I posted this several months ago and have still not found a resolution yet. I have tried basically everything except adding an MSD 6AL. I am not sure that will make a differnce and wanted to see if there were any other opinions before ordering it.

Last year, I built this combination....
AI 190cc heads
11.3 to 1 CR
Custom Cam - 230/238 - 110 .573 lift on intake & exhaust
42 LB SVO injectors
Comp R lifters
Comp 1.6 rockers
52MM TB
MSB 8.5 plug wires
Kooks headers
No cats
No Air Pump
CSR electric H20 pump
No EGR
Tuned by CAM

It makes about 400 RWHP at 6,100.

Since we built it, I have always had a slight dip at 6,200 RPM and it has been getting worse. It now sounds like a severe ignition miss but it ALWAYS starts at exactly 6,200.

Since I have started troubleshooting this problem I have changed....
OPTI to a brand new GM unit.
New MSD coil.
Replaced all of the plug wires with new net of MSD 8.5s
2 new sets TR55 spark plugs. They look good when I take them out. No obvious differences from plug to plug.
Removed and rebuilt the heads. Repalced springs with new set of 977s and Ti retainers.
New ignition control module.
Loaded my tune into another ECM.

None of this has helped. At exactly 6,200 RPM it misses. There are no error codes

I have spent a lot of money chasing this and can not correct it. Other than this, the car runs great. It will pull smooth in 6th gear on the highway at 1,800 rpm and will also run past the miss up to the 6,700 rev limiter.

Any ideas?

Dyno graph here.
http://img53.imageshack.us/img53/9558/picture004xq6.jpg

 

How are the "R" lifters lashed?

 

Did AI spec the cam and valvetrain combo for you? I'm sure they could help you sort it out.

 

Lifters/rockers are preloaded 1/8th turn past contact with the pushrod.

I tried talking to AI when I pulled the heads off. They do not feel it is a valvetrain issue. They believe it is ignition related.