skiprCH

Hi,
Going to tune up my car and was wondering how much advance I should use? My 289 is totally stock A code
I live at 5 thousand ft. if that makes a difference.
Also wondering if the newer type plugs make a difference? I think Bosh and Spitfire are the names of some of the newer type plugs.
Thx, Walt

jlg2002

IMO, For the money the OEM Auto-lite and Motor craft are the best plugs. exactly what advance are you talking about? initial, vacumn or centrifical (or all 3)

groho

Curious, has your carb been tuned for that altitude? I believe the book states initial timing is 6 BTDC, but you can bump it up to 8 without a problem. 5000 feet is way up there, and properly tuning a car for that altitude is going to require jetting the carb down a step or two and lean it out, to get the best performance. Has it been done already?

skiprCH

hi,
I did re-jet my carb to 2 sizes smaller. Not sure what advance you change (initial, vacumn, centrifical) when you rotate the distributor and use a timing light? I also put a Pertronix module in the distributor to replace the points.
Thx! Walt

plainsman1876

4- 6 degrees before tdc. Bosh plugs are only good for rice burners, I use Autolite platnums. Along with motorcraft oil filter and motorcraft oil

groho

set your initial timing at 6 BTDC, and be sure to plug your vacuum line for your dizzy when you set it.

MBDiagMan

And recheck the timing after you retighten the distributor lock bolt.

If you have a stock distributor that has not been messed with, then the 6 degrees BTDC should work out good for you. If it feels really lazy with that initial setting, then the distributor may very well have seen a curve kit somewhere along the way. In that case it will take some experimenting to find the best setting. In the case of a curved distributor, you should set it according to maximum advance, rather than initial advance.

To set maximum advance, you will need to mark you balancer out to about 36 degrees. Your maximum advance is set with the vacuum advance disabled and the engine revved up as you watch the mark with your timing light. Rev the engine until the advance mark no longer advances further. That is you maximum advance. Your max advance should be about 34 degrees or so. This will vary widely depending on fuel, compression ratio, carbon buildup and many other factors.

If you DO have to find maximum advance, once it is determined, you can then look at your initial advance and make note of it for future reference. That way, the next time you have to mess with the distributor, you can just set initial advance without having to rev it up and all that.

However you approach it, drive it afterwards to ensure that there is no spark knock under load.

2+2GT

6°-10° BTDC works best on these, but distributor adjustment is critical, and usually overlooked. Pull the distributor, take it to a specialist, and have it adjusted to spec:

MBDiagMan

I made my way through college with the GI bill and a Sun Distributor machine. I curved quite a few distributors at $10 a throw. Doesn't sound like much money today, but in the early seventies, that was two tanks of gas.

If I were going to bother putting this distributor on a machine, I would not put in a factory curve. I would limit the max centrifugal advance to about 12 degrees and have it all in by 1,500 distributor RPM (3,000 engine RPM.) I would then set the intial timing at about 10 degrees at idle. I would then try the vac advance with a curve similar to the chart above, but with today's gas I think it would be a little aggressive. If not that would be a good thing, that's why I would try it.

If the engine doesn't run right at cruise or worse, if it pings at cruise, start limiting the vac advance until the pinging goes away.

Going through all this with todays fuels would be a project to get it right. For me the variable would be todays fuels. It may very well be that the curve I started with would be way off because I haven't curved a distributor on a high compression engine with today's fuel choices.

For the OP's purposes, the practical solution would be to use a timing light to confirm that the centrifugal and vacuum advances are working and then set the initial. If it then drives well, be happy. Going through a distributor curve change and getting everything right would be a pains taking process best done by someone who has been through it before.

Back when I did it, I did quite a few and it was in the days of 102 octane Premium. Regular in those days was higher octane than is today's Premium. I figured out what worked well. One of the things I also figured out was that a small block Ford due to combustion chamber efficiency would not tolerate as much advance as a small block Chevy.