HELP... 3.8 stage 1 wont rev over 5800

[buizilla]

As stated above, car gets weak at 5600 and is flat at 5800. Air/ fuel ratio will go to 10.1 to 1 if you stay in it. A fast mechanical "type" sound can be heard above 5600 but no popping or back fire so i'm thinking the valves are floating right, well i had (2) springs checked today, results are 150# closed...350# open,which is what RED, Dave Weber, and Tom at Champion all said should be good enough to stop floating. So now i'm looking for more idea's....TIA......Greg Crabtree

A few specs.........................
1) ported 14 bolt GN-1s
2) 1.65 T&Ds split shaft rockers (very nice BTW)
3) 214-214 Comp/ Weber Racing hyd. roller kit
4) .584 lift W/1.65 rockers
5) installed height is 1.830in.....1.842ex
6) heads ordered thru RED with these recommended mods....1.440 O.D. double springs,titianium ret. , Inconnal exhaust valves.
7) Fast B-B, 83s, BB-70Q, PFMIC,

 

[John Wilde]

Have you checked the lobe lift?
We lost a non budget roller in one of our 109 Motors.

Did you ever check your piston to valve clearance?

 

[Nick Micale]

........, results are 150# closed...350# open,which is what RED, Dave Weber, and Tom at Champion all said should be good enough to stop floating. So now i'm looking for more idea's....TIA......Greg Crabtree,,,,.. [/B]

Guess I will have to disagree with Red. Dave and Tom, that is NOT enough spring pressure to keep the valves from floating at that RPM especially with the heavy hydraulic roller lifters and big valves.

Not just my opinion, but been there, done that same thing!

 

[buizilla]

Thanks for the response guys,
John, piston to valve is ok, I put a dial indicator on the #3 exhaust retainer and measured only .416 lift (lifter bleed down???)

Nick, I'm with you on the springs being the problem, also to let Dave, Red,and Tom off the hook they did not guarantee that was enough pressure, just as a good measure to start with. I put a .060 shim under the spring this morning and got 165#closed...380#open. Do you think I should try this?????


Greg...................

 

[Nick Micale]

Originally posted by buizilla
......... I put a .060 shim under the spring this morning and got 165#closed...380#open. Do you think I should try this?????
Greg...................

Yes, certainly try with the spacers. With the installed height of 1.830", the spacers should help move the power band up 5-600 RPM.

 

[Army MP]

Are you sure the rocker arms are torqued right for that cam?
May sound like a dumb question as you seem very mechanically inclined, but just my 2 cents for what its worth.

 

[REDS HOT AIR]

sounds like comp cam lifters with too much preload

run the preload as close to 0 lash as possible without clearence

I was out tonight in a gn1 headed car with billet hydrolic roller and single .600 lift springs set up at 125# closed and went to 3rd gear at 6650 with no problem

14 bolt gn1's with chevy style rockers 1/8 turn past 0 lash

theres more than one RED on here might wanna call him RED A

 

[buizilla]

Actually, my cam kit from Weber Racing came with Speed-Pro lifters, NOT Comp Cam stuff. I have only checked #1 cylinder so far, the pre-load on both lifters was 3/4 turn, which at 20 threads per inch calculates to .0375 pre-load. Sounds like a lot more than you like too see RED. I here Speed-Pro lifters no longer come in his kits its all Comp stuff now (must be a reason for this). Well as of now I think i'll use the .060 shims and tighten the pre-load to .0150 and see what happens.

PS....... the car runs ok even in this condition, I ran a 10.62@129.75 two weeks ago at KCIR at 24# boost w/ my little 9" DOTs. The car runs great(until 5600 comes) it's just out of it's powerband for too much of the pass, I need to be shifting at the 6200/6400 range.



GREG......................

 

[MAX PSI]

I had the exact same problem last year. I have Comp Cams 218/214 hyd roller with the beehive springs. I assumed it was also the valves floating. Mine like yours would rev to 5600 and go flat but still run a mid 10. My problem was twofold, a bad ign. module and starving for fuel. I replaced the module and the car would now free rev to the limiter, but some times it would sputter down the track. I had enough pump to support the HP levels but even with the stock tank full it would airate the fuel. I solved that problem with a fuel cell.