Do I Have A 6.6 Or 7.6 Engine.
Posted December 20, 2012 - 11:32 AM
I ask for clarification as this serial number is very near the cusp of the switch to the 7.6 engine, and there are some differences in valve adjustment (.012 vs. .015) and magneto timing procedures and plug gap (though I have the large 7/8" thread size).
Any comments? Is this a 7.6 that has had the head changed or is it a 6.6??
Posted December 20, 2012 - 12:38 PM
Posted December 20, 2012 - 01:29 PM
L81966, WELCOME TO GTTalk!! Great to have another Gravely guy on here. I think it is generally recognized that Gravely continued to use old stock even though "officially" production of the new engines started in 1966 (or whenever). Also, unless you've had that tractor since it was new, things could have easily been updated. I know Gravely was very keen to try and have tractors updated whenever they came in for service, so things like the oil filter could easily have been done by the dealer. The carburetor seems less likely to have been changed, so that plus air filter location argues more for a 7.6 configuration, the head certainly argues against it.
One change that is often overlooked it the cylinder jug was reworked slightly. I don't know how to tell you exactly what the difference is, but the threaded section where the head bolts go was beefed up somewhat.
Post some pictures of all this stuff and let's see if anything else comes to mind. (Besides, you HAVE to post pics. Its in the contract you signed when you joined up LOL)
Posted December 20, 2012 - 01:34 PM
1963 M-90897 14738 2M4745 L, LI, LS, L8
1964 2M4745 2M18900 H
1965 2M18900 I – 11552 I Large Bearings
1965 2M34215 I – 11553 Small Bearings
1966 2M34216 J-7600 J 6.6
1967 J-7600 J-23680 C, CI, CS, C8 7.6 HP
Posted December 21, 2012 - 02:50 PM