Hey all,

I am contemplating getting a 63 or 64 Valiant convertible to use as a daily driver. I have a truck, but it doesnt get the greatest mileage, about 10 mpg at best. I want one with a Slant and auto trans and have some questions. What is the true MPG of these little "economy " cars of the early 60's? I have heard varying opinions, such 13-15 and as high as 27 mpg. I drive like grandpa so what would I get mileage wise?

2nd question: Where can I get a Weber 32/36 set up? I have heard great things about these carbs as far as their fuel economy, and wondered how to get a hold of one.

3rd: I read in another forum about running acetone? Is that for unrebuilt original motors? Should they be rebuilt for todays low grade unleaded fuel? Would it be better to find a slant from the early '70's?

Any advice and info would be appreciated. Of all the little econo cars of the early 60's ie , novas, falcons, etc, I want a valiant. I have had a 64 dart convt. and would love to have another MOPAR. They truly are great cars. Thanks.

225

Acetone has been touted as a kind of "catalyst" to help fuel burn more completely. You only use a few ounces in a tankful of gas. My reading leads me to believe that it is more or less "snake oil" and of very doubtful benefit. If you wanted to try it you should be able to find more info online, try doing a google search.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

My '64 Valiant convertible, 225, TorqueFlite averages about 16-17 in mixed driving and only slightly better on trips.

You think the weber 32/36 carb and electronic ignition would improve the fuel economy in a 63-64 vert?

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if you stick to a 32/36 and not a 38 you will do about the same as a 1 barrel but better power and performance. when you repoace a 2 barrel with a 32/36 you see an increase in both. I have a 63 vert dart when i was running all stock with a 2 barrel it was in the mid teens around town and in the 20 range on the highway, not over 65 mph. after that it drops due to the rpm issue. need to be geared up for that. GRT

Highly dependent on things like ambient temperatures where/when you drive, engine condition and state of tune, and rear axle ratio. In a mild climate, a 225-auto '63-'66 Valiant with 2.93 rear gears and stock-size tires, in sound mechanical condition, driven sensibly and kept in good tune, should give you about 17-19 in town, 19-21 on the highway. The exceptional cars (or those that have been fussed over to squeeze out maximum economy by dint of careful attention to the carburetion, ignition, exhaust, cam timing, etc.) will give you maybe 19-21 in town, 22-25 on the highway. Figure maybe 1 to 2 mpg more with a 170 instead of a 225.
Hooboy. Complete, total myth. Adding acetone to your fuel system, in any amount, is an extremely poor idea. It will not (cannot) make anything better about the way your car runs. There won't be any improvement in fuel economy, driveability, performance or anything else. There will, however, be extensive damage to the fuel system. These kinds of dumb myths (that's a comment on the myth, not on you!) come out of the woodwork whenever the price of gas goes up. Acetone or mothballs in the gas tank, "ignition intensifiers" on the plug wires, magnets on the fuel line, "Platinum catalysts" on the air cleaner, "turbo air spinners" under the carburetor, hundreds of different gunks added to the engine oil...the list of do-nothing-at-best, do-damage-at-worst mileage scams goes on and on and on.
Another myth. Today's fuel is, in many ways and in most areas, considerably better than the fuel that was available in the 1960s and 1970s. It is of much higher quality from a refining standpoint—it burns much cleaner and leaves considerably less trash in the combustion chambers. The lack of Lead is not a big concern with a slant-6 driven the way you say you drive; there is no need to add anything to the fuel or tear open the engine. Simply drive the car; if it starts out in good condition you'll get a lot of miles out of it before the cylinder head needs service, at which time hardened exhaust valve seats can be installed.
Better in what way?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

So I guess the moral of the story is to jet the carb as small as possible without burning a valve or get a TBI/FI set up for it if you want more MPG.
I think I read from a valiant site that the 62-68 225/auto equipped cars had a 2:93 rear. If one were to put some sort of overdrive tranny in it, would that lug the 225 six and actually decrease the mileage? Or does the slant make enough torque to handle it?

