Rochester Monojet Help

[ST Dog]

Resurrecting an old post.

Anyone got pictures of the monojet linkages?
I think have a problem with the fast idle cam.

'68 GMC, manual choke. Story is the engine was replaced in '72 with a new engine from a Nova (dealer warranty replacement best I can tell).

The number on the carb points to a '72 carb.
I think it was modified some for the manual choke though.
The coil is still on the intake with the linkage rod, but it's not attached to the cab, and no place to attach it either. There is a rod from the rear of the choke shaft to a cam at the base which looks like a fast idle cam.

Anyway, when I close the choke it doesn't move the fast idle cam much (if at all). If I move the cam by hand, noting in the throttle linkage touches it. Looks like I need to bend a tab on the throttle linkage to set the fast idle, but until the choke moves the cam it won't help much.

[68gmsee]

Here's a bump for you...

I've got a Rochester monojet with manual choke on my 68 GMC. I'm not sure how much of a difference there was in the linkages between the early and later years, but I can post a pic later tonight.

Is the choke linkage and fast idle cam the only pic you need?

[ST Dog]

Originally Posted by 68gmsee

Here's a bump for you...

I've got a Rochester monojet with manual choke on my 68 GMC. I'm not sure how much of a difference there was in the linkages between the early and later years, but I can post a pic later tonight.

Is the choke linkage and fast idle cam the only pic you need?

I think so, the rest seams OK. I just want to verify that everything is there, or figure out what's missing.

[68gmsee]

Well, the pics I took looked like crap so I'll get some with a different camera tomorrow morning.

[68gmsee]

Here's a pic. Hope it helps.

[ST Dog]

Quite different. Here's what I have.


(Hard to fit my camera in there for a good picture)

I guess it's all there. I adjusted the linkage from the choke to the fast idle cam so that it pulls the cam all the way at full choke.
Then adjusted the tang closed to that cam to touch and set the fast idle. About 2000 rpm when warmed up at the position the cam goes to for full choke.

[68gmsee]

Actually they're pretty simlar... Your setup is the way my original carb was. I did some swapping out last year but still have all the original stuff except for the oil breather- must have gotten left behind in one of my moves.

The tang is adjusted so that it has a slight clearance when the choke is fully open. As you engage the choke, the lever pulls up on the bellcrank to increase the throttle opening.

When you push the choke in, the bellcrank should "free fall" to it's normal rest position.. Very simple mechanism, but works great!

forgot to add: on mine, the link pushes the bellcrank down as opposed to free falling.