223 question

My 223 only gets about 10 mpg. I use it for work but, is that about right? I dont always haul big loads but when I do, mpg is about the same. Rebuilt the carb allready and everything is stock. I know f100s are not the lightest vehicles on the road. Im a little disappointed. Thought mpg would be better. I was trying to avoid smog here in Cali and get better mpg than a V8. Ive never done a V8 engine swap but I guess its eminant.

 

How's your vacuum?

The distributor on the 223 is vacuum advance only. No mechanical at all. If you have vacuum leaks, either at the intake manifold, or around the intake valve stems, your timing will be all messed up. My 223 was leaking through the valve stems so the timing was always retarded. I ended up doing a Y-block swap.

So, check out your vacuum, and price out having new valve guides put in your heads. Or ream out your existing valve guides 0.003" and buy valves with oversize stems to match.

 

Thanks SRF. Vacuum advance was fine when I got it on the road. Ill check it again. I also replaced all hoses that had to do with the performance of the motor. Would the amount of blow by affect mpg alot? Will that valve work(considering time and money invested) improve mpg? Will I gain 8 to 10 mpg?

Thank you in advance for your time and advice.

 

I had a 223 in my truck when I bought it. Had 3 on the tree and 3.70 gears. It had lots of giddy up and I was rather impressed with it. It had 1/2" holes drilled into the intake manifold for a smog tube to the valvecover. It leaked pretty good and it still had good power. I dont know about milage as I only drove it around a couple days before I parked it and pulled the 223. Doesnt hurt to check the distributor advance though.

 

I would expect about 15 or a bit better around town depending on how heavy your foot is. I ***ume we ARE talking about a PU?

 

If you are questioning the amount of blow by, I am going to ***ume that it has quite a bit. A very good indication the engine is tired, and working very hard. Yes, that will effect mileage. A leak down test, or at least a compression test, that coupled with your vacuum gauge, and you can make a very educated guess about the condition of the engine. Even reading the spark plugs will give a indication what's happening internally. Even with a fresh engine, I would not expect a 10 mpg increase, for a total of 20 mpg. Close maybe, but the gearing in those old rigs and the fact it's about as aerodynamic as a brick, these two factors alone will keep you from those magic mpg numbers a new modern P/U is capable of. BDM.

 

I dont have a clue how many miles are on that motor. But I see I have my work cut out for me. Im not attached to that motor, by any means, but I wish I got better mpg. It sounds like Im better off with a V8 swap. And yes, its a P/U.

 

I have a 223 in my 59 Ranch Wagon and I get around 10-12 mpg. Something may be wrong - but it runs good and has power.

 

I had a 302 and a 3 speed in an F100 long box, that got 18 on the highway with no problem. My guess is that yours is blowing by inside and loosing mpg because of it.