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Original Message
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| Alright! 1974 is something I can work with. |
| By Dave Shoe - 02/11/2001 3:19:19 AM; IP 216.243.158.45 |
First off, you'll need to get a cam if you want a 1:1 HP:CID ratio at the flywheel. Emissions regulations sorta put the binders on any camshaft that could deliver that kinda performance.
Another complication is the compression ratio. Since 1971 was the last year Ford published HP ratings for your motor, you'll sorta have to extrapolate to realize your HP.
In 1971 the CR for the 390 2V truck motor was 8.6:1 (8.4:1 for the 360) and the HP was 255 @ 4400 (215@4400 for the 360-2V). Torque 376 @ 2600 (327@2600 for the 360). By 1972 the CR hit 8.2:1 (8.0:1 for the 360) and they no longer spoke of HP or torque numbers at all. From 1973-76, Ford no longer even published the compression ratio, though the camshaft never changed from the 1971 numbers.
Interestingly, the D4TE block of 1974 frequently had reinforced main bearing saddles (but normal thickness 390 cylinder walls), so that block was designed to take a bit of a hammering, so long as it wasn't bored out too far. With the historically good rods and crank of the 1964-later 390, this appears to be a shortblock that can handle some extra horsepower.
Sadly, it also means you need both pistons and cam to make your shortblock roar. The good part is that 1968 390GT pistons probably weigh the same, so you probably need not rebalance your motor if you wish to switch pistons (I'm presently researching piston weight criteria - don't have results yet). You have "full emissions" heads, which have been the norm since 1968 (and good for an easy 400HP, but limited beyond that point) - so you will need headers which mate to the relocated "full emission" exhaust runners (forget Hooker or Hedman, think FPA).
As I was trending, you'll need headers, an intake manifold (iron CJ, alum PI, or Ed Performer RPM), a carb, pistons, and a cam to get the HP you seek. fortunately, you can easily reach the 400HP number with this combo and live for a long time to tell about it. Note that with the new cam, a new set of lifters is necessary, as are stiffer valve springs and non-rotating retainers and locks. New valves are needed, in order to to work with the non-rotating type of valve stem locks, so you are talking non-trivial stack of ordinary parts to get the HP you seek.
You can save a few bucks by sticking with your stock exhaust setup. That will cost you a couple dozen HP, but you can always "bolt it on" later if you wish, and it's the best item to leave off outta the mix, should you decide to shave some cash from this particular upgrade.
Your 1974 motor really was set up for torque and emissions efficiency. While it's a solid motor structurally, it's not a great motor if you want cheap horsepower. It is a great motor for horsepower if you are ready to do a standard rebuild , however, as the cost of the higher compression pistons and a camshaft kit is pretty much the same as the same as the low-comp stuff.
I could go on, but will stop here. If you have questions, feel free to rattle them off. I've got plenty of wrong answers, and others around here can even offer proper advise.
Shoe.
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This thread, so far...
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