Carburetor fun: Rochester Vs. Edelbrock?

[briscuba]

Hello,
Is the term carburetor fun an oxymoron? Anyways... for those carb experts out there. I have a 1970 402 BB / 400 TH tranny in my SWB C10. 95% sure its the factory BB that put out 310 HP. Truck has headers as well (no heat riser). The Rochester carb turned out to be a 1972, certainly part of the problem. I have beat my head against the wall repairing and rebuilding it. And, even though I bleed Chevy orange, I think I need to go to a performance Edelbrock - which will take away from the "stock" look which at one time seemed important. But a truck has gotta run right!

Any suggestions? Can anyone tell me if they are using an Edelbrock on their stock BB engine now, and happy with it? Which model is it?

Hope that's enough info. to get the thread started. You guys rock!!

[Lee H]

70 VS 72 Q-Jet should not be an issue. I would weigh getting the Q-Jet professionally rebuilt (by a real professional like Ruggles or Murphy, not just a carb shop down the street) VS buying a new Edelbrock and the cost to convert (linkage, fuel line, air cleaner? manifold? etc). Both options will give you years of trouble free service.

[DjS71]

I'm sure plenty are running an Edelbrock 750 on their BBs. $350 new w/electric choke. (+ intake & incidentals if you want to do it right, Here's a kit)

That said, I loved the QJ I had on my 275hp 327. Those beer can secondaries are so much fun when they're working correctly. If it we're me I'd look into having it rebuilt/calibrated by a pro for roughly the same or less than a new Eddy.

You'll get more different opinions on carbs than there are rocks in a river, this just happens to be mine.

[Hugh Mongus]

I tried two different Eddys and was not impressed. They are fine if performance isn't your goal. They feel more conservative to me than a Holley. I switched to a Holley Street Avenger and it was like night and day. This is my personal opinion.

[Grumpy old man]

Use a Quadra jet they run 750 cfm but with the small primaries won't ruin your gas miliage and will run 310 hp stock all day long around town and nothing sounds like a quadra jet when those big secondaries open up The pontiac and buicks came with a quadra jet that would gulp 850 cfm with a little work and it runs the 496 BB up to 585 hp with no problem .

[Doug's68SS]

The Q-jet will perform, there is a classic car drag racing class that requires that you run what came from the factory. That is why i had Cliffs performance build one for my BB I am putting in my truck. The build is cheaper than a New carb.

[briscuba]

I might add that I did in fact have my mechanic rebuild my QJ. He may not be a QJ professional, but a solid mechanic. It is my understanding, however, that when it comes to tuning in a QJ perfectly, one needs to find an expert. I saw Cliffs Performance..? I send it in, etc.?

Awesome help thus far...

[BRL]

Originally Posted by Grumpy old man

...nothing sounds like a quadra jet when those big secondaries open up...

Ain't that the truth!

Running an Edelbrock 625 cfm. on my 350 SBC right now, and they're ok, but I sure miss that toilet flushing secondary sound when a Quadrajet opens up!

If you do go with a QJ, be sure that there is no leakage around the throttle shafts from long time usage.

[engineer_gregh]

I've got a 71 with the original BB although its been rebuilt. I'm running an Edelbrock 750, Edelbrock intake and headers. The intake and carb were on the truck when I bought it. I would love to go back with an original intake and QJet. I've owned a lot of these truck and from my experience the QJet is much better. I've never owned a Holley but I would bet its a better carb than the Edelbrock. I would send that QJet to a good shop and have it professionally rebuilt and tuned for today's unleaded gas. Just my .02 cents.

[geezer#99]

You guys think one quadrajet kickin' in the secondaries sounds good, you should hear two of them. Sounds kinda like a dual quad hemi.
Keep the quadrajet.
For the price of an eddy or holley conversion you can get a custom built one from smi.
https://www.smicarburetor.com/
And he's in Huntington Beach.

But one thing to remember. 9 times out of 10 it's not the carb. It's your timing set up.

[imjeff]

My QJ runs my BBC DD just fine. A common problem they had was internal vacuum leaks. A pro will epoxy those plugs and give you back a very good carb. I believe there is a DVD and/or book that walks you step by step through it.

Jeff

[leddzepp]

Edelbrock 750 on my 402. Zero complaints, runs perfect. Doesn't matter what kind of carb you have, they all do the same thing when properly tuned and set up.

[no1udknow]

when I was younger my pops had a holly 850 on his sbc. Great carbs, so when I got my first chevelle, I talked to him about putting a holley on it and he told me to just let him tune my QJ, he was a master at tuning old carbs. This may sound silly but he used to put a glass of water on the cowl and tune the timing, dwell, and carb untill the water smoothed out. My 70 malibu ran like a dream after he tuned it.

[davepl]

An incorrectly calibrated QJet will be no worse than an incorrectly calibrated Edelbrock, and probably the Edelbrock will be worse since it's a "performance" carb that sacrifices driveability for performance (if there's a free lunch, I haven't found it).

