Cam duration is long & short and is measured in degrees. Lift is high & low and measured in inches. Camshaft duration is simply a measurement of how long the cam lobe keeps the valve open relative to crankshaft rotation. Remember the crank rotates 2 deg for every 1 deg of the cam so the crank has to rotate twice or 720 deg for every 360 deg of cam rotation. A cam with 270 deg duration opens the valve for 270 deg of the total 720 deg that the crank rotates.

 

Monsterbaby
Thanks for your input on this subject, I have an 86 F250 4x4 C-6, and I have been debating this subject in my mind for awhile now and I think after hearing you I will just rebuild a set of stock heads, do alittle porting on the exhaust, add a cam and call it good.
Thanks

 

if u put the dove head's on the 79 it would have around 9.5 comp if you want the 10.5 comp you have to use the 1968 to 1971 piston's to go with the head's.

 

Just to drag you into something a bit different,, because you seem to know your stuff.. I have a 1990 460 EFI (385) what type of heads are on it and should I search out something different.
I have not pulled it yet,, so I don't have casting numbers...I would like to once I piece things together end up in the 450+ HP range.. Just looking to save a few $ along the way by asking ??'s I read thru the above conversation..
Thanks....

 

This thread is 18 years old!

Are you wanting 450 flywheel HP? At what RPM? Usage of the truck?

Scotty J aka 'The Mad Porter' has 450hp EFI packages... Parkland Auto Machine - Home

 

yeah it is an oldie, 450 to 500 at the crank, just a truck occasional hauling of stuff..

 

For 'occasionally hauling stuff', you don't really need high RPM horsepower, you need low- to midrange RPM Torque.

Your truck has E7 heads, which are ~97cc and small valves. 88-92 pistons have a 7cc dish, and 1.752 compression height

The '93-97 7.5s use F3 heads, with 92cc and a slightly larger intake valve.
Ford changed pistons for the '93-up that have larger 15cc dish, but taller 1.772 compression height, and when combined with the smaller chamber heads actually keeps the compression ratio the same at 8.6. The taller pistons made the 'quench' part of the piston-chamber a bit closer to promote swirl that helps to reduce the chance of detonation/pinging.

My recent '95 rebuild used Keith Black 137 1.772" compression height flat-top pistons with a 2.5cc valve relief, the stock (rebuilt) F3 heads (shaved .005 for straightness) for a compression ratio of near 9.5:1, a mild computer-compatible Comp XE256H cam, mid-length headers and a mass-air SEFI conversion. All told, this increased HP and Torque by a bunch. The engine build software predicts ~430 flywheel hp at 5000, and more than 400lb/ft flywheel torque between 2000 and 5000rpm, with a peak of 490 at 4000. Factoring in accessory and drivetrain losses, we're looking at predictions of 360rwhp and 420rwtq.

Engine rebuild costs came in at around $3000, and I spent another ~$2000 for the rebuilt heads, headers, new radiator, new water pump, timing cover, hoses, belts, spark plugs, wires, and the (used) Mass-air wiring