Secondary lean tip in?
- toms73novass
- Posts: 216
- Joined: Sat Mar 04, 2017 6:58 am
- Location: Grand Island NY
Secondary lean tip in?
I know not the standard setup up, but....
I have 140 blow through turbo engine. Finally getting back to logging data.
What I am seeing is that when the secondaries open I get a lean spike in the AFR's. I do not feel it but I would like to eliminate it.
I did NOT have the accelerator pump cups in my secondaries (which are 62-63 bases), after seeing the lean tip in I put the cups in. It may have helped some but the peak is still there.
Ideas?
Top line is the AFR, middle RPM, bottom (blue) boost.
I have 140 blow through turbo engine. Finally getting back to logging data.
What I am seeing is that when the secondaries open I get a lean spike in the AFR's. I do not feel it but I would like to eliminate it.
I did NOT have the accelerator pump cups in my secondaries (which are 62-63 bases), after seeing the lean tip in I put the cups in. It may have helped some but the peak is still there.
Ideas?
Top line is the AFR, middle RPM, bottom (blue) boost.
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1962 700 Wagon
1963 Spyder convertable
1965 Monza
1967 UltraVan 211
1963 Spyder convertable
1965 Monza
1967 UltraVan 211
Re: Secondary lean tip in?
I'm assuming you are blowing boost pressure through stock carburetors. Excuse me if you thought of this ------ back in the days of blow through carburetor turbocharging one issue was the fuel float bowls were pressurized (as they should be to make the cluster work) which in effect was like lowering the fuel pressure into the carburetors and would cause a lean condition. My favorite fix was Rolls Royce who put the carburetor and fuel pressure regulator in a BIG BOX that surrounded the carburetor and pressure regulator. It looked awkward, but worked like a charm.
Now systems use a computer, or fuel pressure regulator with an input to the boosted air pressure to adjust fuel pressure as boost (and float bowl air pressure) increase.
I'll have to say that after decades of engineers dealing with turbocharging via carburetors, going to fuel injection and computers was a huge improvement in engine performance, including just cruising around town.
Now systems use a computer, or fuel pressure regulator with an input to the boosted air pressure to adjust fuel pressure as boost (and float bowl air pressure) increase.
I'll have to say that after decades of engineers dealing with turbocharging via carburetors, going to fuel injection and computers was a huge improvement in engine performance, including just cruising around town.
Re: Secondary lean tip in?
Increase your pump shot on the secondary carb. Easy adjustment by bending the rod. Where the marks are supposed to line up put the line a thickness or two further ahead. 1/32"-1/16"
Ken Hand
248 613 8586
vairmech@aol.com
Corsa Past President
Corvanatics Vice Prez
Chair 2007 Detroit Convention
Co-chair 2014 Tacoma Convention
248 613 8586
vairmech@aol.com
Corsa Past President
Corvanatics Vice Prez
Chair 2007 Detroit Convention
Co-chair 2014 Tacoma Convention
- toms73novass
- Posts: 216
- Joined: Sat Mar 04, 2017 6:58 am
- Location: Grand Island NY
Re: Secondary lean tip in?
The carbs have been heavily modified to handle boost and I do have a variable rate fuel pressure regulator that increases pressure as boost increases. I agree modern setup with FI can overcome these issues easily. The car runs great actually don't notice the tip in just on the logs.
1962 700 Wagon
1963 Spyder convertable
1965 Monza
1967 UltraVan 211
1963 Spyder convertable
1965 Monza
1967 UltraVan 211
- toms73novass
- Posts: 216
- Joined: Sat Mar 04, 2017 6:58 am
- Location: Grand Island NY
Re: Secondary lean tip in?
OK will do. Thanks
1962 700 Wagon
1963 Spyder convertable
1965 Monza
1967 UltraVan 211
1963 Spyder convertable
1965 Monza
1967 UltraVan 211
- Frank DuVal
- Posts: 509
- Joined: Wed Dec 09, 2009 4:58 pm
Re: Secondary lean tip in?
Studebaker also put the carb in a box with the supercharged engines.
Frank DuVal
Fredericksburg, VA
Hey look, blue background!
Fredericksburg, VA
Hey look, blue background!
Re: Secondary lean tip in?
First - I goofed as it was a Bentley that used the box, not RR. Back then they were basically the same car.
Second - I've noticed that these old carburetor accelerator pump bores are getting worn and sometimes you don't get a shot of fuel until the cup moves some. Also there is a check ball in the bottom of the plunger that can cause issues with a poor "squirt".
Second - I've noticed that these old carburetor accelerator pump bores are getting worn and sometimes you don't get a shot of fuel until the cup moves some. Also there is a check ball in the bottom of the plunger that can cause issues with a poor "squirt".
- toms73novass
- Posts: 216
- Joined: Sat Mar 04, 2017 6:58 am
- Location: Grand Island NY
Re: Secondary lean tip in?
It seems to be working well.
1962 700 Wagon
1963 Spyder convertable
1965 Monza
1967 UltraVan 211
1963 Spyder convertable
1965 Monza
1967 UltraVan 211