M37 timing

[Kaiser2boy]

Finally got her up on all four wheels and street llegal with plates and all.
The truck starts very well and accelerates fairly well once warm but seems very flat in fourth gear. The engine runs smooth at all speeds and idle. No putting or missing or odd thumping like a dead or weak cylinder.
I checked the timing and it looks like it is right on TDC. It is hard to be exact due to the angle of the pointer.
I looked on a good web site that has an M37 manual in PDF form. It said to set it at no more than 2 degrees BTDC. with over 70 octaine gas
The degree markings on the pully has 00 in the center and a bunch of fine marks then 010.
I figure the 00 is zero . My stupid question is , is the 010 ten degrees before or after TDC. If that is so then each super tiny line is then one degree?
What happens if I move it to 5 degrees BTDC? Blow up time.
If anyone is wondering if the truck has a governor , it does. I have backed out the stem on the governor to the max. to try and see if that was the problem , it is not.
The next question is how the heck do you get your hand down next to the distibuter to loosen the ajustment nut.

[Kaiser2boy]

OK My bad. I searched the site and found part of my answer in old posts. I still have to figure how to get my aged semi flexible hand down to the lock nut.

4 degrees BTDC and test drive.

[Kaiser2boy]

OK My bad. I searched the site and found part of my answer in old posts. I still have to figure how to get my aged semi flexible hand down to the lock nut.

4 degrees BTDC and test drive.

Oh I see all I needed to do was get under the truck and remove the left splash pan.
I turned the timing up to about 4 or 5 degrees BTDC and it now runs better but still takes a very long time to run without stumbling.

[Charles Talbert]

4* BTDC is the optimum timing set. Sounds like you messed up the governor setting, most likely the reason for flat performance in 4th gear. You need to set it to a max RPM around 3,300, (if you have a healthy engine), then from that point fine tune the governor for max performance. You will need to go into the governor housing to set a proper default spring setting, from there it is relatively simple to set up for optimum RPM and performance. I can talk you through the procedure if you need help.

[Kaiser2boy]

4* BTDC is the optimum timing set. Sounds like you messed up the governor setting, most likely the reason for flat performance in 4th gear. You need to set it to a max RPM around 3,300, (if you have a healthy engine), then from that point fine tune the governor for max performance. You will need to go into the governor housing to set a proper default spring setting, from there it is relatively simple to set up for optimum RPM and performance. I can talk you through the procedure if you need help.

Thank you , I thought backing out the stem on the gov. would be enough. Sounds like I guessed wrong.
I have tried to find info on how to do it right with no luck. Looking at the gov. it seemd to be the only adjustment. I did look inside to try and figure out how it works with not much luck.
A walk through would be greatly appreciated.

[jjefferson]

K2boy-
Charles will steer you right. What we would do with out him I do not know. Often curious how he has time to run MSeries with the amount of posts and questions he replies to. Go Charles go.

If you want a paper copy of the gov and carb rebuild articles I have them someplace on my computer - if you want I can email you a copy.

Jim

[Charles Talbert]

Thank you , I thought backing out the stem on the gov. would be enough. Sounds like I guessed wrong.
I have tried to find info on how to do it right with no luck. Looking at the gov. it seemd to be the only adjustment. I did look inside to try and figure out how it works with not much luck.
A walk through would be greatly appreciated.

**DISCLAIMER**
Ok, before I proceed, let me say this, the condition of your engine needs to be able to stand a correct adjustment. What I'm stressing here is if you have a loose rod bearing or other component, the higher RPM rate of a correct adjustment could cause a problem. A healthy engine will be just fine and will perform better than you ever thought possible, just remember though that you are proceeding at your own risk. No way I can diagnose issues with the health of your engine, you are on your own here, I'm simply outlining a proper governor set up procedure after being asked to do so.

Needed tools: An assistant, a hand held electronic or mechanical tachometer, and a timing light, nut adjustment tool, (covered in the next paragraph), and screw driver. A 4"-5" vernier caliper also makes screw measurement easier and more accurate. If using a mechanical tach, (a Stuart-Warner hand held is reasonably priced at NAPA), disconnect the intermediate drive shaft from the transmission output shaft, place the transmission in 4th gear and take the RPM reading off the trans output shaft, it has a good center on which to hold the rubber tip on the tach drive shaft. It is a 1to1 straight through drive in 4th gear. Have your assistant operate the tach.

First off, the spring default setting should be verified. Remove the governor housing cover and the adjusting screw access plug, if your carb needs a cleaning and rebuild, this is the perfect time. Notice the coil spring that is threaded onto the governor screw, pull tension on the linkage to stretch the spring. Measure the length of the adjusting screw from the bottom end that is threaded into the spring to the flat at the top of the housing opening. The screw length inside the housing should measure 1 13/32", adjust the screw in or out to obtain this exact measurement. The spring default setting is 9 active coils, when the spring is stretched or extended, count the # of coils that are being stretched, (do not count the coils that are threaded onto the adjusting screw as these are not active.) There should be 9 active coils in your count. If adjustment is required to achieve the correct coil count, do so by running the screw into or out of the spring. If coil count adjustment is necessary, you will also have to go back and readjust the screw length to obtain the measurement explained earlier. To do this, adjustment of the slotted nut in the screw opening will be necessary to lower or raise the length of the main adjusting screw that is actually inside the housing opening. (A suitable nut adjusting tool is a nut driver with a hollow shaft. Grind the end to create tangs that engage the nut slots. The hollow shaft allows the main adjustment screw to pass into the bore of the shaft while it engages the nut slots.) Working all the aforementioned adjustments in unison will bring about the proper adjustment of screw length and # of active spring coils. Be sure everything is moving freely as designed and that no binding of any kind is taking place. Take the time to get this right, if these adjustments are not on the mark, you will never get where you need to be. When right, close up the housing and reinstall all parts and linkages so the engine can be started.

