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

Robi

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

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

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

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