Timing How to?

[cstaup]

How do y'all time yer truck? As the wires don't allow any EMP in they don't let any EMP out. What wire do you use to get the inductive sensor to work on a normal timing light?

[raymond]

Couple of different ways. You can get the military timing light adapter that screws into the end of the spark plug cable and into the spark plug. You can also take an old spark plug wire and strip some of the metal insulation, this allows the pickup to sense the spark. You can also take a length of wire core spark plug wire and cut off both ends, shove one end into the distributor, and the other end down into the spark plug. It will work well enough for timing the engine. If using a 12 volt timing light, remember to hook it up to the positive and negative of just one battery or you will be getting 24 volts and buying a new timing light. If you light has advance on it, remember to set the advance for "0".

[rickf]

Everything Raymond said plus a little note, I use a set of jumper cables from one of my cars to power the timing light.

Rick

[ldj1002]

You can time it using a vacuum gauge.

[cstaup]

I have a few old plug wires around, I'll do what Raymond said. In the meantime, I did Rick's two finger timing adjustment (or 1.5 fingers).

[rickf]

Ah yes, the two finger method. Gets her, er...... it started every time. A vacuum gauge will get you close on a V8 but these four bangers with their very low compression will not give a stable enough reading to time it by. I have found that the "by ear" method also not to be very accurate, and I have a good ear for engine change.

Rick

[halftracknut]

I need to throw my 2 cents in here...these jeeps need all the vacuum they can get for the carb to run correctly...

[Ralph Fuller]

Rick: When you say "two finger timing" are you talking about the distance between the oil filter and distributor (circled)?

[rickf]

Sir, YES SIR!

That is just a rough, get it started deal.


Rick

[armybuck041]

I have found that the "by ear" method also not to be very accurate

Isn't that the truth. Last time I tried setting it that way I was shocked at how far out it was when I installed a Timing Light.

That being said, I think a Tach is as important as a Timing Light to do this properly.

I had an issue where I ran out of adjustment in the Distributor before I could get the Timing Marks aligned. Turned out to be that my Idle was too high and was causing some Spark advance. Once I got the Idle down to within specs, I ended up getting the Timing sorted out. It was really a bit of finessing to get both where they needed to be. All things being equal, i'd rather tune this thing up than an M38A1 any day of the week. Zenith or not. Plus it seems to hold its tune much longer, and you can't even compare the Valve Adjustment either. Way easier with the 151.

Scotty

[rickf]

Timing is a big factor in the way these things run, any vehicle actually but 151's are very obvious when things are off. 2 degrees advanced or retarded will make a big difference. You gu6ys with points keep in mind that as the point setting changes it also changes the timing. A little white lithium grease on the rubbing block will make your points setting stay set for much longer. Scotty is right about the idle speed, it has to be low. You cannot go to low but if it is above around 700 rpm then the timing will start to advance. If you hood vibrates then it is too high. Any mutt guy will know what I am talking about.


Rick

[ldj1002]

rickf,
I don't even own a timing light. I time all my vehicles with a vacuum gauge. They all run good including my M151. You said "these four bangers with their very low compression will not give a stable enough reading to time it by". If you don't get a steady reading, you have another problem. The vacuum gauge when testing my Mutt is just as steady as can be. If that gauge fluctuates, it is telling you something is wrong. Now I will agree that if that gauge is not steady because of other problems, you may not get the timing just right. In this case it still will not run right even if you use a timing light. Like was mentioned with rpm too high you will not get proper timing with timing light.

[rickf]

You don't own a timing light huh. I guess none of your vehicles have a high lift long duration cam. I have been a certified master mechanic for almost 40 years and I can get most vehicles very close by ear or a vacuum gauge. I can tell you that if the timing is dead on after timing it with a vacuum gauge then it is only by luck. Try timing a big block Chevy with a 312 duration, 505 lift cam with a vacuum gauge. Then tell me there is a problem with the engine because there is 12 inches of fluctuating vacuum at idle. If you have no timing light then how do you set total advance to 38 degrees at 6000 rpm on said engine? My 151 will outrun most other 151's and I have done nothing to it. Ask anyone who was at Aberdeen two years ago if you do not believe me. The reason is because I had everything set dead on to spec.. With a timing light.
Hey, It's your cat, make it scratch. You will not hurt anything by having the timing off.

[ldj1002]

You are correct, none of my engines do or ever had one with a high lift cam. I was aware you can't time an engine with a high lift cam by using a vacuum gauge. However, when you read the vacuum gauge in a car with such a cam it shows something wrong. My SOL bought a big block 440 with high lift cam an he wanted me to see if I could check timing with vacuum gauge. I couldn't understand the reading I was getting and then I read up and found out about the timing with vacuum gauge on engine with high lift cam, it just don't work. I'm not sure it will work on the cars with computer control either because I have never worked on a vehicle with computer, oh well, very little when they came out. I have worked on car engines only as a hobby and on vehicles from 20's to 70's.

[Francis Marion]

My manual says to connect the tachometer to ground and the "Primary Connector." My distributor cap has a simulated nut molded into it and no hole like the one shown in the manual for the primary connector. Where else can I connect a tachometer to measure RPMs?