Looks like folks have increased their fuel pressure to make the system perform better.
Dug around last night couldn't find the answer.
What is the new preferred D-jet pressure?

Trying to get the car dialed in. I've got about 300 miles on my rebuild.
Adjusted the MPS. Car runs good. I want to dial in the pressure. Then I'll tackle the decel valve.
It hangs up the throttle too long IMO.

More is not necessarily better. AFR determines what is best for your car, you don't want too rich or too lean. Bosch says 28.5-30.8 psi.

There in lies the next question.
What should the AFR be with Ethanol fuel?
I think Oregon is a 10% blend.

Jeff, I'll get the Amprobe LCR meter packaged up so you can do a side by side comparison. I'll PM for your mailing address.

the air to fuel ratio should be the same with the oxygenated fuels or regular fuels. you need more gas to get the right ratio with oxygenated fuels, but the AFR target value remains the same.

mine is set at 29.
anything higher and the car runs to rich
I played with this setting early on to do a few things.
One is to enrichen the mixture...does no good, car bogs down.

The second time I did it I was trying for perfect MPG..
I got it near 40mpg, but it started to get pretty lean at 26lbs.

Even with a larger displacement motor, leave the pressure at 29-32

rich

I got mine at 34 psi and have adjusted the pressure sendor to give the correct mixtures. Of course my gauge would probably only have an accuracy of +/- a 1 or 2 psi.

do you mean you adjusted the MPS (Manifold pressure sensor)?

If you have a stock motor, why would you do any of that?
Just curious?

Rich

Yup, have adjusted manifold pressure sensors via an oxygen sensor Air/Fuel gauge or by reading the plugs.


The latest motor is not stock, 96 mm pistons, cam, Hi flow exhaust system.

However....even on a stock motor, the MPS must be adjusted for todays leaner burning oxygenated gasolines. The MPS factory output values were tuned to 1970's gasolines which WILL cause a lean burn condition on todays fuel. Even folks with carbs have to adjust with a size or more bigger main jet.

I call this new fangled gas, "gas-o-lean"

I don't believe thats an accurate statement from a technical standpoint.
although I would still shoot for around 12.7ish to 1

every different fuel composition has a different stoic value.
the 10% ethanol in pump gas is part of the reason that 14.7:1 is not really stoic for street cars on pump gas anylonger......

Fuel By mass By volume Percent fuel by mass
Gasoline 14.7 : 1 — 6.8%
Natural gas 17.2 : 1 9.7 : 1 5.8%
Propane (LP)15.67 :1 23.9 : 1 6.45%
Ethanol 9 : 1 — 11.1%
Methanol 6.47 : 1 — 15.6%
Hydrogen 34.3 : 1 2.39 : 1 2.9%
Diesel 14.5 : 1 0.094 : 1 6.8%