I'm looking for an intake manifold for a GMC inline six for a 2 barrel carburetor. I believe some of the 302 military engines were equipped that way? Please PM or email with what you've got. Thanks!
Jerry
Found one! It's on the way to me at the moment. Thanks for the search and the offer to send it to me!
Are you doing crazy things to GMCs too? I'd like to hear about it!
Just a minor upgrade to a big rig I just bought- - - -a 1951 3 ton flatbed with a 270, a 12 foot bed, and a vacuum shift 2 speed rear axle. I'll be installing a 2 barrel intake from a 302 military engine and a 3 speed Brownie. 24 forward speeds and 6 in reverse! The truck was bought new for use on Redstone Arsenal in Huntsville Alabama, and probably hasn't been more that 50 miles from there since it was new. It needs some pretty extensive brake work and a rusty floorboard repaired, but otherwise it's in pretty good shape.
.JPG "Big GMC (Copy).JPG")
Cool truck with an even cooler history....! Maybe Werner Von Braun rode in it at one time when he was there....
What a work horse, a gear for every occasion. I think the best my 270 ran was with a single 2 Jet. The 4 barrel Edlebrock is a disappointment. I'd like to try one of my 2X1 setups.
Two carburetors on an inline six is either one too many or one not enough. The 300 cubic inch Frankenstein Chevy 261 I'm building will probably run three side draft Keihin carbs for a Harley Davidson EVO engine on home-brewed adapters, to run one carb for each intake port in the cylinder head. Since only one cylinder at a time is supplied by each port, there's the equivalent of a carb with enough CFM volume and jetted for each individual cylinder.
Before you remove that 4 BBL intake, try adapting a Quadrajet calibrated for something like a mid-1980s Chevy 305 or a 307 Olds V8 to it. The spring loaded flap valve at the top of the air horn will prevent getting overcarbureted, even when those huge secondary throttles are open, and the 3-stack venturis in those tiny primary barrels will do an excellent job of fuel metering at any engine speed from idle to cruise speed, far better than the Edelbrock can attempt to do.
Jerry
Found one! It's on the way to me at the moment. Thanks for the search and the offer to send it to me!
Two carburetors on an inline six is either one too many or one not enough. The 300 cubic inch Frankenstein Chevy 261 I'm building will probably run three side draft Keihin carbs for a Harley Davidson EVO engine on home-brewed adapters, to run one carb for each intake port in the cylinder head. Since only one cylinder at a time is supplied by each port, there's the equivalent of a carb with enough CFM volume and jetted for each individual cylinder.
Before you remove that 4 BBL intake, try adapting a Quadrajet calibrated for something like a mid-1980s Chevy 305 or a 307 Olds V8 to it. The spring loaded flap valve at the top of the air horn will prevent getting overcarbureted, even when those huge secondary throttles are open, and the 3-stack venturis in those tiny primary barrels will do an excellent job of fuel metering at any engine speed from idle to cruise speed, far better than the Edelbrock can attempt to do.
Jerry
Two carbs seems to work OK for me on a 300 ci. Better than any 4V I've tried.
A 300 is a 12 port engine- - - -comparing apples to kumquats! A 2-carb intake, with the carbs still attached, makes a good anchor for a small boat, or a REALLY good paperweight!
Sounds reasonable. 2 has worked well in the past and they look cool.
I like Quadra Jets and I think I have one of those in the carb cabinet. It is not that the one I'm using is bad. It is just not what I expected. It does beat messing with a bunch of linkage. The only 3 carb setup I have is a Harper. It doesn't have all of the split shaft progressive linkage. Complicated but a thing go beauty.
"Double- - - -double- - - -toil and trouble!" Running multi carbs with progressive linkage is like diving headfirst into a witches' brew! Find a carb that's approximately a fraction of the total CFM you want to run, and then build several of them as close to identical with each other as humanly possible. The laws of physics are not "suggestions". If a single carb is designed and calibrated to run an engine of 100 cubic inches, for instance, and you want to use it on a 400 cube engine, you'll need FOUR of them running in synch to flow the right velocity through the venturis. (Honda Gold Wing, for instance) Trying to tip in extra carbs with different throttle plate openings is a disaster looking for a chance to happen. The Pontiac Tri-Power and Olds J-2 systems ran the two outboard carbs in a "wide open or off" situation. They didn't even have idle circuits. Ditto for the secondary carbs on the Corvair Spyder 4-carb setup.
The two most common rookie blunders hotrodders commit is "too much cam" and "too much carburetion". Mother nature can be a real female dog when you start tinkering with physics.