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I have a recently rebuilt AMC 304 in a 75 CJ5 i bought a mallory distributor and im trying to figure out the right timing advance. Right now I have it set at 18 degrees but gets hot under higher Rpm Im trying to figure out if I should advance or retard the timing so if anyone knows where i should start please help
I have a recently rebuilt AMC 304 in a 75 CJ5 i bought a mallory distributor and im trying to figure out the right timing advance. Right now I have it set at 18 degrees but gets hot under higher Rpm Im trying to figure out if I should advance or retard the timing so if anyone knows where i should start please help
<1984 CJ-7 258ci Inline six w/Carter BBD carb(114 hp?),Warner T-5 transmission, Dana 300 transfer case, AMC Model 20 rear Axle w/trac-lock Differential and tapered shaft and 3.31 gears, Dana 30 front axle. The most stock vehicle I've ever owned.
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
<1984 CJ-7 258ci Inline six w/Carter BBD carb(114 hp?),Warner T-5 transmission, Dana 300 transfer case, AMC Model 20 rear Axle w/trac-lock Differential and tapered shaft and 3.31 gears, Dana 30 front axle. The most stock vehicle I've ever owned.
Is this timing for WOT (wide open throttle) with very low vacuum or mid throttle with high vacuum.
Have you tried removing and plugging the vacuum hose and setting the timing at 3500 RPM. If you can set up your timing light to 36 degrees BTDC your timing mark will show on the 0 mark.
36 degrees total is normal for a regular carb'd V-8's I seen as much 44. this might put your initial setting to high for a good idle so you might need to grind out the pin hole (elongate) to allow the idle setting to be closer to 10 or 12 depending on how well it idles and your throttle response time.
This just generic settings. I don't have any specific Knowledge on AMC's or AMC 304 's.
1978 CJ7
Silver paint with black hard top on 33" radials & eagle alumium rims. Good looking ride and have done lots of work to make it look and run great.
Stock equipment is 258 carb, power brakes, power steering, hard top & hard doors (per vehicle gross weight) tilt steering wheel, big brake package with large rotars & drums, T18 Trans with low 6.4 granny gear, Dana 20 transfer, Dana 30 front axle, Dana 44HD rear axle with 3.73 gears. True Trac ft & rear.
I was around jeeps in the 70's and drove a 1973 Jeep Truck. My family had 4 jeeps at the time. We also joined a jeep club back then too. So about 6 years ago looked for a Jeep CJ and found the vehicle above.
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.
1978 CJ7
Silver paint with black hard top on 33" radials & eagle alumium rims. Good looking ride and have done lots of work to make it look and run great.
Stock equipment is 258 carb, power brakes, power steering, hard top & hard doors (per vehicle gross weight) tilt steering wheel, big brake package with large rotars & drums, T18 Trans with low 6.4 granny gear, Dana 20 transfer, Dana 30 front axle, Dana 44HD rear axle with 3.73 gears. True Trac ft & rear.
I was around jeeps in the 70's and drove a 1973 Jeep Truck. My family had 4 jeeps at the time. We also joined a jeep club back then too. So about 6 years ago looked for a Jeep CJ and found the vehicle above.
