So I've got the top end of my F4te 351 taken off, with the motor still in the truck 1993 F-250 ZF5 4x4 RCLB. Truck had good compression and cylinder walls look good so I wont be doing a total rebuild. Im not looking to "build" power, all I want to do is free up whatever i can from the stock heads and intake. My plan is to port & polish my stock heads and rebuild with new valve seals and springs. I have a nice set of ceramic shorty headers from my old fox body that i plan to utilize on the 351 assuming i can weld a bung for the EGR system. My question is, what benefit will 1.7 rockers give me and should i bump the injectors from 19lb to 24lb? Also, is it possible to massage the upper and lower intake to smooth the flow? Anything else I should be doing?

 

Do port the heads putting most of your work into the exhaust ports but don't waste any of your time polishing anything. New Valve guides and seats would be money better spent than new valves and seals, only replace the valves if they don't clean up with lapping compound. The lower portion of the stock intake is a choke point, port match the exits to the heads and radius the kink in the runners as much as you dare. 1.7 rockers are a good addition, they won't make a drastic improvement but it should be noticable across the board. Mustang headers can be problematic on a truck, the collector exits are in a different place and at the wrong angle to mate with the truck Y-pipe and even if you replace that with something custom you may find the frame and firewall make connecting to them more difficult that it needs to be. You can't just install larger injectors and expect the computer to compensate, and besides that the stock 19's can supply upwards of 300hp so there is no need with your current mods.

 

Thanks for the input, I'm glad you mentioned the computer as my other question was with the porting and increased exhaust flow and air flow would I benefit from a tune of some sort? There's a place down the street from me that does dyno tuning, I dont know whats possible being how its not OBDII.

 

Tuning these old EFI systems requires some special hardware and most likely a PCM change in your case as there is very little support for the regular truck PCMs, but it's not likely that is necessary with the relatively minor mods you are performing anyway.

 

Ok good to know. My ultimate goal is MPGs, with that in mind is a cam worth it or will that adversely affect the mileage?

 

If your motor has the F4TE roller cam already.. which should be pretty obvious with the intake off as you'll see the spider assembly, then I'd suggest just adding 1.7 rockers to optimize lift.

 

Unfortunately I dont have the roller cam, I do have a 89 HO 5.0 just sitting around, does that have the roller cam or any other parts I could harvest off it?

 

The 5.0HO does have a good roller cam in it and as long as your 5.8 block has the raised bosses in the lifter valley where the spider bolts down you can transfer the complete roller assembly(cam, lifters, spider, dogbones) to the 5.8. You will need longer pushrods and the Lightning guys liked to advance this cam 4 deg with an adjustable timing set to retain low rpm torque, and I'd suggest adding 1.7 rockers to optimize total valve lift.

 

When you say "optimize" total valve lift, do you mean that something else happens other than a 6% increase in overall lift over stock?

 

Stock heads flow their maximum at 0.500" lift so the closer you can get to that the closer you are to maximum airflow efficiency. You'll still be a fair ways from what I consider optimum airflow for this displacement which is about double what the stock heads flow, but there is no way to get that much air through the stock heads no matter how much you port them and that would also require double the fuel flow so you can't get there with the stock EFI system anyway, but you may as well take what you can get.

 

What length push rods will I be needing to run the 5.0 roller cam?

 

You need pushrods for a stock 5.8 roller motor which are 7.567".