F-head a smoke-n....

Ok, I have a F-head and she has great compression and all cyl. are with in 5% of each other. This motor starts very easy and runs great. My problem is I get about 75 miles to a quart of 10w40... She don't smoke when it starts up, but as she idles and I gas it a bit she blow a slight haze... When I get on it or run around the woods playing I notice it more... Here is a picture of it doing it...

What should I do to fix this or is this just normal?

Thanks,
Pottsy

 

nope, not normal. Sounds like you're getting a lot of blow-by past the rings. check the pcv valve if it has one, but most likely worn or broken rings.

 

I would ditch the 10-40W
try straight 30
IMO

 

Also should I run regular pump gas or should I put a lead additive in it?

 

What Jim said

 

It should have a PCV valve. If you didn't know this, I believe the Jeep was actually the first vehicle to have one.

 

i had a similiar problem, but not as noticable, i bought a new pcv valve and now i get no smoke at all (using 5w-30)

 

no seals IIRC....
valve guides are possible though

 

I'd opt for the single viscosity 30 weight oil. I use 30 weight year 'round and have no problem starting the jeep in winter.

It could be rings or it could be the head. Now, if you have good compression and it is within 5% then I'd suspect the head in general and the valve guides in particular.

That is really a very simple repair. Take the head off and take it to a machine shop and ask for a valve job. Have the valves and valve guides replaced. They'll know what to do. When you get it back, paint it with some high temp paint and reinstall. Torque it to specs (If I remember right it is 70 ft pounds).

don't forget the head bolt under the carburetor.....

While you have it apart you can tidy up the block.

I always get a thread chasing (repair) set and clean out the threads in the block of all the head bolts. You'd be surprised how much crud can get in there. It doesn't hurt for the crud to be there before you take it apart, but when you reinstall the head bolts it does matter when you are setting torque. Dont use a tap and die to do this, use a thread repair kit. They aren't the same, and the repair kit will not cut new metal out of the threads like the tap and die will.

I do the same thing with the threads on the head bolts themselves. If you have a sand blaster, now is a great time to blast away on the bolts.

The manual has the tightening sequence. Tighten them all to around 40 ft pounds, then increase to around 60 ft pounds, then go to 70 ft pounds.

You'll need a new head gasket.

Total cost should be under 150.00 with the long pole in the tent being the time it takes the machine shop to do their work.

Have the shop give you your old intake valves back. They are great tools for special needs. I use one for removing steering wheels.

Total 'touch' time should be a couple of hours from disassembly through reassembly.

good luck.

kamel

 

Fella's,
Thank you... Straight 30 weight worked great... It's amazing how much the oil affected the motor!

Pottsy

 

Question on the Valves...does the F head have Valve seals or just guides. I also have a smoke problem. I have 110 lbs compression in all 4 cly. My jeep sat for many years and I suspect that it is a seal problem if they have them. Also what is valve setting?
TIA
Leon

 

Mine smokes a little too, maybe I'll try the 30 oil. And the PCV valve, where do you get a new one, and where is the valve on the moror I can;t find mine??? maybe a good cleaning is in store, maybe I am just looking for the wrong thing.

 

F-head PCV valve. DeBella's Jeep Parts has new ones for ~$20 IIRC.

http://www.earlycj5.com/forums/showthread.php?t=25715