Just put a new hot cam in my zz3 with springs, rockers and new timing chain. Everything looks clean and in alignment, engine cranks but backfires big time. Any ideas?

distributor off 180*,tying to fire #1 cyl at TDC of #6 compression stroke?

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Bob
Garnet Red 69/SS396/TH400/355 Posi ( 454 now)
94 HD Dyna Wideglide

If valves were adjusted properly, most likely the distributor is installed incorrectly.

Sounds like your timing is way off (with a 180* out distributor it will fire out the exhaust). This is how I set my distributor up when firing an engine.

pull #1 plug and pull the hot wire to the dist.

put your thumb over the spark plug hole

bump the starter until pressure forces your thumb off the hole.

Use a wratchet and 5/8 socket on the vib dampener bolt turn the engine clockwise until the mark on the balancer is at the 10* BTDC mark.

Set the distributor so it is fulley seated in the hole and so the rotor is pointing at the #1 cylinder. You can rotate the oil pump drive shaft with a long screwdriver if the distributor won't seat fully.

Put the cap on and rotate the distributor until the #1 terminal is exactly lined up with where you set the rotor.

Tighten up your distributor, put your plug and power wire back on and fire it up.

This should put your timing within a few degrees of where it should be.

Just getting two spark plug wires in the wrong position will cause a backfire too.

Just a little FYI...With both timing marks lined up together (like when you installed your cam and timing gears)the engine is not at #1 TDC, it is at #6 TDC. This will cause you backfiring every time as the distributor will be 180° out of phase as was suggested earlier.

-Mark.

Thanks for all the great responses. Even though I haven't gotten on the problem yet, it appears the #1 piston wasn't at TDC when I installed the cam. Hopefully this weekend I can get to it. I also have to replace the oil pan seal so can this be done without pulling the engine?

Well the car started thanks to the help from this site. Now one issue I am not sure about is why the number 1 and 3 cylinders have 210 psi of pressure where the other 6 are running at 180. Is it a valve adjustment issue?