RE: 1979 C3 Carburetor
 

I was able to go home (I am in Rhode Island and the car is in Virginia) and look at the Carb this weekend and it was really beyond repair/overhaul. I bought a 0-80457s (electric choke) 600cfm 4 barrel Holley Carb and installed it according to the directions and hooked everything back up like it was on the old one (same type carb).

My problem is it runs fine in the driveway but on the road I can not get it above 80mph. The guy I bought it from says he installed a cam and it has an eldebrach intake so I think it should go a little bit faster than that... Exhaust is new from the headers back. Does anyone have any ideas or should I get on the phone with Holley and see what they say.

RE: 1979 C3 Carburetor
 

good idea changing it out. Now dose it just seem to run out of power at 80 mph or is your rpms at 5-6 grand at 80 mph?? if your rpms are low and it just bogs out at 80 your air fuel mixture screws may be set in to far (not getting enough fuel). turn one in all the way till it seats finger tight and count how many turns (complete) it goes in. I usually set mine at all the way in, then back them out 2 full 360 degree rotations then test drive and go 1/4 turn outs from there driving and feelin it out! make sure you set both equally. they are the small screws facing the front of the motor with the springs behind them on or near the base plate.
a 600 cfm may be a tad small if the motor has been beefed up some what. if its a mild built motor it should be fine.
try this and let me know how it turns out!! hope it helps!!

RE: 1979 C3 Carburetor
 

blknblu68,
thanks. I am going to go back home next week and try that out. When I floor it, I get up to about 3500-4000 RMPs and no more. Does this sound like a tranny problem to you? I know that there was a cable that connected to the bottom drivers side of the carb and doesn't that go to the tranny? Not sure. I will try the screws when I go back home next week.

Thanks

RE: 1979 C3 Carburetor
 

The cable sounds like it might be the kick down cable that downshifts with full throttle.

RE: 1979 C3 Carburetor
 

even with the kick down cable unhooked (good call 73 shark) eventually it should get more top end than 80 mph!!
the kick down cable is basiclly Passing gear when you stomp the gas it kicks the trans into a lower gear for faster accelleration.
let me know what happens when u toy with the a/f mix screws Riley.

RE: 1979 C3 Carburetor
 

One other thing to check is make sure the carb throttle is opening all the way when the gas pedal is pushed to the floor it may be that your not opening the carb up all the way !!! have someone depress the peadl and then see if you can open the carb (throttle) with your hand any further ? you may need to adjust the cable to compensate!!!

RE: 1979 C3 Carburetor
 

Thanks. I will try both of them this weekend.

RE: 1979 C3 Carburetor
 

blknblu68's comment re: throttle not opening all the way caused me to think that what might also be happening is the secondaries aren't opening. I'm guessing that they are vacuum operated secondaries on this carb. So if the primary butterflies are opening fully, then you need to check the secondaries. If there is a hose connected to a diaphragm that actuates the secondaries, I think disconnecting it should allow secondaries to open but not familiar w/ this carb.

RE: 1979 C3 Carburetor
 

Thanks for all the help. I drove back home this weekend and found the problem with the secondaries not opening. On the passenger side of the intake there was a small cover (2 bolts) that blocked some form of exhaust port and it was interfereing with the carb linkage. flipped the little cover over and the problem is fixed. Thanks for the help.

RE: 1979 C3 Carburetor
 

Sounds like someone replaced the EGR valve with a plate????