Well as everyone knows I have been chasing down a nasty valve float problem with my new motor for the past couple of months. The problem was that the motor would pull hard to ~6K RPM then just fall flat on its face and start making unusual noises. I can now happily report that the problem is fixed.

I went to the local dyno and made a baseline pull and clearly saw the float just like before. I then replaced the inadequate PAC 1218's (130#/320#) with some new Manley 221428 beehives installed at (160#/360#). Three hours later we made two more dyno pulls and ALL of the radical power fall off was completely gone. Also the motor was much more quiet as a result of the valvetrain being more tightened up and the valves not bouncing. The motor now pulls hard to 6600 RPM just like it should. Shift point will be 6400 RPM.

On the road it just keeps reving higher and higher unlike before. There is no doubt that according to the attached plot, this problem is fixed as a result of installing valve springs that are able to properly control the valves. The funny thing now is, the inadequate PAC 1218's made 2 RWHP / 4 RWTQ more compared to the better Manley springs. I assume that is as a result of the higher spring pressures which can be attributed most likely to parasitic loss. Obviously I am not concerned with this. One other interesting positive is that nearly all of my random knock retard is gone too.

Engine specs:
355 ci. through M6
Mahle forged pistons w/ 6" rods
Stock crankshaft
ASP UD pulley
Le2 heads
LE 1.5 camshaft
Manley 221428 beehive springs
1.6 Comp pro-mags
LE ported intake
30# SVO injectors
52mm throttle body
AS&M cold air induction
RK sport headers (1.75" primaries and 2.5" collectors)
Borla cat-back
No catalytic converter
E-cutout (open)
Midwest Fabricated 9" rear w/ 3.89 gears
Strange Chromeoly drive shaft
Spec 3+ clutch
Tuned by Bluecat

Final Dyno numbers are:
391 RWHP corrected
355 RWTQ corrected
Here is the dyno plot showing before (blue) and after (red):


Thanks again to all who chimed in on my older thread and helped me along the way.
And special thanks to Lloyd Elliot for his excellent customer dedication. Lloyd took a genuine interest in the problem and offered advice and support till a solution was found.

I am hoping to get this thing to the strip very soon. I am hoping for low 12 second ET's on stickies.

 

Those are some great results! What lifters are you using and what did you set your valve lash to for that run with the new springs?

 

Glad to see someone follow through and get it working! Did you monitor A/F to know whether you need some fine tuning still?

 

I did the exact same thing. I had valve float problems with the Comp 918 beehive springs and went to the Manley 221428 springs as you did. I got the same results. By the way I will also be shifting at 6400rpm.

 

I am planning on sending my heads out to Lloyd next week, would you reccomend me telling him to throw on some Manleys?

 

Rather new stock lifters.
Rocker preload is 1/4 turn past zero lash.

A/F starts out 13.7 and ends at 13.0. It is rather flat across the board.

If you end up going .600"+ lift then I would absolutely ask for these springs. I think the 1218's, 1518's and the 918's can be hit or miss. My setup just needed around 150-160 pounds on the seat to keep the valves closed. It just depends on your lift. I have relayed my results to him.

 

Those results look much better, good work.

 

What seats and retainers did you use with these springs? Also, installed height?

 

Comp 4696 seats.
Comp 795 10 degree retainers.

 

Hell yeah man! That's awesome news
Very nice numbers for that setup and look at that TQ curve

With a solid launch, that should not be an issue.
Work with the shift points, make use of that top end power and solid bottom end.

 

Nice!

 

Thanks guys.
I just need to monitor the springs to see how long they will last. These Manleys are nitrited and should be loads better than the 1218 for controlling the valves with having a tick over .600" gross lift on both sides.

 

I just had the 1218's installed in my LE heads. We will see what happens. I am at the .600 area as well.

 

Get it on the dyno and see if you you get fall off like is shown in blue on my chart above. You could feel this fall off on the road as well plus the valvetrain would start to rattle. IMHO the 1218's are not up to the job with that kind of lift and lasting. The 1518's stand a much better chance but I still prefer the extra pressure of the Manleys.

 

Nice to see things worked out for ya. Like I mentioned before, I had the same problem with the 987s, which was cured by the 918s. Same problem, different cam, with better springs to solve the valve float issue.