Ok guys here is my problem I have a 67 buick 300 in my 67 GS 340 ( non-original motor). It was a 2 barrel motor. It got wrecked and sat for a while, 5 years while I restored it' When I got it done recently the carb was in bad shape. I had rebuilt it earlier but now it was leaking vacume around the throtle shaft. I went to advanced Auto parts and bought a remanufactered one. It turned out to be bad as well. So they took it back no questions asked and gave me another. This time the manager warned me that these carbs really weren't that good at all. I put this one on and needed only minor tuning and had great throttle response and work great. This lasted only about 2 months and then it started to go bad as well. Advanced took this carb back and gave me my money back. I decided to put a holley on it. I had a 4160 that is a 600 with vacume secondaries. I put the carb on and adjusted it up with a vacume gauge. I got it to pull about 16.5 pounds of vacume at idle (650-700 rpm). The problem was that when you put it in gear it wanted to stall. So I had to set the idle up to about 900 and it seems to be fine. This seemed strange but I could deal with it. Once every thing was hooked up we test drove it. The secondaries opened up to soon causing it to bog so I went out to summit and bought the quick change housing and spring assortment I put in a stiffer spring in it and it cured the bog. The major problem though is it seems as though the 300 has lost some of its buttom end pull. Sitting still with the two barrel and nailing it would bust the tires lose for about 30 feet. Now With the holley it will not turn the tire over. It feels strong at the top end. The holley hasn't been rebuilt. So I bought a new power valve and diaphram. I have not installed these parts yet though. Is this a common thing when installing a a 4 barrel over a two or not. Looking for some Ideas guys Thanks Adam
You're taking an engine that was designed for a carb of about 370 cfm and placing a 600 cfm carb on it. There was a long thread here years ago by a 300 guru stating that you couldn't effectively use more than a 500 cfm carb on a stock 300 engine. IMHO, the advice about "Buick 350's love large carbs" does not apply to the 300 or 340 engines, at least unless they are significantly modified.
I was kinda thinking that myself I used that holley because it was lying around the garage I am going to try a couple of more things before I go out and buy an new carb thanks Adam
