Originally Posted by MBDiagMan

Although you are making conflicting statements, we are getting a better picture of what you're looking for.

Modifying an engine for more horsepower will very rarely provide better fuel economy. Typically horsepower is increased by moving the torque peak to a higher RPM. This is NOT conducive to better fuel economy. The world is a compromise. You usually can't have something without giving up something else. Todays engines have accomplished more power and better fuel economy, but they have done it with Millions of dollars in research leading to new engine designs, fuel injection et al.

When you indicated that you want more horsepower and better fuel economy, the story of the teenager wannabe musician came to mind. The teenager told his Dad "When I grow up I want to be a Rock Musician." His Dad said, "I'm sorry son, but you can't have it both ways."

If you're looking for fuel economy, your basic engine is very close to being optimized. Consider your heads already modified. Some people modify small Fords by using the very heads that you have on your engine as their head package upgrade.

There are two modifications that come to my mind that would offer more torque and better fuel economy. The most important improvement would be a set of small tube, full length exhaust headers and properly rejet the carburetor to take advantage of them. This would provide a significant torque increase throughout the entire RPM range.

The second thing would be an RV type cam. The cam in your 73 engine was ground in a crazy era when Detroit was scrambling to find their way to cleaner running engines. In the course of this effort, the 73 engines were some of the worst. They were killing power and fuel mileage in an effort to achieve less emmissions. A real good cam would be a Comp Cams High Energy or equivalent from other cam grinders. These are designed for low compression engines and will increase cylinder pressure and provide more torque with a fuel economy improvement.

My $0.02,

Originally Posted by MBDiagMan

THUMPIN,

I agree with what you are saying in principle. If, however, he has a 2V, I don't think that it's too much head. That head could be too much on a 289/302, but not on a 351. If he has a 4V then you are most DEFINITELY correct in saying that he has too much head. Also the 270H would make a great cam for a 351C, but if economy is your goal, I think a notch down to a 262H would be a better choice. Back to the predicate, if it's a 4V, then the 270H would be better because you have no hope for bottom end power anyway.

Also, new valves won't be necessary unless they are too thin to grind.

OP, is this a 4V or 2V engine? You can look on the top corner of the cylinder heads for 2V or 4V.

Originally Posted by THUMPIN455

Nah I know he doesnt have too much, Cleveland heads are just right.. The 270H makes lots of bottom end, it has power right off idle, fun cam. The 262H works good too, and it wont lope quite as much, havent run one of those in a 4V yet. The 274XE in the Cougar is a bit large for wanting economy, and it will need more stall or gears. Have you tried the smaller XE in the 260s? I dont remember what they call it right now and I dont want to bother to look it up.

I tend to put new valves in since I dont trust the really old ones anymore, lost a 4V to one of them. Even my Pontiacs get new valves now, just peace of mind really.

OP. This is an M head, but its pretty much the same as a 2V head. See the top where there is a bit of paint showing on the corners? That is where you will find a 2 or a 4, if it doesnt have anything there like this head, its a 2V M head. Very easy way to tell if you have a 2V or 4V if it has an aftermarket 4 barrel intake.



Just for fun and basic info.. The left head is a 4V, the right one is a 2V. There is a bit of a difference in the ports, wouldnt you agree?

Originally Posted by stang_boy2011

If I have been told correctly that 2V is 2 barrel and 4V is 4 Barrel, then I have 4V.

Originally Posted by MBDiagMan

You are told correctly, however if it has an aftermarket carb and manifold it could easily be a 2V. The 2V refers to the engine in it's original state. There are many more differences between a 2V engine and a 4V engine besides the carb itself. THUMPIN's pictures show you the difference.

To know if it is a 4V or 2V, look at the corner of the head that shows as a blue triangle at the top of THUMPIN's pictures. It will say 2V or 4V. THAT is what we are looking for so that recommendations can be made on the engine.