Hey All,

I am currently looking at a 73 Dart, 4D, 225 CID w/AC as a daily driver. I've been wanting a /6 driver with AC and I figure with the girlfriends kids, a 4 door is just the ticket.

If I get it I will eventually rebuild the engine in it, or another spare engine I have laying around. So here is the question(s):

I have both a 170 long block, and a 225 I could use for this car. I figure the 170 would give me better gas mileage, but the 225 would be better on the mountains around here and with the AC on.

Would the 170 be totally aniemic with the AC on? How would a 170 do on 6% grade mountains? And how much better mileage can I expect from a 170 over a like built 225?

I would like to stay with a forged crank engine for durability. I know the 170 I have is FC. Are 73 and 74 model 225's still forged crank?

With regards to the AC, is it cheaper to buy R-12 and just fix the existing system up. Or in the long run should I upgrade the system to 134? How much would a 134 upgrade cost?

Thanks for any info and opinions!

Chris E.

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-76 Cordoba, 360 4bbl
-68 Valiant, 273 2bbl
-67 Dart /6 4bbl, Leaning Tower of Power!!!

Without major re-engineering (EFI at minimum, pref w/turbo), a 170 will be maddeningly/dangerously anemic in that heavy '73 Dart going up mountains with the A/C on and a few passengers. You could rework other stuff (high-RPM engine configuration, 3.55 rear axle) but then your gas mileage goal goes ker-flush. Use the 225 and it'll still be doggy up the hills and/or with the A/C running until you swap in a 2bbl and put in a reasonable (2.93, 3.23) rear axle.

The forged crank was used til midyear '76, but there is no durability issue with the cast crank.

A/C questions: See here and follow the links to other threads from there.

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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 have to 2nd the 225 motor is the way to go----

I have a 62 valiant & live in the flatlands-- the 170(120K approx) would not accelerate to safely merge into traffic at certain places in town-- the 225 works great for this & the mpg did not suffer much if at all. I'm running the same 904 auto tranny/3.23 rear gears/carb that was on the 170.
The swapped 225 was from a 65 model car w/approx 50k on it-- this kept the costs down & has been a veryreliable car . Lawrence

You may actually get worse milage with the 170 since you will have your foot into it all the time just trying to keep up.

Thanks guys.

I actually had a 170 in my first car, a 63 dart, back in high school. I remember it being a bit aniemic. But that was over 20 years ago now. Back then I didn't have to contend with driving over mountains either. And there was no AC to speak of in that car!

I do have one other question. And I may be splitting hairs here. The car I am looking at supposedly has 36K on it ( I really don't know if it is 136K but they say it is only 36) The extra 225 I have at my house has an unknown # of miles.

I would like to rebuild a motor for it no matter what, just so I have a known quantity. Would there be any sense in keeping the original 225 with the car from a value standpoint? Or is this a moot point with 73, 4 door slant six car?

Thanks again for any opinions.

C

_________________
-76 Cordoba, 360 4bbl
-68 Valiant, 273 2bbl
-67 Dart /6 4bbl, Leaning Tower of Power!!!

Why not wait to decide which engine to build for it until you have the car and know how well or poorly the current engine can be made to run without major injections of time and cash?

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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, I wouldn't start building an engine until I had the car. After that I'd build it for a project. For fun!

I always thought it would be cool to build a /6 better than the factory ever did. Install it. Maintain the bu-jeezies out of it, and just see how many miles you can actually get out of it. And what would go wrong along the way, so forth and so on.

To answer your question, just for fun!

btw. I am reading your AC posts this morning. Lots o good info!

_________________
-76 Cordoba, 360 4bbl
-68 Valiant, 273 2bbl
-67 Dart /6 4bbl, Leaning Tower of Power!!!