idle problems

Hey I've picked up a f600 with a 262 in it. I've replaced the intake and exhaust rebuilt the carb tuned it up and it still won't idle at low rpm. What am I missing?y

Have you checked for vacuum leaks? With some of these old carb's the throdle shaft can be worn excessively causing a bad vacuum leak. Also check that the distribors vacuum canister is in good condition (I.e. it can hold a vacuum). Good luck

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bubba22349":1mfvy49r said:

Have you checked for vacuum leaks? With some of these old carb's the throdle shaft can be worn excessively causing a bad vacuum leak. Also check that the distribors vacuum canister is in good condition (I.e. it can hold a vacuum). Good luck

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. Ok the distributor is the next thing we will take a look at. Thank you :thanks:

Hi, X2. Did it idle better before you took it apart? When you rebuilt the carb did you check the throttle shaft for wear, the shaft is harder than the carb body and the holes could be egg shaped. Spry carb cleaner at the carb base to check for a leak. Maybe a vacuum fitting was left off or loose. Make sure the choke is fully open and you are not on high idle. Good luck

I put a kit in the carb. Definitely helped it we also rep!aced the vacuum advance that helped alot. So I checked the throttle shaft and it's a bit worn not egg shaped and we definitely made progress it still won't idle without the the chock pulled but that just move the adjustment screw up the choke cam . When we do get idle it's at a higher rpm and the fuel is pouring in instead of squirting. I am told to take it back apart and dip it again and make sure my idle mixture screw is rplaced. Also to take a small wire and check for blocked passages. My question is would a faulty idle mixture screw be suspect? Thank you for your answers. The delayed response is due to my computer skills!! Lacking

Hi, fuel pouring in is a big issue. at any steady RPM you shouldn't really see much fuel in the mixture. The fuel squirt should only be obvious when you open the throttle and activate the accelerator pump. I would double check the float level (your rebuild kit should have instructions and maybe a gauge), shake the float or dunk it to make sure it is dry and does not leak and double check the needle and seat for dirt and correct assembly. Also inspect the idle mixture screw for damage or a groove worn into it before tossing it. I don't poke wire into any carb passage, I take the straw on the carb cleaner spray and shoot the cleaner right into the passages. Good luck

X2 that sure sounds like a float problem now if gas is pouring in. It is normal to see a very light mist like vapor going down the carb throat with the engine running at a low speed idle. So if it's poring in than look for signs of a heavy float (has crack in it that's letting fuel in it) or a too high of a float setting that the wet fuel level is higher than spec. Good luck

Ok I am going back in the float bowel and I did order another air fuel mixture screw.

Fuel flooding in sounds to me like carb is flooding. Could be cracked float, mal-adjusted float, or too much fuel pressure. Has the fuel pump been replaced with a new one?
New fuel pump pressures range from about 5-7 psi. If that carb is a Holley 1904 1bbl with rebuild kit, it will flood if the fuel pump is new because the carb rebuild kit contains a fuel inlet fitting that allows 3 times more fuel in than the original inlet fitting.
A rebuilt Holley 1904 can only take about 1.2 to maybe 2 psi pressure. Any more pressure will defeat the float and cause flooding. Under this condition, the engine will run fine at higher throttle because the extra gas coming in is being consumed.
Fixes for this:
Revert back to the original fuel inlet fitting and needle (if they are salvageable with a good cleaning).
If not, a fuel pressure regulator will work for a while. Not very practical and too expensive to keep buying regulators (many are not serviceable).
Thirdly, but much more invasive, construct an orifice in the fuel line ahead of carb inlet and tee off with a bypass line back to the gas tank. If you wind up needing to do this, look back at older post where I give detailed description and photos of this.

Thank you Dave55courier. I'm sure you hit the nail on the head.

BTW, I hope you don't need to do this but if you do, to see my original post just type in "223 fuel system update" in the search box. It was a couple years ago so you might need to scroll down a ways.
And, that filter at the top of the engine is a MOPAR bypass fuel filter. I'm only using it as a permanent bypass so I should never need to replace it. If you want that kind of situation, put another inline fuel filter ahead of the bypass filter. I located my primary filter immediately ahead of the fuel pump for easy access in case I want to replace the filter.
The orifice is VERY important. I used a piece of metal tubing that fits snugly inside the 5/16" fuel supply tubing immediately ahead of the carb inlet. Since the Holley 1904 carb inlet aims directly at the valve cover, the 5/16" tubing is bent to aim toward the front of the engine pretty closely near the carb inlet. Your new orifice tubing can be about 1-1/2" long and inserted inside the 5/16" tubing where it connects to the carb. As such the orifice is actually partially inserted into the carb inlet fitting when the tubing is fully connected.
My system works perfectly and I've never had any flooding since I installed it.
Theoretically, the way it works is the orifice creates back-pressure in the inlet tubing, causing fuel to back up into the fuel bypass line via the MOPAR bypass filter, then it is just a matter of pressure and gravity pushing the unwanted pressure back to the gas tank thru the added bypass line.
It is kind of a miracle that the addition of the simple orifice and bypass line is just enough pressure relief to allow the carb float to keep too much fuel pressure from inundating the needle seat. Suppose the orifice had not been enough restriction? Suppose the bypass line had been routed in a manner more restrictive to fuel flow? It would not have worked !!!

Ok I will certainly save that post. I am putting a regulator on just to get by for a while, the truck will see little use this winter time enough to gather material to bypass

OK so I put a a fuel pressure regulator on this 262 and that solved the carb issue. It will do thru the winter until
I can put a bypass line back to the fuel tank. I am wondering what to do with motor in the future I would like to get more use out of this f600 and I do know that an old motor like that (which I am finding out is rare) has only about 5000 miles on a rebuild will last for years, I would like to put it in the near future put it in a classic car and use it.Or at least see some else do it. It is not the original motor its in a 1962 f600 and its a 1964 motor. C4TE 6015 C with a four digit 7H22 number under it located driver side below the intake. So one question is what is the value of a motor like this? :thanks:

You are correct those old 262 engines are quite hard to find. Severial years back I was looking for one to build up for a vintage drag race car, values as well as demand are also hard to determine for these old six'es. Best of luck with your project

OK I finally made progress. On the 262 we found a few bent pushrods upon checking the lash on the rockers we found some that were tightened to much and most of them were set around .14 or so. So after a little research I came up with a .19 valve lash so we set them and it fired right up and ran. Now it still has some bugs to workout so new pushrods are on the way and the carb will work for the winter I got some good advice from you all :thanks: I sure am liking this motor and we will update a video of it running when we get it back together.