I'm planning on hopping up my 360 in the near future, and I want to collect suggestions, and make sure I'm on the right track with my plans. First, the vehicle is a '74 F-250, NP435, 4:10's and 33" tires. The truck is already equipped with an MSD 6A ignition, long tube headers of unknown manufacture, and 2.5" dual exhaust with what looks like flowmaster mufflers. Cruise RPM is about 2700 at 60. I'm looking for an improvement in HP and torque, especially from off idle to about 4500-5000 rpm. Also, I dont want to totally kill the fuel mileage that I already have. (currently about 10.5-11 MPG at a steady 60 MPH) The truck is a daily driver, and will be used for occasional 4wheelin' and towing. (and for an occasional blast thru the gears, just to hear a healthy FE roar!) I'm planning on bolt on's now, and possibly a 390/410 conversion in the future. Anyways, here's what I've got planned so far. 1966 390GT S-code intake (already have it), Edelbrock 1406 600CFM carb, Crane Powermax 272 cam (pn 343941) A friend also suggested a carb spacer. Any recomendations? 4 hole or open? 1", 2" or just leave it off? Can this cam be used with the stock valvesprings, and non-adustible rockers? If I have to change the rockers, are the Harland Sharpe rollers worth the extra money? I'm looking forward to getting some good advice from you guys so I don't spend my hard earned money in the wrong places, as I don't have much of it to spend in the first place.

MaydayMike
1974 F250 4x4
1966 Cadillac Fleetwood (for sale)

 

[updated:LAST EDITED ON 07-Jan-02 AT 08:16 AM (EST)] MaydayMike, sounds like your off to a very good start. What shape are your tires in ? I ask only because upgrading to a set of 35s would be an easy way to reduce rpm a bit. I've got 35/12.50-15s on mine and I love 'em. Anyway- if your playing with carb spacers, the 4 hole jobs seem to work better on trucks, when you're looking for low speed power. They are cheap enough that you could get a 1 and a 2 incher and see which one helps you best. I'm running a 343801 cam ( one size bigger than you are considering ) in one of mine with the stock rockers and pushrods, they're doing fine. I did use the new springs that Crane recommmends and would suggest you should too.Also, Spacers instead of the springs between the rockers would be an easy upgrade. When you pull the heads off to put on the new springs, consider getting the 1.65 428CJ exhaust valves installed (with hard seats). The bigger valve and some pocket porting will do wonders for exhaust flow. Now if you really want to wake up the power between idle and 5000 rpm, the longer stroke engines are the way to go. The differance is like night vs day. Getting a 390 crank and rods is easy and will add about 100 lbs-ft of torque all across the curve. The 360 suffers from only a 3.5 inch stroke. The 390 gives you 3.784. As if that weren't enough, adding a 410 or 428 crank ( they're the same ) will add ANOTHER 80-100 lbs-ft of torque on top of what the 390 crank will give. But the 3.98 stroke cranks are getting scarce and exspensive. 390 cranks are cheap and easy to find, any year will work. Have you considered helping the oil flow in this soon-to-be thumper ? Oil fixin' is mighty cheap insurance against future problems. DF

 

Thanks for the info! My tires are nearly new, but I'm already planning to got up to 35's when they wear out. The oiling mods are also in the plans, when I put in the longer stroke (390 or 428) crank. What advantage are the solid spacers on the rocker shaft vs the stock springs? Where do you get 'em? How much?

MaydayMike
1974 F250 4x4

 

>Thanks for the info! My tires are nearly new, but I'm
>already planning to got up to 35's when they wear out. The
>oiling mods are also in the plans, when I put in the longer
>stroke (390 or 428) crank. What advantage are the solid
>spacers on the rocker shaft vs the stock springs? Where do
>you get 'em? How much?
>
> MaydayMike
>1974 F250 4x4


you can get a 390 stroker crank from DSCmotorsports for $375 you'll need chrysler slant six rods I believe, but they should be able to get everything you need, solid spacers are just extra protection. You could also step up to Dove rocker arms (Comp Cams 1046-16)which are better than the Harland Sharps and slightly cheaper at $308vs$319 for the Harlands.