Check the engine intake vacuum and ignition timing, warm engine to normal operating temp, set the timing to 4* BTDC, vacuum at the manifold should be at least 16 inches at full throttle with the governor operating, (3,200 RPM). Should be at least 17 inches at idling speed, (650 RPM). Check the RPM's at full throttle using a suitable tachometer, if the governor kicks out at above 3,200,turn the main adjustment screw clockwise to decrease the static RPM's, half round turn increments works well to establish correct high RPM. If your initial RPM check is less than 3,200, turn the screw counter-clockwise in half round increments to increase the static RPM's. The objective is to get the governor to cut the RPM rate at or very close to 3,200. When the throttle is held momentarilly wide open, your tach should read 3,200. To get a better mental picture of what you are actually doing here, picture this, the more active coils on the spring you adjusted in step #!, the higher the RPM's will go before being cut by the governor, less active coils, lesser RPM rate. Once you have it cutting out at 3,200, not in every case, but more often than not you will get a throttle surge (rapid rise and fall of engine RPM's as if you were pressing down and letting off the accelerator in a consistant rhythm) when the throttle is held in the wide open position. If this occurs, here is how to correct, look down inside the screw opening, you will see a slotted nut, (the main adjusting screw runs into the center of this nut). The nut is threaded into the housing and turning this nut moves the adjusting screw up and down without turning the main screw itself. Turn the nut 1/4th turn clockwise, then correct the change in the RPM rate by readjusting the main screw. If the surging stops, you are close, if the surging continues, proceed with nut and main screw adjustments in 1/4th turn amounts until the surge is adjusted out and a smooth 3,200 RPM is reached.

If the governor seems too flat (slow acting or the engine doesn't rev up readily and sound aggressive), you need to move the nut counter-clockwise 1/4th turn at a time correcting the RPM rate with the main screw until surge BECOMES APPARENT, then remove the surge as outlined above. The point here is to adjust the governor to the point where the surge "just is" eliminated as the peak 3,200 RPM is reached. This step is VITAL to peak performance, take your time in performing this optimum adjustment, a good engine will perform like you never dreamed possible.

Bear in mind the definition of a healthy engine, a proper functioning carburetor, fuel pump, plugs, wires, distributor, (installing electronic ignition will make a huge difference in overall performance), well seated valves and rings, good condition timing chain, sprockets, camshaft, and good compression. If other issues are in play causing lousy performance, while doing this adjustment may improve performance somewhat, don't expect great strides in progress from a correct functioning governor alone. If your engine is at or near the point of needing an overhaul, nothing else will replace the needed rebuild.

[Kaiser2boy]

Whoosh, It's a bit more complex than I thought.
Thank you very much. Now I need two things, first a tach. I think I know where I can get a mechanical one.
Second thing is I have to figure who I can talk into laying under the truck holding the tach while the engine is screaming. I think that is going to be the tricky part.

The engine runs smooth , no clattering or valve noise and has OK oil pressure so I figure it can take a few runs up the scale.
I wil get back at it when the temp gets above freezing.
Thanks again.
Alan in North Central Pa.

[Charles Talbert]

Whoosh, It's a bit more complex than I thought.
Thank you very much. Now I need two things, first a tach. I think I know where I can get a mechanical one.
Second thing is I have to figure who I can talk into laying under the truck holding the tach while the engine is screaming. I think that is going to be the tricky part.

The engine runs smooth , no clattering or valve noise and has OK oil pressure so I figure it can take a few runs up the scale.
I wil get back at it when the temp gets above freezing.
Thanks again.
Alan in North Central Pa.

Not really that complex, the post is a little lengthy, tried to explain as clearly as possible. Just take your time and cover all the bases well, it will come out good.

We have both the electronic and mechanical tachs, my personal preference for this procedure is the mechanical one. NAPA has them listed in the supply and service catalog, in the Balkamp line. We usually do this on rebuilt engines with the trans attached, of course on the test stand is easier than under the truck. On the plus side, you can tell your assistant there is no worry of the truck going anywhere with the intermediate drive shaft unhooked, just chock the wheels well and that's no issue.

From your description, sounds like your engine would stand up just fine. After the set up, it should run 55 MPH well. I'm not saying stay in the throttle at that sustained speed all the time, but it should be there when you need it without issue.

[Gordon Maney]

Thank you, Charles; I greatly appreciate your presence and contributions.

[Charles Talbert]

K2boy-
Charles will steer you right. What we would do with out him I do not know. Often curious how he has time to run MSeries with the amount of posts and questions he replies to. Go Charles go.

If you want a paper copy of the gov and carb rebuild articles I have them someplace on my computer - if you want I can email you a copy.

Jim

Not looking for a pat on the back, I just do what I can in the minimal time I have, I love to share how to do things right, never did enjoy seeing people get headed down the wrong road in any situation, trucks or otherwise. Sometimes the replies come in the form of appreciation, on occassion they don't. One thing you can always count on, I'll tell it like it is to the best of my ability while making a genuine effort to help.

Thank you Gordon for the opportunity.