talking about fuel pressure

Is the backfire steady under a load or does it just do it at idle, it sounds to me like a lobe off the cam, or plug wires 5and 7 are switched around. How were the cams broken in. Ed

just at idle, the backfire goes away under load but the motor lags bigtime underload throughout the whole power curve and is apprx 500 rpm off at wot. the cams home less than 2 hours on them and the backfire started upon first start, this should rule out a rounded lobe.

Then I am back to the wires being wrong or maybe a mis adjusted valve....I have seen a lobe round off on a cam in less than twenty minutes of running time with to much spring pressure and not enough assembly lube or improper assembly.....Ed

yes, i agree. but i saw the cams go in a they were lubed well. valves were torked to specs I watched each one done.
wires are all in the right locations. i really do not want to pull the motor again. what is the best test to see about an mis adjusted valve, my engine compartment is perfect you can eat off the floor dont want too much mess.

If it started upon initial start up, I would think it is a valve not fully closing or leaking---rocker arms adjusted too tight maybe.

What do you mean by "torqued to specs"??????

They should not be torqued unless it is a stock cam with the stock rockers and bolts.

Everything you describe sounds like the valves are too tight.

I would have thought this a roller cam, but if you are concerned about a lobe going away, chisel open the oil filter and check for metal.

Is it popping out the exhaust or intake side?

BT

it is a crane cam and crane roller rockers dart heads

A leak-down test is probably the leest messy, and would tell you exactly which cylinder and which valve or valves. pulling the valve covers and checking the adjustments is messy and time consumming but equally as effective. Griff is right valves donot get torqued they get adjusted to zero lash and then somewhere between 1/4 and 1 turn down to center the lifter piston in its bore. Ed