Another IDA lean stumble ranting ;D

[Erlend / bug66]

Ok. I've already gone through the threads here, on ultimate, shoptalk, aussie-rotor forums and V8s forums.

They are all different


My lean stumble is only at part throttle, stomp it and it's not there. But that could potentially be to noisy


I'm on E85 btw.

Some spec

94x76
42/37 wedgeports
48 IDA w/ 40 vents


Jetting right now:

70 idle on 110 holders
225 main and 155 airs
F7 tubes



300 needles, stock rest.

28 degrees ignition (what it liked on 98 octane)




I have all the jets i might need, and F2s and F11s.

Same stumble on F11s, but haven't tried F2s.


More main and air to get the main in earlier?
More idle?

Any suggestions?

[richie]

So you swapped fuel to E85 from 98 octane, then adjusted the jetting to suit?

but didn't adjust the timing? 

 what rpm does it happen at? roughly? is all your advance in by then? if it isn't then with E85 it might like more initial timing

I can't remember what cam it has in it, what is it?

If not timing then I would go up a size on idle jet 1st and see what that does

cheers Richie

[Erlend / bug66]

So you swapped fuel to E85 from 98 octane, then adjusted the jetting to suit?

but didn't adjust the timing? 

 what rpm does it happen at? roughly? is all your advance in by then? if it isn't then with E85 it might like more initial timing

I can't remember what cam it has in it, what is it?

If not timing then I would go up a size on idle jet 1st and see what that does

cheers Richie

I've read that you can pick up more power with more timing, and that more timing on a NA engine is no bueno on E85..

Web 86C with 1,4 rockers.

pretty much exactly at 3000rpm. timing is set at 3000, so it should be all inn.


I've tried 75 idles at idle in the garage but was rich, like 10,5-11 at idle.

I'll try it after work on the road

[modnrod]

Less idle fuel to stop the fuelling up down low, then fiddle with idle airs (do IDAs have them?) to extend it further through the transition to cover the part-throttle stumble maybe?