I'm not really looking to give up performance to get better mpg, but if I can increase both at the same time that would be great.


Let me put up my cam specs and build info tomorrow and I'll appreciate any knowledgeable input or advice.

 

What distributor and advance curve is in it?

 

Here is my cam info: Grind number: FF 280H-10

Intake Exhaust


Gross valve lift .530 .530


Duration at
.006 Tappet lift 280 280


Valve timing open close
at .006 Int 34 BTDC66 ATDC


These specs are for cam installed at 106 Intake center line


Intake Exhaust
Duration at .50 230 230


Lobe lift .3063 3063


Rocker arm ratio .00 .00


Lobe separation 110.0


This is all I have got, does it tell you anything more?

 

Performance Distributors electronic DUI


timing is set at 35 ?


Instructions with Dist say set the timing at 12 degrees to start.


As you can tell I am no mechanic and forgetting most of whatever I used to know.

 

Something you may not have thought of. As you lower your cruising RPM to 2200 you will be operating with the converter for lack of a better word not "locked up". I know it's not a locking converter but operating at or below the stall speed means the converter will bypass a lot of fluid, this will hurt mileage and produce tons of heat, a sure way to kill a transmission. I have a friend that had a overdrive auto and a 2200 rpm stall converter. In top gear @ 65MPH he was turning 2000 rpm. He had a trans temp gauge and temperatures would soar. He called the Transmission manufacturer and they told him to manually shift out of OD whenever temps rose to raise RPM and stop the bypass of fluid lowering temps. Just my .02.

 

Good info thank you. It sounds like I will be good turning 2600-2700 rpms on the freeway.

 

You have the magnum 280 cam, 230 @.050 on a 110 degree lobe separation. Get the 3.50 gear and you will be happy, let that cam work. You will gain performance and may actually get better gas mileage getting the cam up in the RPM range it designed to work at.

 

Here's the description from Comp Cams...

"Designed for hot street/strip cars, these COMP Cams Magnum series cam and lifter kits require a higher compression ratio, rear-end gear ratio, and stall torque converter than stock. With a very aggressive profile, these cam and lifter kits provide maximum top-end performance for your high performance car."

Chances of that getting any fuel mpg are very slim. 110 LSA is a good clue of that. I'm sure it runs strong once you get into the power band though. I installed a few of COMP 268s in customers cars/trucks long ago, They were excellent street cams.

 

I agree you should be able to use 2.70is gears if your big concern is milage .

 

I agree that a 460 with a conservative cam should be able to pull very "tall" gears. This is why Ford made the 2.47 gears in the 70s. However, his cam is not at all timed for low r.p.m. grunt. Tall gears and his engine would be a mis-match. You wouldn't get mileage or performance.