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I want to add dual carbs to my 1980 L48 for looks so, other than headers and exhaust it's all stock.
Here's my question, If I add a slip linkage will the 2nd carb sit there and not dump a lot of fuel under normal driving conditions?
number 2, When you kick in the 2nd carb, will there be to much gas dumped into a stock engine causing a lack of performance instead of an increase in power.
I had a thread yesterday about adding some performance to my L48 with dual carb setup. After reading advise from other members, i realized that unless I'm putting in a new crate motor I'm just wasting a lot of money and time. considering what it is the performance is pretty good and with the exhaust system sounds even better. I'm hoping the dual carb setup will make it look very cool without a bunch of problems. I'm going to the Jefferson swap meet in April so depending on what I read could be adding a new show piece before the next show. Thanks all
Gary
Not sure what the fascination is with "looks", but it's a waste of time and money for a stock L-48.
Are you going to use two 400cfm carbs or smaller? Because at 800cfm you'll already be over carbureted.
Never heard of "progressive" dual 4's, Maybe you want 3 2bbls instead ? They can be progressive.
It's not the extra fuel that will cause a problem so much - because you can jet and re-calibrate the carbs properly , but the extra air could cause a bog if not setup properly.
You will be running on both primaries at the same time with two 4's , not a big deal or a deal breaker either.
Setup is crucial , you want balanced vacuum secondary carbs for sure. A pr of Holley 390's may be it !
I put Dual Quads on my '65 "FOR LOOKS" on top of ZZ4 Crate engine. Totally stock other then the quads. Twin 500 CFM carbs. Which is way to much for stock engine at low rpms.
But with the progressive linkage (See Below) you can just drive on the back carb and when you mash-it the front card will DUMP lot of extra fuel.
But I still like the looks. More pics ==> Click Here
I have dual 4s on a 455 pontiac gto. It took me about 10 disassembles of each carb to get the right jets and rod combos. I also helped a friend with a dual 4 set up on a mild 350 in a 71 nova. If you are using 2 500 edel carbs this setting will get you close: rear(main) carb-.086 stock jet, stock 065x072 rods, and an 083 rear jet. Front carb-083 front jets, 067-055 rods, 083 rear jets. This was strictly a street set up not a race set up but he did do some quarter mlie runs. Edelbrock progressive linkage is what I used on both cars and of course each engine used different settings due to engine size.
I find it truly amazing that when I post something on here there's always someone who gladly gives negative comments. Maybe my budget is a little smaller than yours but when someone else responds that they have duals for the same reason it's okay cause it's a C2. It's a tech question and that's it, not weather you think it's not worth it because it's not what you would own. Sorry that's not what I asked and what I spend on my C3 impacts my budget not yours, and my likes and wants may not be yours and that's ok to me anyway. I like things that shine I'm from the 70's and that's how it was, old habits are hard to break. But thanks for your opinion anyway cause you just got mine. Speaking of feedback My wife and I bought a 59 Belair 4 door and restored it, yes built not bought. I had multiple people tell me I wouldn't do anything to that it's 4 door wellll 2 1/2 years later and all done now my car has more trophies then there's, and ohhhh I'd own that one. My 59 is in my garage on this site if you want to look at it. But it's not about trophies it's about enjoying the hobby, and having fun, negative people aren't much fun to be around, i'll say some prayers for you and God Bless. Thanks to all who have given me great advise and thanks for the pics Goerge and for all you Debbie Downer's I'm going with dual carbs deal with it.
As mentioned...the dual Edelbrock 500's can work OK. I have a buddy who used them on his 302 '67 Mustang. Literally junkyard shortblock from a pickup...but he did add some good aluminum heads and a used E303 cam along with headers. It ran mid/high 12's and drove great. The carbs were pretty well on the money out of the box.
All that said....a slightly better cam would help...and certainly any other heads...but for what it sounds like you're doing..go for it...they will drive fine with the right linkage setup.
I would spend some time on the timing curve. Try to add some initial timing and then limit the total advance. It will help driveabilty with any carb on a milder engine.
Just wanted to be clear that running dual quads will not improve a small stock engine (takes cam/heads/tuning/etc along with fuel) - just looks good IMO just like all the other CHROME GOODIES I LIKE
George
ZZ4 Crate -- TKO 5 Speed prior to installing in my '65
Last edited by Black_Magic; Feb 21, 2015 at 08:23 PM.
From: At my Bar drinking and wrenching in Lafayette Colorado
I've built and set up several 2X4 setups "just for looks" on various engines, including small block Chevys and 389 Pontiacs. As some people have mentioned above, you will not gain any performance from going with the dual 4's, since even a couple of small carbs will have you a bit over-carbureted. Contrary to popular belief, when you run carbs with excessive cfm capacity, you tend to end up with a lean condition - not a rich condition.
