Timing Advance?

[VAJeepGeek]

Well, after the rebuild the engine was running like junk. Replaced the power valve and checked the timing... a whopping 38*!!! :eek:

Now the accelerator pump is new, the power valve is new, and the timing is at 10*. Much better but I still have a slight bobble when accelarating. How high should I go with the advance, safetly? What are you guys running on yours?

Thanks,

[porchpiggy]

I was checking some of the different years, and if i remember right some when as high as 13*. I think you could advance a little more and see if you get pre ignition ping. Another idea would be to adjust/play with your advance. Maybe if it came on a little faster you could stay at 10*. I run about 9* on a 88 GW with desmog, ed 1406 and intake without EGR, stock cam. At 10 or 11* mine pings when warm.

[letank]

12 is what i have for the 85....

but it should not run like crap.... if yu are in the 5' you will have less power.

if no acceleration... the power valve or the enrichement valve. Of course if you are overly lean... that would do the same... How much manifold vaccum ?

Michel
74 wag
85 wag

Michel

[kidatforty]

With 36 deg. total advance you should end up with around 12 deg. btdc. that's the max you should go. Like porchp.says if it pings, back it down.

[oddfire]

Not so, I'm running 19* with no problems. Timing is a problem with many answers. What kind of modifications have been done, what alttitude are you at, ect. 10* is a good place to start, advance it to 14* and go for a ride, preferably up a steep hill with your foot hard on the petal, as Kid says if it pings back off, if its hard to start back off. If the motor is a rebuild throw away the factory specs and go for a ride with your timing lite, distributor wrench, plug for vacuum line and a vacuum gauge if you got one. Play around with it till you get a good medium, you'll know when its right........phil

[timmirvin]

Same thing happened to me after rebuild. And did just what phil suggested. It worked great except for one thing, so thought I would throw this out for everyone to mull over.

I noticed I had about a 4 to 4.5 degree range that vacuum, power, and economy stayed generally the same (6-10.5 degrees). But engine temp varied. Never had this happen before with any other engine. Used engine temp to find my sweet spot (tad over 8 degrees).

Has this happened to anyone else?? Or is this a symptom of another problem, maybe??

Thanx....
tim

[oddfire]

Timing on these old rigs is really more of a game than it is a science. When I read a post where someone is having trouble with his 74 wag with 240,000 miles on it and it doesn't run good at 8*, I just wish I could be there to show them how really easy it can be {providing there are no carb problems}to get the motor dialed in. Don't be afraid to experement, Like I said before, load up everything you need to set the timing and go for a ride. Mark where the timing was set at first so you have a reference point. A vacuum guage is really the way to dail it smooth. Do to my altitude and the oxygenated fuels used here in the winter, I have to retime for both summer and winter, and it usually is a coulpa hour process to get it right, but my 78 wag runs best at *15, my 76 cherokee runs best at *19 and my 71 cj likes *14, and none of these are factory specs. I'm not saying that there is no limit, but for the most power you can get, advance as far as you can and back off a coupla degrees. Timmervin, I dont know what kind of mods your engine has, but it sounds like you found the secret to yours, my heavely built 401 took a bit to dial in, it is a daily driver and runs like a top with over 150,000 on the clock....phil

[Smooshy]

Mine is at about 15, runs ok with a worn timing chain :(

[timmirvin]

Yeah, never had an engine with as wide a sweet spot as this 360 I have now, really like that.

But what I was wondering was if anyone had seen the temp variance within that range. As I stated before, I have a 4.5 degree range that power, vacuum, and power are equal, as far as I can tell. But temp seems to be real touchy. Meaning it will jump about 5'F per degree each way from 8'BTDC (@6'BTDC+10'F, @10.5+10'F).

Was just wondering if anyone had experienced this????????

Oh, and 360 is pretty close to stock: slight cam, forged pistons, little shave on head...only slightly more compression than stock......got it written down somewhere. "Harley" is a daily driver and trip taker, didn't want to do too much to him......

But sure would like to know if anyone else has seen this.......

tim

[VAJeepGeek]

Thanks for all the great responses...
I was worried about going too high because of heat. Mainly becuase of the performance cam and 360 heads I'm running. I'd rather not cook the internals. smile.gif Today I'll start playing with the timing and just get it through trial and error..

Thanks again! :D