Discussion in 'Wheels, Wings, Mud, and Water' started by MaxxVolume, Jan 12, 2018.
I used to pass the Opel factory in Russelsheim twice every weekday when I last lived in Germany.
Here's a classic multi-carb induction set-up I restored a couple years ago.
The infamous Man-A-Fre 4x2 with four Rochester 2GCs from the early 60's.
This is the more rare "Atlanta" casting (the same as is used on John Milner's iconic Yellow Deuce Coupe in the film American Graffiti).
Here it was when I bought it on eBay:
It was in rough condition but was better than most you'll find nowadays. It didn't have any cracks but there were some voids and surface imperfections from the casting technology of the time. The carbs were not the greatest cores for rebuilding but were not totally-worthless.
The set-up was missing the linkage and fuel block and lines and the manifold had been partially drilled for the "Afterburner" feature which added a direct shot of fuel into the plenums similar to a direct-port nitrous system minus the nitrous. Only one of the four Afterburner bosses were drilled which was used as a full manifold vacuum port.
Here it was all cleaned up. Notice it has most of the lettering where a large percentage of these have missing letters due to casting flaws. This was an above average example of one of the most sought-after intakes in hot rodding history.
Here it is after blasting it with aluminum oxide:
A close-up of the nice lettering:
Here's a close-up of one of the voids in the casting near the top left plenums. While the hole is not clear through the casting, which would cause a vacuum leak, it is kind of ugly and could eventually cause a leak.
Here's another casting flaw at the other end. You can also see where the one afterburner boss is drilled.
Here's the completed manifold assembly. I welded the voids up with Muggy Weld aluminum alloy welding rod and re-blasted the manifold. I considered powder-coating the manifold aluminum color but I decided to do one better and had it ceramic clear-coated. It leaves the aluminum looking brand-new (and more natural) and is impervious to gasoline and heat. A lot better than clear-coating in this situation.
I replaced the carbs with better cores and had them totally-rebuilt and re-dichromated the correct gold color with a few modern upgrades such as chrome socket head cap screws, accelerator pump arms and linkage. The throttle linkage was also upgraded from the crude "Cal Custom" linkage of the time that was used on the Milner Coupe with aircraft quality spherical rod ends make this already touchy set-up a lot easier to dial-in to perfection and will stay that way a lot longer too. The cheesy Cal Custom linkage was very prone to slipping out of adjustment and a nightmare to syncronize by comparison.
The four carbs flow about 800 cfm into direct-port induction. This set-up was the poor man's fuel injection of the late 50s / early 60's and you saw a lot of these on Vettes back in the days. Originally-designed for the 283-327 small blocks, Man-A-Fre eventually made a big block version too however, the big block manifolds are not worth nearly as much as the original small block version is (largely due to American Graffiti). No Graffiti Coupe clone is really complete without one of these babies.
Here it is with the air horns like the ones used on Milner's coupe. Not practical for daily driving but awesome for a show or a blast down Paradise Road if you happen to run into Bob Falfa (Harrison Ford) in his mean black '55 Chevy!
I had a 1970 AAR Cuda' as a kid, when I bought it the six bbl intake and carbs were in the trunk, obviously the previous owner had some problems with the set up and it had a single 4 bbl installed on the engine, so first order of business was to get the six bbl back where it belongs. I cleaned up the intake and had the carbs gone through and rebuilt, previous owner had also lost some of the small minor parts.
I get everything installed back on the engine, turn the key and it starts right up and idles perfect, so I decide to do a little sonic tuning by revving the engine using the center carb throttle arm when suddenly the 2 outer carbs open up and the engine goes to WOT, I release the center carb throttle arm and the engine to my horror is still screaming at WOT, I rush and turn the key off, engine eventually stops after stumbling on for about 30 secs.
I learned a valuable lesson that day, the center carb was missing the mechanical linkage that connects to the 2 outer carbs, the 2 outer carbs open via vacuum diaphragms, the linkage is there to CLOSE the 2 outer carbs...........thankfully the engine was not hurt, I went to a Direct Connection dealer and bought, then installed missing linkage and everything was fine.
Most 6-pack and tri-power (3x2) intakes operate similarly. During idle and low RPM cruising the center carb feeds all the fuel. When you punch the accelerator the front and back carbs open up like the secondaries in a 4bbl. They are basically a 6bbl.
That's why only the center carb has a choke on a 3x2 setup. Rochester 2bbls are designated as "2GC" and "2G". The 2GC has a choke and the 2G doesn't. The Holleys on Mopar 6-packs were the same way.
Since all 4 carbs on the Man-A-Fre open simultaneously, they are all 4GC's and all four have chokes
Here are some cool ads and magazine articles from the 60's on the Man-A-Fre direct port induction 4x2:
Here's an article where they removed the factory Rochester mechanical fuel injection from a 327 Corvette and replaced it with a Man-A-Fre 4x2.
