Hi guys! I have not been around here much as I have been working almost exclusively on the Mustang (69 Vert).

So far, the truck has been going OK, with minimal attention. Now that I have a bit more time to get to it, I'd like to tweak that Six for better mileage and cold start. I am not looking for a hot-rod (yeah, right, hot rodding a straight 6...), just improving the ignition and carb, with a little more umpf if possible. I know about the DSII conversion, but I am ok with Pertronix.

So far, I have a used in good shape Offenhauser 4bbl intake manifold, the original intake is still on the engine. I'd like to do the following:

New carb Summit SUM-M08600VS, 4bl, electrical choke, square bore, 600CFM
Pertronix II (91261) and coil 12V
Distributor: original is in place, with all the modules and harness.

First question is about the distributor. Should I change it for a new old-style points distributor, like that Cardone 30-2610?

Second question is about the whole process. What should I plan to do and how? I tried to search all over for some details but I came a bit bare on that particular conversion. I have the new carb adaptation more or less figured out, though all sound advice is welcome.

Thanks all for your help.

 

Unless you plan to race your 300, there is no way you'll need a 600 CFM carb; a 390 or 470 will be perfect for a DP manifold. If you have a C (single plane) manifold, a 2 barrel carb (Motorcraft 2150/Autolite 2300) will be best to maintain the low-end torque of the stock 1 barrel.

If you have the stock DSII in place, that will be perfect with the Offy manifold with a better curve setup and advanced timing.

Also, if you have not yet, search up the EFI exhaust conversion. The stock exhaust manifold is undersized on a stock motor, much less a hopped-up one. To save complication, you should likely do the intake/exhaust upgrades at the same time, complete with a Remflex gasket set. Make sure to use studs to ease the installation of the 3 separate manifolds. However, you'll need to make or buy a coolant-heated intake heater that typically splices into the heater core plumbing, since the stock "log" exhaust is what heated the carb.

Hope this helps!

 

That pertronix unit only fits a points style distributor. If you want to use it, you will have to get a older points dist for a 300 six.

I know why you want to use the 600cfm. They are way cheaper. Those smaller 390 cfm carbs are like double the price. I think some guys have used the 600, even though it is a little big.

If your goal is fuel mileage, you had better stick with the 1 barrel stock type carb and intake.

 

That's your best advice, the stock carb will return 20 MPG easy, assuming optimum gearing/speed

 

Thank you guys for the advice.

The carb and distributor are stock, like the rest of the truck, and I do not get 20 mpg or even close to that number. As I said beforehand, I haven't looked too much into it so far due to my other project vehicle. As it is pretty much done, at least the big part of the restoration, the focus is now on the truck.

If I keep the stock carb, it will certainly need a rebuild. I guess it is the starting point. Then I'll have to really look into the engine bay to figure out what has been done by the PO, cuz it seems to be somewhat messy.

Thanks again for the info!

 

the 300 is in no way an economizer. its just not designed for such.

its bore stroke , head design and so on make it an under 20 mpg engine.
the one barrell off the falcon from the mid 60 era seems to get you closest to 20. unloaded with manual trans and tail wind.


it is designed for heavy work loads, longevity, and reliable simplicity.

expect 13 be overjoyed if you get 14 or 15

as is with most things ford, GM had the better ideas.
use the hei or fords duraspark if you must
gm rocker arms

gm valves if you pull the head.

port passages will give you most bang for money.
headers: waste of money

efi manifolds; great if you build carb heat/cooling.

my favorite combo is
factory intake FISH carb and efi manifolds....zoooooom baby watch her fly

be sure you play with spark plug heat ranges #1 and #6 are too cold/hot respectively.

oil cooler from a 460 pick up will make your engine purr not rattle.

300 loves propane, consider that for economy.
propane here under 2 dollars/gal.


theres more but how far u wanna go with this?

coli on plug, fitech, turbo, electric water pump, its all been done and the six loves it all.

someday u will want to rid urself of the fiber cam gear

ur motor has 200K left in her with care thats a lotta gas.

 

Your 1986 was "born" with a computer controlled feedback carburetor. The feedback system, when working properly, performed well and returned excellent gas mileage. My son's 1984 also had the feedback system and could get 26 mpg @ 65 mph [before gasohol]. However, his had manual OD transmission and 2.47 rear gears. Your truck, with automatic transmission and no overdrive will not get as good gas mileage, but should still get 18 or better mpg.

My 1986 with 4.9L, 4 speed OD and 3.08 rear gears started off life [when I bought it from the original owner] getting 8-10 mpg, due to the feedback system no longer working. Changes have been made and it now gets between 17 and 24 mpg.

Check under the hood and see if you see missing or cut vacuum lines. Is the MAP sensor and Oxygen sensor still connected? Check your distributor and see if there is a vacuum line going to a metal can on the base or is there a group of wires going to the base of the distributor?