I have a 91 305. I replaced the stock cam with an aftermarket from Jegs. I aligned the cam and the crank gears at 0 degrees. I can get the car started but it backfires through the carb regularly. The plug wires are correctly installed. I have adjusted the distributor several times and it either will not start or starts and runs but backfires through the carb. Any suggestions or ideas would be greatly appreciated. Thanks.

 

By "0 degrees", do you mean you aligned the gears dot-to-dot, used the zero degree markings on the crank gear, or what? Did your timing set have more than one slot for the crank gear key?

Dot-to-dot is the #6 cylinder firing position. If you put your distributor in with the rotor pointed to the #1 cylinder spark plug wire terminal, you're 180 degrees off. However, if that's the case, the engine won't actually start, but will definitely backfire through the carb.

 

Thanks for the reply. The crank gear did have 3 settings. 4* before, 0* and 4* after. I set the cranks gear to 0* (12 o'clock) and the cam gear dot at 6 o'clock, and you are right it would not start. I did the 180 swap and it starts, but backfires through the carb a lot. Like pop, pop, pop, pop, etc. less than a second between pops.

 

Are you sure you used the right mark on the cam gear? Are you sure you have the spark plug wires back on in the proper order?

 

Yes and yes. I am thinking it may be incorrect valve clearance. I had the heads cleaned, installed new push rod and rocker arms. After reading some, I don't think that I tightened the rocker arms correctly. I am planning on follow this procedure to tighten them.
1) Loosen all of the rocker arms.
2) Bring the engine to the TDC mark (doesn't matter if it's on #1 or #6 firing position).
3) Take the slack out of all of the rockers (just take out the slack, nothing more at this point).
4) Rotate the crankshaft 1/2 turn.
5) Take the slack out of any loose rockers (should be 12 of them loose, but check them all).
6) Rotate the crankshaft another 1/2 turn in the same direction (back to TDC).
7) Take the slack out of any loose rockers (should be 8 of them loose, but check them all).
8) Rotate the crankshaft another 1/2 turn in the same direction.
9) Take the slack out of any loose rockers (getting the picture yet? There should be 4 loose, but check them all).
10) Give each rocker one additional full turn down.
11) You're done.

Then I will see how it runs after resetting the distributor on #1.

 

That's a very simple way to set the rockers with a hydraulic cam.

 

Thanks for your help. It is running now...after resetting all of the timing and adjusting the rockers. Now just some fine tuning....thanks again!