Hello,
i have a lincoln with a 400 engine, and did most of the recommended mod's.
How hard i try it, i can't get it past 10Mpg.

I've installed: Edelbrock manifold, new valve springs, retainers, hyd. lifters, RV cam, Impco 425 carb, open plenum aluminum spacer, MSD6AL box, MSD Coil, MSD distributor, MSD cables, new oil, filters, and plugs, gapped, dual 2" exhaust with magnaflow mufflers.
I had the heads off, and put them on again, in order to see in what shape everything was. Everything looked fine, no carbon buildup, mess, etc.
I have the light silver springs installed, drove a while without vac. advance in order to set everything, and currently have it at 16 deg. initial, and 21 deg. total. Seems fine to me.
now, i know it's a heavy car, smog block, low CR, but i must be able to do better, right?

I also have another towncar, with just a stock setup, only full MSD setup, and a impco 300A gascarb, and i get 14MPG out of it!!

Anybody got some advice on what i'm looking over?
What more can i do, other than fully rebuild the block? (in order to get higher CR and so..)
Don't intend to, as labour is costy over here, and i can't do it myself...

Any info highly appreciated.

Thanks.

 

The only thing that I see that can help is a set of headers. The only other thing that I know would be to have your heads surfaced and ported, or just replaced with aluminum aftermarket heads.

 

do they both have the same gears in the rear end? Do they both have the same transmission? The motor is only about 1/3 of it. Also the new motor will get better mpg as it is broke in and everything loosens up. You need 5,000 miles or 2 oil changes to really know.

 

Try installing a wideband O2 sensor like they use to tune EFI setups. You can get one that will display the fuel/air ratio on a dash mounted display.

It should work for Propane with just a recalibration. I use an Innovate LC-1, but that needs a computer. Innovate and others make widebands that have direct readouts.

You can try it in both vehicles to see the difference between the two.

Innovate Motorsports Wideband Air/Fuel Ratio Tuning

 

Rear gears are equal, both C6.

I have the innovate xd16 installed...
AF is 16.5 stationairy, up to 15.7 cruising, and 15, 14.5 at WOT.

 

Is that normal for Propane? It's lean for gasoline.

Does the other vehicle have the same AF readings?

 

I don't know about the other verhicle.
For gasoline it is lean indeed, for propane its nice.
Gasoline has a stochiometric of 14.5, propane has a stochiometric of 15.7
So, stationairy is a tad lean, and driving conditions are nice up to a tad rich..

thanks,

Stef.

 

are they both propane dedacated, or is one duel fuel.

 

The gold one (with the 300A) is dual fuel, with the rochester carby.
The white one (with the 425 and all goodies) is all propane only..

 

Propane is a lower energy product tha gasoline, so it seems to me that 10 MPG on Propane is reasonable. The 14 MPG figure is the one that is suprising.

The mods that you have done are mostly to improve performance, not necessarily fuel mileage.

Propane is slower burning than gasoline, so I expect that 16 degrees initial advance is about right for a low compression motor, but I think that the total advance should be quite a bit higher than 21 degrees. There is a tech note on the Innovate site that talks about spark advance and fuel burn rates. Basically High Octane fuel and low compression wiil create a very slow burn. The peak pressure from the combustion may occur too late in the Power Stroke to be effective at RPMs much above idle.

 

i think there are 3 diff impco 425 mixers each one runs a little richer or leaner depending on witch one you use, not shere if that would affect mpg that much but could be some of the reason. i would swich 300 and 425 if not a big deal and see if that does anything for you. i have reaserched propane some and think that i read that the 300 mixer is one of the most efishent and the 425 is on the other end. try raso enterprises website Alternative Fuels :: Index for more on propane. lots or info on propane there.

 

Thanks.
I know the site, already a member there for some years now
The reason the 300A is most "efficient" due to the fact that it's probably not up to the task..
thats why i installed the 425 in the first place, to have more CFM's..
That could indeed be one of the reasons the other has a better milage (as it's probably running too lean..), BUT: i had the 300A on this car also (before the modifications) and it ran a little better milage then, but not as good as the other Lincoln..
So, thats why i expected that with all the upgrades and the 425, i'd get a good milage..
There are different 425's indeed, but i thought that the differene wasn't that great.
I ordered a lean valve just to try to get it better, but in my opinion that's not the main cause of the car running bad milage.. (it probably will improve a bit, but would also have when it already run a good milage...)

 

if i remember right the 425 mixer was made for industreal engines narrow rpm range ,but lots of people started using them for cars and trucks were as the 300 was made for car and truck applucations, but i could be wrong.

 

you're mistakin' with the 600... Thats a industrial type.

 

i could not rember for positive i do rember the 600 is a monster in size looks more than double the size of the 425. i know there the same make of car but do they weigh the same. older cars can have lots of things added or taken off them to change the weight alot. if there was say 700 1000 lbs diff that could also have a big effect on mpg. would not trust sticker weight go to the scale if possable.