I have a 63 valiant with an auto trans, and a transplanted 73 225. The engine runs good, but doesn't idle well (think it's the carb throttle shaft).
1. Should I expect any issues from running a 73 engine with the 63 trans?
2. If I have to replace the Holley 1 bbl, what should I look for to get the best fuel mileage?

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I'm sure I can do this without disconnecting the battery. What could possibly go wrong?

Oops, yeah, when you put a '68 or newer engine in front of a '67 or earlier automatic, you need to install an adaptor ring between the smaller early torque converter nose and the larger late crankshaft counterbore. You can get the adpator ring from Pat Blais, tflitepatty@verizon.net .

Carburetor: Look for a good one, which means no parts store "remanufactured" units — they're junk. Are you running the 1963 rotating-rod throttle linkage? If so, it's harder to find a good carburetor that'll work well, and you may have to send a good original "core" to be professionally refurbished...

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

Thanks for the reply. I don't know if the spacer was put in or not, since I bought it already done. If it doesn't have the spacer, will the tranny break. Or maybe just wear out the front seal?
It does have the rotating throttle linkage. It is a Holley 1 bbl.
I went to this site... http://www.carburetorexchange.com
They offer a carter bbs for $139 (plus core) or a Holley 1920 for $159 (plus core)
I looked at what they do and it does include a re-bushed throttle shaft. What do you think?
I'm replacing a Geo Metro with this car, so I need to maximize fuel mileage, or have a stroke from the shock! Any tuning advice is greatly appreciated.

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I'm sure I can do this without disconnecting the battery. What could possibly go wrong?

Wife had a Geo metro,got around 40 mpg,expect ABOUT half that with a well tuned slant,mark

I have a carter BBD 2bbl, and I get about 20 MPG city. It was similar with my 1920, when I got it to run right.

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'74 Duster 225 Super Six w/904
14" Cragar SS wheels

My 62 Signet,2,800lbs car in very close to perfect tune gets between 17 and as high as 23mpg,,,2 ,1 barrel Holleys,dutra exhaust manifolds,re curved dist,ALOT of playing,reading posts,to get it this good,mark

I purchased a new 1920 Holley Economaster which gets very good mileage on my 74, but not on it's own. A distributor recurve is a must do, to get the best mileage and performance from the carb. Upgrading to 2.25" exhaust is another help for better fuel economy. Driving with a vacuum gauge also helps promote better driving habits, resulting in better mileage.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

All the above suggestions are excellent. but even then, you will never duplicate the gas mileage of the Metro.

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Casually looking for a Clifford hyperpak intake for cheap.

Thanks for the suggestions everybody. I'm not trying to duplicate the mileage of my metro! I'm trying to have a mid-life crisis by reliving my youth, during which I drove many mopars. One of my favorites was a 61 valiant wagon. with pushbuttons, of course. But, is it possible to acheive better than say 25 mpg? I get about 18 in town and 22 highway with my 63 studebaker wagon. It has a 259 v8, with 3 speed stick and O/D.

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I'm sure I can do this without disconnecting the battery. What could possibly go wrong?

My recipe for good mileage is to build the motor for low end torque.

2 1/4 inch exhaust minimum, two barrel carb ( I prefer the Holley 2280 for mileage), electronic ignition (HEI is best) with a recurved distributor, mill the head to increase compression, and maybe a cam swap.

You can get over 25 MPG, but most people who have done that with a slant six have manual transmissions or at least a lock-up auto tranny.

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Casually looking for a Clifford hyperpak intake for cheap.

Without the spacer ring you'll eat the transmission front pump seal and bearing, and you'll get vibration.

I have no info or experience on the quality of rebuilt carburetors coming from The Carburetor Exchange, though I regard it as a good sign that they don't try to service a whole whackload of different years and models with just one carburetor like the factory-remanufacturing outfits do. But I'd still want more info. They mention cleaning the castings, and they mention throttle shaft rebushing, but they don't mention re-coating/re-passivating the castings to prevent corrosion, and that is absolutely critical. Carb castings that have been chemically cleaned and bead blasted but not re-passivated will grow white powdery "potmetal mould" in very short order, which clogs up the carburetor's passages. Also, there are problems and inconsistencies in their application listings.

