CaliC20

I hope I fixed the problem I was having with the hesitation acceleration issues on my 1966 C20 3/4 ton 4 speed manual transmission with a 327 engine and a 2 barrel Rochester carburetor

after I did the rebuild I don’t remember removing anything from the bottom passenger side of the carburetor but I had a screw blocking this hole that I didn’t know at the time was for air

the truck was running like crap hardly power like gas issues but today I removed that screw completely not knowing what to expect and you car hear sucking air,

I took the truck for a drive and what a difference that made, response is so much better now I can take of on 2nd gear and give it gas unlike before when I took off the truck moved but I had to get 3rd gear in because the truck wasn’t going any faster

so my question is for those that know more about this carburetor what goes there?
mis there a special adjustment screw to let air in the carburetor like the mixture screws on the bottom front of the carburetor?

or it goes to some vacuum line or exhaust line?

any help will be appreciated thank you
let me attach some pictures of my carb


uretor

kevinkpk

Those are idle air mixture screws. Best advice is to set them at half the way out. Alot of times carb shops would put a plastic stop on them so as to not be able to turn them either way in or out. Since you have manual brakes, manual transmission, the only vacuum line from the carb is vaccum advance, and pcv valve.

CaliC20

great information, thank you

Rednucleus

If you are talking about that diaginal hole above the front idle screw, it must be an unused vacuum port if you hear/feel air sucking in with screw out. If you put finger over the hole, how does it run? if it runs better with the screw out, seems to me that says you are too rich - don't think the screw should be out unless you are hooking something in the hole that needs vacuum. Please keep in mind I'm a veterinarian, not a mechanic!!

CaliC20

that is correct that’s exactly what the truck is doing now that I removed the bolt it was there and that bolt don’t have any holes on it where you can adjust or connect a vacuum line
now that the bolt is removed truck idles badly but it takes off really good, (that’s not a bolt that came with the carburetor, previous owner had it like that when I bought the truck) truck has a lot of power compared to the way it was when the bolt was blocking the air intake.
I don’t know if that will hurt the engine by running like that with the hole wide open nothing blocking or attached to it.
if the hole is open what could happen? Too much gasoline going in the carburetor damaging the plugs only or something else?

Rednucleus

Would be creating a lean condition - too much air, not enough fuel - hopefully smarter folks will post soon to help you out.

CaliC20

Now that I removed the plug truck performs better it seems quicker and faster, before it had too much hesitation and not enough power

CaliC20

is not working better! Is running the same
this morning after removing the plug it did run better
but now almost 10 hours later I turn it on took it for a drive and is running the same as it did before.

maybe I need a new carburetor? Since all I did was a rebuilt.

im looking at a few on eBay and other sites that run from $300 to $500 any input on where to look for one?

Rednucleus

When you did the rebuild, how did you clean it before re-assembly?

CaliC20

I followed directions from YouTube post and I used carburetor cleaner and needles to clean to holes I do don’t know I had to adjust the float so I didn’t I just installed like it came out of the box I didn’t remember seeing that adjustment on the video I was watching and I didn’t bother searching to find out why I had that paper with numbers on it
maybe that’s the problem? When I’m going downhill it runs worse that going uphill or a flat street