Carb school
 

Welp another question trying to obtain knowledge and make up my mind. as most have noticed I ask a lot of question and might seem like im not taking yall advice and I am sorry if thats the case i am just trying to piece together what i know and what i think and just get input....


Right now im cruising around with a bone stock 350 minus an open element K&N that needs cleaned and some shiny valve covers. one thing that has been bugging the hell out of me since DAY ONE! the quadrajunk. i dislike this carb but im giving it another chance.

My issue is the thing bogs down really bad. I have a guy who says for 125$ he can completely rebuild it and tune it for me and will run as good as any holley or edel.


So do i pay him to rebuild it?

Watch a youtube tutorial and read up on it and do a quick tune on it?

Trash it and find a good used 650 edelbrock? (if this one does anyone have a good one they wanna sell for a good price?)

Re: Carb school
 

Some ppl like the old quads because they are gas savers, little flappers open normally and big ones when u want to go "faster!" If u don't care about gas mileage, not gonna be to big of a diff if your driving it like I do!!!! Then go with a holly based carb easy to set and modify plus they can be bought cheep on CL. I'm not a fan of edlebrock, they are much harder to tune and mess with for a novice. That is my take.
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Re: Carb school
 

Im trying to find something quick for a swap to get rid of it bogging down. No BS for me to even spin a stock set of all season generic 235/70 tires i have to hold the throttle and jockey the brake til it breaks loose then shell spin til the cows come home but i miss being able to leave the line in a cloud of smoke.... granted that was with a tunnel rammed 468 but yea.... lol so im looking mainly to get away from it bogging down and not having any balls for right now. its one of 3 (soon to be 4) vehicles I have in my driveway and im only 24 so i can afford to have it down for a weekend or two if needed but i dont want to lose the little bit of summer i have left for swapping and intake, cause then ill wanna find a RPM air gap and while the dizzy is out i might as well grab a MSD 6a setup. then hell itll be easy to pull pushrods and lifters and freshen that up so while im in there i might as well grab some 1.6 RRs and hell the cam will be freed up lets....... see where this goes and why I am really pushing to get something quick with 4 bolts and a wire or two if needed HAHAHA

Re: Carb school
 

thats my only rebutle for a holley hahaha

Re: Carb school
 

Is the big bog when you climb on the throttle?
On the passenger side front of those carbs is a flat screw going from the passenger side to the drivers side that adjusts the secondaries.
Once set a allen bolt keeps it from moving but 99% of the time the allen bolt has fallen out letting the screw back off and creating the worlds biggest bog.
Lynn

Re: Carb school
 

a qjet makes more low end and mid rang power then a holly or edl. i have one on my 86 and lovethe ****ing thing. starts with no choke at all( wired open) at 0* all winter long and pulls good. i tuned it once in 8 years and have not tuched it ever. no bog no lag. i say if the motor will stay stock qjet. i have an edl 1406 and it is good but the qjet is better on the low end but the edl walks buy on the top end

Re: Carb school
 

Totally agree with Lynn. What's happening during the big is that the "dust flaps", which are the covers for the secondary butterflies, are opening too fast and leaning out the mixture causing a bog. Adjust those flaps a bit tighter and use loctite on that Allen set screw.
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Re: Carb school
 

To check if it is indeed the secondary airvalve is too loose just tap on it with your finger. If it stays open it needs to be adjusted. If it snaps shut it's good. To adjust put a small flat screwdriver on the screw and loosen the lock screw. Don't let the screw move freely (keep the screwdriver on it). Back it off about 1 turn, tap on the airvalve and tighten the screw until the airvalve just closes when you tap it. Turn it one more turn and lock it down. Most carbs have a setting of 1 to 1 1/4 turns. You don't want to take the screwdriver off at any time. THe spring will pop off the tang inside and then you'll need to pull the top off the carb to fix it. And you don't need loctite on the set screw.
If your airvalve is good when you first check it then look inside the carb with the motor off, stroke the throttle and you should see two strong shots of fuel. If not your accelerator pump needs replaced. In that case a rebuild is in order.