They claimed that the driveability was improved with a 30 HP gain in performance.
Correct on the center carbs having the choke, But with the Rochester Tri-power set ups (GTO) the outer carbs are OPENED and CLOSED manually by a progressive linkage connecting all 3 carbs, with the Holley set ups Corvette (427), Mopar (340-6 440-6) vacuum diaphragms open the outer carbs and linkage connected to the center carb CLOSES the outer carbs.
If you would of repeated the scenario I did on a GTO with the outer carb linkage disconnected, the outer carbs would of not opened.
That is really sweet!!
Back in 1970 I was in college and worked for an auto parts chain store in the Sacramento area (Roddy Discount Auto Stores - now defunct). The manager of the store I worked at had a buddy that built a bucket T roadster. Back when Mopar came out with the 2-4 cross ram intake, one of the aftermarket companies came out with an adapter that would turn a single 4 bbl manifold into a 2-4bbl cross-ram setup. This guy bought TWO of the adapters, and mounted them on an in-line 2-4 manifold, giving him 4 4bbls, all mounted on a big block Chevy. He topped it off with 4 Holley 650s. Wayyyyyy too much fuel, but it sure was impressive to see it coming down the street.
You realize how much those are worth now?
Buick's larger V8 "nailheads" were all Wildcat engines, so you had the good stuff. Our '65 Wildcat sedan had the Wildcat 445. I can't recall (without looking) if the base Rivvie had the Wildcat 445 (401ci) and Wildcat 465 (425ci) options, but @MaxxVolume's Rivvie Gran Sport had the Super Wildcat, the 425ci engine with the dual carbs. The GS/Super Wildcat package also ended up on '66 Wildcats, a rare option there as well.
I had a BMW 2002 4 cylinder with dual Webers. Best sounding four banger ever!
There's a story about some of the crew at MicroAcoustics getting BMW 2002s, and being so enthusiastic that they named their next piezo cartridge for it.
A long time ago I used to spend my afternoons trying to tune 3 SU carbs attached to the 4.2L double overhead cam 6 in my father's beat up 67 convertible E-type Jag - series 1 1/2, before pollution controls. We worked on it together, a father and son sort of thing. He no longer has it, as we could never afford to restore it properly; and I got into a lot of trouble with it anyway ; but it sure was a lot of fun.
Those Cuda's are tough. My Grandma (yes my Grandma) had a 383 Cuda with a slap-stick automatic transmission (forget the year - 72?); that I slap-sticked form 2nd to reverse (accidentally of course) at 80 mph on a back road in NJ. My cousin (passenger) and I stared at the stick for a second while the Cuda dutifully threw the engine into reverse and the car just started to lock up the rear tires as I grabbed the stick back into 3rd. Gained control of the car only to find a Mustang locking up his brakes as he was right behind me. Guess I wasn't the only one without a brain out there that day.
You can`t change the past, but I get truly sad when I think of several of the cars that I`ve owned, and let slip through my fingers:
1958 Impala convertible, 348 "Stone Crusher" w/ Tri-power
1966 Grand Prix, 421 HO Tri-Power, 4-speed, those nice finned aluminum 8-lug wheels, 12 bolt 3.42 Posi....a few years back, I researched this on the Pontiac Registry, and was absolutely shocked at how few of that combination were produced.
The Riv Gran Sport, of course....
A `55 Chevy Sedan Delivery, with a 396/425 HP (4-bolt main, solid lifter) motor, Super T-10, 12 bolt rear, 7 leaf springs, it was a runner.
And, my Crown-conversion, L79-powered mid-engine Corvair. That was the ultimate sleeper....
There is an Offenhauser Chevy 1955-1985 SB TRI-POWER intake manifold for sale right now on eBay for $51....
Then you find a beat up Chevy Nova any year as long as it’s a 2-door and find a Chevy Nova staition wagon for suspension, brakes and sway bars. Then you find a 350 engine and an auto tranny from an auto wrecking yard with low miles on the cheap.
Screw automatic....that combo would have to have a 4-speed !
Me personally, I'd skip the two door and just buy the wagon. But I'm weird and like old station wagons.
Agreed on the wagon, but I'd go Colony Park over a Nova wagon. Then again I'd take a Park Lane Marauder or a Riviera or something along those lines over a Chevelle, Nova, Mustang or comparable. I want nicer seats.
Oh, definitely! I wish we had been able to hang onto that Wildcat until I got to high school, but rust ate it. Of all the old cars we had back then, that is the only one I wish I had been able to drive.
But, we only have room for so many cars!
'72 Alfa Spider, 2 dual side draft Dellortos.
'74 Maserati Bora, 4 dual down draft Webers.
Separate names with a comma.