Tuning a 460

[junkyardjeff]

I was told it could not be done but I am going to see if I can squeeze a little more gas mileage out of the 460 I have in my 66 F250,I do not know what was done to the motor but would run circles around a untouched 460 I had in another truck and has gobs of torque right off idle so I am going to take advantage of it.     I had to replace the vacumn advance on the duraspark distributor and the replacement is adjustable so I got it to where I want it and slowly bumping up the initial advance,the plugs are burning a medium brown so I am going to get a tuning kit for the edelbrock carb and see if I can get it a touch leaner.      Right now it does better then the original 352 around town so even with the 3.54 gears I will need overdrive on the highway so I will have to decide if I want to keep the C-6 and add a Gear vendor type o/d or go with a manual trans and find a NV4500,right now I am going to concentrate on the motor burning every drop of gas and not wasting any.      I am going to see if I can get this thing to get around 18 on the highway empty and I know when its loaded mileage goes out the door but it will be running around empty more the 90 percent of the time,when I am done I do not want this motor spinning too much over 2000 rpms on the highway in o/d and will see what happens.

[wayne petty]

invest in a vacuum gauge... an air fuel ratio display...  a rubber 2 gauge mount.. or a piece of wood you have drilled and trimmed to sit on the dashboard.. or mount as a temp installation.. use a cigar lighter type of pigtail to power it and make it easily removed...

find a muffler shop that will install an oxygen sensor bung in your down pipe or collector if you have headers...

if the oxygen sensor in in the down pipe.. just past the manifold.. you can use a one wire sensor...

if you have one thats in the collector.. you really need a 3 wire heated oxygen sensor from a 94 chevy truck application.. some switched power to supply the heater circuit...


now you can get in and dial in your air fuel ratio..

at idle...  during idle transition..    on the primaries..  during cruise acceleration..  on the secondaries..

what.. its something that i picked up from reading C9's (rip) posts..

about tuning for cruise rpms..  when i dug deeper..

there is something called the IFR... idle flow restriction.. it should be called the idle transition circuit restriction...

at idle.. the fuel being drawn into the engine is limited by the idle mixture screws...

when you come off idle..   there are idle transition slots that start to feed fuel in a progressive manor..   because the throttle blade is opening and exposing more of the idle transition slots.. you get more fuel pulled thru..

this allows the carb to flow and keep a decent air fuel ratio from idle. thru idle transition to low speed cruise where the primary mains and the idle transition circuits are BOTH feeding fuel..

if you get the primary throttle open far enough.. the fuel from the idle transition circuits stop most of the flow ...

in edelbrock carbs.. the idle transition feed restriction is  in the primary booster venturi behind the idle air bypass bleed...

http://i1207.photobucket.com/albums/bb476/waynep712/AFB_AVS_airbleeds_zps9b83323f.jpg


http://i1207.photobucket.com/albums/bb476/waynep712/AFBidle_channel_restrictor.jpg


the issue you are going to have.. is a big engine.. 460 on a universal sized carb.   the idle flow restrictors are going to be on the small size.. this might show up as a bog.. but with the air fuel ratio display.. you will see that the A/R goes lean off idle...  


picking up a precision jet drill set..  or one of the welding tip drills from snap on or some other suppliers.  and going up ONE drill fraction size at a time..  on both idle feed restrictions..  and driving it..

why go up on the idle feed restrictions.. these are set up for a 350.. give or take.. when you install on a bigger motor.. you need more fuel thru the IFR to keep it from going lean before you bring the mains in... if you have this issue.. you will have to tip deeper into the throttle to make the engine run at these RPMs.. and that will cost you more fuel...


there are also .. spring kits for the primary pistons.. these need to be selected so that the pistons are fully seated at idle in drive.. but as you tip into the throttle.. the pistons just start to move upward as you apply load..

i have wanted to drill and modify one of the small hold down covers for a long time.. with some kind of tube.. so i can drop a dip stick in.. and monitor the piston movement depending on the engine load...

there is a LOT written for power tuning the various carbs... but very little written on economy tuning...


here is an article to start you off.. but does it really talk about the idle transition circuit tuning..    perhaps i should drive over to edelbrock and get with them about this issue being glossed over in much of the info..

http://www.mustangandfords.com/techarticles/engine/mufp_0501_edelbrock_carb_tuning/viewall.html

[Warpspeed]

Right now it does better then the original 352 around town so even with the 3.54 gears I will need overdrive on the highway so I will have to decide if I want to keep the C-6 and add a Gear vendor type o/d or go with a manual trans and find a NV4500,

Problem with the C6 is that it does not have a lockup converter, and fitting an overdrive to it may not help as much as you expect.
If you want to stay auto, how about an E40D transmission ?
This has both an overdrive and a lockup converter, and being electronic, you can tune it to work exactly how you want it to work.  

