out bent valves.

 

Is there any way to check without removing the heads

 

IT IS NOT CLEAR to me whether it runs at all or just backfires?

IF it does not run, you may have the distributor "180 out". When you install a new sprocket (it's not a gear) and match the sprocket timing marks together, THAT IS NOT "no1" ready to fire, it's no6.

So pull no1 plug, stick your finger in, and bump the engine until you feel compression, then watch the timing marks and bump up to about 10 BTC or so.

Now look at the rotor and see if it points to no1 plug tower

IF IT RUNS but poorly, you probably did indeed bend some valves. First thing is make absolutely certain that the new pushrods are the same length as the old ones.

To check for bent valves, you can run a compression test,

or run a leakdown test or even just pressurise individual cylinders through the plug hole

this is a little difficult because you have to bring the cylinder under test up to "it's own TDC (not the timing marks!! except no1, no6) and get it to stay there while testing.

If you can figure what every 90* is around the dampener, you can mark it. You'll have to measure it's circumference around, and divide by 4 Every 90* will be TDC for a pair of cylinders on opposite strokes

 

last time I had a 318 jump time all the exhaust valves ended up getting bent. DOn't try to start it until you get the problem fixed