440 Timing....what is my timing reference point?????

[firefighter3931]

The timing curve might be a little lazy which would account for the less seat of the pants kick you are now feeling. The old setup had more ignition lead down low due to the excessive mechanical advance. 

You can get some of that back by changing the springs on your advance weights. There are 3 different springs available ; light/medium/heavy. I've found one light and one medium works really well and brings the total timing in sooner which makes the engine more responsive to throttle position changes. 

Best thing to do if you're interested in further fine tuning would be to map out the timing curve in 500rpm increments starting at 1000rpm. Check the timing at those intervals all the way up until it stops advancing and report back.

Ideally, what you want is the total all-in by 2500 rpm or thereabouts. 


Ron


Ps. Blocking off the vac advance will have zero effect on the outboard carb activation.

[Dodge Don]

I have the spring set from Mallory. Been reading their info on set combinations and curves. I'll let the shop figure it out once and for all. Thanks.

One of the things that pisses me off is that I've had 3 shops do the timing to specific specs (Ron gave me)....and now I discover that not one of them went into the distributor to adjust the mechanical advance leaving it at 28*.

I'll be extremely specific on what I want done this time. 

[firefighter3931]

Don,

Hopefully you're not taking it back to any of those shops that tried to tune it....all three fumbled the ball on the goal line. 

Wherever you take it make it crystal clear that they are not to adjust the mechanical advance !!! The only thing they should be doing is swapping in the correct advance weight springs (Med/Light) and maybe some carb tuning if they have a chassis dyno and know how to use it 


Ron

[Dodge Don]

Don,

Hopefully you're not taking it back to any of those shops that tried to tune it....all three fumbled the ball on the goal line. 

Wherever you take it make it crystal clear that they are not to adjust the mechanical advance !!! The only thing they should be doing is swapping in the correct advance weight springs (Med/Light) and maybe some carb tuning if they have a chassis dyno and know how to use it 
Ron

Well looks like every shop around here has a several week backlog. So I may have to try this myself again.

Here are the Malory Advance Curve kit instructions
http://prestoliteperformance.com/media/instructions/mallory/Mallory_Instructions_yh_series_mechanical_advance_kit_29014.pdf

If I recall, an based on the instructions, I think I had the Purple spring and the Brown spring. Since I'm assuming we are still looking to retain the two stage advance curve....by looking at the Figure 1 I'm guessing that I should replace the Brown spring with a Pink spring to get more response? Now that I've done this I'm pretty sure I can do it without removing the distributor.

Thoughts?

Also, I know you prefer to leave vacuum advance off, but just for curiousity sake...if I left everything as it is right now and reconnected the vacuum advance what do you think that would do?

I noticed that I've had a hard time finding a good idle at start up without ending up with a high idle when warm. And my power brake assist after start up /idle is not as good as before....gets better when warm and out driving.

[firefighter3931]

Looking at those instructions ; i would go with a single stage advance curve and use a pink/grey spring combo to start out. I'm used to the Mr Gasket spring kit that comes with heavy/medium/light springs and this Mallory kit has more options.  

The grey pink combo should give it increased mechanical advance right off idle which is what you want.  

Usually, the vacuum advance will cause surging issues when at steady cruise. The vac cans are designed for stock engines making 15in of vacuum at idle so when you add a performance cam it plays havock with the timing when vacuum is reduced.

Idle at startup is allways problematic unless you're running a choke setup. I prefer no choke and just feather the throttle until it will idle on it's own and then let it warm up to operating temp. Set the idle speed at operating temp and just coax it along until it will idle on it's own...then let it warm up. Just the nature of the beast with carburated engines running on junk fuel  


Ron

[Dodge Don]

Okay so if I replace both springs...which new spring replaces which old spring? Or does it even matter?

The Purple spring is larger (O.D. and length) than the Brown Spring.....

...and the Grey spring is larger (O.D. and length)  than the Pink spring.


I'm assuming I replace the Purple spring with the Grey spring.........and replace the Brown spring with the Pink spring

Both the Grey and Pink springs are visably lighter springs.

[firefighter3931]

It doesn't matter which spring replaces which.....just install the grey and pink and let-r-rip ! 


Ron

[Dodge Don]

So I was telling Ron by PM that this morning I pulled the dizzy and swapped out the advance springs. Re-timed engine and took her out for a test drive....wow what a difference. The car ran great, very responsive and tangible power/torque increase!!  Felt great. Really great results.

[firefighter3931]

Good work Don, you did what three shops were unable (or unwilling) to do ! 

It's allways rewarding when your tuning efforts show positive results 


Ron

[flyinlow]

In the words of Lieutenant  Columbo, " If I could just ask one more question"

I am still welding and grinding. What distributor are you working with that has adjustable stops?

[Dodge Don]

In the words of Lieutenant  Columbo, " If I could just ask one more question"

I am still welding and grinding. What distributor are you working with that has adjustable stops?

Mopar Performance Electronic Distributor (which is really a Mallory YH rebranded).