So I have a web cam, and it isn't stock. So I tried stock timing at 3500 , and I tried timing using a vacuum gauge. I tuned it to 19 inches of vacuum with a steady needle and then backed off to about 18. That seemed to run too hot even if vdo isn't reliable. Now I have changed so I am pretty sure I am retarded

Is there a method? Am I correct in thinking that changing the cam compression ratio and cylinder volume might make the stock timing marks less relevant? Help? Oh, and thanks to all.

Yes. More or less.
I forget where mine was set but I timed off "0" with an adjustable timing light. I want to say mine was timed at 27 or 28. By 30 I was pinging hard on high test gas.

Remember, to advanced makes it hot, so does too retarded. You need to find the sweet spot. Fuel also plays a roll. And of course tin leaks too.

27 degrees btdc is the goal.

Doing that at 3500 rpms is supposed to ensure that you are setting it at full advance, so you will be correct.

Now, how you determine that is the trick.
Not all fans have the 27 degree mark on them.

There is a technical article on pelican that shows you how to make a gauge to mark your fan.
I use red nail polish on the fan, or white...whatever is easiest to see.
Clean it well with something first so it stays.

I also use a simple trick, cause I am not as flexible as I used to be.
I paint the correct mark, and all the way across the fan to the other side.
It's a ton easier to see in the hole when you are looking at the other side of the fan.

Rich

....Make sure all stock "cooling tin" is in place (in area of heads?)
then consider all that has been said?

Yeah the tin is as it came new, with every piece tight and sealed. The flapper works etc.

I painted the mark on the wrong side of the fan too. So the different cam doesn't change the optimal timing?

The thing runs just great although I am getting backfiring. Crusing in the 12 --14 air fuel ratio, goes rich when the throttle opens and lean whennit closes. I get backfiring now, wich I am not sure how to interpret. Happens on transition to coasting. I have spent time messing with the mps, but I could do more if I knew what to do.

so, Djet.
That helps to know.

Where is the backfiring from?
Exhaust means you have an exhaust leak...at the head or in part of the heat exchangers or muffler.

Fix that.

rich

The af gauge works sweet. I wish the other ones worked so well. I still have the stock unit that pulls in fresh it at high vacuum. I figure there is some fuel and air slipping away to make an explosion, read as backfire, advice on tuning the d-jet would be nice. I truly appreciate the ffort.

If its backfiring through the exhaust, it's a leak, not a djet issue.

http://members.rennlist.com/pbanders/DjetParts.htm

Ignition timing is timing, cams are cams. Timing is independent of the camshaft, profile. 27 degrees at 3000 RPM is good, 30 is most likely safe.

The Cap'n