I have a late (December) 1978 FJ40, I've had it since May. PO had desmogged and installed a Weber 38 carb with an electric choke and no cut-off solenoid. It always started and ran reliably - but it also ran rich. The manifold would get extremely hot and there was a smell of gas when it got hot. It dieseled when shutting down.
Some additional pertinent info:
* Stock US 1978 distributor, vacuum advance is working.
* Measured vacuum steady at 15
* Poor compression numbers (low teens, more than 10% variance between cylinders)
The weber install was pretty sketchy- adapters fashioned from PVC pipe etc, but I tried to make it work. I adjusted the timing with the bb right on the needle (it was retarded a few degrees to start) and tuned the carb as best I could. Made little difference. It did idle better, but all the other issues remained.
My plan is to get one of the Japanese carbs from CityRacer, but while I'm waiting I ordered a cheap carb from Amazon and an adapter from CityRacer to plumb it to the original air filter. I bolted it on, re-adjusted the timing, and adjusted the carb. The initial result was not good: no power, super hot manifold (600 degrees after some city driving), vacuum down to 14 steady. It stuttered when it came off idle: I had to be careful to accelerate slow and smooth to keep it from dying. It did fix the dieseling at least.
After scratching my head a while I decided I would adjust the timing by ear and vacuum instead of by the mark on the flywheel. I just kept cranking it CCW, and eventually was stopped by the diaphragm hitting the oil filter. It must be 20 degrees advanced at this point but the truck seems happy. Acceleration is responsive, the manifold is cooler, and idle is maybe a bit less smooth. The gas smell is diminished - I still smell exhaust but that is a different issue.
Questions:
How much advance is too much?
My 14yo son, who has been helping with all of this, suggested that maybe the distributor is off by a click. That seems plausible if a click is something like ~7 degrees - how would I know if this were the case?
Thanks
Some additional pertinent info:
* Stock US 1978 distributor, vacuum advance is working.
* Measured vacuum steady at 15
* Poor compression numbers (low teens, more than 10% variance between cylinders)
The weber install was pretty sketchy- adapters fashioned from PVC pipe etc, but I tried to make it work. I adjusted the timing with the bb right on the needle (it was retarded a few degrees to start) and tuned the carb as best I could. Made little difference. It did idle better, but all the other issues remained.
My plan is to get one of the Japanese carbs from CityRacer, but while I'm waiting I ordered a cheap carb from Amazon and an adapter from CityRacer to plumb it to the original air filter. I bolted it on, re-adjusted the timing, and adjusted the carb. The initial result was not good: no power, super hot manifold (600 degrees after some city driving), vacuum down to 14 steady. It stuttered when it came off idle: I had to be careful to accelerate slow and smooth to keep it from dying. It did fix the dieseling at least.
After scratching my head a while I decided I would adjust the timing by ear and vacuum instead of by the mark on the flywheel. I just kept cranking it CCW, and eventually was stopped by the diaphragm hitting the oil filter. It must be 20 degrees advanced at this point but the truck seems happy. Acceleration is responsive, the manifold is cooler, and idle is maybe a bit less smooth. The gas smell is diminished - I still smell exhaust but that is a different issue.
Questions:
How much advance is too much?
My 14yo son, who has been helping with all of this, suggested that maybe the distributor is off by a click. That seems plausible if a click is something like ~7 degrees - how would I know if this were the case?
Thanks