TCCoA Forums banner

1 - 13 of 13 Posts

·
High-Mileage 4.6L Thrasher
Joined
·
3,232 Posts
Discussion Starter #1
I had a litle bit of time today,so I went out to the shop to try something out.I have a new set of PI cams here,along with the springs,retainers,locks for them.
I've also got a complete '95 longblock here too,so I decided to see just how bad the clearance would be if I put the PI cams in the old '94-'95 F4AE heads with the PI valvesprings.
Pulled the old NPI cam off,and removed 6 of the 8 followers to make it easier to check just one intake and exhaust valvespring.Put in the the PI cam,and used it to see how much clearance there was and how close it would be to coil bind. Intake was OK..there was a little bit of clearance left at max lift(.510"),but the follower was compressed-so there really is little to no clearance on even the intake side. Knowing it would not really work, I went ahead and turned to to open the exhaust valve...uh-oh, no way this will work.
It reached coil bind with approx .010" lift to go,and the follower was completely compressed.
Now that I knew the old '95 springs wouldn't work(as I had suspected),I pulled the exhaust spring,and installed the new PI spring,retainer,and locks.
Tried the cam again,and then I actually got less lift on the newer spring than I did on the older spring before it had a problem with coil bind.I guess this is from the PI spring being a slightly longer freelength,and not having enough room to handle the lift.
So,looks like those with the old heads can either swap them to the newer F5AE castings,or just use the Comp Cams low lift cams to make more power.
JL
 

·
Boost Happy
Joined
·
1,971 Posts
good job jl for checking that out and letn this guys know that the PI cams and stock springs or pi springs wouldt work on the F4AE /94-95 heads , but they will be fine with comp cams and comp spring kit Rob and Hans are getn good numbers and are not haveing any problems .


Jurgen
 

·
Amateur Expert
Joined
·
1,662 Posts
Thanks, JL for checking that out! Hopefully that might help some before they waste $$$ on PI cams when they won't work for their setup.
 

·
Registered
Joined
·
215 Posts
so we use the cams for the small ford? do you have part numbers? cuz i have about 300 dollars coming..and i want to do some mods
 

·
High-Mileage 4.6L Thrasher
Joined
·
3,232 Posts
Discussion Starter #7
The comp low-lift modular cams are $570,and the proper springs are $190ish.
JL
 

·
Registered
Joined
·
3,178 Posts
Since we're on the subject of cams... How much more of a problem do the higher lift (.543") Comps have relating to valve springs? Obviously a pre-96 head is out of the question without machine work (so why bother), but even on a F5AE head with comp springs I'd think theres at least some issue with reliability.
 

·
Registered
Joined
·
1,064 Posts
Silver95Bird said:
Since we're on the subject of cams... How much more of a problem do the higher lift (.543") Comps have relating to valve springs? Obviously a pre-96 head is out of the question without machine work (so why bother), but even on a F5AE head with comp springs I'd think theres at least some issue with reliability.
They advertise as .550" lift cams and the note only says they can also be used in pre-1999 heads with retainer to guide clearance modifications.

http://compcams.com/Technical/Catalogs/106-03/HTML/66-67.asp
 

·
High-Mileage 4.6L Thrasher
Joined
·
3,232 Posts
Discussion Starter #12
4point6r0x0rz said:
What about those Competition springs and PI cams?
No,there's not enough area for lift.
JL
 

·
Registered
Joined
·
1,566 Posts
I know its kind of off the subject but Johnny I saw your post on another site about the PI intake on the NPI heads...Woult it be smart to have the intake ports welded and reshaped to get rid of the need for RTV. I myself am actually gonna run PIs on the 5.4 but I saw that and had to ask. I know on the SC the ports are cut and rewelded to get better flow numbers...Just a thought.
 
1 - 13 of 13 Posts
Top