Hitting a brick wall at 5500 RPM

[toomanymodz]

I've got my new combo set at about 19 psi thus far and the tranny in Drive shifts at around 5250. I decided to hold it in 2nd gear and see where the engine pulls up to. Well, as soon as I hit 5500 it totally nosed over and stopped pulling. The first thing I thought was fuel. I reviewed the powerlogger and both the narrow-band and wide-band O2's look perfect and zero knock. In fact I don't see any readings that are out of the norm. The next suspect is valve springs. These are brand new GN1's. Surely the springs were setup correctly. Any ideas?

 

[Phoneguy]

Bobby at RPE replaced the springs on my new GN1's with dual springs when he built my motor. My cam is larger than yours but not much. I don't know what the pressure is on the off-the-shelf GN1's but Bobby obviously didn't think they would do the job. It could be the springs. What is the fuel cut-off on your chip?

Bryan

 

[Grumpy]

Don't "assume" !!

 

[Chuck Leeper]

" These are brand new GN1's".... Likely the problem. I had the same problem with "new" GN1 springs. Were supposedly "roller springs"....They were JUNK. Replaced them w/ 918 Beehives... WALA! Rpms well above 6K.

 

[Grumpy]

" These are brand new GN1's".... Likely the problem. I had the same problem with "new" GN1 springs. Were supposedly "roller springs"....They were JUNK. Replaced them w/ 918 Beehives... WALA! Rpms well above 6K.

been there an done it

 

[toomanymodz]

Wonderful....always something. Looks like I'll be swapping valve springs soon. Product quality has gone down the toilet.

 

[tonka]

I don't see it in your sig. but thought I'd ask, do you have a two-step installed?

 

[bison]

For a build where you are looking for power I'd be checking all if that. I wouldn't assume anything. You need around 150 on the seat and 450 at full lift to run 30psi/6000rpm. Ive seen improperly setup valvetrains in probably half the cars I've worked on. Even when assembled by some reportedly top notch builders. Then again unless you received a spec card with each installed height/pressure you really can't blame anyone since product could be boxed wrong. If anyone has owned the parts before you it's anyones guess what's been done to them. I've received new springs and had one of them be for a flat cam when I ordered them for a roller. 95lbs@1.75" when it should have been 135-140lbs. Not good. Most won't catch it.

 

[toomanymodz]

No two step. I checked the Comp 918 beehive and they have 130# seat, so they just might be what I need. I'll check with the manufacturer to see what springs the GN1's come with. They were purchased new.

 

[toomanymodz]

I just got off the phone with Brian at Weber. My heads have PAC #1200 springs, which are fine for my application. I told him what I was experiencing and he has a car that is in his shop right now that is experiencing the exact same problem. They have increased spring pressure, tried solid roller lifters, tried closing spark gap, tested the ignition module, coil etc. He has spoken with Jack Cotton, Caspers and a bunch of others about it. They are scratching their heads. Not to say the root cause is the same between the two engines, but it sure sounds interesting. The symptoms are exactly the same. Hmmmm.