I put an autometer Air/Fuel Gauge in the car to help tune it.  I've got the sensor on the passenger side just about 3-4 inches below the header (I've got red's dual tube headers) before the pipe takes a turn and heads to the back of the car.

My question is if anyone knows what kind of readings I should be getting under different throttle conditions.  Right now I've got it set so that once the car is warm and at idle, the gauge shows Stoich.  (the proper mix so there is excess fuel or excess oxygen... i guess)  But then once I hit the the throttle, it takes a brief dip to the rich side and then goes off the gauge on the lean side. Is this expected? 

I've got a holley street avenger 570 cfm that runs pretty well, but I don't want to be starving the engine if I can get some additional power out of it.  Are my jets to small?  

They only give detailed information in the install sheet on using it with fuel injection - they say in that case when you floor it, the gauge should go to the rich side because the engine is going to send as much fuel as possible for max accel.

Any help always appreciated! - John

John: Lake Forest, IL



'57 Fairlane 500 - Looking better every day.

That's not normal. Is the power valve functioning? Check, at a steady cruise, and see what the reading is. 2500 rpm or so. that should tell you about the main jets. The power valve should add additional fuel, at lower vacuum readings (0-6,5) or so depending on what valve is in it. Should actually show rich like 12 12,5 at full throttle. Might be too lean in the secondaries also....

                      

Frank/Rebop

Bristol, In ( by Elkhart) 

Frank, you were right on this one...  The heavy spring was installed for the vacuum secondaries so I swapped in the lightest one and now i've got fuel at all RPM's. 

I need to do a little fine tuning though - Full throttle from a dead stop and it accelerates great no problem, but if I'm cruisin and I bury it I get a little hesitation before it takes off.  The medium spring however leaves a small section of RPM on the lean side, so I'll have to cut and bend the light one to give it the slightest amount of additional pressure -

- John 

John: Lake Forest, IL



'57 Fairlane 500 - Looking better every day.

Try jetting the front jets up too #56 or 57s and see if that helps.That will sometimes take out the hestation you experience on quick acceleration and keep the engine from running too lean.

-Gary Burnette-