Hey fellas, just thought I'd tell you a lil story on my valve train issues... New-used GT40X heads.......(someone else bought them and had them converted to screw in studs n guide plates and never even bolted them down) ... using a reground Hydro roller.. .512 lift... no tachometer in the car.. noticed that at high rpm it would start to sputter and break up... bought a tach.. first thing after installing was to see what the RPM is at cruise and then what rpm the sputter starts... As it turns out, I am rolling down the street. put it in neutral and just floor it.. tach goes up to 5200 or so and then it just gets crazy.. explosions out the tailpipes and it just won't rev past 5300.. Pull one of the valve springs off, and take it to a machine shop to have it tested at my installed height.... 72 lbs..WTF? So needless to say new springs are in the works... looking at the PAC 1220, Lunati 74820 and Scorpion SRP 1220.. which looks like they are all the same spring just rebranded... let see what happens.. maybe there is some power to be gained also..
I bet those springs are for an older SBF with a lower installed height. The right springs will fix it...
the installed height is 1.88x so even with a 30 shim under them they would be at 92 lbs.. which is still weak sauce.. on another note.. I was a bit surprised that the rule of thumb is for a hydraulic roller to have between 125 135 at the seat... there are many guys running 140-155 at the seat with the OE lifters... Guess I am going to be one of those guys as the above springs are that tight..
Installed height on 77 and earlier heads have a lower installed height, like 1.66-1.700, thats why I think they are wrong. I have E7's on mine now, the installed height is more like 1.88 like yours. The later model heads also have a different height on intake and exhaust. I bought Cranes for my late model heads and the retainers/locks are different on the intake and exhaust.
Did you have to to do any machining of the valve guide boss?? the valve guide boss with locating cup,that locates off the boss, is .970.. so no dual springs would fit.... I wonder what issue I am going to have with the valve tip height issue...hmmm
The Cranes I bought were the "beehive" style for stock heads. Will work with smaller roller cams. If the heads have been machined for normal springs, that opens it up for more selection. See if they did that.
Funny, I didn't even look at the crane stuff in my research... I thought crane went under? what part number you get?
I never bothered looking as I only took one off, a Intake.. but after talking to you i did some more research and now have to look at the exhaust... I bet they are different as i remember seeing the Ford logo on the stem of the valve, so most likely they are the "factory" valve... And the exhaust is the one that i would have a issue with, right? So, HYPOTHETICALLY, If my install height on the intake is 1.88, then the exhaust install is going to be somewhere in the 1.7xx range, ASSUMING, it having the traditional GT40 stagger??
Mine are not GT40's so I really can't say. I'm mostly stuck in the 80's on 302 stuff. I've been doing 460's since the mid 80's, and no new tech on 302. I just stuck this late model 5.0 in the Maverick a few years ago and bought these springs. I think they might be the ones you need.
SO I went out today before work and removed the exhaust spring.. I tried measureing the tips to see if there is a .100 difference like most have stated.. the most I got was .010 difference.. I vaguely remember coming across a thread on the corral I think where a guy had a issue with the crane setup.... but I don't recall exactly.. but I was wondering if FRPP used a different set up than the production GT40 (p) heads.. the exhaust valve does have g302 under the ford logo.. got to find my frpp catalog...
It's been few years since I put mine on. I bet you need more if a 351w type spring, taller. That will make things simple since they should all install at the same height.
the crane springs are close to the same specs to the lunati, pac, scorpions and they are cheaper by almost 40 bux... the only thing i see is not being able to use the +.050 set of red keepers they come with.. but I would think I could reuse my 7* ones that the heads already have... I looks like ford didn't use the same intake valves in the GT40x heads than they did in the cast iron versions... the FRPP catalog shows both with the same tip length of .383
I just bought a set of cranes,99872,go look in the catalog & ck them out.131lbs @ 1.875 on the seat & should give you around 300 open w/ your lift.They actually recommended one just a little stiffer for my solid cam but I`m using titanium retainers so I think I can get away w/ them.
