port size, what rpm range?

Discussion in 'Classic Mustang Specific Tech' started by muh'stang, Dec 16, 2003.

  1. I have an '85 302. Im undersizing & offset grinding the crank to accept 5.2" rods, leaving me with about 317cid. The heads I want to use are from a 351w, car. They have 1.94"X1.76" intake ports, and 1.24"x1.04" exhuast ports. The 302 heads have a 1.94"x1.04" intake port, and identical exhuast port. What rpm should I try to make my power at? ill hope to run a slightly overstock cam, but things change.
  2. The dimensions for the intake ports are wrong. I've seen those dimensions somewhere else in a database, but wherever they came from they are incorrect. They are more like 1.94 x 1.25. I ported my intakes to 2.10 x 1.26 approximately (whatever the felpro 1262 gaskets are). The exhausts are ported to 1.48 x 1.25. 160 cc intake volume now and 1.94/1.6 valves. Just shy of 220/180 cfm flow. Ported, they'll support your 317 to 7000 with the right cam.
  3. Thanks for all of the other info. So how do I figure out what the right cam is?
  4. also, I was thinking about it at work today. All this port size and head flow makes my brain hurt. Will these heads support my goal for about 300-325 flywheel hp with the right cam?
  5. Sure...easily. It's a total package though. Heads, cam, intake, headers, compression ratio, ignition system.

    If you really want to pull nicely to 7000, a 282S Comp Cam will do the trick and be streetable in a daily driver. If you don't mind even more radical idle and less idle vacuum ( not good if you have power assisted brakes ) and a higher stall converter (if you have a automatic trans), then a 294S would be a real killer 317 street cam. Both cams I mentioned are flat tappet solid lifter cams. Compression ratio should be about 9.5:1 for the 282S and at least 10:1 for the 294S.

    A dual plane aluminum aftermarket manifold and a 600 to 650 cfm carb would also be in order.

    Where is the location you mention in your profile?
  6. I live in BC Canada.
    Thanks for all the input, Im actually going EFI with Speed Density. Now I know the stock stuff pretty much cuts out around 275 horse. That part is easy to upgrade, however I would like to have a long block ready to achieve 350~ rwhp so I do not have to take it all apart again. I am going to use an 80s model SROD 4 speed manual transmission. My car is a 1987, I posted in here because you guys know how to make an engine run without thousands of dollars in bolt-ons that barely do any good.
    I dont know what size valves yet, but for kicks lets say I use the stock ones....are you still reccommending the comp cams 282s? (that was a Comp. Cams product right?)
    I used to think that the bigger the ports the more power you have all around. Then I learned that well in alot of cases some heads will hurt your "street" performance, as well as some cams. So Im in left field wandering around lost, thanks for the help.