There is a guy over in the Fordsix forum who is making X flow heads for the 300, and also U flow heads with larger ports, valves, etc. The issue with the 351 heads is that they are three sections welded together, not two. Leakage of coolant is a prob, too. On that note, I once interviewed a 300 racer who happened to be a retired ford engineer. He swore that Ford produced some 300's with a x flow head and turbo setup that made hp equal to a 460. I would love to open the hood on some old truck in the junkyard and find a 300 with an x flow head and a turbo! That would make my decade!

 

Just to add my thoughts to an old thread, the first thing I thought of when reading all the early posts was, what rear end gear ratio was in the I6-equipped trucks, vs the V8-equipped trucks? Lots of sixes come with lower gearing in the diff, don't they?
I'm guessing that with options they can all be similar, but going just by some (Early Broncos for example) Ford installed 3.50's with the V8's and 4.11's with the small sixes (the 300 was never an option for them). With optional 4.11's for the 8's and 4.56's for the 6's.

And carburetion? The V8's had modest sized 2bbls, but what did a 300 come with for number of venturii and CFM? A smaller carb might not have any top end, but will usually pull super strong off the line.
Someone mentioned the "massive flywheel" of the six, which would make a difference. But were they really that different? If so, that would account for some off-idle feel as well.

Just some random thoughts thrown into the mix.

Paul

 

My first truck was a 1978 F100, 300 six , 3 speed on the tree. It was a bare bones custom, 2 wheel drive. I wish I still had that old truck, it would haul any load I threw at it . Dad needed hay for the horses that summer, we put 52 bales on . On the way home the road dipped into a gully. I wasn’t driving fast, maybe 30 mph. The truck went down into the gully and back out in high gear. Dad says “ there is no way a six cylinder could do that”. When we got home first thing he made me do is open the hood, just to prove it was a 6. That old truck wasn’t fast, and always got 17 mpg, loaded or empty.

 

I don't want to say that any engine is 'better' than another, because each has +'s and -'s. Each is good when used according to those traits. I loved the 390 I had. With it I towed a trailer from LA to Portland, OR and back. It also took my son and I 700 miles down Baja with a boat and camper, and loaded with enough c...p for an army, and it never batted an eye. Now that I no longer tow, I have a 300 that is fun and peppy, but also highly modified. I have no fantasies about it being faster that a v8. It is a tractor engine that supplies power at low rpm's, and, with the mods I've done, it supplies the hp of a stock 360 with a 2v carb. But for anyone wanting about 250 hp, I'd say to go with a v8. Because to get a I6 up to that level takes a bit of money, whereas you just drop a stock 360 in and bingo, you have 250 hp.



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