Holley/Demon Carb stumble
If its too rich, worst case is foul the plugs bad.
Too lean at WOT, I'd be afraid of burning a piston. Maybe that depends somwhat on the timing but I'd play it safe.
.029/.029/.029
IMO too little restriction on the air into the wells.
Start with less, change if needed.
Here's what weird looks like.
When AFR looks like this, jetting isn't going to fix it.
First thing I did when returning to the dyno was confirm what I suspected, which was the secondaries were the main issue.
Take a look at the AFR curves starting at 4000 rpm, which is where 3rd gear full WOT begins.
AFR for primaries is flat. We can jet up or down within reason and its going to stay flat.
AFR with secondaries looks goes lean and rich and lean again like a yo-yo.
So clearly I need to fix the seconday curve. Where to start?
AFR above was picked picked up with a tailpipe sniffer.
Lets look at these runs on a logger (WBO2 in a bung) for a little more speed and detail.
The first thing we notice is that its going lean as the secondary throttle open, and then goes rich.
This is classic "too many" or "too large" holes from the air well.
There is also the possibility it relates to the secondary idle system. H'm. After all there's little time at WOT for anything to stabalize.
Finally, there is a long drift lean from 4750 rpm (13.7 seconds) to 5800 rpm.
My logic has been this way.
The drift at the high rpms is probably main air bleed. So first experiment should have been smaller SMAB (shove some wires in).
But I didn't have the sizes needed with me. Ended up just switching around the e-hole I blocked with only little effect.
Now I've got it set up and ready to test again.
I'm thinking it will be flatter, and probably richer than best power. But I'm not going to jet leaner until I see that lean drift go away!
As fate has had it, I haven't been able to get on a dyno or the 1/4 mile with a logger since then.
And now the car headers - although I don't think that will effect the curve - but of course I want to see what the new ET, and Mph are. :)
That's a big drop. I'd play it safer and go 2 jets.
If its too rich, worst case is foul the plugs bad.
Too lean at WOT, I'd be afraid of burning a piston. Maybe that depends somwhat on the timing but I'd play it safe.
.029/.029/.029
IMO too little restriction on the air into the wells.
Start with less, change if needed.
Here's what weird looks like.
When AFR looks like this, jetting isn't going to fix it.
First thing I did when returning to the dyno was confirm what I suspected, which was the secondaries were the main issue.
Take a look at the AFR curves starting at 4000 rpm, which is where 3rd gear full WOT begins.
AFR for primaries is flat. We can jet up or down within reason and its going to stay flat.
AFR with secondaries looks goes lean and rich and lean again like a yo-yo.
So clearly I need to fix the seconday curve. Where to start?
AFR above was picked picked up with a tailpipe sniffer.
Lets look at these runs on a logger (WBO2 in a bung) for a little more speed and detail.
The first thing we notice is that its going lean as the secondary throttle open, and then goes rich.
This is classic "too many" or "too large" holes from the air well.
There is also the possibility it relates to the secondary idle system. H'm. After all there's little time at WOT for anything to stabalize.
Finally, there is a long drift lean from 4750 rpm (13.7 seconds) to 5800 rpm.
My logic has been this way.
The drift at the high rpms is probably main air bleed. So first experiment should have been smaller SMAB (shove some wires in).
But I didn't have the sizes needed with me. Ended up just switching around the e-hole I blocked with only little effect.
Now I've got it set up and ready to test again.
I'm thinking it will be flatter, and probably richer than best power. But I'm not going to jet leaner until I see that lean drift go away!
As fate has had it, I haven't been able to get on a dyno or the 1/4 mile with a logger since then.
And now the car headers - although I don't think that will effect the curve - but of course I want to see what the new ET, and Mph are. :)