Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Fri Feb 17, 2012 10:08 pm Post subject: Hand brake and timing questions
I got a good bit accomplished today, but have a couple of questions.
1)I cleaned and gapped my plugs, adjusted the idle, adjusted my points, and adjusted my timing (using a timing light adaoter and light) to 5 deg BTDC. Before I adjusted it, it was around 10 - 15 deg BTDC (I would guess). Trouble is, it ran a LOT smoother and had more power before I adjusted it. How can this be?
2)I installed my hand brake parts on the drum. The lever, pads and stop are all new. I pulled the rod (that connects the hand brake handle to the lever) off of my parts Jeep and cleaned/painted it. When I hooked it up to the handle, it is about 1" from the brake pad lever. Is there that much adjustment for the pads, or is my rod too short/broken off? It kind of looked like it might have been broken off.
1-Factory ignition timing settings were a compromise to allow easy starting, prevent pre-ignition or pinging and attain a reasonable amount of power. The grade of fuel played an important part as well. Since the battlefield would normally mean less then perfect fuel with an often low octane rating this required a bit of retarding of the spark.
Now today we have 87 and higher gas, 24 volt electrical systems and less complicated surroundings to run the truck in. The higher 87 octane over the original minimum rating of 63 alone allows us to advance about 4 or 5 more degrees. You still must avoid slow turning of the starter caused by excessive advance timing which results in overheating of the starter and shortened starter life. So 9 or 10 Deg BTDC is not an unrealistic modern setting. The slowing down of the starter occurs when the mixture is ignited in the cylinder earlier causing the piston's upward movement to meet extra resistance from the earlier ignition of the mixture.
Today we have variable spark timing controlled by our computers so the spark is often at or past TDC during start up and then quickly adjusted for smoothness, economy and power.
2-Yes, it is possible your rod may be a bit short. The A1 hand brake always suffered from rapid wear of it's linkages. This resulted in many different methods of eliminating slop and rattle. Added tension springs, added bushings in elongated holes and shortened rods or links. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Fri Feb 17, 2012 10:51 pm Post subject:
Well that's good to know - she ran much better before. I guess I'll put her back where she was (I had it set there by ear/guesstimating!).
Yeah, I had another rod that I bought years ago - it sat around on the workbench for the past 5 years. Now that I need it, I can't find it anywhere - ain't that always the way it goes! If anybody has one that they could measure (so that I could compare) - just the rod, without the yoke. I would appreciate it.
Joined: May 14, 2009 Posts: 972 Location: South Dakota
Posted: Sat Feb 18, 2012 7:03 am Post subject:
The faster the idle, the more advanced it will be. A old "field" rule of thumb is to adjust the distributor for fastest idle, and then back it off 100 RPM. It will be close to right on. Like Wes said, if it fights against the starter while cranking, you are too far advanced. John
Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Sat Feb 18, 2012 8:28 am Post subject:
That's pretty much what I did before I got the timing light out - it ran much smoother with better throttle response then. I'll reset it tomorrow. I'm going to borrow a compression gauge today from my father-in-law to check that. I'm also going to check the vacuum and fuel pressure. I have a suspicion that I have a sticking valve by the sound of the engine.
About the hand brake rod - I'm thinking about making my own if anyone has the length. It seems like a pretty simple job since I have the "special parts" (yoke and spring) already. Just have to pick up some rod.
Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Sat Feb 18, 2012 5:50 pm Post subject:
OK, I re-timed the engine "by ear", and it is running much better now. After she warmed up I did a compression test twice. The readings the secong time are (1-4): 137, 77, 125, 130. When I had the head off before I re-sealed the engine, I thought the #3 cylinder had the stuck exhaust valve, but I guess it was #2! I am guessing that is the problem - intermittant sticking.
I did a vacuum test, but I didn't have a fitting that would fit the manifold plug, so I hooked the guage up to the hose at the fuel pump. According to my readings, that is completely wrong! I had a very erratic reading when cold (jumping quickly between 2 and 12"). When she warmed up it was a little more steady, jumping between 9 and 10"). When held at about 1200-1300rpm she held at 11". I know these numbers are very low according to the manual, and am guessing that the PCV system and all of the line up to the manifold had a lot to do with it. So, the manifold says to remove the 1/4" pipe plug from the manifold - that would be the one on the left side of the 'T', correct? And leave the steel line on the right connected? I removed the steel line to start with and couldn't find a fitting to adapt the vacuum guage. How do you remove the pipe plug? I didn't see any flats on it.
Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Sat Feb 18, 2012 5:59 pm Post subject:
I forgot to mention that the plugs were black and sooty - that means she was running rich - would that be because of the timing?
Also, I measured the hand brake rod out at 9/32" - do they even sell that anymore? Of course I have a 6' piece of 1/4" already laying around. I might pull the yoke off and see if I can thread the rod for the yoke, but my guess is that the threads won't be deep enough.
Matt
Last edited by wilfreeman on Sat Feb 18, 2012 10:02 pm; edited 1 time in total
Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Sat Feb 18, 2012 10:01 pm Post subject:
I don't think it stays open, I think it is sticking a little. It runs pretty rough until it gets warm, then smooths out. When I was originally timing the engine (checking TDC with the plugs out), the valve looked like it was opening and closing - but I'm not sure if it was completely closing or sticking. I'm going to check the valve adjustment when I can get a side cover gasket - hopefully that's all that it is.
Wes, I am not sure about where to connect the vacuum gauge. Is it on the left side of the tee under the carb, or one of the pipe plugs beside the carb?
A sticking valve will not only refuse to close occasionally it will also refuse to open occasionally. The added stress this causes on the valve train is not a good thing. Sticky valves if repaired as soon as they act up are often fairly inexpensive repairs. Those allowed to hammer the valve train to death will cost more in parts like cam followers, bent valve stems and worn out cam lobes.
If you look closely at your TM 9-8012 page 80 you'll see the illustration and read the directions for correctly attaching and using the vacuum gauge. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Sat Feb 18, 2012 10:34 pm Post subject:
True-true. I'll have to get that side cover gasket ordered and check the valve adjustment to rule that out ASAP!
I figured out where to hook it up by looking at p104 in TM9-8014 and then looking at p43 of TM9-8015-1(for a clear picture of the area. So I take the plug out and attach the gauge for plain old manifold vacuum - got it!
Adjusting valve lash does not solve the sticking valve issue. That hard to open valve will cause you a lot of grief the longer you let it lie there un-repaired.
You guys should post your model jeep with your signature element so we always know what model we are discussing.
The M38A1 connection is the plug in rear side of manifold vacuum "T" just below the carb and is easy to connect to.
Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Sun Feb 19, 2012 10:38 am Post subject:
I am not sure about the valve adjustment - maybe it's not even sticking. I feel that I should check the valve adjustment before I assume the valve is sticking. I just assumed the valve was sticking according to the 77psi on the #2 cylinder that I got with the compression check. I remain hopeful that it is only a minor problem this time - even though she is fighting me all the way!
Yeah, I realized that I didn't specify the vehicle after I made my last post. So I was thinking the right area to start with - so how do you get the plug out of the "T"? It didn't look like it had any flats on it like a pipe plug - is it an internal allen socket?
To my defense (for seeming like I'm not reading the manuals), the photos (in the downloaded copy and my printed copy I bought years ago) are very dark, so you can't really see any details. I read the descriptions, but not being able to see where the arrow goes or where the A,B, etc are are of no help to me - that's why I am on here asking for help. I consider myself to be of at least average mechanical ability, if not above. I just want to be sure of something to make sure I am doing it correctly so that I don't mess something up or cost myself unnecessary time and money.
I'll go try to figure out the signature thing right now.
Matt
M38a1 (x2), M416 trailer, M100 trailer, M101a1 trailer
There now we will always know what model jeep you have.
The valve should have about .014 clearance when closed. If the valve appears to be in the closed position and you have a gap between the valve stem and the adjuster then the valve is free to close. If it still leaks then the valve is not seating or the seat is loose or cracked. Adjusting the valve clearance will not solve this issue.
So put simply, put that piston TDC on compression, open the side valve cover and jiggle that exhaust valve. If it is loose and has a gap then the problem is in the valve, guide or seat and not the adjustment. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Sun Feb 19, 2012 11:37 am Post subject:
Yep - that's my plan as soon as I can get another side and valve cover gasket - check the valves.
I typed the signature in my post - couldn't figure it out in the profile, so I asked the question about the signature and avatar. I think I tried it before with the same results, but didn't have time to play with it that day. It's rainy and chilly today, so I guess I'll stay in the house and play on the computer instead of playing with the 'a1.
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