IDF jetting for 1800

[bushoarder]

Evening

I have an 1800 (41x34) heads and have 40 idfs fitted. It’s a stock motor so I would assume that there are some standard jet profiles that work?

I have

28mm vents
120 mains
55 idles
F11
33 pump

Seems to guzzle fuel but better than 50 idles and 130 mains!

Bogs a bit now I’ve gone 55 idles so I assume 50s are needed. On the 55s the idle screws are many fewer turns out.

Anyone any thoughts? Will rolling road it eventually but there must be a closer ball park setting.

Also, annoyingly backfires on over run but only on long over runs from 3krpm. Exhaust leak or too rich?

All help appreciated


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[Ephry73]

32 vents


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[bushoarder]

I ended up with the following after rolling road:

Mains 125
Idles 50

The rolling road didn’t look at vents etc. I had it too rich on 135 mains and spot on elsewhere. With 125s it’s running at 11-13 afr

Would you suggest 32 vents in a bus? 28s would give more torque wouldn’t they?


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[Ephry73]

I suggested that based on the jetting you had. Stepping down the main was not a bad idea.


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