Assuming a good answer to the casting re-passivating question, and assuming the listings I looked at aren't too badly snarled up, if you decide to go this route, you'll want to focus in on a Carter BBS rather than a Holley 1920. And don't just buy the #1205 they list for your '63. See if they'll build you a custom carburetor consisting of their #1212 equipped with the throttle shaft and lever from their #1164. This will get you a more advanced BBS with gradient step-up valve, more precise metering, full-bypass idle air supply, and other refinements that improve driveability and fuel economy. If they won't do that for you, then get the #1164.

There are other things you can do to improve economy, too. Tune-up parts and technique suggestions in this thread. Make sure the valves are adjusted properly. Consider an HEI upgrade. Get an Electric choke kit. Do the fuel line mod.

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

Our 63 Valiant also has a 225 in it with an auto. Mild cam, clifford 4bbl intake, clifford headers, holley 390. I drive it every day and get roughly 16-18 in the city, 20-22 on the highway. I've gotten as high as 25 mpg on long high way travel trips.

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Linder Tech.com
Bubba's Trailer Park

Thank you so much for the info everybody. I think I've got enough to start with and see how far that gets me. Thanks esp. SlantsixDan for the trans and carb info... Here we go.

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I'm sure I can do this without disconnecting the battery. What could possibly go wrong?

Good advice all. Good tune-up and eliminate vacuum leaks IMO are the most cost effective. I have a 73 /6 that I'm making a DD out of. When I did research on the engine, I found that the 73 models have the lowest torque and HP ratings of any of them. Bummer.

The faster the engine turns, the more it burns. In 1963, most did not think much about fuel economy with gas at 30¢ per gallon. Consequently, you may have a lower gear ratio (higher numerically) than the 73 and on did (post oil-embargo). I suspect the rear in your 63 is probably a 3.23 or even 3.31. This gear will require more rpm to maintain a given speed than my 73 which has a 2.76:1. I've seen 8¼ rear ends with 2.45:1 gears behind a /6. There should be a tag on one of the bolt of the axle housing that will say what it has, or you can decode the build sheet if you have that.

Besides switching from gross to SAE net ratings, horsepower declined due to emission regulations. The 73 engine was brought into compliance. IMO, EGR is probably the most power robbing part of the treatment. If you can put a 63, or any non-EGR intake and exhaust manifolds on your engine, it ought to perk up.

The only other thing I can think of to improve fuel economy is to have the cylinder head milled. A lot can be taken off of this head without any changes to the valve gear (.090). It will improve engine efficiency and should improve gas mileage. There is a point in milling a cylinder head where higher octane gasoline will be required. I've heard that the engine still runs well with 87 octane. That's where I plan to go when I finally need to pull the head on mine.

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You can't fix stupid. - Ron White

That's not necessarily so. An undergeared car (final drive ratio too high/numerically too low) will require heavy application of the accelerator to get the car out of its own way. Every newly-green light, every moment of every traffic jam, every freeway on-ramp, every high-altitude and/or steep highway hill, every around-town errand will have the carburetor's power valve wide open and/or the accelerator pump giving a full shot. Choosing the optimal final drive ratio for fuel economy is not just a matter of picking the lowest number. It depends on factors including the engine and transmission configuration, tire size, car weight, operating altitude, driving conditions, etc.
There were no 3.31s installed in A-bodies. Ratios in '63 Valiants were 2.93 (standard equipment with 225/auto) or 3.23 (standard with 225/manual and 170/auto or manual. 3.55 and 3.91 were available by special order but were not common in domestic North American cars. Of course, this particular '63 could have had a different rear axle swapped in over the last 45 years, but in all likelihood the replacement would be taller (lower numerically) than the original, not deeper (higher numerically); there were more 2.93 and 2.76 7¼" rear axles made than 3.23s or deeper.

Rear gears taller than 2.76 (such as 2.45 and 2.26) are not worth considering unless all you ever want to do with the car is cruise all day and all night at over 80 miles per hour.

Looking at the build sheet won't tell you what final drive ratio is actually in the car, it'll only tell you what was installed at the factory. You can determine your rear axle ratio easily according to these instructions.

There is no need to swap manifolds on your engine. It's likely the EGR was disabled when the engine was installed in your '63, if not before; if it is still intact, it takes less than a minute to disable it altogether, without removing the intake manifold. And there is no performance difference at all between a '63 exhaust manifold and a '73 exhaust manifold.

Blindly milling a set amount off the head is not a good way forward; if you think you will want to increase engine compression, you really want to CC the heads and determine the actual starting compression ratio (the published ratio is nominal only) and then determine how much to mill based on that measurement.

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