Hello,
I have a 1988 ford f150 that I am building up an engine for. The engine is a 90's 302 with roller lifters. when I opened it up, I found out it has 4.030 h654p pistons, which will setup for about 9.7 comp ratio once I go with my new heads and 0.027" head gasket. I have a fitech with aftermarket intake I am going to use to control fuel/air and timing.
I have a set of GT40P heads I am going to install. I was looking into best cam options, and from what I can tell, the option for me would be to go from 1.6 to 1.7 rockers, which would increase my lift from 379/395 to 402/419.
I am geared 3.55, with 33 inch tires and rough country 6" lift. At 110km/hr (68mph), my current 302 engine spins around 2100 rpm with my A0D in OD. So im looking for some increased torque at lower RPM vs big power at high RPM I will never reach.
comp cams cam selector tool recommends 31-412-8 cam for my application. It has 480/480 lift. This is a bit more than the lift I would get by got to 1.7, but likely not worth 300-400 dollars increase to my project.
if I go with the 1.7 rocker and stock cam option, I don't have to tear down my motor any further. The cylinder walls are very fresh looking, this donor motor has almost no miles since it was last rebuilt, so I am thinking of leaving crank bearings/seals/cam bearings alone.

Is there going to be major advantage to go to an aftermarket cam?
If not, can I keep stock valve springs when I go to 1.7? I am assuming I can, but not sure, as I will now be putting more force on the springs due to the higher ratio.

Thanks,

 

Have you measured the existing cams lift and duration? A '90 truck motor would not have had a roller cam so you may have a car motor, if it was a HO the stock cam is pretty good but if it was a sedan motor the cam is junk.

Something wrong there, I bet you have not recalibrated the speedo for those larger tires. My '90 had the same gears and trans and with 31" tires it only turned about 1800rpm at 110k so no way your motor is turning faster with bigger tires. 2100rpm would be 85mph by my calculations.

Unfortunately there is only so much low rpm torque you can get from this displacement, and the really bad news is you pretty much have it right now. The ONLY real solution you have to increase vehicle performance with this motor is build it to move more air which will make more HP but also more torque at the same time, and then you have to gear it appropriately to take advantage of the new powerband. That new powerband will be 2000-5000rpm give or take and appropriate gears for a 5.0 truck with 33" tires start at 4.10 and go up, it would not be unreasonable at all to put 4.56 gears in it.

As far as cams go I cannot overstate how much of a bottleneck the base cams were in this plane jane car and truck motors, you would see no gains at all from better heads, they were that bad. There are loads of aftermarket cams that will work well and produce loads more HP and TQ, some will require new valve springs too as the factory springs are pretty weak and run into coil bind at about 0.500" lift. But first figure out what you have now, if it is a HO a set of 1.7 rockers is all you need to get really good results. The HO cam produces 0.444" lift and 266 deg duration at the valve.

 

 

Yes the low lift suggests a sedan cam, a '94+ spec truck cam would be a cheap upgrade if you found one used, add 1.7 rockers and it pretty closely matches the Comp Cams 35-512-8

 

The stock springs on any late SBF are notoriously weak & are easily replaced for under $100 from multiple vendors.

Regardless of what you cam it with, float or dropped valve are easily avoided one of their kits.

Not the place to cheap out if you're doing any engine work over cause you WILL drop the hammer sometime.

Just sayin' mind you.