Hello! I have a 83 Z28 and just recently replaced my Quadrajet with a edelbrock 1406 Carb.Got the thing tuned and running smoothly,and revs up great but when i take off down the road it runs very rough (sluggish) when you give it gas.If you barely press on the gas it runs fine but just a firm press and sluggish again.Ok i'll start by what i removed,I removed most of the A/C stuff because the compressor was locked up and i really dont need A/C,i removed the EGR and replaced it with a EGR block-off plate.Replaced the stock radiator with an all aluminum 3 core with 2 12" fans and replaced the tranny cooler with a aftermarket all aluminum tran cooler.The only thing i have yet to replace is the fuel pump,but was told this will most likely NOT be the problem.I am lost please help!

 

Could be because the distributor that is still in the motor is computer controlled (the advance that is), and if you get rid of the Q-jet, than you have to get rid of the stock distributor as well, and replace it with a vacuum advance dizzy.

 

if you get rid of the ccc carb you need to get rid of the dizzy to they work as a pair . You need to get 1 with vacuum advanced the stock 1 works off the computer and with the carb gone it has no idea what to do.

 

AH ok i will give that a go and see if that clears things up a bit!

 

Summit has them for $90.

This is the one I got.

http://www.summitracing.com/parts/SUM-850001R/

 

Or, better yet, put the q-jet back on and sell the Edelbrock. Save money, and have a better carb in the end.

 

Alright you got your answer now quick before five7kid gets on and tells you to put the q-jet back on delete this thread before he sees...... oh wait. ....... never mind

 

i think i would replace the engine before i went back to quadrajunk!

 

 

may as well. you're already throwing money away.

 

As stated, you ever wonder why NHRA Super Stocks ran them in the 60's & 70's over all other carbs, they give the easiest tunability and the most power/ cfm. ( I am refering to the Quadra-jet)

 

Check and adjust the acc pump that can make is sluggish. Also depending on the year of the carb I think 90 and newer, it has a power valve blow out protector, so if it is older that a say 1985 and you had a backfire you might have blown the power valve, that to can make it sluggish. But before you do any thing check your timing again and make sure it is dead on.I am sure you did a full tune up right? plugs, wires, cap and rotor? Then go to the carb and try to fine tune, but only after you know that the tune up is good to go. IMO holleys are the easiest to tune and rebuild.

 

since when did Edelbrock or Q-jet have powervalves?

 

My bad. It was after midnight and I just got off a VERY long night when I posted. No need for sarcasm dude, I am human and mess up now and again.

 

Ok i replaced the CC dizzy with a Vac advanced dizzy and got the timing dead on but the problem still occurs.The edelbrock is a 600cfm carb and the stock is a 500cfm.Could this carb really be to much for the 305?

 

Ok its just to much Carb for the stock 305.I put the quadrajet back on it and it runs fine and runs down the road fine as well so i will either get the 500cfm 1403 or just leave the Quad on it but thanx for all the comments!

 

Leaving the Q-jet on is probably your best option. Don't go with the 1403. That 1406 isn't too much for your car, it's just not tuned correctly. Stick with the Q-jet.

 

The problem you are having is related to the stock tuning of the Edelbrock carb. I had the exact same problem. The carb comes stock tuned very lean and desperately needs a re-tune. You should grab an Edelbrock #1477 rebuild kit, read the manual that came with your #1406 carb and notice the reference chart for tuning the carb. I re-tuned mine pretty close to the middle of the chart for a balance between power and fuel economy and it made a HUGE difference. Also, if you change your vaccuume advance line from "ported vaccuume" (the higher port on the front of the carb) to the manifold vaccuume port (the lower port on the front of the carb) you will gain better timing control at a small sacrifice in fuel economy. I found those two modifications made a major difference in the performance of my 305. PM me if you want any more info from me about the changes I did.

 

is a 1405 edelbrock tuned lean too?

 

My bro's still fiddling with the manual, I think I'll pass him on to you. lol

 

Yeah, I can try to help him but I'm no pro. I'm still learning as I go, I just found that a few minor changes to the stock calibration of the 1406 made a HUGE difference in performance. Don't let the Eddy haters get to you.

 

The 1405 carb is a 500 CFM carb, tuned for performance on a 305. Running one on a 350 may give an overly lean condition. You could tune the 1405 to run on a 350 but I would recommend at least 600 CFM or more for a 350...

 

hi , not sure about that ,.,,a 1405 is a 600cfm like a 1406 ,,,the diff is that a 1405 is tuned a little richer than a 1406 which is tuned for fuel economy...that's what the edelbrock website says...that's why i bought a 1405 and had the elec choke come with it ,,because i figured going to a 1405 would be better on my 350 with a cam and rpm intake and headers rather than a 1406 tuned for economy ...i just wondered if anyone out there had any ideas about the 1405 and if it ran lean like a 1406....

 

I've had 2 1405s one on a 350 and one on a 305 and they both ran rich out of the box. Even edelbrock days that some tuning will be necessary.

 

I stand corrected, I was apparently thinking of a different model. As far as tuning the carbs, both models should be simular in tuning procedures. Just follow the charts. It may take a few tries before you get it exactly how you want it.

 

The only difference between the 1406 and 1405 is manual and electric choke. They are both 600cfm. #05 has manual choke, #06 is electric. i had the 1405 on my 350 and swapped for the 1406. didnt like the long wire for the choke handle look.

 

the 1405 and 1506 are very similar..but the 1405 is supposed to be calibrated for a little more performance than the 1406 according to edelbrock and their website...this is why i got a 1405 on my 350..and then installed the electric choke on it ,,runs very well...

 

:O hmm. didnt know that... i might grab a 1405.. i live in houston so i am able start my car with a wide open choke suprisingly lol. it has to be super cold outside for my car not to start without a choke

 

No need to find a 1405, the only difference is the out-of-the-box tuning.