Hi all. We were able to get my 64 for c800 coe firetruck started today but the idle is pretty low. We were not able to find an idle set screw or any way to set the idle. It has a 534 with a Holly carb with a governor.

Any help is appreciated. I'll snap a picture of all the linkage around the carb if that helps.

Here's the carb info

C3TE-9510-D
List 2156-1
431

 

Hope this pic works...
it's the screw at bottom, just above the word "line" where it says "fuel line" at the bottom caption

 

I'll look for that screw when we're messing with it next. There's extra cables and lines attached to set the throttle for running the pumps, so things got a bit confusing on this one.

 

 

That screw is all of the way in.

 

Thank you sir. Do you have diagrams of the brake and clutch system? That's our next thing to fix.

 

Does it move the throttle shaft when you adjust the speed screw in and out?
Do you get an rpm rise when you pull the choke out the first half inch or so?
Are the idle mixture screws having any effect? They are on the secondaries on this goofy carb...

 

I'm not sure what your goal is with this truck but when I bought my 63 c850 with the same engine someone had put an Edelbrock 1405 600cfm carburetor on it. Given that these old motors redline around 3200 rpm 600 cfm is more carb than it needs.There is a bit of a dead spot in the throttle right around the point the secondaries open but I've driven vehicles that came from the factory that were worse.
I was considering going to a smaller carb or finding an original to go on it. I did eventually get an original this past weekend. Honestly the truck runs good the way it is so rebuilding the factory carb a low priority.

As it is it starts way better than it has a right to even after sitting for weeks. I rarely need to use the choke.


One concern is that there is no governor, It would be easy for someone to over rev the engine. I'm the only one who drives mine so it's not an issue.


If the original carb is too far gone or if you need it reliable right now, you could do a lot worse. If you're going to put a lot of miles on it, I'd go with something with a bit lower ctm rating. There are rev limiter options out there but so far every one I've found is for 4000 rpm and up. 4k revs on a 534 is a quick way to grenade your engine. I've thought about trying one designed for a 4 cylinder as it would think the engine is spinning twice as fast. Once again I'm the only one driving it now and I know not to push it so it's been a low priority.

 

So we took the carb off the rebuild it since it was full of gunk and found out that the arm the idle screw pushes on is bent. Look like someone cranked on it or who knows. But bending it back should give us adjustment back. The screw might have been missing the arm altogether also.