HELP - Question about unleaded gas in old Jeeps

I have a 1956 CJ6 with about 79000 miles (F4-134 engine) that is still running fine because although I no longer drive it much I do start it up frequently. I've had it 26 years and only put about 1000 miles on it myself. I have been using unleaded regular in it, but have wondered whether I could be do some damage to the engine? I saw today a lead substitute product at Walmart and wonder if maybe I should be using something like that?

I also am getting a little gas drip onto the top of the engine block at the bottom of the carb on occasion. It will usually start and idle without this drip, but if I choke it too much or drive around the block a few times the drip appears. Is it possible the float needs adjusting and it is overfilling the carburetor and coming out an overflow hole? Is there such thing as an overflow hole? The manual says the carburetor is a Carter YF-938SD. Any opinions on either topic? Thanks in advance for any advice!

[krabysniper]

Yes you are doing some damage to it but for the amount you are running it I would say it would be of little consern. The big issue with leaded and unleaded fuels was that the lead in the fuel in the old days helped prevent the valves from wiping out the valve seats. A cure for this is to pull the head and have a competent machine shop install hardened seats. But I really wouldn't worry about it until you are having running issues. Some of the snake oil's they are selling as a lead substitute are just crap, some perportedly work. I personaly have never used any so can't say as to which may or may not do you some good. Maybe one of the other resident "experts" will chime in with an opinion. [img]images/graemlins/grin.gif[/img] As for the dripping of fuel, yes there is a bowl vent on all carburetors of old, and yes most likely resetting the float level should solve the problem. Hope this helps. Peace dude [img]images/graemlins/cool.gif[/img]

[stump_breaker]

I asked a similar question some time ago about lead substitute in gas. I did a Google search and like what was said, it lubricates the valves and seats on older engines. Seems like they used a softer metal way back then. I was wondering if a substitute would benefit a newer engine for the lubricating effect. Never really got an answer so I figured it was a moot point. I agree with Kraby, go get you a head job.....er, on your Jeep that is, when you start having trouble. If you're wanting to stay all original, do some research on the WWW and see what everyone else is doing.
You're probably right on the money with the float adjustment. Maybe even a rebuild just for poops and giggles. Them old seals bound to need changing by now. I'm going to say no on the overflow hole but then I'm no carb expert.

[krabysniper]

It's not that they used softer metal back then, they didn't harden the valve seats because the lead in the gas took care of lubing and softening the impact of the valve against the seat. When they took the lead out of the gas in the 70's (due to environmental impact) they found out that the valve seats would start getting wiped out due to the lack of the lead, so they figured out how to harden the seats by sending a huge electrical charge thru just the seat area which creates changes in the molecular structure of the steel in the seat area making them much harder than the surrounding metal, it's anly a small area but it does the trick of taking the abuse of valves slamming into the seats at seat pressures over 250 lbs and at cycles of 500 times per min at idle speeds, and 4000 times a min ro more and 500 plus lbs of seat pressure in a high performance engine. As for will lead substitutes be of any value in the newer engines, no, not really with the exceptions of the ones that give a boost to the octane which in conjunction with a performance tuned engine could net you increased performance.

[tincan]

On the carb leak: Is appears you let the jeep sit for long periods. You may have water build up in the bowl that has eaten a hole in the bowl = new carb.
If you let it sit a long time, add Stabil to the fuel.

My dad's 68 GTO still has the original engine and used no lead subs even when it served as his DD. After roughly 30K miles of unleaded DD use it suffered no visible ill effects.