Ryan5.0

I am about to begin my search for a pair of GT40Ps and have a few questions that I hope you all can help with.
At present, car is bone stock with the exception of K & N CAI and Flowmaster cat back. I'm currently building a new rear with 3.73s. I will also upgrade the TB, MAF, exhaust (O/R H-pipe + headers) and intake manifold at the same time.

What years did Explorers use the Ps?
Will stock length push rods work?
Can 1.7 RR be used without causing any clearance issues?
What camshaft would work well with this set up?
Any other considerations? (other than the headers)

Any other advice or info would be greatly appreciated. Thanks in advance.

347gt90

They came on 1997 explorers and use the same length push rod. Also you have to use special header for the GT40P's because of the sparkplug placement in the head.

meiguoren33

1997 1/2 and up Explorer, They'll have four bars cast on the outside and GT40P cast under the valve cover. Oh yeah, the BBK equals I have do not fit, I found out the hard way.

Ryan5.0

Thanks for your help.

gspfunk

BBK unequals or FRPP shorties will fit, or you can use plug wires w/ straight connectors. You should be able to use 1.7's w/o clearance problems, depending on how big of a cam you go w/. You will want a valve spring kit for the heads, though. Also, 96-97.5 Exploders had GT40's, 97.5-99? had P heads.

Ryan5.0

Thanks again. I am aware of the header issues, will probably go with FRPP. I thinking something along the lines of a "B" cam but would welcome suggestions on cam specs. Should I replace lifters at the same time? If so, what do I need?
At what point during this build does ignition need to be upgraded? Last question--Would I benefit from installing 24# injectors after the H/C/I and will I need to upgrade the fuel pump? Other than that I think all of my questions have been answered. Thank you to all that replied.

gspfunk

You should be okay on clearances w/ the B cam and 1.7's. I would still do the valve spring kit though. I would replace the lifters more for peace of mind, even though they may not need it at the moment, you don't wanna have to crack it all open agian in a few months or whenever they decide to crap out. The ignition should be okay...I went w/ and MSD blaster TFI coil and MSD superconductor wires, but they aren't a necessity. Upgrading the fuel pump would be a good idea, period, but it can wait if you don't have the funds to do it now.

Joel5.0

If you go with a B-303, or any other cam alternative, that will increase valve lift over the stock lift of .444", suggest you look into upgrading the valve springs as well, specially with 1.7 rockers. OEM exhaust springs will bind @.510" lift, and a .060" gap, from the total "working" valve lift, is the minimum recommended. TFS, Crane, FRPP have alternatives that should work fine w/out doing any machining or head work to fit them. FYI check this Valve Springs FAQ article from Crane, on valve springs selection. Hope this helps. My 2ยข.

Ryan5.0

Thanks Joel and Funk, you have helped tremendously. I asked no questions concerning the valve springs bc I know they have to be upgraded to prevent high RPM float. I am going to do things right the first time if at all possible. I have a great machinist very close by who has an excellent rep for cylinder head work. I plan to have the heads cleaned up a little and port match them with the intake manifold. I am now searching and purchasing the parts in hopes of completing everything this summer. I'll keep you posted.

Ryan

gspfunk

Have him do a valve job on them, too...

Definitely keep us posted....good luck!