[joshewing02]

I am trying to get the most out of my 1970 Cougar 351C 4V M code engine which has 11.4/1 Compression ratio. I have a Holley Carb I believe a 750, with a KNN Filter. And flowmaster exhaust and mufflers (no headers). That being said I have a few questions about how I need to time this thing. I am replacing the Harmonic balancer now since it has slipped so much that at idle it reads at 65 BTDC. Mallory 1256704 Max-Fire Distributor with a mallory high performance coil. Keep in mind that I do run 100 octane fuel in this engine. So I set the idle with the vacuum plugged at 6 BTDC. Now this is where I am unsure, with this distributor it is fully programmable so I can do steps or a solid curve for timing. I set mine to 22 starting at 1000 all in by 3000 rpm. Just to be safe I set the rev limiter on the coil to 6000k. It also has a option on how much vacuum advance and when to start ect that I did not touch because I am unsure what to do here. No manual seems to cover this because I guess it was just built in to the distributors? So any advice on where or what I should start the vacuum advance at and basically the total timing. I am just looking at the best overall settings to get the most out of this engine. Any help would be great thank you guys.

 

[doctordesoto]

the factory manual in the dist/ign section talks about the advance curve---if you know where it starts and how much @ total , you should be able to plot the factory curve--same with vac curve---i had to find and purchase a vac delay valve for our 390 gt(10.25 to 1 )to slow down the vac advance---you will help yourself if you can find someone with a dist machine and know how to use it---pre 72 distributor seem to have better factory curves than the smog years

 

[jman271]

I have a 69' 351w, 750 edlebrock, and a rowdy cam so my results may differ slightly than what you get.

I disconnected and blocked off the vac advance hose from my distrib and set my intial timing at idle, (about 900-1000 rpm), to roughly 10 deg btdc.

I fiddled with the carb idle setting and got it to run as smooth as possible at that range and then set the distrib lock nut.

I then re-connected the vac advance hoses to the "timed" vacuum port on my carby, (my carby has two ports, timed and fixed, the fixed is blocked off with rubber pluggy), and then ran the car to proper engine temp and held the throttle linkage to 3500 rpm to see what my max timing was. I have it written down, but it was like 33 deg or so.

This seems to be a good initial setting for my needs, I run 94 oct with a yellow bottle of "octane boost" from Advanced auto. I feel no pinging under load, runs pretty cool, and idles smooth.

I don't think you need a tutorial, but I am embeding a link to youtube on ignition timing, they help explian it better that I can and it is good useful info.

Best- J

http://www.youtube.com/watch?v=UYGU7mTwsZc