Vintage MOPAR pistons available

[austinsailor]

I have a friend with a machine shop, he does much of the older engine work around here. He has a stack of pistons he asked if I could find buyers for, and I'm guessing some can be used by people here.

I posted a chart of what he has here:

http://austinsailor.net/parts/PISTONLIST.html

Mainly 33-41 plymouth and some dodge truck/desoto 3 3/8 sets. Includes the pins, no rings. new in the box, (pretty dusty boxes!) at $100 a set. I'm buying one 3 3/8 set as soon as I take the head off my 48 Desoto block and see how much it needs to be bored.

Feel free to email me with questions or for pictures or measurements or whatever you need.

austin.sailor@yahoo.com

Thanks,

Gene

[austinsailor]

Well, I learned something this week. A person on this board wanted a set of the 3 3/8 pistons for his Canadian Dodge, which has 3 3/8 bore. As a check, I measured the piston pin diameter and the distance from the pin to the top, fully expecting them to match. Surprise - they are not the same. I guess the Canadian version used a different rod length.

Now, I'm not so sure they'll fit my Fargo, either. I guess I need to tear it down to see. I may not be able to use a set either. Bummer.

[Merle Coggins]

Are you sure they're for a Mopar engine? I recall talking with the guy that did my engine machine work. He was telling me that back in the day they used to use Continental pistons in Chrysler engines (or vice-verse) since they were very similar. In some cases I believe he mentioned some performance increases. I suppose a different pin height would effect the combustion chamber size.

Merle

[austinsailor]

No doubt they are mopar. They are correct for the motors I have, We're re-measuring at both ends to make sure we haven't made a mistake. I'm measuring in inches, he in MM, but it seems different. I don't know if specs at this level are available anywhere.

If I had time, I'd tear down my Fargo to see how it matches up, but that won't be soon.

[Kevinb71]

Here is a link to a SilvoLite webpage that has some piston specs. There is also a continental page just google "Silvolite Continental"

Hope this helps.

http://webpages.charter.net/beckracing/slvpg36.htm

[austinsailor]

And I think it may be me. The charts show about what the fellow with the Canadian dodge measured on his old pistons, not what I did on the new ones. I need to re-check, maybe have the machinist look over my shoulder, and maybe use his calipers, not mine!

More info to come.

[austinsailor]

Well, you learn something new every day.

I went in this morning and re-measured the pistons. My numbers were correct, so I asked the fellow who owns the shop to help me understand what I was missing.

Turns out, the compression height will vary by manufacturer, and other things. He said that the height will often be higher on replacement pistons, and there was a good reason, but he didn't recall just what it was. Anyone know?

And, having a .020 higher piston won't be a problem, as the head gasket is .075, so all you'll get is a bit more compression. More compression is not a bad thing.

Thanks to Kevinb71 for the link to the piston chart, that helped a bunch.

[Kevinb71]

Glad it helped. Good luck with the project.

[Roadkingcoupe]

So Austinsailor and myself have been trading info and comparing 3 3/8" pistons from the US 1934-1942 Desoto (also used on 34-41 US Dodges).

The Canadian 25" block cars use the same size piston (3 3/8") HOWEVER the two pistons use different rings???

US PISTONS

3 3/8" pistons use

12 - 1/8" rings for the top two rings

12 - 5/32" rings for the bottom two rings

Canadian Pistons

3 3/8" Pistons use

12 - 3/32" rings for the top two rings

12 - 5/32" rings for the bottom two rings

Would anyone on the forum have any input as to why the pistons (when fitted with the correct size rings) could not be used in either the US or Canadian 25" block motors with a 3 3/32" bore?

hope that makes sense?

Edited March 13, 2011 by Roadkingcoupe