As I am looking to pull the 351W out of my 95 F350 in the near future to at least change out the oil pump (pressure reads a bit low) and replace a leaking pan gasket, I was curious if any of you engine gurus might have some thoughts on whether the GT-40 or GT-40P heads would be the preferable upgrade. While both utilize the same size intake valve [1.84"] - marginally larger than the stock E7TE heads' 1.78", the GT-40's exhaust valves are 1.54" versus the GT-40P and E7TE @ 1.46". And, how does the GT-40P head's smaller chamber size [58-61cc] impact power/torque when compared to the GT-40 and E7TE size of ~62-66cc? I currently have a set of rebuilt GT-40P heads on the shelf but am not opposed to saving them for another project and finding some GT-40s if they would be a better choice for this application.

It burns virtually no oil and recent compression check showed readings of 140-150 PSI at 454,000 miles - virtually unchanged from the prior test done at around 250,000. And, while the engine is out, it should probably get a new cam to improve breathing. Thoughts on upgraded roller cams as well for improved low end torque for my 7000# baby?

If upon teardown I find that a rebuild of the bottom end is necessary I will probably also do an internally balanced stroker build. But if the bottom end appears ok I plan to just leave it alone and see just how far it will go.

dn.

 

Most definitely put the GTP heads on the motor, the valve sizes are but one part of a much better head design that flows 30% better than the stock E7TEs.. that's 196/138cfm vs 155/106cfm. Stock CR on the 5.8 is about 8.8:1 so P heads are only gonna push that to just over 9:1.. nothing to worry about.
The stock cam in that vintage motor is a really good RV grind, if you were interested in making more HP there are others I'd suggest but considering the size of your trucks I'm gonna say just add 1.7 rockers to get more valve lift and help those better heads move more air.

 

The 2-3cc (nominal difference) is nearly negligable on a 351 displacement motor. Just me, but I'd opt for the std GT40 heads, these don't have the odd spark plug angle that complicates header choices.

 

Thank you for the info. Do you have any recommendation of particular brand/model of rockers?

dn.

 

Pedistal mount Crane or Ford Racing rockers are a sure bet but others here have had good luck with Scorpion as well.