General Category > Quadrajet Carb Talk and Tips

Got it installed and running

(1/3) > >>

GSP7:
Weather warmed up and snow is melting. So I got my old worn 17080513 pulled off my '81 350 sm blk, K20 chevy truck. Spent several days cleaning up the intake manifold and then masked it off an fresh painted it chevy 1620 orange.

 This morning unmasked every thing and reassembled that I took off, and got the new replacement, rebuilt with Cliffs parts, 17080213 carb installed on the chevy 350 and running. Checked for leaking fuel at the filter fittings, none.  Adjusted the new electric choke conversion as it got warmed up, fiddled with the idle mixture screws alittle and then back to two turns out. Slowed the idle down.

Warmed up, choke off, I throttled up to 2000 and slowly closed the choke flap, no increase in RPM... ok for now, it seems. Had a wet towel and fire extinguisher handy  ;D didnt need it so far

Took the truck for little spin down the hill and back to my house ran pretty good . Maybe a tiny hesitation at after first taking off(mid throttle). Accelerator pump and response from dead stop was crisp.

Eating lunch.... Ill pull it back in the shop check 4 bolts and air horn screw tightness from first warm up and cool down.

I put in new #72 jets and Cliffs Custom 50m rods.

APT I set at 3 1/2 turns up for starters. I used the Orange power piston spring recommended by Cliff

The new Idle mixture screws I installed at 2 turns out, to start with.

Tomorrow I play with it more trying to tune the APT etc.

The distributor timing was set at a safe, 8 degrees advance at idle, with vacuum advance plugged with the other carb.

Any tips on getting the carb dialed in?


.

lightning boy:
Congratulations! I would warm it up and run the mixture screws in until you can hear a lean roll from the exhaust at the back of the truck, then turn the screws out until you see the highest vacuum reading. Make sure there is no nozzle drip from the boosters. As far as the APT I trun the screw down until it starts to buck and surge from part throttle acceleration and then turn it out until that goes away plus a quarter turn. this will be the leanest you can run it.
I know you set the initial timing at 8* but I would see what the total timing is too. Good Luck.

GSP7:
Got idle mix screws adjusted, set timing up to 10 degrees at idle with vacuum plugged, set idle about 500 + rpm

Messed with APT at 2000 rpm and closing the choke flap. Original setting was 3 1/2 up . It never went up in rpm and I ended up going all the way down with the APT screw. It still wouldn't increase in rpm closing the choke flap at 2000 rpm.

 Drove it around with APT completely screwed all the way seated down . Drove fine. But no matter what setting APT or timing there is a hesitation costing about 30 mph and the accelerating, there is a hesitation

The reset the APT to 2 1/2 turns up , just because. Drove it some more. Runs fine still, but there is still a hesitation when accelerating from costing about 25-35  mph and then accelerating, I get a hesitation before the truck accelerates


Not sure what is up with being able to turn the APT screw all the way down and seated and runs ok. ?
'
Its a 350cu.in. sm blk chevy, 1981 4x4 truck. 17080213 carb has new 72 jets and Cliff's 50ccustom rods. It Isnt the original carb that i removed which is a 17080513

.

GSP7:

--- Quote from: lightning boy on March 03, 2025, 01:24:21 PM ---....... As far as the APT I trun the screw down until it starts to buck and surge from part throttle acceleration and then turn it out until that goes away plus a quarter turn. this will be the leanest you can run it.
........

--- End quote ---

Like I said above,,,,, I was able to turn the APT screw all the way down and it didnt cause any issues at all, not even and "buck and surge" at all. It drove the same with the screw down seated, cept for the hesitation... Im wondering what's the deal? Its a 3/4 ton truck carb if that matters #17080213


.

quadrajam:
Are you sure the centrifugal and vacuum advance working OK?  What is the vacuum at idle?
How bout the vacuum revved up a little like 1200 rpm or so?
Were the hanger arms straight and level?

QJ

Navigation

[0] Message Index

[#] Next page