Buying a New Carburetor

[colyank]

Just needed a little input on buying a new carburetor. I have a 1972 350 1/2 ton Chevy pickup truck and I’m shopping for a new carb. There was a Rochester Quadrajet on the truck and it needs to be replaced. I looked in the LMC Truck book and they have an Edelbrock performance carb and stage 2 quadrajet 750 CFM divorced choke. They also have a remanufractured Rochester as I had on my truck before. Just looking for some insite or input on what direction would be the best to go as I don’t have much knowledge when it comes to carburetors. Also would it be difficult and or what are the steps to changing to an electric choke.

Thanks

[dmjlambert]

I bought Quadrajet with electric choke from National Carburetor. It is their part number ND4478 made for 1981-86 truck that they put together for me with 1969 style throttle linkage. They set them up on an engine, and test them. All I had to do is bolt it on and start the truck. I adjusted the choke and the fast idle. Lifetime warranty and I did send it back to them once when I had a hesitation issue, they fixed it for free and sent it back. It was a couple hundred dollars, and works with the stock fuel pump, does not require an external fuel filter, or rubber fuel line. Now I see they are $229. I would repeat that purchase if I got another truck.

http://www.nationalcarburetors.com/cat-chevytruck.html

[truckster]

National is a good choice. So is an electric choke. All it requires is one 12v wire that's hot when the engine is running.

You say you don't have much experience; I would recommend you stick with the Quadrajet. In my opinion it's the best 4-barrel carb ever made, anyway.

[Steeveedee]

Originally Posted by dmjlambert

I bought Quadrajet with electric choke from National Carburetor. It is their part number ND4478 made for 1981-86 truck that they put together for me with 1969 style throttle linkage. They set them up on an engine, and test them. All I had to do is bolt it on and start the truck. I adjusted the choke and the fast idle. Lifetime warranty and I did send it back to them once when I had a hesitation issue, they fixed it for free and sent it back. It was a couple hundred dollars, and works with the stock fuel pump, does not require an external fuel filter, or rubber fuel line. Now I see they are $229. I would repeat that purchase if I got another truck.

http://www.nationalcarburetors.com/cat-chevytruck.html

Indeed. And that chromate job makes me want to send my old faded factory-original carburetor to them for a rebuild, just for the plating.

[colyank]

[QUOTE=dmjlambert;8282151]I bought Quadrajet with electric choke from National Carburetor. It is their part number ND4478 made for 1981-86 truck that they put together for me with 1969 style throttle linkage. They set them up on an engine, and test them. All I had to do is bolt it on and start the truck. I adjusted the choke and the fast idle. Lifetime warranty and I did send it back to them once when I had a hesitation issue, they fixed it for free and sent it back. It was a couple hundred dollars, and works with the stock fuel pump, does not require an external fuel filter, or rubber fuel line. Now I see they are $229. I would repeat that purchase if I got another.

I looked into buying what u suggested and they didn’t really explain that well what adjustment need to be done with the throttle. Also was their anything else that needed to be tweaked to be fit for my truck. Thanks
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[dmjlambert]

Originally Posted by colyank

I looked into buying what u suggested and they didn’t really explain that well what adjustment need to be done with the throttle. Also was their anything else that needed to be tweaked to be fit for my truck. Thanks

Well I have a 1969 truck and those have a rod behind the gas pedal that pokes through the firewall and another connected rod to pull the throttle on the carburetor. You probably just have the more "normal" throttle cable setup in your truck, so won't have to have them put together anything odd like they did for me. Mine is a Frankenstein Quadrajet because they combined the throttle linkage from 1969 on a 1985 Quadrajet body. You could probably just order a regular ND4478.

[colyank]

So the only difference between the 72 Quadrajet and 81-85 is the electric choke? Also could you explain where to get the power from for the electric choke
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[rockyrivermark]

Rule # one. Don't buy anything from LMCrap.
Not even fasteners.
750 cfm is too much for stock 350
Eddy 600 cfm 1406 works nicely on a 350.
Electric choke easy addition. Just need ground and 12v ignition to it.
RRM

[Greasey Harley]

My suggestion is, call these guys:
https://cliffshighperformance.com/
Cliff Ruggles Literally wrote the book on Q-jets.

[68is4me]

I would also keep the factory quadrajet and rebuild what you have. They have the performance and good fuel mileage all rolled in to one. If you don't know much about them send it off to a good shop.

I also recommend Cliff not sure how long it takes him to rebuild them now, but at one time he was really back logged with orders.

[mike16]

Originally Posted by Greasey Harley

My suggestion is, call these guys:
https://cliffshighperformance.com/
Cliff Ruggles Literally wrote the book on Q-jets.

Yea, It offends some people if others express an opinion of thier own or different opinion.

dont blame the carb.

Qjets are excellent carbs.

