tuning questions???

[mdwyer]

71 GTX 440 .040 static 9.25 compression, 346 heads, summit big cam, hp ehaust manifolds- h-pipe, stock avs and intake, mopar electronic dist. kit (mallory dist).

car is up and running. set base timing at 10. timing curve(question for ron) is at following.
rpm                         timing
800                           10
1100                         15.5
1400                         22
1700                         30
2000                         36 all in

car has slight detonations under 1/2 to 3/4 load. vaccum advance has not been connected.
have not look at plugs yet. just wondering if the ignition curve needs to move up and how do you do that (who's kit springs?).

thanks for all your help.

mike

[jg68]

71 GTX 440 .040 static 9.25 compression, 346 heads, summit big cam, hp ehaust manifolds- h-pipe, stock avs and intake, mopar electronic dist. kit (mallory dist).

car is up and running. set base timing at 10. timing curve(question for ron) is at following.
rpm                         timing
800                           10
1100                         15.5
1400                         22
1700                         30
2000                         36 all in

car has slight detonations under 1/2 to 3/4 load. vaccum advance has not been connected.
have not look at plugs yet. just wondering if the ignition curve needs to move up and how do you do that (who's kit springs?).

thanks for all your help.

mike

The timing might be coming in too fast at 2000 rpm, what fuel are you running, those mallory MP unit have light springs, i'll bet it'll stop pinging if you put the total all in at around 2800, you'll have to play with different tension springs.

BTW, how does that Summit cam sound?, i'm going to be installing one in my 446

[mdwyer]

I think you are right, curve is coming in too fast. Have found Mallory advance kit which should help adjust the curve.

Cam sound good. Not some big old MP 108 sounding but you know there is something in there. Very good low end, lots of torque!
Installed and degreed at straight up. So far so good, just have to start tuning!!

thanks,
mike

[jg68]

I think you are right, curve is coming in too fast. Have found Mallory advance kit which should help adjust the curve.

Cam sound good. Not some big old MP 108 sounding but you know there is something in there. Very good low end, lots of torque!
Installed and degreed at straight up. So far so good, just have to start tuning!!

thanks,
mike

Thanks

[firefighter3931]

Mike,

The advance curve is coming in too quick like Joe said.  The MP distributor comes with a medium spring and a heavy spring. You want to keep the medium spring and replace the heavy spring with a light one from the Mallory kit to get the advance rate where you need it to be. 

The mechanical advance is adjustable so you'll have to play with it to get around 20-22* of mechanical advance. I would shoot for 16* at idle and 36-38* at 2800-3000 rpm and see how it responds. 



Ron


Ps.

(1) have a look at the plugs for some color....you may have to jet up because lean will also cause detonation

(2) make sure you have the right (heat range) plugs in there. I lke the NGK XR-5's for iron head pump gas builds.

[mdwyer]

ROn,

Sounds good. Ran some 93 in her and the ping went away. Waiting on the mallory kit and will begin tuning soon.

thanks,
mike

[firefighter3931]

Waiting on the mallory kit and will begin tuning soon.

thanks,
mike

Cool !  Get-r-done ! 


Ron