running rich

[MOTORHEAD]

Got in 2 test drives this afternoon with the 120 holders, 1st drive with idle mix set to 12.5-13 A/F, lean idle. "Punching" it moderately showed mixture going lean with the stumble, and much backfire when backing off the gas. 2nd drive with mix set rich 10-11 A/F, but smoother, Punching it showed mixture also going lean (15-16) but no backfire when off the gas. At this point I would surmise it needs a larger pump shot ? Carbs had blocked pump valves when I got them , but were replaced with .50's. I think I'll try advancing the initial timing first. Zrayr: just read the info you showed, very interesting.
I'll report results as soon as I have some!

[zrayr]

Originally Posted by MOTORHEAD

".............. Carbs had blocked pump valves when I got them , but were replaced with .50's. I think I'll try advancing the initial timing first. Zrayr: just read the info you showed, very interesting.
I'll report results as soon as I have some!

Did you run it at all with the 00 acc. pump bypass valves ? I have 60's now and am thinking about doing some experimenting in that area.

My 10 & 14 degree bushings are on the way. We'll see if I have any benefit. Right now the car seems to like 22 initial timing best as far as idle quality goes. A lot of my off idle stumble went away with going to the lightest dist. springs, but sometimes the idle will hunt a bit with them. It just starts advancing too soon, so I'm trying the next lightest combo.

Originally Posted by MOTORHEAD

".............When I mentioned A/F meter to Inglese he said " do you want it to run right, or do you want to chase numbers?"
I want both, as much as possible. I realize there exceptions and trade-offs.

Ha ha, he's said much the same thing to me. He's right about one thing, you can get the best performance out of a set of Webers when they "appear" by the numbers to be running a bit rich (especially on the low end). Just my experience so far.

Z.