1972 Datsun 510 back fires on 3rd gear

[kf6rcp]

Hi! I was wondering if any of you may have the same problem with your datsun 510. Basically, engine starts to back fire wehn in high speed somewhere around 3rd or 4th gear and will loose power and die and let it rest and it will start again. I changed the fuel filter, fuel pump, distributor. Cleaned weber carburator, spark plugs, slaved in a ignition coil, changed rotor and distributor cap. Only thing I have not changed is the spark plug wires and timing chain. What do you think is the problem. Please help. Been troubleshooting for months now. Any ideas will help. Is it a timing issue? Runs good on idle all day long.

[oregondime]

what kind of motor? thats a good possibility that its a timing issue.. the wrong kind of ignition coil could do it too. also check if all 4 spark plugs are getting a nice strong spark and tan colored.

[kf6rcp]

HI! Thanks for the reply! Its a L16 engine. I did check the timing and it is good. I just could not tell if it the chain is loose or not and will it cause the problem? A mechanic looked and said it might need a to rebuild the engine since unleaded fuel is being used and the engine was made for leaded fuel/regular fuel. I took out the valve cover and the timing chain seems loose on the right side facing the engine. No sure if that is normal to have some slack. Also, I noticed the distributor rotor moves like .5 inches counter clockwise. Should the rotor be steady and should not move when engine is shut down?

[oregondime]

a loose timing chain can def mess you up. check and see if your still at tdc. are you sure that your distributor is fully seated in there? if the rotor is a loose sloppy wiggle thats not good

[kf6rcp]

Thanks again! I pretty sure its in there. There is like spring tension on the rotor when you move it counter clockwise. No sure it that is normal. Ofcourse I had to put some pressure to make it move and then it goes back....not sure how it is mechanically linked in there. How about the unleaded fuel will that be a cause for this?

[DISLEXICDIME]

are your valvs adjusted is your carb adjusted do you have Points ?

[kf6rcp]

Hi! I did not adjust or mess with the valves. I have MSD electronic ignition. Nothing really to adjust on the 32/36 weber carb. Adjusted the 2.5 turns out on one of the screws.

[oregondime]

try starting with really rich and slowly leaning out. what kind of backfiring? a slight sputter or bucking like a horse? did it work like that before you went to msd (if you switched it yourself).

[kf6rcp]

Hi! It worked fine for 4 years with the MSD ignition and this problem came up. Its a slight sputter then try to step on the gas pedal to keep it up then it eventually dies let it rest for aminute or two then it will start up. The back fire mostly comes up the intake carb.