Timing Issues?

[Family Truckster]

Greetings,
I have a 1983 CJ-8 Scrambler with a 304 engine from a 1981 CJ-5. It has a Howell TB sitting on an Edlebrock Performer intake and cam We rebuilt the Jeep a few years ago. A few weeks ago it began to miss at higher RPMs. Now there is a popping sound. My question is: Could the timing chain jumped a cog? And, if so, how could I determine this wthout first disassembling the front of the engine?
Thanks,
Dave

 

[69jeepcj]

It is possible that the chain jumped a tooth, lobe on cam is wiped, dist vac advance can diaphragm ruptured, if carb has power valve it could have ruptured as well. All can cause your symptoms, there is more but I would start here.. I assume you have some mechanical knowledge: To check chain, bring #1 piston to TDC on compression stroke, see if your timing marks on the balancer are on zero, take off your dist cap and see if the tip of the rotor is pointing to the #1 plug tower on the cap. If it is the chain didn't jump, now lets see how much slack is in the chain. With the dist cap still off, use a socket on the crank pulley nut or using your hands on the belts, manually turn the engine one direction while watching your dist rotor, as soon as the rotor starts to move STOP, now take a mental note of where your balancer is (the timing marks is best) and rotate the engine in the other direction while watching the dist rotor. Again, as soon as the rotor moves stop! look at the balancer and see how far it turned before the rotor moved. That is the slack in your chain, and if you used the timing marks you will have a good idea of the degrees of slack. There should be NONE! for the vac advance can, just pull off the hose to the can, and suck on the can, if you suck air the diaphragm has a hole in it. Could this be just a carb adjustment?

 

[Family Truckster]

I will begin my diagnosis using your suggestions. In place of a carb, I have a Howell Throttle Body. Yes, I have turned a few wrenches. In fact, we tore the Scrambler down to a bare tub and frame and rebuilt it three years ago. Thank you for your help. In your personal opinion, should I consider a DUI HEI distributor swap?
Dave

 

[69jeepcj]

Wel the ignition system on these jeep are not the best, the ignition module is notorious for failing... Im kinda bia to the HEI, I swaped from points ignition to the HEI and absolutely love it over the points. I don't know if you would see any performance increase but I think you would have better starting and smoother transitions from idle to cruise with a HEI. Only draw back is you would be using a dist that was not designed for you engine and there for you may have to remap your advance curve in the dist. That is done by adding heavier or lighter springs to the dist weights, it takes some playing with but not that tough. You may be able to put it in and it be just fine, all depends on how close the timing curves are between the two dist. (yours and the HEI) They are very cheap at junkyards and just about any will do, easy to install.. just one 12volt wire, so I think you should give it a try if you run across one.