Have a '71 Maverick, gonna put in a 302 V8 to replace the I-6 250 cubic inch in there right now, and trying to replace the C-4 transmission. I've heard a T5 would be good for mileage without sacrificing performance, plus manual's always better. Any thoughts or suggestions? Was also considering an AOD conversion, but again, as I understand, a T5 would be superior.
My thoughts; it depends on several factors. What ur main intended use for the car. If I am mainly racing - I keep the C4 and have it modified. You will also have to obtain a clutch pedal assembly if ur going manual. If you have a stock 2.79 axle the AOD or T5 won't be that efficient. I wud think in terms of at least 3.55 to 1 ratio. It seems like ur partial to the manual trans. In that case If ur prepared to make the mod's I wud go for it. Those are my thoughts.
If your worried about gas mileage, buy something newer, and lighter. A 30+ year old car isn't your best best, the bus will be cheaper.
Not commuting with it or anything, but at the same time I'd like to drive it a bit more frequently than weekends. I have a truck for anything long distance. With the parts in my car now, I get about 11 MPG, and I think that's a bit ridiculous considering the lack of power it has. Then again, it's stock using the original '71 parts. And thanks mojo for your thoughts. I'm now considering keeping the C-4 trans, but as I understand there are some issues with that modification in regard to the flywheel, etc. If I kept the C-4, would a 302 still be my best bet?
I don't understand how you get less than 18-21 mpg with a 302 and C4....... My stock but well worn 73 302 (111000+ miles) and performance built C4 get 21 mpg. I can get better but I do like to DRIVE it, if you know what I mean.
Trans Issues I don't know what issues ur refering. Check out this site to give u a little insight on C4 issues. http://www.mustangcentral.net/tech/c4.html. If I am going from inline engine to V8 it will be the SB 302 based 302-347. The 351's are a tight fit. My 302 w/ longtube headers is close enough for me, barely any room between the shock towers and sparkplugs. I think most who use the 351's shave the shock towers. It basically comes down to what amount of power, torque, patience, ego and resources ur willing to expend. As for mileage I see folks on here claim to get mileage in the 20+ mpg w/ modified V8's. I have only had my 73 Comet since July. It has mild cam, headers, 600 Holley; idles at 800rpm - so it's a relatively mild. The guy I bought it from did'nt have any reciepts but the engine runs like a sewing machine, very little rust and the price was right. I don't really know fuel mileage, I will check on it this spring. U may have other issues w/ the engine the reason ur mileage is poor . There are a lot more people on the forum who have vastly more knowledge than me - Im suprised none have chimed in on ur post. Those are my thoughts. Hope the link helps you.
Heck i was flooring the maverick every chance i got with the old 302 and still got 18 to 20 mpg Now i floor it and watch the gas guage go down 1/4 of a tank
Check to be sure your choke is opening all the way. Check all of your vacuum lines for leaks. Spray carb cleaned around the carburetor base and see if it will pickup rpm...see if the exhaust changes colors. Check your piston top dead center with a piston stop and compare it to you balancer TDC. It's possible the ring has slipped on the balancer. Then check the timing again. If everything checks out then rebuild/replace the carburetor. You should be getting around 19-24 mpg.
Something is out of tune, that I am sure of. My 71 F100 with a mild 460/c6 and 3.25 gears can get 14-15 mpg if I try. I would do like suggested and start checking out the carb, timing, vacuum leaks and such. Might have a brake dragging somewhere. Torque converter might be screwed up and slipping way more than it is supposed to. All kinds of things could be causing the low economy clint
when i had my 69 bug with the stock 1500cc motor had /exhaust /intake/2bbl carb /electric dual spark distributor / and got 13 mpg ON A 4 CYLINDER MOTOR and was super slow then i put a 2054cc motor in it with the same mods and was kinda fast then i got about 20 mpg i am using a t5 trans in my mav with a 3.00 ratio to 1 rear end my first gear was abot 25 mph and second at 45 to 50 thats what my speedometer would read but when i took it to the track my speedometer sed 75-80 in 3rd gear at the finish line but the track sed i was going 93 mph i am sure my speedometer it wrong because i never changed the speedo gear
Something (or a number of things) is very wrong. When I had a 250 in my car, it always got high teens to low 20's, and it had over 230,000 miles on it. The 200 I have in there now gets low 20's during these cold months, and mid to high 20's in the summer.
