I have an 86 z that I put together a couple of years ago. Been driving it all over without problems-good gas mileage, etc. Vortec 350 with HOT cam, 750 edelbrock, etc. Tonight I took it to the strip for the first time and with good traction (drag radials) it would stumble and stutter all the way through first gear and it would start to run ok at about 5500 rpm. When I would shift into 2nd it would run ok all the way to the end of the 1/4. My buddy said off the line I had black smoke coming out of the exhaust. Has anyone else out there had problems with the edelbrock carbs like this? I drove 100 miles home afterwards and it ran great-stomped on it from a roll and it ran right to 6000rpm. I am thinking the gforces are causing the fuel to slosh where it shouldn't be in this carb thus causing the rich problem. Ran 102.5 mph but it would not et at all-14-15 sec with one 13.40 when I opened the N2O-still I have ran a 12.60 with spray on my gtech on the street-but the traction is not as good as the track. Maybe I have answered my own question but I would really like to find a fix for this because the carb has worked so well until now-26 mpg on the hwy and just plain old runs good. I do not want to put a Holley on because I have the stock air cleaner and hood clearance is a problem. Thanks

 

I have the same problem with the 600 on my car. I think that your right about the forces messing things up. I am curious to see what others have to say.

 

I've never had an issue with these carbs, they always ran great for me. Here's some suggestions, hope they'll help.
1. If you look inside the carb there is usually a little sheet metal baffle that keeps the float from being influenced by acceleration, is it still there?
2. I don't understand the smoke condition, and I'm not there to see it, but if you uncap the headers, that's usually going to make the carb go lean. It's been my experience that any time you uncap the headers, you need to richin' up the carb.
3. pump shot, did you change the rod to another hole on the accelerator pump?
4. It seems like the fuel prssure is ok, if the car is "shooting ducks" from low fuel pressure, it will usually be in 3rd or 4th gear on the high end.
5. Check the secondary power valve(air flap) is it adjusted properly?
When Carter Carbs used to make these, and they still do, they made something called a "trick kit" that had all sorts of jets, springs and metering rods for the carb. Someone probably still makes that kit.
I hope this helps, if not I have a number that you can call.

 

Don't some of the edelbrock carbs have a weighted counter balance on the chocke or throttle plate for the secondaries?
Could this not be choking the secondaries under extreme acceleration?
Do you really need the choke plate for drag racing?

 

No, (work with me here, it's been awhile) What yuo see on the secondary is the air valve, as this is opened by vacuum, it allows the secondery fuel system to meter. There are primary and secondary throttle plates in the base just like a Holley, and a choke on the primaries, but that air valve and it's adjustment is the key to making these carbs work. It is weighted, at least on most models, and that weight counters the engine vacuum to create a smooth transition to the secondary. What happens is that you hammer the gas, both the primary and secondary plates open. The front uses the accelerator pump, jet size and etc to meter. As the car accelerates the vacuum increases and the secondary air valve opens , this lets the secondaries meter. There are 2 little "hatches" held on with screws just in fron tof the valve on the top/sides of the carb. Carefully loosen the screw and rotate the hatch to the side. Inside is the metering rods, they should pop up if not stuck. Make sure that they spring up and down and don't have any crud on them. Then carefully re-install them (DO NOT FORCE THEM!!!). These rods go into the main jets. All of this can be adjusted, the main jet size, rod size and taper, and the spring. You also need to make sure the secondary air valve is not "flopping" open, there should be some tension on it and it should close by itself. I don't recall where this adjustment is, like I said, it's been awhile, but these are great carbs. One other thing, if you change this carb go to a Barry Grant, not a Holley, I knew Barry personally growing up and I would highly recomend his work.

 

I believe Barry Grant carbs use Holley dimensions. I don't think it will solve his hood clearance problem. Right?

 

Correct, they're somewhat Holley based. I really like the set up that he has on it now, he just needs to work out some of the bugs.

 

I have a few Holley's laying around already so I would not have to buy a new carb. I was running it thru the complete exhaust system-no open headers here. I did change the adjustment for the accelerator pump shot-I needed to do that just to drive around with it. It had a lean bog until I moved the rod. I will tear it down tonight-have not looked at it since I put it on 2 years ago-maybe time for some maintenance. Thanks

 

that's what is so greta about those carbs, I mean a 13 second car that gets 26mpg!! Life can't be all bad. They are sort of an install and forget type of unit.

 

Yeah...and with a HOT cam. That's a great trick! Let us know if you can dip into the 13's without the spray.

 

There's no adjustment for it, you have to disassemble the carb and modify the counterweights.

 

Easily will run 13's without spray. I have run low 13's on the gtech-which is within 2 tenths of the track. Just have not ran at the track until now-no problems or stumble on the street. I think it is leaning out on me-even with the black smoke I think the secondaries are opening too quick and with street tires it just spins them-with the drag radials it needs more fuel. Here are the specs on the whole motor-97 chev pickup motor (warranty-I paid $600 for it and put new bearings in it) cleaned up the heads and milled the bottoms of the retainers for clearance, used the GM 5673 intake and the HOT cam. 26.7 mpg is the best I have seen-it is amazing. 18 degrees initial 36 total timing. 3.23 gears and a tremec 5 speed. Idles at 800 and runs at 160 degrees in any temp-I would take it anywhere. Need to get the AC going again-anybody have any tips to find leaks??

 

AC leaks? Somone sells some UV stuff to put in your ac system, you use a black light to spot the leaks, works really well or so I have heard.

There is also some red dye you can put in the system too. I read about this on the open roads forum at woodall's
(an RV tow vehicle forum)

 

Like I said Apeiron, it's been awhile...