IDF Flat spot

[Blue74l]

can only assume i have to play with jetting but here is the story.

Been playing with the IDF's cause i want to get rid of a flat spot.

If you slowy drive up it is smooth, until you hit about 3500 revs. It is about 30-35kms/hr in first or 45-50km/hr in second. At this point if you hold it there it burbles loudly and falls on its face. If u shift before this point it is as smooth as. It is just sooner or later you have to cross this point
You can easily drive through this flat spot but it does make for a bit of on/off of the carbs.
I like it but the wife doesnt
I dont think it is accelerator pump cause it runs smoothly up to that point.

Blocked progression ports?

Jetting at the moment is
40 idles 1 1/2 turns out
120 mains
180 airs
32 vents
F11 E tubes
Stock valved 040 heads

When we had dyno day a while back i had the same idles and 130 mains.
The graph said i was rich on the mains.
13? on idles and 11 after that.
So i have dropped to the 120's


The carbs are IDF 36's and as such dont have access to air bypass screws.

Would different E tubes give a smoother change from mains to air coming in? This is where the problem lies.


If you just floor it it takes off and pulls hard.
If you rev it in neutral (no load) it revs nice and smooth up past 5ooo no worries

Barry