Re: Carb school
 

I've got a 383 stroker, mild cam, dart 202 heads, dual plane eldo intake and........ A 600 cfm 1406 carb. 355hp to rear wheels, 13.5 afr and 13mpg. Thats with a sm465 trans and 308 gears. Runs smooth as glass and I tuned it myself. I'm no carb guru. My last truck was a 98 with a 305. Only changes to the carb was rods and springs. Just my 2 cents.
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Re: Carb school
 

Ok guys i believe the allen screw is still in place because i remember reading googling and youtubing it and couldnt find and allen key for it. But i will try that and when it bogs its any time i stomp on the throttle fom very low rpms. Does anyome happen to know the size of the allen key? I will be looking later to check and find what allen key it is and try adjusting it
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Re: Carb school
 

try 3/32,
but my one looks like a torx

Re: Carb school
 

What's your base timing set at? An engine with retarded timing will
have a bad bog. Bump your timing up to about 8 to 10 degrees btdc.
Make sure your advance weights in distributor are free.

Re: Carb school
 

When I had my last truck, an '86 305, I knew it was going to remain mostly stock. That's why I knew I wanted a mostly stock carb. I researched high and low for rebuild kits, then for not much more I found Mountain Man Fuel Systems I think it was on Ebay Motors. I think it was around $180 shipped, with a 1 year warranty as long as you sent your stock carb back to him as a core (if you didn't send it back within 30 days no warranty for you). Since my truck was my daily driver at the time, I didn't want to be down and out if something broke or needed to be replaced during a rebuild, so swapping it out with one already rebuilt was better for me. Of course "since I had it off" I replaced the intake with a Summit Stage 1 intake kit, but that was all the farther I went with it at the time. Started with just the key every time after that, it was setup near perfect out of the box. I think I went about a 1/4 turn on the mixture screws and everything else was perfect.

Re: Carb school
 

Check the accelerator pump first then bump your timing. Did you tap on the airvalve?

Re: Carb school
 

Agree with Grumpy... Q-jets are legit when work is put into them. Hang onto it.

Re: Carb school
 

i have a edelbrock and its nothing but trouble its boggy also its been tuned many times timing has been checked im rebuilding a holley now.alot of people i know have no luck with edelbrock.i think i got a qjet just sitting from late 90s

Re: Carb school
 

havent checked my timing thats another thing i wanted to to was advance the timing a little but wanted to make sure the carb was set before i started with anywhere else. im afraid if i start just changing things then i would be just chasing things. so i just wanted to start with one thing then move on. but hopefully tomorrow or this weekend i will be able to check the airvalve and get that set.

Re: Carb school
 

Rule of thumb is and has always been 'timing first, carb second'.
You might find after you set your timing that there's nothing wrong with your carb.

Re: Carb school
 

ok very well. ill have to track down a light tomorrow and bump the timing up a little

Re: Carb school
 

Aim for 12-14 initial.

Re: Carb school
 

How was the Edlebrock tuned? If it was tuned correctly it wouldn't respond how you're stating and that goes with any carb. Edelbrocks are very versatile and simple, they're a great street carb.

Re: Carb school
 

Big x2 jabes1. I'm use to fuel injected. I tuned my eldo on my own and hit the nail on the head. If I can. Anyone could make an eldo run good
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Re: Carb school
 

it was tuned to edelbrocks specs.i may have just ****ty one from factory,but honestly about everyone i know throws them in a corner here.nobody i know has luck with them.me myself i just dont care much for them.alot have good luck with them alot dont.alot guys here use holley,quick fuel,demon,etc

Re: Carb school
 

There are some good rebuilders if you search online. I have had Edelbrock, Carter new carbs and rebuilt Qjets. I currently have a rebuilt factory Qjet on my 454 and it runs well. I would just get a rebuild from a specialist in Qjets - I think most mechanics are not skilled enough to rebuild Qjets - it takes some experience, tools, good quality parts to do a good rebuild, not just a cheap rebuild kit.

