Hello all,

I have a 1967 F100 with a 240 inline 6. I am currently going through the rolling chassis/driveline but do not have a whole lot of experience apart from general repairs (this is kind of a learning experience for me!) Here is my issue: the engine seems to sputter/almost stall out when you hit the throttle. I believe my carb is an autolite 1100, I've done some research and I believe it is the accelerator pump causing the issue. I've tried to do the adjustments like suggested, but I can not seem to physically get the thing to adjust. Could anyone guide me in the right direction? does it need a rebuild? should I just replace the thing with another model - and if so should I stick with single barrel?

Thanks for the help!

 

It's a great engine, I would not change the carburetor out unless it was in bad shape or unrepairable for some reason. If it hasn't had any attention in a while though, yes it would need it.

It is tempting to buy a new carburetor when engine problems occur. I know, because I've done it myself. And I'm sure Holley and those guys love that.

But it doesn't really work out very well that way. I think it's a mistake, not trying to beat up on you don't misunderstand, but if you aren't up to speed on what's installed there now - that is tailor made for the engine - a shiny new carburetor may not really help. And may hurt. Without getting off into the weeds explaining why you should really spend $5000 and rebuild the entire engine to fix this problem, I'd suggest getting the Ford Shop Manual for your model year truck. Sniff around the internet and should be able to find a free copy of a .PDF for the 1100 carburetor or two.

Have to study it and understand the carb a little bit. Then adjust everything back to the way it was when Ford delivered it, and de-install all those half-assed crappy mismatched wrong parts that were put on in 1982, etc. Modern gasoline will tend to eat up accelerator pump diaphragms.

People are also famous for leaving out parts on their "rebuilds". Check ***** and things like that. This is why the manuals are so important, they have the exploded diagrams for reference, and show all the gee-gaws and frazzlewhiznits that interface tangentially with the encabulator nozzles etc. Some of those inline 6 engines used loadomatic distributors that must be paired with the correct carburetor or it won't run correctly.

 

Thanks for the reply, Tedster!

Don't get me wrong, I am not going to act like I know what I am doing, because I don't!
But I did forget to mention, this 240 has been rebuilt. Although it was re-built a long time ago (1991 I believe the tag says), I don't believe the engine has many miles on it since the rebuild. The truck had been sitting in a field a number of years ago when I bought it. I just changed the spark plugs at the start of this month and they all looked to be in very good condition.

Anyways, I'll definitely stick with this carb if it is doable. About three years ago I had bought a NAPA rebuild kit and a friend of mine who grew up tinkering with carbs and what not helped me put it together. I know Mikes Carburetor has kits for the 1100, but which one should I be purchasing? I will definitely be looking for PDF manual for these 1100's, im eager to learn about them!

 

A "rebuild" on a carburetor is kind of a misleading term. It's mostly cleaning, and renewing the rubber parts that degrade. But cleaning and/or rebuilding a carb is more than just shooting a can of carb cleaner through it. There are quite a few basic bench settings or adjustments made to the carburetor before re-installing on the engine. Many people forget about the adjustments that need to be made after installation.

And a rebuild is ordinarily part of a complete Tune-Up. The reason this is important is because the carburetor expects everything else to be plussed up and squared away, including though not limited to good compression, ignition and ignition timing in spec, and no vacuum leaks. All of those things affect the engine manifold vacuum. The carburetor simply will not respond or adjust the way it should without a thorough Tune-Up, and you'll pull your hair out trying, blame the carb, etc.

Another thing that should be in your toolbox right next to the Shop Manual (Nod your head "yes") is an inexpensive tool called a mechanic's vacuum gauge. The first thing to check during your carb rebuild should probably be the gas tank. If it sat for a long time it could have a lot of rust, water, sludge and crap in it that will clog lines and filters and screw up your handiwork. Then any old rubber fuel hose along the way should be replaced. Low pressure shop air backflushing the lines may help fuel flow.

Then measure the fuel pump pressure output with your new vacuum gauge. If pump output is too high or too low, the carb cannot be tuned or calibrated properly and again, the engine will not run right no matter what.

It only takes about 30 seconds to do this, don't even have to start the engine to do it. 5 or maybe 6 psi cold is plenty. More is not better here! The auto parts mechanical fuel pumps sold today don't seem to be very good in this regard, they run excessively high pressure. So be careful about replacing parts, there is a lot of junk out there.

It's kind of like what they say about painting - 90% preparation, 10% actually laying paint.

 

Rebuilt in 1991. It's time for another rebuild. Kits are cheap.