F-Head Tune Up

I just purchased a 58 CJ5 with a stock F head. It ran but poorly. So I replaced, points, condenser, plugs, plug wires, cap, rotor, fuel filter, fuel pump (went to electric) with regulator. I set the timing with a light based upon the service manual instructions. Did not replace the coil.

It now runs about the same - like crap. Starts ok, but misses badly upon acceleration, and even back-fires occasionally. Blue smoke sometimes. I checked compression and all cylinders are 155-160. The carb is an after market JC Whitney with what appears to only be one adjustment screw for air flow ??

Any suggestions are appreciated. Thanks,

Mike
63suv

 

"Starts ok, but misses badly upon acceleration, and even back-fires occasionally."

That could possibly be an air leak in the carb or at the carb gasket. Over-tightening can bend the carb base flange ears.

I'd double check the point gap, and excess slop in the distributor shaft bearing, too.

 

I never had any luck with the Solex. LeRoy just doesn't like them at all and did the same thing to me with a new one..... so it sits on the shelf all shinny and new and I rebuilt the YJ. Sounds like the accel pump is not keeping up, easy to push it along with a rev or two and see if she is better. You may want to just rebuild a good ol YJ, there are a tun of them out there and they are easy to work.
Good Luck,

 

Copy from the tech page on Solex.....but LeRoy just don't like it.
http://www.film.queensu.ca/CJ3B/Tech/SolexCarb.html

 

Symptom suggests either ignition advance (if equipped) isn't working right but most likely the accelerator pump in the carburetor isn't working right from your description.

 

Suggestion from a self proclaimed Dummy. (I am the one they write all those books for):

Try adjusting the timing a little either advanced or retarded and see what happens.

One thing I found was that the timing went completely out the window when I installed my Pertronix unit. I ended up timing the thing from the number three cylinder.
With the points in it timed from the number one cylinder.
Go figure.

Plus mine was one of the blocks without timing marks on the timing gear cover.
Once I got the points set, and the distributer setup with the number one tower in the 5 o:clock position, I then made my own indicator pointer on the cover. That worked pretty decently with initial timing.

 

I know this sounds too obvious but did you check that the wires are in the correct firing order. Mine did the exact same thing and I discovered I had two wires reversed.

 

Check your plugs and wires too... just cause they are new doesn't mean they are in working order. I had a miss I couldn't figure out until I swapped the plugs around and the miss followed the plug... new Autolite plugs.. one was bad. I also have seen new plug wires that are bad.

 

Thanks for all the good suggestions. Replaced the carb with a new solex, then reset the timing. Starts and runs great at idle but still sputters upon acceleration. Accelerator pump is probably the issue. Has any adjusted the accelerator pump on a Solex ? Does it cure acceleration issues ??