Jacobs Ignition System

From: CSiano@banyan.com
Date: Fri Jan 19 1996 - 07:54:24 EST


>One of you fellow Dakota owners wrote recently about a Jacob's ignition
>system you had installed. Has that new system actually increased HP and
>milage, as claimed by the mfg? How much more mpg did you increase, and do
>you actually calculate your milage or just wild ass guess? I'm looking
for a
>reliable way to increase milage and some people I've talked to tell me
>they've gotten better milage doing somethings. When I ask if they
calculate
>their milage each tank, they usually say "Oh, I get a few more miles out
of
>each tankfull, but they don't really know how much.

OK, try this:

'94 5.2

Off dealer lot: 5 tanks at an average of 15.8 MPG

K&N open element filter: 6 tanks at an average of 16.4 MPG

All Synthetic fluids + K&N oil filter + carbon fiber brake parts: 5 tanks
at an average of 18.2 MPG

this configuration lasted for a while and periodic checks showed a low of
17.6 and a high of 19.9

November 1994, new 'oxygenated fuel': periodic checks drop to low of 16.9
and high of 18.2.

Added MP computer, Jacobs ignition and indexed spark plugs. (oxy fuel
discontinued) low of 17.8 and high of 20.7 with average of 19.6 over 8
tanks.

Periodic checks over the summer stay about the same.

On Oct 12, I added 31x10.50 Mickey Thompson tires on American Racing
Aluminum rims. Next two tanks dropped only slightly, but now all
calculations are performed on 'corrected mileage' based on the published
diameter of the MT over the published diameter of the factory tires. Since
the history of these 'corrected' numbers are not firm, I am going to
withhold the numbers and simply deal with trends.

Fall and winter this year have seen the typical 2 MPG drop of the oxy fuel,
and a slight drop overall. I suspect that the oxy sensor is starting to
get worn, so that is on the replace list for spring. I see no benefit to
replace exhaust parts yet as most cruising is done under 2500 RPM, and
around town its closer to 1200. Headers and a more open exhaust are likely
not going to make a major difference for the cost.

Hope this is what you wanted. I keep a log of all modification,
maintainence, and periodic mileage checks. The truck now has 31,000 miles
on it in just under 20 months.

Engine oil: Castrol Syntec 5w-50
Trans: Castrol Syntec 5w-50
Xfer case: Mobile 1 Synthetic ATF
Diffs: Valvoline Synthetic 75w-140

Oil Filter: K&N Performance
Air Filter: K&N open element 14"x4"
                        AirForce Pre-filter

Ignition: Jacobs Omni Pak
Wires: Jacobs
Computer: Mopar Performance
Spark Plugs: Champion Gold .045" gap indexed.

Fuel: Shell 93 or Irving 93 mostly.

Christopher Siano | "How do you control this thing?"
CSiano@Banyan.com | "Who Cares, Go FASTER!"
                     | -Suicide
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