Need to replace the original carb on 81 vette. Can not get the original to run right after rebuild. Any suggestions, trying to get car up and running after ten years and give to my daughter. so far have put new calipers, rotors, exhaust system. Looking for what is the easy and safe.

All comments welcome.

 

I replaced my Quadrajet with an Edelbrock performer carb, it ran great straight out the box. I know Quadrajets are good, but I think the performer carbs are great value for money. On my '81 I rebuilt the entite top end with new heads, cam, intake and carb, all from edelbrock so they matched perfectly.

 

Same here great investment.

 

Solutions that don't require that you change your intake manifold:

The easiest right now solution is to replace the Q-jet with one of the Holley 4165 (mechanical) or 4175 (vacuum) carbs. They are pretty much a straight bolt-on replacement for the Q-jet and are readily available.

You can also get a reman Q-jet from you local parts jobber. While quality sometimes leaves something to be desired, if it doesn't work right, you can take it back.

You can also try to track down a rebuildable core and try to rebuild it yourself. Easier said than done, though, since this is time consuming in the search for the right carb and there is no guarantee that you'll have a useable carb in the end.

 

Did you ensure that the runout on the new rotors was in tolerance? With the stock design of caliper seals a rotor that has excessive runout can cause the seals to suck air into the system (a bad design if ever there was one) which is far from safe.
As for the carb, you'll no doubt get a barrage of posts from people telling you to junk the carb & computer system as they're rubbish, etc, etc (they're not liked on this forum ). I've got mine running well, as have several other people. Have you get the factory workshop manual for the L81? It's got a lot of info on setting up the carb. Apart from the normal things like air leaks at gaskets, etc, you've also got to set the rich & lean stops for the "dancing needle", set the IAB & check that the TPS is adjusted correctly. These aren't difficult to do, but you really need some gauges to do it. I recently went to Calif & tried to get some (Napa, Pepboys, Marine engine place(!)) & didn't find any. They are available, but I haven't a clue where. The IAB setting will be roughly right if it's backed out 4 1/2 turns from fully seated & the idle mixture screws are set 3 1/2 turns out for a good starting point. To accurately set the IAB you need to hookup an ANALOGUE dwell meter to a test point & adjust it until the dwell reading is correct. What I did (Bubba admission!) is to adjust it until the idle quality was the best I could get. I turned up the idle speed slightly, adjusted the IAB until I got the highest (a most regular idle), dropped the speed a bit, adjusted it some more & so on (it's very similar to setting the idle mixture on things like Amal carbs). After I set it I checked the position & it was very close to 4 1/2 turns out, so I can't be far off. I did this after setting the mixture screws 4 1/2 turns out.
The TPS is adjusted by using a simple wiring pigtail, but I don't know where to get one of those either!
Are you sure it's the carb causing the problems? Is the computer setting any fault codes?
Somebody to ask would be Dallanex. He's set up his E4ME and knows where to get all the bits/what to do.
It would also be worth asking on the L81 forum (http://l81vetteregistry.com/) as somebody there should be able to help.
If you take the "throw the computer away route" then the simplest (& cheapest) option would be to fit a carb & distributor from an '80 or earlier.
Also check the vacuum hoses for leaks. After sitting that long they might have sprung a few at the connections. I know mine had a couple of leaks that were a real pita to find & caused it to run really rough at low rpms.
Good luck!

 

You won't ever convince Paul to scrap that computer

 

But the one in the Vette is the only one that's never given me grief! It does what computers were originally promised to do in that it doesn't need constant upgrades, doesn't lose mappings randomly, spitefully change its video attributes from day to day, etc, etc, etc. It just sits there & does it's job without pestering me. I like that in a computer

 

Yeah, but it's just like all computers from the 80's.

IT'S SLOW!!!

Even I junked my computer crap and went the traditional way of vacuum advance and turning screws.

 

:devilsadvocate
.... relative to modern computers, which will be slow when compared to ones in the future. How fast was the processor that was on the Apollo missions? The CCC system may be slow, but it's a lot faster than I am Does it need to sample more than every 100msecs when it's fitted to a car with smog heads, poor cam, crap exhaust design & a dire CR? And if it's so bad, then how can it handle decent aftermarket heads & much better cams, only falling over when manifold vacuum drops to low at idle? And why does mine have lower emissions than cars only 3 years old that still have a cat in place? Not only have they got cats, they've also got modern processors in them
Or..... 70's C3's are like all 70's smog mobiles - THEY'RE SLOW, so they don't need a fast processor!
I figure that this forum is to help people out & advising people to junk their entire CCC system & spend a bundle of cash to replace it when there may just be a simple adjustment needed isn't really helping them. Advising to junk it if the carb is knackered, or the ECM is burnt out would be sensible, but the original post mentioned a rebuild (& not much more). It could be something really simple like the lean stop not set correctly, where 15 mins of fiddling will get it running right. If he swaps out the carb then he really needs to swap out the distributor as well, then remove/modify any emission controls still in place as the computer has an input to them & then, if it's an auto, hook up a method to get the converter to lock. Seems like a lot of work (& cash) to pump into something that he's just going to give away & may just need a couple of hours spending on it to tune up & get running right (isn't that what we all like to do with our cars?).
That's why I pointed him at the L81 Registry, there could be somebody there who can help him sort it out quickly (& if not, I suggested stuff from an '80 or earlier, which should be easy to find & will slap on there fairly easily). Asking about CCC systems here just gets the usual "throw it all away" response. It's like somebody asking what to do about a motor that burns oil & everybody leaping in & saying "Hell, s**t boy, that's knackered. Drop in a 502 crate motor". It could be that it just needs the valve seals changed.
Now, if it was a lot later than '81 & was running a version of Windows then I'd say "Take it out, lay it on the ground & take a felling axe to it"

uh-oh, I said that 70's C3's are slow There's no chance of Dep looking in on an 81 carb post is there? Oh boy, that'd really stir things up around here

 

See now look what you have done, you have got him all fired up now

 

Not at all I'm just full of the joys of life - I could have died in the Vette on tuesday night. It was close, very, very close. You won't see this said very often, but what saved us was the Vettes brakes! I am very, very impressed with my VB&P O ring calipers I can't believe that we're still alive & that I still have my Vette, by rights we should have been spread all over the road. 2 days later & I'm still pumped up on adrenaline. Tonight I'll take the only known cure for it: beer. And lots of it.
Whether the stock E4ME is fixed, or another carb is fitted, I really don't care: just make sure those brakes are in perfect working order, morons can appear on the roads at any moment.

 

Thanks guys for the info. Got car back today, or rather my daughter did. Work done, it was new carb, rotors, calipers, pads, exhaust sytem (total, mufflers, pipes. from headers back), new brake lines, new fuel lines, engine electrical (tune up) changed out all fluids and hoses on engine. So all she has to do is get the AC charged and buy a set of teetop bags. All for 3 grand and a year warranty on everything that was done.

 

I must say that I'm with Paul. Part of the fun and chalenge of the '81 is the carb and computer system. To me, it's part of what makes these cars special, right down to the 85 MPH speedometer.