The PT Boat Forum

Forum Category: PT Boats of WWII

Forum Name: PT Boats - General

Topic: Needed 4M-2500 blueprints

Anyone know where they are hiding ?

Specifically, I'd like to know the diametral pitch of all gears used in the construction of the 4M-2500 Packard marine engine.

Thanks for any help!

Posted By: magneto | Posted on: May 26, 2011 - 7:44pm
Total Posts: | Joined: Unregistered

The Operating Manual (TM55-1010) for the 4M2500 is available from PT Boats, Inc as part of a collection on CD. However, while it contains a number of constructional drawings, the only one with any kind of quantitative information related to gearing is this illustration:

Al Ross

Posted By: alross2 | Posted on: May 29, 2011 - 12:55pm
Total Posts: 919 | Joined: Oct 30, 2006 - 8:19pm

There is actually a slightly better set of engineering drawings on pages 111-112 figs. 106-108 in restricted operating manual Packard marine engine model 4M 2500 types W7 through W16 or corresponding W7 through W10 plus others.(small manual 5 1/2" x 8 1/4") There is a good photograph of timing gear train in the maintenance manual TM 55-1011 section I page I-1 Perhaps someone at Packard motorcars international has some original prints

Posted By: rcr | Posted on: May 29, 2011 - 7:41pm
Total Posts: | Joined: Unregistered

I think I have seen a drawing of the supercharger drive train somewhere. We had to replace our center engine supercharger drive shaft ~2 years ago when it snapped during a backfire during startup. It was due to a sticking carburetor. Anyway the 1 inch steel drive shaft was twisted and snapped like a twig. I will look around and see if I can find the drawing. I think there are 3 gears involved in the drive of the supercharger fan. Are you even interested in this? Jerry PT658 Portland, OR

Jerry Gilmartin

Posted By: Jerry Gilmartin | Posted on: May 29, 2011 - 8:07pm
Total Posts: 1288 | Joined: Oct 8, 2006 - 11:16pm