I have the base timing set at 5 BTDC Im looking for a mechanical advance setting. I have the mechanical advance set at 18 degrees so with the 5 degrees base and the 18 mechanical I'm at 23 BTDC total advance but I've read that these old AMC's need a lot of timing advance I've read a total of 40 plus degrees on some but that sounds a little much thanks for the help sorry you mis understood me
Good for you getting your advance curve plotted and fixed.
I feel the initial advance will be in the 3-6 range in general. The total advance will be in the 30-35 range. Can be more but the engine has to be healthy and you take a change of doing damage. If you have a gen use jeep..... 4 wheeling, tails, maybe a trailer full of wood sometime.... then the vac advance is what is gong to work with engine.... under load the Vac Advance gets minimized, then on the hwy cruise you vac level is up/ carb throttle plats mostly closed, and there is a fair amount of advance and will give good economy.
So the guys asking for the distributor type, yes should be looking.
The next resource is the Jeep Field Service Manuals have the advance curves for the 16 and V8. There also vary by Cj light or Full Size Jeeps heavy. So look at the correct manual/auto, the CJ... you get the idea.
I ploted and matched the Jeep FSM curve, never get a rattle , no dead spots on throttle.... just runs great.
Some of the guys saying 10-12-16 sometimes for initial advance have a
Limited DuraSpark Distributor with a small 3 deg mech limit slot... Just screws it all up... And having all that adv in there 100% time is not a good idea.
I think I am at 5 initial no on a
Will need a vac guage, time light w/ advance is handy.... carefull Jeep Hammer said the fancy ones do not always work. Use the balance tape on the first go around and see if you similar reading on balance tape and time light advance indication.
There is also a caution the time lights are set up for a V8... use them on I6 or 4 bangers and there can be some pretty big errors. Got think about this for a bit... faily complex.. Neighbor bud has older nice snap on and I have the Actron.... so I called product management... they did not have ans so... I guess we can thinnk on this one.
Gotta take a look a the FSM advance curves.. I know i have the I6 scanned but not sure of the V8 so take a look.
Your assumption was correct...... Too Much ADVANCE make the engine run hot... your plugs will be white .... The way to think of it the flame and heat of combustion is in the cylinder longer with more advance. The heat has time to soak the cylinder with heat and get hoter. Get rid of combustion sooner and will run cooler. Also too much advacne will get piston knock and its pushed back too soon. Not good. Also too much advance, lean, hot ... can be a second kind of detonation where the heat sets off the fuel early before the spark plug even fires off.
The SPARK PLUG STRAP.... can give you some great info. Do you know how to read your spark plugs? I have a few very good links some where. The ground strap is a good indicaiton of heat/ proper operation temp.... The ground strap will have a temp line somewhere in the middle 1/3 of strap. Cold the line moves to the threads or at threads almost.... Hot moves heat line on strap more to the or closer to the center electrode.
I think 2500 all in is too early for V8....did not look yet... but these rev higher. The I6 if healthy can have all the mech advance come in at 2500 because 3500 is screeming pretty good for
AMC 258 i6 / 4.2l . My
AMC 258 i6 / 4.2l will hit 4500 pretty easy and know that is red line area. V8 shoudl be about 5500 maybe 6k red line.
Find the advance curve
JeepHammer has some nice write ups on this if you search some.
Good luck,
FRed
