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Differences between 170 and 225 distributors?
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Author:  TylerW [ Sun Dec 30, 2018 5:00 pm ]
Post subject:  Differences between 170 and 225 distributors?

Hey guys:

I've been doing a lot of work on my latest slant vehicle, which is a 1968 Valiant 100.

I noticed early on that the original 170 long block has been replaced by an early 70's 225. I have my suspicions that it was a reman'd long-block instead of a used junkyard engine because they swapped the original manifolds, distributor and carburetor over and there is an actual Mopar water pump on it(dated 1984).

My question is about that distributor: is it worthwhile to swap it with an actual 225 unit or is it something I'd never even tell the difference? I have a complete '71 225 I keep as a spare and I could use that distributor, but I'm not going to bother if it's not worth it.

Thanks.

Author:  kesteb [ Sun Dec 30, 2018 5:46 pm ]
Post subject:  Re: Differences between 170 and 225 distributors?

There is no difference in the distributors. The big difference would be, do you want points or the better electronic ignition.

Author:  TylerW [ Sun Dec 30, 2018 6:13 pm ]
Post subject:  Re: Differences between 170 and 225 distributors?

I appreciate the reply, but there are differences. In 1968 alone there are 4 different distributor part numbers....manual and automatic, 170 and 225. The advance curves are different among all 4 of them. I was just curious if anyone can report on the drivability differences between them. I am fine with points. I've had a lot less trouble with the points than I have with the various electronic ignition failures I have had, both original Mopar stuff and a worthless HEI retrofit.

Thanks again.

Author:  drgonzo [ Sun Dec 30, 2018 7:42 pm ]
Post subject:  Re: Differences between 170 and 225 distributors?

I've had good luck so far with my HEI conversion and recurve. Having said that, I raced a lot of dirt track laps with points ignitions with the only problem being a set of points that just seemed to short out(when trying to load onto my trailer). Popped in a new set and I was off to the races. A well set up points distributor with a good curve can perform quite well.
Come to think of it lots of races have been won with points ignitions and drum brakes. Just sayin'.

Author:  GTS225 [ Mon Dec 31, 2018 4:21 am ]
Post subject:  Re: Differences between 170 and 225 distributors?

OK Tyler, technically, you're correct about differences in distributors. I think Kesteb was trying to say there is no difference in the outer dimensions of the physical unit.
All the differences would be in the vacuum advance pod, and possibly advance weights. Those can be changed out such that the distributor is correct for the engine it's in, rather than the engine it came out of.
I can see where you'd rather have points than electronic. Points are a very simple and easy to understand ignition system. Less wiring needed, and can be worked on on the side of the road when necessary. (It's what I have for ignition in my T-bucket.)

Roger

Author:  Dart270 [ Mon Dec 31, 2018 4:52 am ]
Post subject:  Re: Differences between 170 and 225 distributors?

Hi TylerW,

Welcome to the site! Looks like you have a cool stock of Mopars.

I would bet the advance curves are different, but I have no idea if you can look up the advance curve, springs, vac can, etc. Most 225 distributors from that era did not have a great curve anyway, so perhaps the best way would be to use a dialback timing light to map the curve that is in there, then adjust from there. I am with you that the huge number of failures of HEI swaps/ECUs has kept me from changing to that system. I have mostly used factory electronic distributors from the mid-late 70s 225 applications and then recurved from there as necessary. I combine these with a MSD or other box. I have also used a Pertronix points conversion setup on a points dist and it has been perfectly reliable.

You are right that points cannot be beat for simplicity and in a stock application they last a long time.

Happy building and cruising!

Lou

Author:  TylerW [ Wed Jan 02, 2019 2:38 pm ]
Post subject:  Re: Differences between 170 and 225 distributors?

Thanks....I'll get a light on it at some point and see what the curve is like.

Author:  halfafish [ Thu Jan 03, 2019 11:16 am ]
Post subject:  Re: Differences between 170 and 225 distributors?

If you decide to recurve your distributor, there is a good explanation by DusterIdiot in the articles section on how to do so.

Author:  Tim Keith [ Fri Jan 04, 2019 9:57 pm ]
Post subject:  Re: Differences between 170 and 225 distributors?

You're Tyler's Neighborhood Garage on Youtube. "Rebuilding old Mopar parts on rainy days"

I generally like your cars better than Tyler Hoovie's, or rather - I might own your cars.

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