ClassicGuy

Hey everyone. I'm looking into buying a Mustang Mach 1 with a 351 Cleveland engine. I've always wanted a Mach 1, love the fastbacks, but I'm a bit concerned about the gas usage associated with that Cleveland. A few years ago it wouldn't have mattered at all, but the way gas is going I think it might just eat too much. I was wondering if anyone can give me an idea of kilo/miles per liter/gallon. I know I can change some of the settings in the engine, change the gear ratios, to get more milage with some acceleration saccrifices, which I would be happy to do for the time being, but the logic of this move is really determined by the currant usage. If the car only gets 12 miles per gallon, theres nothing I could do with the gears to bring myself to buy it, as much as I love the car.
Hope to hear from someone on the subject.

zx2guy

cleveland 2v or 4v? has the motor been modified to take regular unleaded?
year?
my cougar ('73 351c 2v) does about 10 to 15 mpg, however my car isnt set up for unleaded, it needs a carb rebuild, the motor needs rebuilt, the tranny needs rebuilt. so whats going on with mine might be totally off. if you get the car and milage is a concern ild pull the motor anf drop a 2v 302, w/ a c4 which has been known to be the most efficient of the auto's for the time (if the mustang is auto) while you are at it you can rebuild the motor (if it needs it) or drop an economy cam into it. and put a smaller carb on and adjust everything acordingly.

__________________
ford guy.... i know, and im sorry.

MagicRat

12 mpg is pretty pessimistic. That Mustang is a relatively light weight car and should do better. My '77 Lincoln with a 460 cid engine is 1000 lbs heavier than your Mustang, less aerodynamic and still manages 17 mpg on the highway,

Note:A manual trans will get slightly better mileage than an auto.

IMO you are on the right track, but there are cheaper ways than gearing to increase mileage. Tune your car properly. Make sure the vacuum advance on the distributor is working properly. Try advancing the ignition slightly from stock specs, but watch out for ping/detonation.

Tune the carb. Rebuild it if necessary and learn how it works. It can easily waste gas if it's leaking, (especially internally) the jetting and/or accelerator pump is set up too rich, the choke stays on too long when cold, etc.

Do you have a 4 barrel carb? Often the stock Autolite (Ford) 4 bbl carbs get better mileage than a 2 bbl on light throttle applications, because of their small primary circuits. So do not be in a rush to change the stock carb.

Spaking of which, aviod aftermarket carbs, if the stock carb is running properly. The Holleys, Edelbrock, Carter carbs, etc, (intended for performance) can be tuned for good mileage, but they are often set up out of the box to run a bit rich and reduce mileage.

A good set of headers and decent exhaust increase mileage (and power) a bit, maybe up to 10%.

If you have a solid (not clutch) radiator fan, get rid of it! Install an electric one instead. Even a clutch fan can be wasteful. You only NEED your fan in very slow moving traffic anyways,( when you move a bit faster, it just spins, creating drag and reduces mileage) so an electric fan with a thermal switch will save gas. You might be able to adapt a fan from another car (wrecking yard) or there are aftermarket fan kits available.

Keep an eye on your tire pressure. Never use old-style bias ply thres; they waste gas Use radials and run them at 30-35 psi (rear and front). The stock recommended tire pressures are often too low for radials. BTW this oversimplifies the tire issue regarding radials, tire pressure, weight, handling etc. The selection is actually more complicated, but you get the idea.

Does your car have a chin spioler, or air dam underneath the front bumper? If not, try to locate one, either aftermarket or adapt one from another car. It does not have to be huge or prominent. Many GM cars from the '80's had a very simple, almost invisible piece of plastic as an air dam. This reduces aerodyamic drag from air passing below the car.

And finally leave the stock camshaft in it. Some aftermarket cams, especially the radical profiles kill mileage.

__________________

I still say a church steeple with a lightning rod on top shows a lack of confidence

ClassicGuy

Well its going to be a 2v with a stock carb, automatic trans, no other mods to the engine. Its a '72 Mach 1 so its got the air diverter on the front end and a rear spoiler, but the rad fan is just that, the classic belt driven fan.
Like I said I'm looking at both cars, the '73 mustang coupe with a stock 302, and the '72 Mach 1 with the 351 4v edlbrock intake and enlarged carb (in the 600 range, can't remember right now) but I'll be reducing it to a 2v with a stock carb. It's my understanding that the 302 didn't do much better for gas mileage than the 351, only 2-5mpg. I'd love to get the Mach 1 because I think the finished product is amazing, and I think the journey to get there would be more enjoyable, but at the same time I can't afford to restore a car of all the money is going ino the pocket of oil tycoons.

zx2guy

how much do you spend on gas in a week? i spend about 45 bucks alone on my zx2... the cougar...a week of driving that could very well double it. not to kill your idea... but if the car is going to be your daily driver... unless you are really close to work i really wouldnt go for the idea. however if the car will basically be for enjoyment... then by god go for it. im just thinking if you put everything on a fixer upper... you might get shot in down time.

__________________
ford guy.... i know, and im sorry.

ClassicGuy

It's an every day vehicle. I spend about 60 a week as it is with a 6c p.o.s. Plymouth, the thing eats gas like no ones business and I'll be happy to see it go. I'd much rather see a worthy car eat my money than that thing.
I drive 30 minutes to and from work a day, its not often I drive under 80kph.
The Plymouth gets about 24 combined miles (highway and city) so something like 21 mpg city, the 315c will get (or so I can find) about 12mpg before tuning so I am looking at about double the gas. If I can get the 351 up to 16mph city I'd be dancing.
As for putting everything into it, I really don't need to, she runs as it is. My restoration work would be primarily concentrated on the interior after new floor pans ext, then ext body work, the motor runs well.

Pretty much all I'm looking for is confirmation or correction of my 12-15 mpg city claims, but I'm having a hell of a time.

Either way, whichever I buy I'll be posting pics, first classic.

zx2guy

good luck man. i wish i could afford 120 a week on gas. im just hopin you wont end up like me and have the car taker a dive on you.... i would drive the cougar more often but, with the motor in the condition it is... no, parts are too expensive.

__________________
ford guy.... i know, and im sorry.

72' Stang 351 H/O

Are you getting basic 2 barrel carb or the 4 barrel H/O version or the C/J?