On the systems I've built, I've set them up so that the front carb was the primary carb. Both front and rear carbs have active and functional idle systems, and it's important that the idle speeds and idle mixtures on both carbs be set up exactly the same so you have the same idle air & fuel flow through both ends of the engine. I've then used an adjustable progressive linkage from the front carb to the rear carb, which delays the opening of the rear carb until the front carb is at about 75% of its throttle opening: Smaller engines need the rear carb to be delayed more - bigger engines can take the rear carb opening sooner.
Opening of the rear carb, when engine demand does not need the airflow, does not result in fuel "pouring into" the engine. It results in a massive lean condition, with air, and no fuel, entering the engine. This will cause the car to fall on its face. This "fall on face" problem is due to excessive airflow capacity for the engine's needs, with inadequate fuel enrichment as the throttles open. It's a tuning issue you'll have to work on to get the timing of the throttle opening rate just right. If you have more time than money on your hands, it will keep you entertained for quite a while.
This is why I love this site other than the nah sayers and they have there own problems. I love tinkering with my cars I built them so why not tinker. I have never done a dual quad set up so this is why I asked a simple question. Sticking with the dual's cause it will look better for a 1980, I am planning on going to 3 2's in the 59 because that will look better in that car. Thanks for all the great advise and when I go to Jefferson in April I will be looking for some new toys for the rides. Thanks again and God Bless all.
Good luck and enjoy, I've been watching this thread because I have a dual quad set up ready to go on my c3. I love the dual quad look and think the tri power on 59 is perfect , gives a vibe to what they did back when. As far as the only for looks aspect do people think every feature on their cars are designed fully for function? How about styling?
Well I have went on the same inane rant about some posts on here just get negative replys because some people are just that way but the truth is this is the net all types of people on here and some might be as smooth as shark skin on 80 grit sometimes what is viewed as negative is just the way some cats say it to help someone from making a mistake, it's up to you if hurting engine performance is worth it. or you see warning of that negative...
I have a 69 bb, I want a tri power badly, but they cost more than a good fuel injection system so it just wouldn't work in my head to pay more for something that will never perform as well as even one carb but is just "looks" cool.
I liked that idea of driving on the middle carb then when I needed it the outer two kick in, but I like more the idea of one simple carb, tuned to get down and boogie when I desire.
I do not believe that when designed the dual 4 intakes with one carb in front of the other were meant to be ran progressive, it's certainly not an optimal way of using that design intake,
A lot more eye candy would be a cross ram with side by side 4's but you cant run them progressive at all, they have to come on together and it's a high rpm intake it will kill any low torque you had.
But I wonder if you could just put a thin block off under the front carb and just run off the rear carb, at least you would have three times the cfm you need.
I am old school custom my self, Almost bought a 4 weber set up that I needed like a hole in the head, but again the single 4 barrel wins out, it will have some old school cool air cleaner. In the world of old school hot rod parts they have adapters that bolt to a 4 barrel intake, they make them for dual carbs and tri powers, many cats set them up to work progressive, take a look at vintagespeed.com Inglese has a cool old school set up it mounts two side draft webers out each side and can be ran progressive, but the intake must be open plenum to work correctly when you romp on it.
still it's going to be a looks thing, one carb would do better.
I do support whatever you desire even if it is for looks, just try to do it in a way that you will be happy with....
Here was the 81 wide body I built in 89...see I dig eye candy mods...
Cousin of mine owns a 56 vette with a two speed powerglide with two fours on it. Car is original i suppose it would be 265 cu. I rode several miles around the city streets of Wichita Kansas in it ran like a top. Your 350 should be fine.
On the systems I've built, I've set them up so that the front carb was the primary carb. Both front and rear carbs have active and functional idle systems, and it's important that the idle speeds and idle mixtures on both carbs be set up exactly the same so you have the same idle air & fuel flow through both ends of the engine. I've then used an adjustable progressive linkage from the front carb to the rear carb, which delays the opening of the rear carb until the front carb is at about 75% of its throttle opening: Smaller engines need the rear carb to be delayed more - bigger engines can take the rear carb opening sooner.
Lars
I'm surprised you set the front carb up as the primary. I'm thinking that all the setups I've seen have the rear carb as primary. I always assumed that was for even fuel distribution. Please expound oh carb master.
It's going to be a trade off, no way will a 2 4 intake work great ran progressive, it wasnt designed to, ask the builders of these intakes what they think of the idea....
Dual carb set up.
just like all the other CHROME GOODIES I LIKE 