I would invest a few bucks in Doug Rowe's book on Q jets. different editions cover the different carbs as the qjet evolved.The oldest edition covers the ones typically found on our trucks. newer editions spend more time on the electronic carbs. Rowe is aware of the distinction and his book reflects that. I believe it is so popular that it is being republished. That says alot.

They are simple carbs to work on if all your going is cleaning them and replacing a few parts from a rebuild kit you would be bucks ahead if you bought "THE BOOK" written by an excellent and knowlegable person, ROE.Not a poser. no chewing gum and pencils....

riggles book covers modifications for racing while ROWE's does and excellent job of that and good deel more on solid rebuilding information on the various models. Roe knows his stuff so when you get your carb back from... who ever.... you can distinguish what parts came from what carbs they canibalised. When you build your own You already know.

and the QJet kit is also affordable. so I would buy Dough's book and a kit and give it a try. and if that does not work out. There are many many knowlegable and experienced rebuilders out there; Who walk the walk.

[americanmusc1e]

What problems are you having with the carb now? The quadrajets are pretty bulletproof if you drive them often enough.

Definitely make sure your plugs and wires look good and you ignition system is in tune including timing (and dwell if you have points). You'd be surprised how many carb problems an ignition tune up will fix

10 years ago when I had a stock 350, I bought a brand new Holley 4160 and put it in place of my quadrajet (with a square bore to spread bore adapter). Nothing changed. The truck didn't run any better and it wasn't any faster or slower.

However, If i was going to put on a new carburetor, I'd go with a Holley style. 500-600cfm on a stock 350. If you need a square bore to spread bore adapter get the four hole one. The factory intake does not need more plenum volume trust me. Folks claim you can squeeze more fuel economy out of the carter/edelbrock/quadrajet style carbs, but I haven't seen it. Holleys are much simpler to tune and rebuild than the average carter style too. Holley has a whole tech section on youtube devoted to tuning their carbs.

I personally run megasquirt EFI on all my projects because I really like to tons of extra wiring and electronics. No I really just love to tinker and there is so much detail you can go into with tuning air and spark.

[Steeveedee]

Originally Posted by mike16

Yea, It offends some people if others express an opinion of thier own or different opinion.

dont blame the carb.

Qjets are excellent carbs.

I would invest a few bucks in Doug Rowe's book on Q jets. different editions cover the different carbs as the qjet evolved.The oldest edition covers the ones typically found on our trucks. newer editions spend more time on the electronic carbs. Rowe is aware of the distinction and his book reflects that. I believe it is so popular that it is being republished. That says alot.

They are simple carbs to work on if all your going is cleaning them and replacing a few parts from a rebuild kit you would be bucks ahead if you bought "THE BOOK" written by an excellent and knowlegable person, ROE.Not a poser. no chewing gum and pencils....

riggles book covers modifications for racing while ROWE's does and excellent job of that and good deel more on solid rebuilding information on the various models. Roe knows his stuff so when you get your carb back from... who ever.... you can distinguish what parts came from what carbs they canibalised. When you build your own You already know.

and the QJet kit is also affordable. so I would buy Dough's book and a kit and give it a try. and if that does not work out. There are many many knowlegable and experienced rebuilders out there; Who walk the walk.

What offends people is belittling what they say, deriding the work of people who have been doing it for decades, and making baseless accusations about what parts were put on a carburetor someone sent in.

But you already knew that...

[davepl]

Originally Posted by rockyrivermark

Rule # one. Don't buy anything from LMCrap.
Not even fasteners.
750 cfm is too much for stock 350
Eddy 600 cfm 1406 works nicely on a 350.
Electric choke easy addition. Just need ground and 12v ignition to it.
RRM

I restored most of my truck with LMC stuff. Not everything is great, but it's no worse than anywhere else.

I'd vote for a properly rebuilt Q-Jet or an Edelbrock 600. Worst case, a Holley 3310 works on most anything, but they're pretty crude by comparison for driveability.

[rockyrivermark]

Originally Posted by davepl

I restored most of my truck with LMC stuff. Not everything is great, but it's no worse than anywhere else.

I'd vote for a properly rebuilt Q-Jet or an Edelbrock 600. Worst case, a Holley 3310 works on most anything, but they're pretty crude by comparison for driveability.

Sorry everything I got from them was sent back garbage.
For me Gmc Paul's worth the extra money

[davepl]

Originally Posted by rockyrivermark

Sorry everything I got from them was sent back garbage.
For me Gmc Paul's worth the extra money

I think it depends on who makes it, not who sells it. GMC Paul sells generally very nice stuff.

OER, for example, is generally good regardless of where you buy it.

[GASoline71]

Originally Posted by davepl

Worst case, a Holley 3310 works on most anything, but they're pretty crude by comparison for driveability.

