58 replies to this topic

[McGuire]

Originally posted by Fat Boy


From experience many moons ago, the reason I wouldn't buy an Edelbrock is that as soon as you get into a corner one side of the carb goes rich, the other goes lean, and the engine dies. That carb is fine for going in a straight line, but seems to give up the ghost at about 0.5 lateral G. I liked the tuning features, none of them would make it live in a corner.

The Edelbrock carb is of course essentially an updated version of the Carter AFB (stands for "Aluminum Four Barrel"). These carbs have rarely been used for road racing...and I think you have nicely identified one of the reasons.

That said, the major flaw of any single-four barrel setup with a V8 is mixture distribution. One carb in the center, and eight intake ports of inevitably different lengths and flow capacities...Introduce an additional issue, say, fuel inertia in cornering, and you got trouble.

[Big Block 8]

Originally posted by McGuire


I always liked the ol' Rottenchester QueerJet and was very comfortable with it, but as a small cog in the GM evil empire I had the right parts and info all around me. Later on as the stuff became obsolete, the easiest way to get parts was to scrounge the junkyards. The best Q-Jet components (vacuum breaks, secondary metering rods, etc) were to be found on certain Cads, Buicks and Oldsmobiles, and you could buy old carburetors for $20 per 55-gallon drum-full.

I'm one of those damn university fops, so I've never had the priviledge of being surrounded by first hand experience for prolonged periods. Although in my current job I actually am doing a lot of wrenching - but the problem is, that for that particular project, there pretty much isn't any prior experience on this planet available to help me out. Not anyone who would voluntarily share that info anyway.

Regardless, at the hobby front I've had to rely pretty much on printed info and advice, as my limited budget and spare time don't give much room for trial and error. So far I've been more or less successfull with my ventures - no big explosions so far. *knock, knock*

Originally posted by McGuire

Of course I would love to say I carefully planned that combination, but essentially it all came together through Pure Dumb Luck. The engine was assembled entirely from found objects, stuff lying around my shop and at work..many of them near the dumpster.

Well, I'd say that's even more impressive.

[Big Block 8]

Originally posted by McGuire


The Edelbrock carb is of course essentially an updated version of the Carter AFB (stands for "Aluminum Four Barrel"). These carbs have rarely been used for road racing...and I think you have nicely identified one of the reasons.

That said, the major flaw of any single-four barrel setup with a V8 is mixture distribution. One carb in the center, and eight intake ports of inevitably different lengths and flow capacities...Introduce an additional issue, say, fuel inertia in cornering, and you got trouble.

I'd add that Edelbrock rebadges and sells Rottenchester QueerJets along with Carters too.;)

They've tried to convince me that at least the Carter versions of the Edelbrocks even have the exact same rods/jetting than those available under the Carter badge, so it's better to buy just a "Carter" for a cheaper price.

I do recall, that at least some Rochester versions have been used in some form of road course racing, with reasonable success, I just don't remember the exact story at the moment. It's possible it was a twin setup though.

[McGuire]

Originally posted by Big Block 8
I do recall, that at least some Rochester versions have been used in some form of road course racing, with reasonable success, I just don't remember the exact story at the moment. It's possible it was a twin setup though.

The QuadraJunk has been used successfully on GM cars in several forms of Showroom Stock road racing. It Can Be Done.

Rambling off topic again....Speaking of American V8s and road racing, a great class for hot rodders is the SCCA's American Sedan category. Only the past two generations of Camaro/Firebird and Mustang/Capri are allowed, maximum 305 CID, very strict engine regs sorta like the former NHRA Super Stock rules. All brands must run the same 600 CFM Holley. Chassis rules are restrictive too, stock floor pans and sheet metal with roll cages, no tube framed panel cars ... the class reminds many of the old Trans Am of the 1960's, but with current sheetmetal. It's Cheap Racing (relatively speaking) and technically stimulating, plus everyone says the cars are a hoot to drive, as you can imagine. It's a "National" category so you can also qualify for the Runoffs.

[McGuire]

Originally posted by Big Block 8


I'd add that Edelbrock rebadges and sells Rottenchester QueerJets along with Carters too.;)

Yes, and the various lineages can get complicated. Edelbrock sells reproductions of the Quadrajet M4V and M4M manufactured for them by Magneti Marelli, and also offers a line of remanufactured original Rochester Quadrajets. Meanwhile the main Edelbrock carb line is based on the old Carter Aluminum Four Barrel.

Also, a significant number of the original-equipment Quadrajets produced back in the day were actually manufactured under contract by Carter. These carburetors are for all intents and purposes identical to the Rochester version, except the name "Carter" is cast into the airhorn and/or main housing.

Carter provided a lot of carburetors for various GM models through the years. Many 4-bbl applications (especially the dual quad setups) used Carter WCFB's (White Cast Four Barrel) and later on AFB's, instead of the Rochester 4GC. And some got Holleys, especially the highest-performance applications: 302/295 hp, 327/365 hp, 427/425 hp, 427/435 hp (3-2bbls) etc...

[Menace]

Well, the weekend is approaching and I can get more time to tinker around. This thread is awesome!

[Big Block 8]

Thanks for the carb info, that's interesting.

Originally posted by McGuire

The QuadraJunk has been used successfully on GM cars in several forms of Showroom Stock road racing. It Can Be Done.

Hooray!

Originally posted by McGuire

Rambling off topic again....Speaking of American V8s and road racing, a great class for hot rodders is the SCCA's American Sedan category. Only the past two generations of Camaro/Firebird and Mustang/Capri are allowed, maximum 305 CID, very strict engine regs sorta like the former NHRA Super Stock rules. All brands must run the same 600 CFM Holley. Chassis rules are restrictive too, stock floor pans and sheet metal with roll cages, no tube framed panel cars ... the class reminds many of the old Trans Am of the 1960's, but with current sheetmetal. It's Cheap Racing (relatively speaking) and technically stimulating, plus everyone says the cars are a hoot to drive, as you can imagine. It's a "National" category so you can also qualify for the Runoffs.

Sounds good, it would sure be a hoot to try that.

[McGuire]

Originally posted by McGuire
Quite true about the Pontiac BB vs. SB thing, as Pontiac V8s are all essentially descended from the same 287 CID engine introduced in 1955.

How Pontiac did that was by incorporating room for displacement growth in the basic design. The Pontiac block had 4.62" bore spacing and a 10.25" deck height. Most of the first-generation American V8's were designed this way...though not necessarily for maximum expansion but probably more because they weren't so concerned about producing the most compact layout.

The smallblock Chevy was arguably the first American V8 in which a serious effort was made to make the engine as compact and light (read "cheap" in terms of production engineering and cost basis) as possible. It used 4.40" bore spacing and a 9.00" deck height -- and was easily 80-100 lbs lighter than the other V8's of the period.

[McGuire]

Other distinguishing features of the Pontiac V8: it has always liked 10-12 degrees more duration on the exhaust timing vs. the intake, and one or two degrees more lobe separation. Also, Pontiac has traditionally run a 30 degree angle on the intake valve seat, where everyone else typically runs the standard 45 degrees.