Posted by Bob Fetters on May 19, 1998 at 01:36:44:
In Reply to: 231 Tuning Questions posted by Henry Jacobs on April 24, 1998 at 00:20:31:
Henry, My own experience was first with the stock 230 in my M37. Then with its 265 industrial replacement. Back in 1962 when I bought my M37, regular gas allowed 14 to 16 degrees advance on both engines. I am at 6000 feet in elevation and 4 wheeled to near 12,000. The best advance was about 12 degrees for driving around on the flat at 6000 ft. I did find my brother-in-law was much slower with his M37 but he was running 2 degrees after TDC. I finally sacrificed highway speed for better hill climbing and went to 6 degrees before TDC. Current gas still works OK at 6 degrees. When I installed the 265 in 1968, I had a full balance job done on the engine. On the flat the truck will get to 70 MPH at about 3500 RPM (24volt sun tach.) As the highway grades increase, the speed comes down due to horsepower. I have turned the engine to 7000 briefly under load while in lower gears trying to get unmired. I do not know the exact number of miles I have put on the truck since I put in the 265, but after 30 years, I am having the engine rebuilt. The bearings showed little wear. The cylinder walls were worn only slightly but the rings were worn enough to cause considerable oil consumption. I did not pull the sodium valves to check wear, but the side play seemed minimal. I will know more next week when my motor shop is finished. Properly set up, these engines will run and run well. Back about 1975 my brother-in-law had his 230 balanced before we put it back together. It is still running like a top and sees nearly daily service. (Best timing setup is usually by vacume unless you have a radical cam or are striving for quicker acceleration or low RPM torque.) BOB