Since there's no benefit to switching, get your QJet redone by Cliff Ruggles or Carb Connection (Kirkland, WA) or any other reputable QJet person. Just not yourself or the gas station around the corner. Either might work, but with carbs I'm willing to pay more to get it right. Makes or breaks the fun and character of the truck.

I still think someone should make an EFI unit inside a carb body with injectors and a step-up fuel pressure pump. You could feed it 7psi of fuel and 12V ignition and it'd do the rest. Make it for under a grand (if that's possible) and get rich slowly.

[SonomaComa]

Awesome thread, although I am quite a bit late on it. Lots of great info here.
I now think I will have my Q-jet rebuilt instead of switching to Eddy or Holly. I just picked up a 1969 C-20 with a 350. I was told by the owner that their Father purchased it new and they had it for years. So it sounds like Q-jet is the way to go but why do so many peopke back away from rebuilding their own? Now a days with so many books and internet why shy away from it?

[DjS71]

Give it a shot, people shy away because of the difference between book learnin' and On-the-job training. Fear of failure I guess? IDK, grab a kit and throw it in there. I might have a book around the garage you can have, I'm waist deep in an LS swap so I'll likely only ever use it to level out a table. Might take me a day or 3 to reply to a PM if you send one.

[52napco]

Seems the consensus is keep the Qjet....Which im0 is the only way to go. I have all mine restored by Bob Stone in PA. It's the best $250 you'll ever spend. I've got several Edelbrock
I'll send you for free..... I personally have never had any luck with them.

[special-K]

They are all good carbs. If Quadrajets are a bad carb I wonder why Edelbrock offers a copy.

Comparisons are usually putting a 40+ year old Q-jet vs new Eldy. Faulty comparison from the get-go. I had an Edelbrock Q-jet copy (that came on it) on my '72 for 15 years. Never touched it. Did top end and put a Q-jet I had rebuilt by the local shop I've used for 30 years for at least 1/2 the cost of a new carb and am very very happy, just as I have always been with all the Q-jets on my other trucks.

GM built some of the best designed longest lasting trucks in 1967-1972. Nothing "needs" changed.

[palallin]

One note: to get the optimum performance (in the general sense) out of the Q-jet, you really need to have the original set up for heat riser, choke, etc. Don't expect the system to perform as designed when you've tossed out many of its components.

[68is4me]

I also vote quad, But before you get to crazy on the carb what is it doing, are you even sure it is a carb problem? Timing, vacuum leak, bad wires and plugs could all make you think the carb is bad. I would 1st get it nailed down to make sure that it is actually a carb problem.

But on a side note I did do the cliff ruggle's book and the kits from him. Rebuilt it myself but it does get rather expensive if you don't have all the tools to do it right, jewelers bits, vacuum gauges, small punches, small grinders and lots of patience. At least after buying all the correct tools I can build more if I have to.

[68is4me]

Wow, just realized this is a 3yr old thread

[special-K]

^^^ That's ok, it was brought back up by another member yesterday with the same question. You are now talking to him and not the OP

[slikside]

Old thread, yes...but good discussion never dies out!

One thing to keep the in mind when going Q-jet, especially if you don't already have one....the later the model, the better. They were being revised pretty much right until they were discontinued (early-mid'80's).

I have a '72 C-10, that I thought had the original carb, but was pleasantly surprised to find on the rebuild that it had a julian date late in '76. It's been a while since, and can't recall exactly what the improvements were, but I recall that point from Ruggles book.

Also, you get what you pay for ina rebuild kit. Go with one from ruggles, or other Q-jet expert.

[69 MOD]

Another vote for the Q-Jet

The main problem is the throttle plate "butterfly" shafts get loose through the years and develop a vacuum leak.

Make sure the company you have repair the carb has the bushings installed before you put it back together or you will be chasing problems you don't know you have.

I've been lucky enough to have a good carb shop that has done my base plates for years, they'll even drill out my idle circuits if I ask to richen the low end.

[Steeveedee]

When you do go to rebuild your Q-Jet, get Cliff Ruggles' book, and get the rebuild kit from him, too. On my truck, the cam that lifts the metering rods on the secondaries broke (dropped down inside the well where it lives, not into the engine). His kit will have that cam, and a new float and accelerator pump diaphragm that resist ethanol. Best kit I ever bought. It even has a new secondary air valve spring, which can get old and not work as well. That MIGHT have been extra; its been a few years since I rebuilt mine. The truck starts and runs like a champ with the original carburetor. I took the throttle plate to a local carburetor guy to get the bushings for the throttle shaft. $50 got all four bushings (though putting bushings in the secondaries is kind of pointless). If you have the time, you can send your carb to Cliff. He has a long waiting list, though- last time I checked, it was a year- but that may have changed. If you give him the information on the engine, trans, etc., he can calibrate it for you. The thing is, with a carburetor that old, someone may have been into it, changing jets and metering rods, springs, etc. Cliff can make that all correct, or properly modify it for your application.

I guess you can tell which way I vote! I've had Edelbrocks and haven't been all that pleased with the longevity- they needed the throttle shafts repaired much sooner than my Q-Jet. That carb got the bushings at about 212,000 miles.