actually, by the time I'm done I'll probably go past 76 questions.. I have a '76 with a decent body, older(still kicking, not original) 305/307 and a 350 automatic. rear end is a 3.7x? manual trans rearend. Most of my driving is highway and with the price of gas, I'd like to get better mileage, while upgrading to a new or rebuilt engine. 350 makes sense, 2 or small 4 barrel, mileage cam, etc. 4 speed? 5 speed? 4 speed auto w/od change rear end ratio? which way do I need to go for good highway mileage?? do I need to change the driveshaft for any of this?
IF you want good gas mileage here is how I was able to get around 18 mpg in my 1961 gmc pickup. I put a stock 350 motor with a 350 turbo transmision. After that i check the rear end gears and changed them to 3.73 ratio. Like i said i was getting in the area of 15-18mpg on the highway and around 10-13 in the city. For your last question- you will not need to change the driveshaft for this switch. GOOD lUCK, GM61
I would go with a 350 mild cam, dual exhaust, high performance HEI, good set of plugs, cart r, or rochest.. carb, throw a 700r4 behind it ( it is like an inch longer then your turbo 350, which should be fairly easy to adjust out) I think the splines are the same as a 350 too. I am not sure what your current axle ratio is , but with a 700r4 which has a 3.06 first gear versus 350 turbo which has a 2.52 you could probably go with a 3:43 or even 3:23 ratio without turning into a big dog ... depending on the size tires you run.. Or you could build a 327 hybred.. 350 bore engine with a 307 crank and 327 pistons... I have always had great milage with these motors. 327's get great milage, rev fast, so with a 700r4 behind it you could have a fun truck to drive, but if you plan on pulling anything go with a 350 the lower your axle ratio (numerically speaking )is the more milage you will get, however below 3:23's your off the line is going to suck but your top speed will increase. example... 3:23 get a lot more milage then say 4:11 ratio. good luck. let us know what you decide on. hope this helps ... Eugene 68 chevy 69 gmc 76 blazer 92 4x4
