Ok so i have been diggin deep on carbs, 2 vs 4 endless discussions all valid points and takes. However i stumbled upon some guy that put a 4BBL carb onto 2BBL intake manifold with an adapter plate 4-2 just set up in reverse. They did it and it fired up and worked, how well is my question. Has anyone here done this, or heard of this? Just find it really interesting and think it could be cool if it works and is reliable. Would love to hear your thoughts!
There would be absolutely no benefit to doing that, but to answer your question, are you crazy?, No, maybe a little naive.
I most certainly disagree with the previous posts. Back in the mid 80's my buddy had a 1967 AMC Rambler with a 6 cylinder engine and 3 on the tree. He converted it to be a floor shifted car so he could hit 2nd gear faster. Then he bought the exact mentioned carb. spacer above. He took the 2 barrel off of the car, placed the spacer on the car, and he put a Rochester 4 barrel carb. I had laying around on it. We took it for a test ride..... It performed quite well as he conservatively drove down the street. At the first traffic light he floored it through the gears. If I remember correctly, right around 4000 RPM, the 4 barrel finally opened up and there was quite a performance gain according to our butts!!! He kept the car just like that until the engine finally died almost a year later. Naturally with that little performance gain that showed up around 4000 RPM he explored the upper RPM ability of his new engine. In other words, he was constantly winding the crap out of that little 6 cylinder until it blew up! To much fun!!!
Sure, but that adapter is a huge restriction to airflow. One way to see how much would have been to install a vacuum gauge on the engine and monitor it while driving. Looking at the WOT vacuum level would tell you how much. Normally, you want to see very close to zero vacuum at WOT. The more vacuum, the more restriction. It would have been interesting to see what it was. Maybe that Rambler 6cyl liked it, but it would certainly be counter productive for our engines.
I totally agree with you Larry. We were just having fun drinking some beer, but it did make a little difference.
I'm sure it did. The spacer probably provided enough of a restriction so that it ran good with the smaller engine.
I can see an adapter working UP TO A POINT, then the additional airflow from the 4 bbl. would be restricted trying to squeeze thru 2 holes. Good beer drinking experiment tho
I have had this very setup ony 300 for probably 18 years. Its just a Mr gasket adapter fliped upside down. I did open and blend the ports on the 2 barrel intake to match the adapter. I did it because the Rochester 2 barrel was worn out and the two rebuilds from auto zone were worse then my original. I have had a couple Holley's on it and an edelbrock. The carb runs great( till recently). It has a little more up top than the 2 barrel did. At the time I didn't have the money for a factory intake and wanted to drive the car. It worked so good that I just left it that way. At wot the vacume reads 0 on an autometer vacume gauge. On thing to keep an eye on it hood clearance . I had to use a drop base air cleaner. And grind down the wing nut. I put to tiny dimples in my freshly painted hood. Is this an optimal set up for sure not. But on a street car I would be surprised to see much difference between it and the factory 4 barrel intake. Plus I thing I paid 20 bucks for the adapter. Much cheap than a factory cast iron 4 barrel intake.
I was thinking that too, but wouldn't it just perform like the 2BBL wide open? Manifold would get the same amount of air in, however get the benefits of the 4BBL for the lower rpm/cruising.
There is a difference between doing it because of financial constraints and doing it because you think it will actually provide you with better performance. That adapter will be a restriction to the total flow of a Quadrajet, or any other 4bbl carburetor, there is no two ways about it. Waterboy and 1adam12 used it on small engines, so it probably worked OK, but it's not a good idea unless you have no other choice.
Decades ago a friend of mine his 2-jet took dive on him.... He called me asked if I had any 2-jets I didn't any just just Q's and Holley's and some fords.. He comes over and we head over to anther buddy place to get a intake none to found.. Ask his dad whats in his stash.. Again zilch,, This is weird its just a SBC. Then his dad remembers his friend has a 2-4 adapter but no intakes or 2jets. Next dad jumps Into his tow truck drives over to get the car thats down and brings it too his house. His friend brings the adapter. Those two old guys rebuilt the Q tuned installed it and the adapter, tuned the motor.. Had him running in a few hours. He was not lead footer but he drove that thing back and forth from Tacoma WA to Pullman WA for years.. And bragging about the fuel mileage... I drove the car it had a better acceleration improvement over a 2jet... HP no ... Now as Im typing I think those to old guys disabled the secondaries. Now FWIW I think those two old boys (they would be over 100 years old today if alive) had more fun tuning a MPG motor. than a HP motor..
my 72 has a adapter and a edelbrock 4 barrel on it. was like this when i got it. it runs good and isnt thirsty but ive never driven a 2 barrel 72 so idk how much difference it is over the 2 barrel car. that said i wonder if you milled out a 2 barrel intake to a dual plane open enough for a 4 barrel and put new studs would it run as good for a cheap way to get a 4 barrel intake. just an idea i had once.
You have room on that plate to fit two 2bbls and connect the linkage. Instead of Tri- power you'll have Double-power ....
