Thanks John, I am not sure about my timing light because I adjusted my timing to 7 degrees btdc and went out and drove it and it run great with no preignition.  I am really happy with the way it is running.  Any thoughts about my timing light?  Why is it showing half of what it is?   

Robi

Robi, your engine is 320cu in with CR around 10.2:1. Total timing will likely need to be 36-37 for maximum power. Initial advance of 14 should be enough.

The MSD instructions give distributor advance in crankshaft degrees while all the old manuals give advance in distributor degrees and are doubled for crankshaft degrees.

We used the 2 blue springs and blue bushing on our recent build and it worked well.

If you are monitoring air fuel ratio with an O2 sensor it will need to read a little richer than if the engine is on a dyno with air hat and fuel turbine readings. On a SuperFlow dyno the best power is found around 13.5-14.5:1. We have run some Y-Blocks in the 15:1 range and they'll still make power but these are not O2 readings.

I would guess that O2 readings should be 12.0 to 13.0:1. 

Limiting the vacuum advance to an additional 10 is a good idea.

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

The MSD distributors has way too much advance for the yblocks. With your initial of even 12^o which is low as RB said and the vacuum advance adding 16^o then mechanical advance even using their largest stop bushing is 18^o now has a total of over 46^o. That is way too much total. With that much total advance when you adjust the distributor to stop the pinging you will not have enough initial advance and will have a very crappy idle then when you adjust the distributor to get a good idle you will have detonation at high rpms or under load unless you get the total timing under control . I like to get close to 36^o total as a starting point.



My engine likes between 16-18^o initial with 10^o vacuum and 10^o mechanical. I run full manifold vacuum to the distributor.



I used to make my own 10^o advance limiter bushings when I still had access to the machine shop. The largest bushing you can install in the MSD is about the 10^o one as there is no room left.



The vacuum chamber on the MSD's are also non-adjustable. These are Chebby type vacuum chambers. Pertronix or Crane cams sells adjustable ones with an allen wrench to adjust the spring and an adjustable permanent stop to restrict the amount of movement. Not sure of the permanent stop being included in the Pertronics package. It looks like a rooster comb and held in place by one of the canister mounting screws



I have found a supplier for the mechanical stops. Price is cheaper than I can buy from a machine shop.

If you have the means to machine one I still have the specs.



http://www.4secondsflat.com/MSD%20Distributor%20Tuning.htm

This guy is a mopar guy but has some very good info on tuning a MSD.





marv

Are you using the MSD instructions for setting the advance curve? Based on your observations, you have the red bushing and 2 silver springs, according to the charts they provide. The other bushings look like they will provide about 18, 21, and 25 degrees of advance. Have you tried those?

Does the curve match what they show in the chart? If it does not, I'd give MSD a call. I wouldn't expect it to be spot on but for instance, if you're using the 18 degree bushing and getting 27, there is a problem. A distributor from a company such as MSD should not be that far off.


Lawrenceville, GA

Thanks for the input I will reply back when I do some more adjusting.

Robi

Your timing light sounds like a modern equivalent of the ‘dial back’ lights to which I'm referring.  I’ll suggest borrowing a conventional timing light and comparing the timing reading against yours at both idle and with the engine sped up to where the total timing is in.

Lorena, Texas (South of Waco)

It is digital with up and down buttons to adjust advance.  I will install both heavy springs and try it.  I will also maybe try to richen up mixture a little bit.

Robi

Does your timing light have a knob on its backside for timing curve adjustments?  If so, then that will be a 'dial back' light.  With the MSD spring kit, the lightest springs typically has the timing all in at 2500 rpms.   Any other spring combination of springs should have the total timing coming in at a higher rpm.  Putting the original stiff heavy silver springs back in and working backwards from there would be a good starting point.  Runing the engine at less than optimum ignition timing will not be detrimental to the the engine other than making for some additional heat that must be carried away by the cooling system.

Lorena, Texas (South of Waco)

With the vacuum advance unhooked all the timing is in at 2500 rpm.  I do still have one stronger spring for my weights.  Right now I have the middle -late springs in.  I may have to install the heaviest springs.  You think I should adjust my timing when it is totally advanced.  My timing light is a digital light.  Will it be a problem if I don't have enough initial advance?

Robi

Have any particulars on your combination?  As you mention, your combination may be marginal for pump gas.

 

Your basic ignition timing adjustments should be made with the vacuum advance unhooked.  Using a dial back timing light can also be a problem as many of these vary in the timing readings they put out.  The older MSD instruction sheets use to be specific in what timing lights were recommended for ignition timing adjustments and there were no dial back timing lights on that list.

 

When you say you have 39° timing at 2500 rpms, does this mean that all the timing is in at 2500 rpms or that’s just where you’re setting the total?  If the timing is continuing to increase after 2500 rpms, then the total timing ideally needs to be set at an rpm point just above where the mechanical advance in the distributor is pegged out.  But that brings up another point.  Previous experience has shown that having the total timing in at 2500 rpms is likely too low.  For the EMC engine, I found that a lazy curve with the total timing coming in at 3400 rpms made more power in that particular instance.

 

I had a stroker Y on the dyno yesterday that had been simply timed with the initial settings and raced that way.  It has a stock distributor with an electronic conversion.  The total timing on that engine came in at 4700 rpms and was 26°.  Made 274 HP.  Kept bumping up the timing in increments and with each increase was rewarded with a HP increase.  The same engine was making 306 HP at 38° total and this is a pump gas engine.  The only problem is increasing the timing also leans the fuel mixture and in this particular case, the engine has a 3X2 setup with the Holley 94’s.  The jetting was already on the lean side before adding additional advance to the ignition.  There’s an easy 15-20 HP left on the table in this instance by not jetting the engine up fatter.  Because a single four intake and Holley carb will be on the engine when it leaves the shop Monday, there was no time wasted in tinkering with the jetting on the 3X2 setup.

Lorena, Texas (South of Waco)