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1929 Gray Marine 6-40 6-cylinder Newb...

Old Marine Engine » Gray Marine Gas Engines - 4, 6, and 8 cylinder » 1929 Gray Marine 6-40 6-cylinder Newbie Questions « Previous Next »

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Montgomery Gisborne
New member
Username: junk_lover

Post Number: 1
Registered: 11-2016
Posted on Sunday, November 13, 2016 - 10:17 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

Hello veteran Gray Marine afficionados! I am new to this site, my reason for joining is to hopefully learn more about a complete Gray Marine motor and gearbox I recently purchased. I am very keen on this motor, which has 7-3-29 noted on the cylinder head and has 526117 1 below the date. The block has the number 526865 embossed on it and the serial number appears to be P647769. The transmission is complete, shifts through the gears nicely and the motor spins easily with the plugs removed and ATF poured down the spark plug holes.

The coverplate of the gearbox states that this is a 6-40, which I presume means that it is a 6-cylinder with a scant 40 hp rating. I presume this to be about right since I've seen larger carburettors on a modern lawn mower! The serial number on the plate reads 1840 A.

What exactly do I have? Who built the actual motor, which I presume was sourced from an auto manufacturer back in the day. If I can figure out how to post phots, I will, or I can be reached at emotive@hotmail.ca. I am located on Prince Edward Island, Canada and thank anyone and everyone who can assist me here.
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Montgomery Gisborne
New member
Username: junk_lover

Post Number: 2
Registered: 11-2016
Posted on Monday, November 14, 2016 - 08:28 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

I just checked the Gray Marine motor... I was a little off on the serial number, it is 1240 A. I also measured the bore and stroke, by my measurements it is 3 5/16" (bore) X 3 7/8" (stroke).

My calculations bring this to a displacement of just under 64 cubic inches... that's pretty small! By looking at the block one might think it was of greater volume, but the math doesn't lie. Question - If I were to try to increase horsepower by installing a larger carburettor, what are my practical limits? Realistic expectations here.

Monte
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Jim Staib
Senior Member
Username: drrot

Post Number: 212
Registered: 09-2008


Posted on Monday, November 14, 2016 - 09:35 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

Monte,
Using the formula Pi x (r2)x stroke x cylinders I come up with 196CID.
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John E Tierney
Senior Member
Username: bud_tierney

Post Number: 63
Registered: 10-2009
Posted on Sunday, November 27, 2016 - 10:56 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

If you're still looking for engine ID, a McCord gasket catalog says it's a Pontiac, and the head gasket given is listed for the 29-32 6 Cyl 35/16x37/8 (split head, 2 of 3cyl each)...
Any 0ld-Pontiac/GM site should get you all the literature/info you need...
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Jordan Heath
Member
Username: fireballing

Post Number: 8
Registered: 09-2013
Posted on Friday, February 10, 2017 - 08:54 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

Montgomery, do you still want the 1929 Gray literature you contacted me about? I had it copied for you in expectation of at least recouping the copy fees. Have not received a reply. Please let me know. Thanks, Jordan
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Jeff Rains
New member
Username: jkrojai

Post Number: 1
Registered: 11-2004
Posted on Friday, March 10, 2017 - 08:58 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

Is this last post the same Jordan that has a thing for Mercury boats?
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Tubapete
Visitor
Posted on Friday, March 10, 2017 - 06:42 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

Jordan, I have just learned that my Launch Verity, a 43 foot gentlemans day launch river boat based on the Thames at Windsor, had a Gray Marine 6 cylinder petrol engine installed in 1929, and ran with it until 2004, when it was replaced by a modern Perkins diesel. The boats original 1906 engine was a Renault Marine petrol engine. I would love a copy of the Gray engine details if you have them

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