Quote: With right I meant pretty even at all rpm's not leaning at higher rpm's.
You may be on the right track. It depends on throttle position. If you are opening the throttle a bit at higher rpm, then the leaner AFR is normal. More throttle is needed to hold higher speeds steady so this is a tough variable to nail without a TPS.
Quote: But you're right, 14AFR at cruise and leaning out more the more you step on it do scare me.
Yes, the graph was clear(Higher vacuum = lower load, Closer to 0 = higher load) However it doesn't show the leaning out at the level I'm experiencing. (15-16)
Thats only due to the peculiarities of my setup. With more dynamic (and static) compression the motor would have more heat and more effecient combustion. It was OK on pump gas 10 years ago but now is marginal. The trend and pattern is prtty univeral, but the numbers and the PV location will vary considerably.
Quote:
Do you use a throttle stop to accelerate at the same rate every time?
Throttle stop is an interesting idea. I think the way to do it on a dyno may be to hold the throttle steady against a load and let the vacuum vary. The way I was trying it was to watch the vacuum gage and vary the throttle to 'crowd' 14"Hg then 12" then 10".
If you can get the rpm working with your logger, and maybe an extra set of eyes and ears, you can probably do this safely on pavement rather than rollers. Put it in 3rd gear and start the acceleration from 30 mph each time. Urich was recommending 30-80 mph but you could cut that top speed down if needed. You'll have the advantage of the rpm rise logged vs a stopwatch. Could it be done with throttle stop instead of vacuum gage? Don't know. I'd have to think about that. If you hold the throttle steady, the vacuum will rise with increasing rpm. So you'll not get the high load/low vacuum data in the higher rpm range.
Here's the post with dyno log of part throttle runs. When I've done crowds on the street, they are often short and not repeatable enough to compare. But it sounds like you may have the right situation to do it.
The Mike Urich and Bill Fisher Holley book is definately worth buying. There's a newer edition with Fuel Injection but you don't need that one. Urich was VP of engineering at Holley. I think that gives him a technical edge of the majority of authors.
Not sure what is up with your RPM logging. That's the big downfall of the Innovate stuff. Its not that user friendly and its a little flakey. I'm using an LM1 with the LMA3 (aka Aux box). I'm no longer using the rpm input, but the frequency channel set for rpm.