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Well, don't get carried away. If you have a choice between a jetting setup that gives you 23 mpg on the highway with bìtchy driveability problems, or one that gives you 21½ mpg on the highway with good driveability, pick the latter.
TBI doesn't necessarily give you good MPG or good-anything else. The TBI system used by Dodge on 3.9-, 5.2- and 5.9-litre engines in trucks and vans from '88-'91 is notorious for poor mileage and driveability, for instance. Proper EFI (port fuel injection) is very expensive to set up. Remember to do your payback-time maths before buying anything. You can very easily spend $2000 or more on parts and labour (your own or someone else's...is your time worth more than $0.00/hr?) getting an EFI system put together, installed and tuned. How many years/miles would you have to drive the car to realise a savings?
In '62-'67, many of them did. Starting in '68, most of them got 2.76s.
Depends on how fast you're planning to cruise on the highway. If you're looking at flyin' along all day at 80 mph on level or downhill roads, with next to no weight in the car, then by all means, go for it. With any of the common ~30% overdrives, your effective final drive ratio will be 2.05, which is way too tall for most purposes.

Also, the only relatively easy/inexpensive overdrive trans swap into the kind of car you're looking at involves starting with one of the few that were built with 4-speed manual transmissions in the first place. Anything else, see above regarding payback maths.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan,

You type way faster than me bubba, lol!

What I said about the 70's 225 being better was based on it being equipped to run on unleaded gas. It was more of me thinking out loud. Sometimes you get the best answers by asking questions you never meant to. Ha, ha.

The numbers you posted about these little cars mileage makes me want one more., I fugured all those claims from other slant owners I know would be true. Are there numbers anywhere to give you all the correct settings, carb, exhaust size, etc.? I know of a guy in Columbia that builds old early 60's 230 chevy's and he has gotten some amazing mileage out of them he says. He basically just chalks it up to building the motor "acoording to the 'new' tech spec." So if you were to start with a fresh rebuild, is that what it would to take to squeeze some more mileage out of it?

That is a good point about return of the investment in an OD tranny. I would rather just spend the money on a weber 32/36 conversion kit, maybe go up one tire size if possible and call it a day.

Ya'll reckon these little valiants can pull a little equipment trailer with my tools and stuff?

Thanks for all the feedback. Keep it coming.


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Over 100wpm!
No need. The earlier ones are fine with it.
Yep, see this post.
Can't say—the statement as issued does not parse. What exactly does he mean by "build to the new tech spec"?
That kind of depends on what your tools look like. If they look like hammers and screwdrivers and tape measures and wrenches and drills and saws and stuff like that, no problem. If they look like concrete mixers and posthole diggers and tree shredders and suchlike, maybe not. What line of work are you in?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

No big stuff. I would just be pulling a wet tile saw, basic tools, etc. The biggest thing would be some sheets of backerboard and or boxes of tile. But it wouldnt be too often. Maybe once every other weekend.

What I said about the settings and such really was a inquiry as to whether a general mechanic I take the distributor to to have it installed as well as the carb and such would have this info to "optimize" everything. I could probably get the ideal size exhaust specs from some of you guys here.
Oh, and I definitely dont have the funds for MPFI. Way outta my ballpark.

But of course, I haven't gotten the little gemstone valiant just yet. I have to find one first. I've found one, but it is way too far away.

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This rules out the 2.93 + overdrive combo.
Absolutely not! You're lucky these days if you find a general mechanic who can be bothered to bother following the factory specs for stock equipment—and that's if you supply the specs! The two options for the kind of tweaking you're after are:

1) Do it yourself

2) Find a super slant-6 specialist if one exists near you, and start writing checks.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I appreciate the feedback. I will definitely have to find a specialist around here....though, in the meantime, I will have to the find the car first. If ya''ll know of anyone near SC who has a 63-64 valiant convrt. slant/auto trans, let me know. Thanks.

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In the late '70s and early '80s when I was driving these cars as the second/third owner, I was getting around 17mpgs. In my '65 Dart with a 250,000 mile '78 OEM SuperSix, a 318 BBD, 4 speed and 2.45 rear gears, I am getting 19mpg, during the summer. In the winter I get considerable less.