Jenvey TB Induction Noise??

[slomove]

A few weeks ago I converted my Zetec with Webers and Emerald ECU to
Jenvey TBs. Engine is running great and after about 20 iterations of
WB lambda logging and injection map tweaking I got it about as
perfect as can be done.

However, I still have a harsh metallic sounding "chirping/rattling"
noise under certain load conditions that wasn't there with the carbs.
I hear it mostly in the mid rev and mid/high load range when
accelerating. It is loud enough to be heard over my pretty noisy side
exit exhaust.

First I thought the engine might be pinging (honestly I don't know
exactly how a pinging engine would sound) but AFR is solid at 12.5-13
when that happens, ignition conservative and using good fuel. I even
tried octane booster without difference. So, if it is not pinging
what can it be? Are the Jenveys known for strange induction noise at
certain throttle opening conditions (I am using an ITG common foam
filter box)? Or do the injectors make some noise? TADTS?

Thanks

Gert

(I have also posted this question on Seventorque and Birkinowners. So you can skip this item there....)

[JohnCh]

Not sure this is going to really answer your question since it's hard to compare sounds via e-mail, but I've noticed that my Jenvey's sound "harder" than my DCOEs did on previous engines. The difference is akin to the one I've heard when tuning the Webers and going from an overly rich set up to something closer to optimal. I've attributed this sonic difference to the fact that the Jenveys eliminate the Weber's auxiliary venturis and thus the combustion chambers have a less obstructed acoustic path into the atmosphere. Of course I am in marketing, so it is probably best that I leave questions like this to the engineers in the group and instead focus my time on explaining to you why this noise will add years to your life and also make you more attractive to women ;-)

-John

[Anonymous]

You may need to retard the timing a little. Might be a knock.

[1turbofocus]

"First I thought the engine might be pinging (honestly I don't know
exactly how a pinging engine would sound)"

The best way i can describe Deto or pinging is a tin can with about 10 to 12 small stones in it and then lightly shaken , If this is your noise take some timing out and it should cure your problem

Tom

[slomove]

Thanks Tom, good description and somewhat similar to what I hear. I will play with the ignition map and see if it goes away....

Gert

[1turbofocus]

Also keep in mind improper A/F will also cause this

Tom