CaliC20

So I have this 66 Chevy C20 with a 327 5.3L 4 speed manual transmission shifter on the floor all original it has a 2 barrel carburetor that I rebuilt and I cleaned the gas tank has a new gas filter
truck starts right up check the timing and it runs great parked if I give it gas it responds nicely
Now this is where I’m at a loss
when I put it on drive on 1st gear the truck barely moves the RPM’s go sky high I have to switch to 2nd gear to get it moving and it takes off but again the engine revs high and it gets sluggish so I have to put it in 3rd gear only then it opens up and drives normal and faster 4th gear is not problem nor the reverse
i have new spark plugs I check the valve adjustment timing and all looks good
what I’m missing? The distributor components?
the truck was sitting for 5 years before I bought it
one mechanic told me it was the clutch that need it replacement
Who has any input on this problem?
i been doing all the work myself from the brakes to the engine
I read on another site that this trucks don’t use the 1st gear unless loaded but the 2nd gear barely moves the truck before I have to get the 3rd gear to make it move faster
any help will be appreciated thank you

kevinkpk

1st gear is used for towing, you need only start in 2nd gear unless you have a load on it (trailer). RPM's are good, runs good, it's good.

Gumby22

I agree with kevinpk on this - I don’t think you have a problem - it sounds like normal transmission operation.

If the clutch was the problem, the engine would rev up in all gears and you’d smell the clutch burning as it slips (smells just like overheated brakes). And even assuming there’s something else wrong, it would be in the transmission, not the engine.

Normal upshifting should occur anywhere between 1500-2500 RPM (it all depends on the gear and vehicle speed). If you think something is wrong, try to note the vehicle speed as you shift from 1-2, 2-3, and 3-4 and post the results here - that may provide insight to the issue.

And if you haven’t done so already, change the fluid in the transmission as well.

CaliC20

thank you for the information I just did the oil change on the manual transmission it was black when it came out, I get around 20 miles an hour before I have to switch to 3rd gear but once on 3rd gear it won’t go past 35 miles and hour before I get the 4th gear in, once on 4th gear it goes but I have not driving it on the freeway or the open road only on the streets. Also I noticed driving down the hill the carburetor sounds like is too much gas going in and is not fast like it should I have a 2 barrel carburetor I don’t know if I did the float the right way the measurements for the float
I’m gonna open the distributor cap to see if that is good since I have not touch it since I got the truck
the thing is some days it runs good and some other days runs like crap! I remove the fuel line just to make sure fuel was clean and it is.
i have not replaced the cap rotor or spark plug wires only the spark plugs could that be part of the problem since the truck was sitting for 5 years?
it’s been 3 years since I got an older car my last one was a 77 Pontiac Trans Am Firebird 6.6L that run better than this truck but of course that was a car not a truck

CaliC20

I had a 68 Dodge D200 automatic transmission with the original engine but headers intake Holley 4 barrel carburetor and it run faster than this Chevy
i also had a 76 Ford F100 automatic transmission and the engine had the same as the Dodge they both run better than the Chevy it seems

unless I’m expecting this truck to run faster and do a burn out, to be fair I never had a late model Chevy other than a 99 suburban that run pretty good

after checking the distributor everything seems to be in order and the truck drives what seems to be ok I was just expecting more power and faster and longer drive before shifting
I will have to check with the GPS to see the true speed just to make sure the speedometer is correct since it shows 30 miles at 4th gear
but is driving now is just too slow for me but again back in the 60’s what was the speed limit 55 MPH?

kevinkpk

It was 70 mph. I'm attaching a rochester 2gc link for your carb.
Rochester 2-Jet Carb Manual- The Old Car Manual Project

CaliC20

great information about the carburetor thank you.

CaliC20

Finally got it all figure out, truck is slow at take off after finding out how this trucks work I’m able to drive it the way it was designed to be driven not like a 2021 truck
I got a set of 16” steel rims with tires for $125 since the original rims had some old tires that need it replacement
truck runs and shifts good so far no overheating issues
Brake lights are not working it could be the switch and the lights on the hood don’t turn on only when I use the turn signals work I will check those out soon
Over all I’m happy with what I’m done so far and the way it handles and drives
the best part is that I’m doing all the work myself no mechanic help
thank you all that help with the links and information

CaliC20

The carburetor was missing a spring from the carburetor to the front of the engine
gas pedal was not returning all the way up like it normally would it was a little low and gas keep going into the carburetor even do gas pedal was not pressed
it was a long spring the problem
now it runs better

chevyboy@22

Check fire at plug,if you have it,check fuel pressure,if you have fuel pressure at carb,then you may need to make sure you are incorrect timing.