Sorry man, but that is a completely false statement. Holley carbs have more tunability as far as "driveability" goes than any other carb out there. The "out of the box set it and forget it" doen't apply to any carb. Which is why a lot of cats can't use a Holley.

Now then... a 3310 is a little big for most applications. An 1850 will generally work way more betterer on small cube engines.

Without knowing what this carb is being bolted to... it's hard to make a recommendation.

Gary

[davepl]

Originally Posted by GASoline71

Sorry man, but that is a completely false statement. Holley carbs have more tunability as far as "driveability" goes than any other carb out there. The "out of the box set it and forget it" doen't apply to any carb. Which is why a lot of cats can't use a Holley.

Now then... a 3310 is a little big for most applications. An 1850 will generally work way more betterer on small cube engines.

Without knowing what this carb is being bolted to... it's hard to make a recommendation.

Gary

Without knowing what carb this is being bolted to, I'll stick with my 3310 recommendation. The 1850 is fine also but could be too small for a lot of our truck motors.

Your assertion that the Holley is more tunable is just nonsense. I mean the Holley doesn't even have half the systems that that the Q-Jet has. I've got nothing against Holleys, but for driveability there's a reason GM didn't use them except for high-perf stuff that drove like crap anyway. Many reasons.

There's also a reason you can stick a Q-Jet on a Chev 265 or a Cadillac 500 and it'll run well on both, you know. And you can do it without taking the lid off the carb or changing the jet (same jet in both cases, I think, a different rod which is a 10 second change).

[GASoline71]

Originally Posted by davepl

Without knowing what carb this is being bolted to, I'll stick with my 3310 recommendation. The 1850 is fine also but could be too small for a lot of our truck motors.

Your assertion that the Holley is more tunable is just nonsense. I mean the Holley doesn't even have half the systems that that the Q-Jet has. I've got nothing against Holleys, but for driveability there's a reason GM didn't use them except for high-perf stuff that drove like crap anyway. Many reasons.

There's also a reason you can stick a Q-Jet on a Chev 265 or a Cadillac 500 and it'll run well on both, you know. And you can do it without taking the lid off the carb or changing the jet (same jet in both cases, I think, a different rod which is a 10 second change).

Just because it's a truck doesn't mean it needs more CFM...

Being able to tune a carb properly is a lost/dieing art. Q-jets are not a simple carb to the layman anymore than a Holley is sooooo hard to tune. There are some really good Q-jet rebuilders out there (Like Cliff Ruggles). Cost a lot of $$$ to have them done correctly. A well tuned new Holley can be had for 2/3rds the cost, or at a comparable price. I know there are stupid expensive Holly's out there too... so it would have to be a basic model (3310, 1850).

Trust me when I say that the Q-jet is a great carb and I've owned and rebuilt (includiing shaft rebush) many of them. I do like a Q-jet, but since I can tune pretty mcuh any carb to be a driveable on a daily basis... I'll stick with a Holley. I know GM had to use a carb to cover all their bases from a 265 to a 500 so why not have one carb to cover all bases.

I know we can agree to disagree... as we both have our own opinions on what "driveability" might be.

Gary

[D.PASSMORE]

If you are interested, I have this carb for sale. Read description and see if it meets your needs.

http://67-72chevytrucks.com/vboard/s...d.php?t=751483

[morepwr]

Q-jet get a lot of bad raps but when they are rebuilt properly and tuned according to your engine and climate, they can be great running and smooth driving.

[truckster]

There's a screw on the fast idle cam. You turn it in to increase the speed an out to decrease it. In all likelihood, you're not going to need to make any adjustments to it, because they flow test it before it leaves their shop.

[truckster]

The later Quadrajet is slightly different, including a heavier casting. It's actually a better carb. Any place that's hot will work for the choke. You can tap into your IGN on the fuse block.

[dmjlambert]

To power the electric choke all you do is connect a wire from an IGN UNFUSED terminal on the fuse panel to the electric choke's terminal. So it has power when the key is on. The choke electrical connector is available at the auto parts store or by googling "electric choke connector".

I think there are probably lots of differences between 72 and 81-85, but I don't know exactly what they are. There are more ports on the newer style carburetor because there were more vacuum accessories as the years went on. I bought a package of rubber plugs at the car parts store to block all those extra ports off, and bought a nylon threaded pipe plug from the hardware store for my unused power brake vacuum port.

I ordered the carb for a 69 truck online, and then followed up with a phone call to ask if they could outfit it with electric choke. The sales guy seemed quite knowledgable and helpful and said they can't just add an electric choke to a carburetor that was designed with a divorced choke, and they had to build a different carburetor that was originally equipped with an electric choke, and they could put it together with the linkages that would work for 1969. They could probably do the same thing for your 72, if the throttle linkage needs to be different for your engine.