Rpm too high!!

[cerryblazer]

Hey guys! a question please
thanks!
i rebuilt my engine, all is ok, just a thing is weird.
i started engine for a first test, i removed valve cover, i adjusted valves and it ran good.
but when i reassembled valve covers, i started the engine again but, without touching accelerator pedal, engine speed (RPM) were so high that i had to shut it down!!
i saw that carb throttle linkage stop, doesn't touch fast idle screw as before!
someone has some good idea!?
Thanks for attention guys!
Fabio

 

[Keitha]

Simple things first: Can you manually close the carb linkage to slow it down? Could a simple throttle return spring solve the problem? Is your linkage out of adjustment?

 

[cerryblazer]

thanks for answer.
i tried to close linkage manually but it's too hard, just if i turn manually the choke, throttle linkage touches the idle screw on the driver side, but as soon as i push down accelerator pedal, throttle linkage turns back but it is too distant from idle screw, as if i push down accelerator to the floor!

i tried to remove spring and accelerator cable, without nothing, but the problem remains.

 

[Russell]

Try turning the high idle screw down a bit. I believe it is in the upper pass front side of the carb.

 

[Fordum]

Oh, man.
I saw this thread earlier, but didn't have a good idea.
I just reread it, and spotted what I missed before. Or you had not written it yet

Its your choke.

When the engine is cold, the choke is trying to close. But there is a fast idle cam attached to the choke that will not let it all the way.

When you press down on the accelerator, that releases the cam, and the choke closes all the way.
Then, when you let go of the accelerator, the fast idle cam holds the throttle open until the truck warms up.
The truck will continue to fast idle even after its warm, until you press the pedal again and let the cam move back.

It sounds complicated, but its real obvious when you see it.

Most of the carbs had a fast idle adjustment screw as well as a regular idle adjustment screw.

Forget about the linkage and idle adjustment screw. Hook all that back up, and go around on the other side of the carb.

Take that black or brown cap off of the choke. The heat spring should slide out of the slot in the end of the choke shaft.

Turn the choke shaft to the wide open position, and open the throttle slightly and let it go back to idle
Then, watch the choke linkage inside where the cap was against the carb, and turn the choke shaft to the closed postion. It will not close all the way.

Hold it there lightly, and while watching the linkage next to the carb, open the throttle slightly.
You will see the choke close, and the stair-step looking fast idle cam start holding the throttle open.

If the part that sits on the stair-step is an adjustment screw, that is the fast idle adjustment.

If you are looking at the carb, and none of this makes sense, then you may have a different carb from the ones I am used to, so someone else may have to give it a shot.

J.

 

[cerryblazer]

Hey guys! i solved the mystery!
i don't know how, but the idle fast screw on the passenger side was almost totally screwed in!!! so throttle linkage couldn't go backto the idle stop position on the driver side.
incredible because when i removed carb, i don't touch everything about screws or linkage.
unless the past adjustment, before rebuilding the engine, it was totally different than that necessary now.
can i ask you another question or i must open another topic?
ok i write
i replace old thermostat with new one 195°F - 91°C, it's correct that the arrow on the water indicator is between first and second notch?! it should not before the first notch? it's a chevy 305 engine
thanks guys for the precious help!

 

[Keitha]

Glad you got the idle/carb worked out. Let's see a picture of your Balazer...

 

[cerryblazer]

sure!
let me upload something online.
hey have you got idea about my last question please?
about thermostat!
sorry but if i don't post my doubts on "coloradok5" where i can post them?