This spring sometime I would really like to perform a personalized "test 'n tune" session on my car, which has a '70 Buick 350 with a 2 barrel carb. It may be tuned just right or it might be off a little, I don't know, but I assume it could use a little "fine" tuning just to get it right. I seem to be getting between 14-16 MPG in town under normal acceleration and about the same or just a bit better on the highway at 55-60 MPH. If I speed up to about 65-70 MPH it seems to get kinda bad on gas, and in town I notice from leaving a stop sign, even after the engine is 100 percent warmed up, it still can hesitate at times, which it only has around 70 thousand original miles on it and has new bosch platinum spark plugs, which might need a slightly bigger gap as well. I am running a .30 gap on it, but it seems to be running rougher than it should. Ran fine for quite a while with the gap set up at .30 but seems now like it might need a bigger gap. I might try .35 or so and see if it runs smoother(keep in mind that I am running HEI, .45 seemed to be too much gap on my last set of plugs as I got spark knock). But at the same time I would love to tune my carb. sometime. Speaking of carb tuning, I gotta know how to use a vaccum guage as well. What kind of vaccum reading should I be getting for a stock 350-2 buick engine w/ no smog emissions crap, and where should the vaccum reading be at if it's tuned in to where it should be at? Any help is much appreciated! Thank you, in advance!:beer
Cody: First thing I'd do is fine tune the distributor. I know you didn't ask about dist. tuning, but you'll realize a huge gain in performance if its not up to snuff right now. Try to get initial timing up in the 10 to 14 area and limit your mechanical timing to achieve a total of 34 or so. So if you have 10 initial you'll want to limit mechanical to 24, all in by say 2,500 rpm or so. Once your dist. is tuned you can then go after the carb. Hook up a good vacuum gauge to any manifold vacuum source (something with full vacuum all the time, like the trans modulator fitting). Now turn the idle adjustment screw out so the throttle blades are closed. Lightly seat the two idle air adj. screws in the front base of the carb and then turn them both out 2 full turns. Start the engine. Alternately turn in or out these two air mixture screws and adjust for the highest idle vacuum reading. Turn one in or out until you see a movement of the needle on the gauge. Then do the same to the other one. Repeat several times til you're satisfied you have the highest reading. I would think with a stock 350 2 bbl you should be close to 20 inches of man. vacuum. By switching to a good 4 bbl. QJ you'd gain in the performance area substantially and more than likely in the fuel economy area too.
Hey Dave, Thanks for the info. and advice, I really do appreciate it much! I will use this info. to tune it in during the spring sometime. Also I would like to do a 4 barrel swap in the summer and have a dual exhaust system(w/ the stock manifolds or headers maybe if the budget permits at the time) put on. I am thinking of getting an aluminum intake and a good rebuilt/or just a flat-out good 4 barrel Q-jet. I would love better fuel economy and performance, both of those would really be something I would love to have. As well, I will check in to the timing before all in the spring, as I might as well have it all "fine tuned" while I am at it.:3gears: Once again, thankyou very much!:beer
