1.7rr and stock springs...need help

[Old Guy with 87 GT]

i was wondering how many guy run stock springs and 1.7s and if you've ever had problems with valve float

.....i just put crane full roller 1.7s on my car ......i replaced the springs with brand new stock ones and had a complete valve job done ,(all tolerances checked and ok)

well my car pulls great up till about 5,500 rpms then just stops like it hits a rev limiter......i was wondering if it could be caused by valve float ......i started having a drop off in power at around 5,500 before the mods ,it used to pull all the way up to 6,000 when i firste got the car but started getting weaker above 5,500 gradually as i drove it ....figuered it was just the valve train getting old ......

well i did the above mentioned mods,i just now got it broke in enough to feel safe winding it up and i discovered it just loses ecceleration at 5,500 just like its hitting rev limtiter....i need to get some input on what could caus this

*related details*
autogage tachometer, my bottem end seems in good shape ,most everything sencor wise has been replaced with in the last year, i have new cap, wires ,plugs and coil....fuel pump and filter are brand new......no other magor mods ....list>2 1/2 full exaust ,no cats,equal lenth headers ,15*timing ,180 thermo, heads shaved .02 and mildly ported (just the exuast side and polished both sides) ,crane 1.7s ,adjust reg (44psi) ,no thermactor or related plumbing.....everything else is stock (including intake and tb)with a speed density computer.........

any insites from the guru's would be appreciated, hell any insights would be appreciated

[fiveohpatrol]

well I'm no guru but i have had experience in this area.

I put the exact rockers on my car with about 100k on the clock and never took the RPM's up high enough to get the valve float but after I swapped to a T-5 I started noticing it at about 5400 and higher. It felt just like you say, its like it hits the rev limiter.

I got a set of dual comp cams springs from summit for like $70, put them in and the problem was gone. It pulled much harder up top and could actually reach the real rev limiter

get some good springs and you'll be set

hope this helps,
-Drew

[Old Guy with 87 GT]

thanks for the reply fiveoh........thats what i was syspecting was the problem ........i put new replacment springs in the heads cause i thought they would be suffitient enough,guess not .....bummer

for the most part i don't wind her up that high ,i'm probly going to run it a little bit till i get time and more money to replace them ......do you think that running it will harm the valves or anything else

[whiterod]

definatley sounds like valve float to me, also by looking at your mods you state your fuel pressure is 44 psi that sounds a bit high to me. seems like it should be alot lower, 39 is stock and i believe on a mostly stock car people get a little more performance my lowering the pressure, just something to look into

[oldman86]

Hey oldguy,

Some thoughts from oldman. Ford tells me a stock cobra 5.0 with factory cam and gt 40 heads ran 1.7rr's with a little heaver valve spring. Ford says you should not be getting valve float, (assuming stock cam), unless non- cobra springs were installed. Now I find there are two part numbers justifing this. My gt40 heads have heaver springs to accommodate an e303 cam; But the retainers are such that the 1.7rr's had to be machined, (past post). It runs and runs good. I might hit the track and DO IT! Now with all that given I don't like machining a perfectly made product just to fit. I'm still learning.

Later--oldman