Whatever you do, get a manual choke kit ($12) - that way you will know for sure that your choke valve is open all the way when you are driving and closed all the way when you first start it up. With an automatic choke you never know where the choke valve is, either hot air or electric.

It could be that your choke valve is not opened all the way when hot now - I would check that out first.

Re: Carb school
 

well i didnt have a timing light but have always ran the advance until its hard to start then get on it and check for spark knock.... needless to say after a little working on the timing for a few minutes shes running a lot better! I need to get a light on it and get it where i want it plus probably throw some new plugs wires cap and rotor just to be sure

Re: Carb school
 

:but: I've never had any issues with any of my electric chokes as long as it's working and adjusted.

Re: Carb school
 

dumb question.... I run regular 87 in my truck right now. and started bumping up the timing a little. and once i start advancing shell run like a raped ape, but on higher RPMs ill start getting spark knock.... If i back the timing off she loses the power. could i either put in new hotter plugs and wires cap/rotor. or can i run 91 octane to help out?

Re: Carb school
 

Run higher octane and see what it does. What's your compression?

Initial timing and total timing. Ported or manifold vacuum for vac advance?
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Re: Carb school
 

Keep the timing cranked up but put on an HEI vacuum pot limiter. Cuts back your excess timing. Pic in here.
http://www.chevelles.com/forums/showthread.php?t=343241

Re: Carb school
 

its just a bone stock from the factory 350 all i have done is chrome valve covers (just had them laying around lol) and a open element. and figures.... i just filled up the other day and well 20 gallons at 3.37..... kinda sucks haha



damn now i remember why my ol man always threw away HEI kits and we ordered MSD Billets..... which i might have at the house a brand new MSD billet and I have a 6a box here just need to get a coil

Re: Carb school
 

You are very fortunate. I have never had one work properly, consistently. The worst part was when I was driving on ice right after starting up the vehicle cold, and the choke stayed closed almost all the way, and the engine revved up a lot - try to ease away from a stop sign on ice at 20 degrees below zero.:lol:
Plus, Edelbrock choke valve was too big for the opening and got stuck from time to time, plus thermostat coil on electrics never opened up far enough, or too far - never could get it right. I am not very lucky.

Re: Carb school
 

octane in gas is used to slow down the burning speed of the air fuel mix. More compression speeds up the burning speed.
On a stock motor ,higher octane is a waste of money. Get the timing right and you will have better power and mileage. The HEI is a pretty good and tunable distributor. If your inclined to tune it ,do it at a 1/8 drag strip. You can make small changes and with accurate measured times of acceleration and you can see what works and what don't. Plus drag racing is a lot of fun, and its really fun when your getting faster.
On your timing I would start with the base timing and bump it up a degree at a time till it stops improving. You will probably wind up with a base timing of about 10 to 12 degrees btdc.
after that get a advance kit for your HEI. It has counter weights and about six springs. You can mix different spring tensions. In my case a stock 350 with a th350 and 3.42 gears I ran fastest with one stock spring and the next lightest spring from the kit. But every engine is different ,so test it.
If you keep the Quadrajet, I would if you stay fairly stock, You can tune it too. I got a book on it and learned a lot. I found out that the secondary's when they open they raise a pair of tapered rods up thru the jets and not all rods are the same. In my case my rods were pretty thick limiting fuel flow. I found some junk Quadrajet with thinner rods and wound up knocking off a 1/2 second in the 1/8 mile. These rods have letters stamped in them to identify them and they are discussed in that Quadrajet book.

Re: Carb school
 

I just got a pro billet hei

If your base timing is to high like at 15*btdc and your mechanical is giving 25 because its worn then the combination will give you 40* which while is not bad it's still a tad high esp if your octane is low. Worn hei distributors give a lot of advance sometimes more than 25* in bad cases

Try and get 38* by 3500 rpm at least. 10-12* initial is about what stock-even cammed engines like
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