I would look for a carburetor the was easy to tune the accelerator pump. Depending on your driving habits, that's a lot of volume to cover with a quick right foot.
Newer Holley carbs are way advanced over what we used as kids . Look for annular discharge and 4 corner idle adjustments . Leaks and busted power valves are gone .
Carbs are like which car make you like; some like Ford, some Mopar, some GM. One thing to note though is when it came to factory high performance in the '60s, you'd find a Holley under the hood more often than not, no matter which car brand you like. That was the only carb common to all the Detroit manufacturers. Holley's have gotten a bad rep in some quarters but it's generally due to ham-fisted owners. Overtightening the float bowl screws will warp parts, causing leaking among other ills. Overtighten them enough and you'll ruin the carb. My avatar currently has an Edelbrock on it, but it's due to come off. Mine has issues with staying in adjustment, and I know more than a few other owners who have been less than happy with them. I also don't like the way the vacuum connections are configured, makes 'em hard to hide. Planned replacement will be Summit's remake of the '60s-70s Ford Autolite, which has basically been updated with some of Holley's best features and uses Holley jets and small parts. It's getting pretty damn good reviews and the price is very attractive. But truthfully, with that crossram you're only choice should be a Holley. That's what you would have found 'back in the day' bolted to it. My only suggestion would be if it's strictly for street driving, go conservative on the carb size. A smaller carb will help considerable with low/mid range throttle response. I'd do a 500 or 550 CFM personally; that will work well up to probably 6500 rpm before the motor runs out of breath. I ran a 450 CFM on a single-plane torquer 289 on top of a built 302, and it ran like stink to 7K. That's really fast , no matter which gear you're in...
Biggest issue we all have done and some still do is over carbing . Bigger is not always best in this world .
If I did run a Q-jet (I think that's what was on it originally?) what cfm? Is there such thing as a 550ish cfm Q-jet with electric choke?
Up until the mid-1970's, all Q-Jets were approximately 750, 800, or 850. Some of the late 1970's, early 1980's may have been downrated, I do not know. Basically the Q-Jet (like the Carter TQ) is an "on-demand" secondary. Instead of looking at the total CFM only, look at both the total CFM, AND the CFM on both primary and secondary. So the 750 is a 150 / 600. The 800 is a 200 / 600. And the quite rare and valuable 850 is a 250 / 600. The small primaries result in high venturi air velocity, and really good lower RPM performance, and that huge variable secondary is available when necessary. The other well-known spread-bore, the Carter TQ (until the mid-1970's) were 800, 850, and 1000. The 800 was 200 / 600 The 850 was 250 / 600 And the 1000 was approximately 325 / 675 I have an 850 on my Pontiac 350 and it runs like a scalded dog! And for the Holley fans, Holley offered both a 650 and 800, but I do not know the primary/secondary breakdown on the Holley. Jon
Of course I just sold a TQ9800 series a few months ago. Never even thought about using it. Duh! I considered the dual AFB, but it's going to be REALLY tight against my A/C compressor. Might not fit at all. I was hoping for some input on Demons. Their spread-bore design has some appeal for me. Anyone use them? Thx for the suggestions.
How big was your poll sample ,how many people in the repair business ? I'd surmise a more accurate statement would Be " of the mechanics I know of have talked to , the majority had problems with Holley". Like carb king mentioned , most problems are due to ham fisted technicians . Just because someone makes a living at parts changing doesn't make them a mechanic ...
I have 2 of those... One is the "Gold Claw" which flows around 795 cfm... And the other is a 750 Demon... Both are great carbs..... I like the gold claw the best because it has interchangeable venturi sleeves and boosters....
