Cammer Rocker Problems

[jayb]

One thing that is confusing to me is that he says he is picking up ET by revving it that high.  I think he started off shifting at 8K, and then kept going higher in RPM and getting better ETs.  I would think he'd be down on power if the valvetrain was completely out of control, and that would show up on the ET slip.  Go figure...

Also, my customer explained that the reason the rocker when through the valve cover is that after it broke it flipped over backwards against the exhaust rocker, so it was sticking up high and punched through the valve cover when the exhaust rocker opened.

[blykins]

I don't think it would have to be completely out of control. 

I've had some guys come in with hydraulic rollers that were running great until the heads of the exhaust valves broke off.  It just takes a little bounce/contact over a period of time.

IMO, a 180-190 lb seat load is just not enough for an FE sized valve at 8000-8500 rpm. 

[jayb]

FWIW, the stainless steel Manley valves that used to be in my race FE are heavier, about 150 grams on the intake and 130 on the exhaust.  I ran 240 on the seat and a little over 600 over the nose, and only took the engine to 7800 RPM through the traps.  On the dyno you could start to see some valvetrain issues showing up in the HP trace around 7300 RPM.  So I agree, his springs are not strong enough at 8800...

[jayb]

I am going to take a crack at this from a different angle. Are his shafts regular thickness or HD ones that are thicker? We all saw Bill Connely spintron video years ago. As a MFG  of shafts I had access to a spintron  long ago but with a wedge head at a different angle than his. Viewed the shaft long ways. Stock shaft vs, spacers vs Hd shafts vs spacer. What a difference in the wave. Get a surf board LOL. But an idea. This solved alot and yes frequency changed/ resonance. Maybe what you guys think.

 Doug aka pumpbldr
Precision Oil Pumps

Hey Doug, I asked my customer about the shafts and he said he got them from you, so I assume they are the HD versions - Jay

[hbstang]

so i guess he is still running stainless steel valves?i think real race cars should have titanium vales at that rpm hes running.
what do you think? maybe jay is running ti valves in his race engines.

[mbrunson427]

Jay, I have contact info for the GM over at PAC if it would help. I'm sure he'd find this situation intriguing and want to jump in and help. If you want it, send me an email and I can reply with his info.

[jayb]

Mike, thanks for the offer but in the meantime this guy has switched to titanium valves and better springs.  He is also going with a set of my non-adjustable rockers, which is the right choice with titanium valves.  I think his odds of surviving at 8500 are a lot better with this combination.  We will see...

[Barry_R]

I'd agree on that.  Might be "not the right spring" as opposed to "not enough spring" - but we've all learned to crutch the issues by adding pressure when we don't have access to spintron data.