Has anyone experienced valve float with a 280 sized cam(specifically BC's) and a Ferrea Beehive spring? i have a noticeable loss in power and im wondering if it's starting to float.

 

What makes you think its valve float? A noticeable loss in power usually indicates a boost leak.


-Bink

 

Exactly right binky..If you have springs then you should not experience that in any which way..B.c cams are mild cams the 280 cams they make are not real true 280's like gsc or kelford..The best way to determine if your really getting float and slap it on a dyno and see if the graph dips..

 

i'm assuming he means a noticeable power loss in a certain RPM range which would be valve float due to valve spring resonance?

 

I have the car apart for the winter so getting it on a dyno is impossible. But yes, RsMike, thats what im talking about. Is the seat pressure high enough for say a GSC S3?

 

So, are you reving it higher then stock? What are you reving to? Valve float comes from the valve bouncing on the seat-- You put the higher rated springs in for a reason rt? What are their specs over stock? This isnt your problem is my guess, I am thinking if you have valve bounce you would be at 8500+rpm's and have bent valves by now. What was the last thing you changed before noticing the power loss...the springs? If so how about looking at the cam timing, if you are not spot on, it will move the power band around, so you could notice a loss of power up top or across the power band.

 

its past 9500rpms the power drops. from 9500->10,000 the power drops pretty bad. again, i haven't taken it on the dyno to see a curve but butt dyno tells me its dropping.

 

9.5k revs!!! What turbo are you running?

 

the small cams cant breath that high.

 

assuming you have a turbo and cams and springs for that rpm range a couple of lads here in the uk had cars hitting a brick wall at high revs. changed the inlet manifold for a well respected name 1 i forget which exactly and they opened right up again

 

well im trying to figure out if its my springs, or something else in my set up that needs to be changed.

 

bigger cams, problem solved.

 

+1 on larger cams.

What turbo & intake manifold are you running? Has the head been ported? At that high of an RPM all of these factors become very critical.

 

6262 with the large .82 hot side and ams vsr.

 

BC 280's are definitely holding you back with that setup.