Or go full manual transmission.

Taller gear may only be of benefit if you live in dead flat country.
If you live in the hills, taller gear than 3.54 may actually hurt economy.
A good spread of ratios + overdrive will give the best of everything.

[Warpspeed]

Right now it does better then the original 352 around town so even with the 3.54 gears I will need overdrive on the highway so I will have to decide if I want to keep the C-6 and add a Gear vendor type o/d or go with a manual trans and find a NV4500,

Problem with the C6 is that it does not have a lockup converter, and fitting an overdrive to it may not help as much as you expect.
If you want to stay auto, how about an E40D transmission ?
This has both an overdrive and a lockup converter, and being electronic, you can tune the electronic brain to work exactly how you want it to work.  

Or go full manual transmission.

Taller gear may only be of benefit if you live in dead flat country.
If you live in the hills, taller gear than 3.54 may actually hurt economy.
A good spread of ratios + overdrive will give the best of everything.

[junkyardjeff]

I will most likely go with a manual trans to get o/d and would a Holey carb be easier to tune for mileage.

[wayne petty]

attention.... this is a GREAT training manual that everybody with an edelbrock AFB/ AVS/thunder carb should read

http://www.mymopar.com/downloads/mtsc/273.pdf

this is the companion video for it...

everybody should book mark this..

the theory for one carb is the same for other carbs.. they just have the components in slightly different areas..

somebody might also want to paste these links in the TECH section...

[kb426]

One of my friends had an efi version in a 3/4 ton pickup in the late 80's. he drove reasonably and made 20 mpg with it. I believe it had a manual trans. I had several 460 powered trucks in the 70's. The best I remember getting was around 12. That was with autos and 373 gears with 9.50 x 16.5 tires. I never had a tach but was driving 70 mph most of the time. It will be interesting to see your progress.

[junkyardjeff]

Its going to take me some time to do this,no matter what I do with a trans its going to cost me some money.  There is going to be no cheap way to get overdrive with that motor and sometimes I think I should of put a 351-w and AOD in it but could not pass up the 460 since it was cheap.

[tomslik]

old trick was to use a 429 timing set (69ish) on a 460...did wonders for the power, can't tell ya about the mileage...

[jaybee]

Makes sens to me, tomslik. Some Ford motors used a retarded cam after about 1971 or so...I'm not sure exactly when.

[junkyardjeff]

I think it has the older timing chain set since it runs great and has plenty of power,it would run circles around the other 460 I had.

[chimp koose]

ford cams were retarded starting in 72 if I remember. Before you go in and advance the cam ,I would make sure the exhaust was doing all it could to help with economy. Seems a bit less labor intensive.I advance the cam whenever I do a timing set . Noticeable boost in low end torque.

[kb426]

I changed the timing set on a 78 Ford pickup. It was doggy before and doggy after. Same mileage too. I had a 74 that ran great, a 77 that was ok and the 78 that no mater what, it was poor. I let the next owner mess with it. The timing set that I put in the 78 was 4 degrees advanced compared to the original. Because it made no measurable difference, that must have been something else going on. This was a new truck with about 5000 miles on it.

[jaybee]

A bit o/t but this thread reminded me of one of those stories I haven't thought of in years. Through the mid to late 70s there was a shop in the Omaha area with a neat little side business swapping 429 CJ or SCJ engines and Sure Grip diffs into then-current generation F100s. It was a very smart move for them. The 429s were available from Ford in long block form at very reasonable prices (as I recall brand new Boss 302 long blocks were $1400!). 460s were current in Ford trucks at the time so everything from engine mounts to accessory brackets was available new.

One of those trucks came to live in my home town and it was a sweet ride. The owner decided one night while scoopin' the loop to impress someone or maybe all in visual range from a stop light. He nailed it off the green and smoked those L60-15s for a solid block.

I don't know if he impressed the people he meant to, but the town cop that had pulled up right behind him at the light was decidedly unimpressed.