Fuel Usage Difference Between 351C and 460

Posted in the other forum as well.

Hi guys!

So, 2wd truck, short bed C6, freeway flyer gears.

Pretty light for a pick-up. Base model 1989, hand crank windows, no AC, no carpet.



How much of a miles per gallon difference, if any, would there be between a closed chamber 4V Cleveland and a 460?



Both will have mild streetable "larger" than stock camshafts, free flowing dual exhaust.



The 460 will have a Ford version of the Performer RPM, Scott Johnston big valve D0VEs and custom cam, headers, probably around 9.5 compression.



The 351C will have stock iron intake and exhaust manifolds, custom Brent Lykins cam, stock unported 1971 CC 4V heads with stainless Ferrea valves, probably around 9.5 compression.



Thanks for any input.



Bruce

1EFF100 wrote:Posted in the other forum as well.

Hi guys!

So, 2wd truck, short bed C6, freeway flyer gears.

Pretty light for a pick-up. Base model 1989, hand crank windows, no AC, no carpet.



How much of a miles per gallon difference, if any, would there be between a closed chamber 4V Cleveland and a 460?



Both will have  mild streetable "larger" than stock camshafts, free flowing dual exhaust.



The 460 will have a Ford version of the Performer RPM, Scott Johnston big valve D0VEs and custom cam, headers, probably around 9.5 compression.



The 351C will have stock iron intake and exhaust manifolds, custom Brent Lykins cam, stock unported 1971 CC 4V heads with stainless Ferrea valves, probably around 9.5 compression.



Thanks for any input.



Bruce

This will all depend upon the part throttle Brake Specific Fuel Consumption at whatever torque level is sustained.

Most people don't believe me but my old 75 long bed
460 would get 15-16 mpg. It was bone stock with a holley 750. You really had to baby it to get that much though. On the other hand if you drove it hard you could watch the needle drop. It would average 11-12 mpg normal driving. 3.08 gears and c6.

My uncle had a '78 3/4 van with a 460 in it. Got 20 mpg. He attributed it to using Lubrilon.

stanger68 wrote:Most people don't believe me but my old 75 long bed
460  would get 15-16 mpg. It was bone stock with a holley 750. You really had to baby it to get that much though. On the other hand if you drove it hard you could watch the needle drop. It would average 11-12 mpg normal driving. 3.08 gears and c6.

We had a couple F150's in the 70's/80's and they got around 15. One SC and one regular cab. Three O gears in the rear, recurve the distributor and initial timing around 15/16. Advance timing via 429 timing set and an Edelbrock carb. Obviously that was driving normal as well. Back then 70 mph was fast and gasoline was actual gasoline not corn crap so I wouldn't be surprised if that would not be the results now.

maybe strap on come cow magnets.

The 1971 351c with stock 4v heads with 410 gears only got about 6 mpg that was with a 292h comp cam in my 69 F100 swb. If I was going to build another one for the street use I would use the 2v heads and buy a aftermarket 4v intake for the 2v heads

Uglytruck wrote:maybe strap on come cow magnets.

I don't know what that means.

69F100 wrote:The 1971 351c with stock 4v heads with 410 gears only got about 6 mpg that was with a 292h comp cam in my 69 F100 swb. If I was going to build another one for the street use I would use the 2v heads and buy a aftermarket 4v intake for the 2v heads

Man, that's terrible mileage. Did you have your foot in it all the time? lol
Pretty sure none of my 460s have gotten that bad.  

Uglytruck wrote:maybe strap on come cow magnets.

Back in the early 80's a farmer came up with the idea of lashing some cow magnets to his fuel line and claimed it produced some really good fuel mileage. Then the copy cats got in on it and made similar claims. Theories began to abound as to why it worked ( supposedly ) Some said it caused the fuel molecules to repel each other creating much improved atomization.  I seem to recall that there were some entrepreneurs that were even marketing magnets for that purpose.  Anyway....I was trying to be funny...didn't work

Uglytruck wrote:

Uglytruck wrote:maybe strap on come cow magnets.

Back in the early 80's a farmer came up with the idea of lashing some cow magnets to his fuel line and claimed it produced some really good fuel mileage. Then the copy cats got in on it and made similar claims. Theories began to abound as to why it worked ( supposedly ) Some said it caused the fuel molecules to repel each other creating much improved atomization.  I seem to recall that there were some entrepreneurs that were even marketing magnets for that purpose.  Anyway....I was trying to be funny...didn't work

Ah, okay. Now that you mention it, I seem to remember something about that magnet thing. Don't remember the "cow magnet" part though.  
Shoot, maybe I SHOULD try them. lol

1EFF100 wrote:

Uglytruck wrote:maybe strap on come cow magnets.

I don't know what that means.

69F100 wrote:The 1971 351c with stock 4v heads with 410 gears only got about 6 mpg that was with a 292h comp cam in my 69 F100 swb. If I was going to build another one for the street use I would use the 2v heads and buy a aftermarket 4v intake for the 2v heads

Man, that's terrible mileage. Did you have your foot in it all the time? lol
Pretty sure none of my 460s have gotten that bad.  

No that was driving it normal but it didn't get much worse putting my foot in it but when I would step on it it would move on out

Uglytruck wrote:

Uglytruck wrote:maybe strap on come cow magnets.

Back in the early 80's a farmer came up with the idea of lashing some cow magnets to his fuel line and claimed it produced some really good fuel mileage. Then the copy cats got in on it and made similar claims. Theories began to abound as to why it worked ( supposedly ) Some said it caused the fuel molecules to repel each other creating much improved atomization.  I seem to recall that there were some entrepreneurs that were even marketing magnets for that purpose.  Anyway....I was trying to be funny...didn't work

Anyone that believed that would probably believe that Covid 19 is a natural occurrence in nature. Even back when we had lead in the fuel, lead is not affected any by a magnet. I'm certain that fuel wouldn't be.

I don't have a truck, but I can say that when I swapped the 351C to a 429 in my 72 Mach1, the mpg went down by about 2, from 13 to 11. The engines were in similar states of tune & that was driving 'normally' i.e. having a bit of fun regularly.

In 1975 I bought a used 1974 F-250 with a 460 from a guy who said he just wanted to get rid of it because of the terrible fuel mileage.
It got about 8 MPG with combination city/highway driving,
I restricted the EGR; (not totally removed it),
put dual exhaust system on it,
Installed a straight-up timing chain set on it.,
re-curved the distributor ... 16 initial - 36 total in at 3,200 RPM; still used the vacuum part.

Just those 4 things got it up to 13 MPG ... a 61% improvement.

The Cleveland would be good for 2-3 mpg better.