Hi all

No matter how I insert my Disti back into the block (and "rotating" leads around the disti so as to be able to start the infernal lump in the first place....), I am either too far advanced, or too far retarded to get the exact "right" BTDC (the norm according to most is somewhere around 4 to 6....).

I see the following: -
1) After = +- 8
2) Before = +- 12+

For option 1 above (and when retarding as far as possible...), I suffer from significant power loss at higher revs.

For option 2 (and when advancing as far as possible), I suffer from pinking at higher revs.

What am I missing here?!

Right now I am running at higher revs than I feel comfortable with, and pinking is in evidence - my gut feel is that I will do some damage if I continue at this rate....

 

what ,if anything, else have you done to the engine ?? with the #1 cylinder at tdc on compression stroke....the rotor should be pointing at the #1 terminal on the distributor cap.....and the timing tweaked from there. the old school method would be to keep advancing it a bit untill it starts pinging and the back it off some . I think my 3.9 is about 9-10 degrees advanced . if your plugs / wires/ cap/ rotor are worn out it will add to the ping factor.......are you using good fuel ?

 

Thanks XCELLER8

It is a '94 / '95 lump, and I am the 3rd or 4th owner, so just about anything could have been done to it in the past....

Plugs, leads, cap and rotor are all new, so that should not be the issue.

Fuel is good, and new filter fitted in the last few days.

Could there have been stretching of certain components over the years?

I think I will just see if I can fiddle while driving (old school rather than relying on a light and "probably wrong" timing marks...), and see if I can find that elusive sweet spot

Cheers

 

over time, the timing chain can wear ( as well as the cam)which is likely why most of these older 3.9's need to be advanced farther than the original specs...loosen the distributor lock down bolt just enough so that you can turn it with some resistance...start it up and go for a drive...advancing it a little bit at a time untill you get spark knock....then back it off some.
also I should have mentioned to check both the spring loaded mechanical advance, and the vac advance for proper operation, if either one is not working or binding up ...it will effect the performance