F-Head Engine Issues

Ok, it's been a long time, but I'm finally able to concentrate on my cj5.

Background: Bought my 61 two years ago not running. Seller claimed that it ran, but must have "electrical issues". Me and a buddy tinkered around a bit and got it running. Replace just about all of the fuel and electrical components. I also replaced the carb with a solex. It ran great for about a day. Cleaned PCV components, vacuum appears to be ok, adjusted valves already.

Problem:
When you rev it up, it will spit and sputter and backfire through the carb and lacks power power when driving.

Solution:
When you place your hand over the carb to reduce air flow, it will rev up like its brand new.

Seeing as I've done just about everything possible outside of the engine, what else could be causing this?

Suggestions, Opinions, Experience anyone?

 

float level not set corectly? from what you are saying you either have a vac leak or not enough fuel to air, checked the fuel psi? fuel flow?

 

this also causes as what is refered to as a "lean misfire or lean backfire"

 

Yeah change the plugs I had kind of same problem went to a hotter plugs man what a difference Autolite 295 was too cold. The motor really runs great now 1961 CJ.:hurrican:

 

You said it ran great for about a day, I wounder if you might have picked up some crud from the gas tank. If you are running a good fuel filter check and see if you are getting fresh fuel to the filter. If no filter you may want to check the carb to see if it picked up some trash.
Another possibility is since it idles OK but poor on acceleration your distributor isn't advancing. If I recall correctly my F Head didn't have a vacuum advance t was purely mechanical. It's possible the counterweights under the breaker plate have become corroded so they don't advance the spark. If you have access to a timing light see if the timing advances when you attempt to accelerate.

 

Thanks for all of the replies thus far. That was fast.

I will be diving into it tomorrow and this weekend. I may as well go ahead and replace the spark plugs as well...again. I've been using the J8Cs, What else would you recommend?

 

Heat range on the plugs can kinda depend on the altitude you run the jeep at, from what I understand. If you're at sea level, you want to stick close to the factory spec. The gasman and I live in the mountains, and it works out best for us to run a plug 1/2- 1 range hotter. This holds true no matter the specific engine... I've got a 258. If you live closer to sea level, I'd stick with the factory spec for starters.

I stick with champions, because they work well in my situation. Plugs are cheap, so it doesn't cost your first born to experiment a little.

I'd start with the basics first before I started looking for the perfect plugs. Make sure the carb is tuned and operating properly, new parts properly installed in the distributor, a known good coil, known good wires, good grounds, fully charged battery with clean connections, and plain old factory specified plugs should get you a good baseline to improve from.

 

OK, I gotta ask...what's the start valve? Sounds like an inside joke, but never heard of a start valve and could find anything in the documentation.

A lot of the basic stuff has been covered, in some case several times. New coil, plugs, wires, pertronix, fuel filter, fuel pump, battery, etc, etc.

My plan of attack this weekend:

1. Check fuel by making a hillbilly gas tank and hanging it above the carb. If it runs better, then I'll concentrate on the fuel system.

2. If #1 don't help, dig further for vacuum leaks.

3. If #3 don't help, check into the distributor advance, timing, timing chain, etc.

 

x2 :iagree: takes place of the choke butterfly, fuel enrichment valve

 

Ok. I think I figured out the majority of the problem...no gasket between the carb and the airhorn. I had it idling and took a peak at the airhorn and thought "hey, shouldn't there be something there?" Made a quick cork gasket and installed it. Bingo. It still spits and sputters a little bit, but its about 80% better. I'm going to get a new rubber gasket, new plugs, check for additional vacuum leaks, and try to fine tune everything. Thanks for all of you help.