my dad and i just cranked our 383 in the duster. motor freshly rebuilt. everything new. we are getting plenty of fuel, and the dist is getting spark. we are getting backfires through the headers, and no firing. we messed around with the distributor a bit to make sure it wasnt a minor timing adjustment, and still nothing. we swapped the wires 180 degrees and got backfire through the carb. any input appreciated.

Pull number one plug. Bump the starter so number one is on the compression stroke. Line up the timing marks at tdc. Look were the rotor is and get the dist, in the right place and verify the firing order at its correct rotation. A fresh motor that does not fire right off is a good candidate for a wiped cam lobe.

PULL THE DIST. SET # 1 CYL @ TDC.ON COMPRESSION STROKE .( WHEN BUMPING ENGINE OVER WITH # 1 PLUG OUT AND A FINGR COVERING THE HOLE, OR BOTH VALVES CLOSED at TDC. ) THEN INSTALL DIST WITH ROTOR POINTING TO #5 CYL AND SLIDE IT IN .ROTOR SHOULD BE PONITING TO APPROX # 1 PLUG WHEN DROPPED ALL THE WAY IN. ROUTE WIRES IN ORDER FROM POST ON THE CAP WHERE ROTOR IS POINTING. SOUNDS LIKE TIMING IS OUT 180*. ADVANCING THE TIMING WILL HELP IT START ,IF ITS RETARDED TO MUCH IT WILL BE HARD TO CRANK>

1 8 4 3 6 5 7 2 Counter Clockwise rotation.. Bring #1 up to TDC on the compression stroke & see were the rotor is pointing.... It should point to #1 located like the picture below...

As mentioned A fresh motor that does not fire right off is a good candidate for a wiped cam lobe

pull the plugs & bump it at the starter relay till you feel psi start to build significantly on your thumb over the #1 plug hole (front drivers side) then hand turn it some more with a 1&1/4" socket/breaker bar till the timing marks are at 10BTDC if a mild cam or 15BTDC if a wild cam. Turn the dist housing till the magnet is dead even with the tooth that places the #1 dist cap terminal over or nearly over the rotor with the vac can in its' correct general location with room to be turned either way. As said check that the wires are routed 1-8-4-3-6-5-7-2 CCW from that point & you can reroute the wires if needed but keeping the OE #1 wire location is highly recommended for standardization & preventing future mixups & lets the wires nestle neatly with the shortest lengths possible and you can reclock the intergear if need be so #1 is where you want it rather than relocating the wires if you want to do it that way & sometimes different dizzys are phased different between the bottom tang orientation and the rotor clocking & the intergear needs to be lifted up & rotated as having the intergear slot parallel as the book says does not always work. Pull the intake & regoop the cam. You have alot of money and time in this & cam issues are notorious so no time to skimp now expecially since you are so close. Read "breakin secrets" at www.mototuneusa.com (5 minute read). Make a mark with a white marking pen 2&7/32" clockwise from the OE TDC slit on the dampener which is 35 degrees & when it fires have the guy manning the light turn the dist to get that amt at ~2500 rpm with the vac adv capped. Stat out. Front of car elevated (air pockets). Shop fan in front of rad. Any issues/leaks shut it down ASAP then fix it & restart it continuing with the 20 minute time frame. good luck EDIT when you lined up the tchain/gears dot to dot (6&12 o'clock) #6 is firing not #1 as commonly believed and you would want the rotor under #6 plug wire but the above will take care of it for you. Holler how things go

ok.
just wrapped up for the day.
we pulled the valve cover and triple checked our timing. we are on the correct stroke and now not getting any backfiring at all.
cam looks fine, its a used mopar 484 from my buddy that upgraded.
we pushed the car out of the carport into the sun, and upon trying to crank, we are seeing gas/air being pushed out of the carb. shouldnt it be getting sucked in like a vacuum? carb is also spitting gas out of the front breather tube. it is a 750 holley that came off my 72 RR, over 2 years ago.
thanks for the replies....hoping to get it running!!!

Needle & seat are flooding. Might pull the assy's out & clean them with a shot of starting fluid or replace them & might be a good idea to pull the bowls & see if it's good inside & that'd let you invert the bowls & with a drill bit set the dry float level dead on when you go back together

make sure that your push rods aren't to long and holding the valves open. run a comp. test see what you have. seen it before . pushrods too long holding the valves open no compression no start.

might want to drain the oil and change the filter. At least pull the dip stick and see if it smells like gas. As for used cam...I hope you got the used lifters that went with the cam and they are all in the correct order. That 484 cam isn't going to be easy to dial in. While the carb is apart I'd drop a 4.5pv in it. Also make sure your floats are set. If not it will push fuel up and out of the bowls.
Good luck

i have not cranked it more than necessary. wednesday i am pulling off the timing cover to check the timing chain. have a feeling it is not properly set. checking pushrods, etc too for any damage. gas is fresh high test, so i doubt that is it. i will let you know what happens on wednesday,
thanks for all of the replies...hopefully you are wrong about the motor being beat up!!!

Alright, I got off a little early today and decided to get a head start. I was happy to get the front end pulled off without having to remove the radiator/fluid. The crank sprocket was installed on the square slot, not the circle. I have everything lined up and feel confident no contact between the cam and piston was made. Small cam. Tomorrow I will get new gaskets and try to fire. No wonder I wasn't getting compression with the finger test!
I will post videos tomorrow.

Well that was my guess....timing chain off.... glad you found it! I'm also happy you didn't knock a piston up into a valve!!! Put it together and fire that sucker up!

Just got through swapping the crank sprocket. lined it all up, regasketed everything and RTV'd it. Fired up 1st try. sounds awesome!!!!!!
no smoking, except the header paint. could not be happier!!!
thanks for all the advice everyone, and thanks moparts!!!

Glad you got it figured out

Finish breaking her in and let her rip!
Awesome news.

We want to see the burnout videos!