does anybody know what size carb came on 340 4bl, what cfm. i have a 500 cfm on it now but it seems to be a little small , would like to put on a 750.
I've never seen a cfm rating for the original carbs. Think they would be in the 500-550 range. I have an Edlebrock 600 Performer on mine and it's plenty of carb. The linkages are different, expect some tinkering to adapt a different carb. Also, a new air cleaner, as the original won't fit an aftermarket carb.
thanks,have you run your car at the drags. i take it yours is also a 340. if you have what did it turn. you said it was plenty of carb. did it come out of the hole good. i am trying to get mine in the mid to high 14 second times. that might be hard but i am going to try. a have got to the low 15 second range ,don,t know if a can get there with stock gears and convertor.
My car is an heirloom to me, so while I do make modifications to it, it has never been raced or timed at a track. As far as stock performance, the old Car Life magazine did a track test on a new 1967 GS 340, which is mechanically identical to my car. The best time in the 1/4 mile was 16.7 seconds at 81 mph. That ought to give you a benchmark of what to expect with a stock drivetrain.
AFB carbs for '66 340 I looked into this about three years ago when I first got involved with the smallblocks. I checked my notes and here's what I recorded at the time (Buick "X" Files). The 1966 carbs for cars with automatic transmissions are not exactly the same as the cars with stick transmissions. The A/T carb is p/n 4055S and has 1.125" primary and secondary bores. According to the carb shop I contacted it can be rebuilt in stock form and flowed to around 480-490 cfm. The S/T carb is p/n 4056S/SM and has 1.437" primary and secondaries. It can be rebuilt and flowed to around 500-510 cfm. The difference in bore size is just to get the carb to work with the ramp up of rpm in an A/T or M/T car, respectively. So a safe bet would be to replace the stock carb with an Edelbrock or Carter 500. If you further, the 650 may give you more top end, but I'd bet that out of the box, it would kill some of your low end performance.
thanks for your info on the carb pinhead. i think i will try the 650 cfm ,i don,t know if it will work or not but i am putting a ram air set up on it. i am also going to put smaller tires on to help get out of the hole.hope you can make it to norwalk for the race if you are planning to come .
Yea I had a carter 510 on mine when I got it from my grandfather. I recently did a rebuild on the engine with a more aggressive cam and bored it .60. I switched from a holley 600cfm to a eldebrock 600cfm manual carb and it loves it.
Rick; You're welcome. I enjoy dabbling with the 300 motors and have found some of the stuff applies to its 340 big brother. Unfortunately, I've never been to any of the national Buick events, even though I've been building only Buicks since 1990. If our new business can make it over the hump this year, I'm definitely planning to make the trip next year. By then, I'll have a decent paint job on the ol' hot rod and maybe the 12-bolt rear end swap done too. Mark
harry, with our 67 340, we went 15.0's at cecil county. a friend of mine has some headers. would like to try them and a larger exhaust system. pinhead64us, the headers were made by tubular automotive years ago. you must know them. john
You bet, know them well. Years ago I had a '63 Ford Falcon with a tunnel rammed 289, 4speed, 9" rear with 5.13 gears and a straight axle. The made a set of fender well headers for the car that I later had chrome plated. Bought the car from a guy who raced at the old Connecticut Dragway in Colchester. Nice strip car. Nightmare street car.
GSJohnny, That 15.0 time is very interesting. About two years ago, I was talking with the owner of a 1967 GS California at a show. He had the original article from Car Life in a scrapbook. I was surprised at the slow times they reported. Wonder why the difference with yours, assuming yours is dead stock? Maybe you're a better driver....
