Airbox adjustment?, This L-jet is driving me nuts! Options

[deserttoad]

I saw a page on PP website for adjusting the airbox flapper goodie with an ohmeter, but the illustration doesn't match mine. I hope I have the right one!

This is a 1975 1.8, L-jet as far as I can tell. The photo below was taken with the engine running at idle - I noticed it seems to be adjusted almost to the end, and the wire is bent a bit, is this normal? I've played with it and got the car to idle, but I want to do it right, how do I set it correctly? Right now to car is running quite well, but I want to make sure everything is set like it should be. The previous owner had done some pretty crazy things to get it to run, and he did them very poorly. All it really needed was the correct fuel pump, and new vacuum lines.

thanks,

DT

[ClayPerrine]

There is a procedure that is used to set the afm correctly. It involves a particular gauge and a chart that has the correct ohmmeter readings. You can't set it without the gauge.


I have the gauge and the chart. But the meter I have is broken. It is a specialty tool, and I need to find someone who can find out why it doesn't power up.

[sean_v8_914]

you should not have to mess with that. did the PO de-tune teh AFM?

[Katmanken]

The boxes are sealed and they are a pain in the A$$ to open. The one you show is opened. The airflowbox holdsis a flap that hooks to a potentimeter and a carefully ballanced spring to push on the flap and counter the force of the incoming air.

The spring CAN be adjusted, but you better know what you are doing and I don't recommend it.

What you should do to check is check the resistance at different positons of the flap at the points where the connector attaches. Not sure which contacts to use but there aren't many. Move the flap, and look at the VOM-a changing resistance is what you should see. They silkscreen the pot on the board and constant rubbng of the arm can wear a groove in the conductive paint and cause erratic behavior. That's what the VOM is for, checking for wear by measuring the resistance as the flap position is changed

If a groove is worn into the conductive paint, sometimes you can loosen the philips screws and slide the board slightly to place the arm on fresh portion of the conductive paint. It's a bitch to do as they locktite the heLL outa the screws. Retighten the screws and recheck for smoth resistance change with the VOM.

Ojh yeah, look for a bent flap. Sometimes the engines backfire and the backfire damages the flap. That is why you shouldn't start an L-jet while pumping the accelerator.

Ken

[deserttoad]

Thanks for all the input guys!

Where might I find the correct resistance to set it correctly, the page I had didn't look right, but sounded real easy.

And yes, the PO had the lid off, and had it really messed up - wouldn't idle at all, and sputtered bad when revved up. Once I learned a bit about how it worked, I had the car running and moved it a little by hand until it idled good, then adjusted the screw - seems to work pretty good, but I'd like to make it closer to perfect.

thanks again,

DT