Still the Holley is more of a race oriented carb. It has more adjustablity than other carbs, but much more drivablity problems than other carbs
Most carburetors have some degree of adjustability. I would not consider that the Holley is more adjustable than a genuine Carter AFB; but I would certainly concede that more tuning parts are easily available to the average enthusiast (today) for the Holley versus the Carter. But as many tuning parts ARE available mail order for the genuine Carter AFB as for the Holley. Unfortunately, since many are either low-production, or worse, made-to-order, they are generally more expensive. One issue that greatly effects one make of carburetor requiring more adjusting than others, is the original selection of the carburetor. LOTS of Holleys and e-clones are sold by unknowing sales personnel who have no clue as to what carburetor the enthusiast actually needs to unknowing enthusiasts that believe that bigger is better. If the wrong carburetor is selected, tuning becomes either very time-consuming, or virtually impossible. One other consideration is that many enthusiasts are more tolerant of less than perfect carburetion if the vehicle builds good power at higher RPM. Bogs, hesitations, and horrible fuel mileage are all acceptable to many enthusiasts (and opinion, shouldn't be!). Enthusiasts with factory engineered muscle cars may be much less tolerant of these conditions after some snake oil salesman has convinced them that a brand x carbs would do everything but roll down the windows. The second line in my signature block summerizes this post. OP - I cannot answer your question about the Demons. When a new carburetor comes out, my first consideration is the availability of specifications in general, or for a specific application. NONE of the newer 4-barrel stuff, other than Holley, have any O.E. application experience; and very little if any specifications. I will grant you 50 years ago, I might have enjoyed buying a new carburetor, and totally disassembling so I could "blueprint" the calibrations (air bleeds, restricter, bypasses, vents, venturii diameter, and booster relationship, etc., in addition to the fuel jets which are often the only consideration of the novice). But today, I have no desire to do so, thus will stay with the conventional companies. Jon.
I like the sound of that. A Chevy 327, that intake with a single carb top and finished off with a Carter ThermoQuad! The only drawback would probably be the number of people who don't know what it is that want to argue with you about why it won't work.
Well now, sometimes I only open my mouth to change feet!!! I had actually completely forgotten about the Z-28 style "cross-ram", and the copies made. I have an old Edelbrock X-C8 I bought as an impulse buy, and that's how I "see" a cross-ram; no removable top and carbs mounted up high; the fore-runner of the Tunnel-Ram style manifolds.. I always wondered how efficient the Z-28 manifolds and copies were; it just seems there would be fuel puddling due to not much velocity on a street car; but what do I know anyway? I can't say I've ever actually seen one of those manifolds, with the removable tops, on a street car; easy to swap between single and dual 4 barrels though. Never seen one on a race car either. Thanks. I am Butch/56sedandelivery.
I've been doing this hot rod thing my whole life and I have used about all the carburetors you can think of, I profess to be a absolute hack when it comes to building a carburetor and I just want one to be as trouble free as possible, saying that I have had much better luck with the Edelbrock Carburetors and I believe they are well suited for a driver hot rod. HRP
Okay here is my two cents. And a story or two. I had a Carter AFB on my 350 in my flat bottom race boat for about 20 years. It would sit in the garage over the winter every year and every spring all I did was get fresh gas in it never touched any adjustments whatsoever and it always crank right up and ran like a bat out of hell. Knowing that Edelbrock had bought out the patents or whatever they did for the AFB I chose to put an Edelbrock on "The Judge". Upon first start all I did was adjust the idle screws and it ran just fine for break in. When I got her on the road my gas mileage was not what I expected so I bought and installed an oxygen sensor meter so that I could read out the fuel/air ratio on the dash at various RPMs and loads. With that and going back to the Edelbrock installation and also the website charts for selections of jet sizes Etc. I swapped out the correct jets for what I was looking for which happened in end up being the leanest you can get for both sets of jets. Even before that performance was just fine except I was running rich everywhere. I have read that most out of the Box carburetors will run rich and that seemed to be the case with mine. I have been running for years now with lots of miles with the smoothest Transitions and good gas mileage that could ever expect. One of the features of the AFB and Edelbrock is that there are no seals or gaskets below the fuel level (no fuel leaks ), it's really easy to change out the jets by just taking the top off of the carb, accelerator pump adjustment is nothing more than moving a pin. Regardless of your ultimate choice for a carburetor if you want to get it right you just about have to have an oxygen sensor so you can see where you are. Good luck!
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