Ok, I've finally got the car running decently, and I figured I'd throw her on the dyno to see what it would do. The car has been STREET TUNED with no tweeking on the dyno or dyno tricks. It definitely still has some horsepower left in it. Here's a short list of what's done:

-Forged 355: Balanced and blueprinted, Eagle 4340 crank and H-beam rods, and SRP pistons (~12:1 SCR)
-Locally ported and polished stock castings flowing 285/205 @ .600 with 2.0/1.57 valves
-Joe Overton custom grind cam (similar to, but slightly smaller than a gm847)
-Gasket matched intake
-58mm BBK tb
-Jet Hot LTs with true duals dumped at the rear
-Street Tuning by Timmy the Tuner (Mad Scientist)
-M6 through a Ford 9"
-All supporting bolt ons

The numbers were:
rwhp 403 @ 5800
rwtq 395 @ 4700

I am on dial up at the moment, and I can't get the graph to upload. I'll do it when I go back to school next week. I can't figure out why the car peaked so early. At about 6500 it was falling off really bad. It felt like a rev limiter. The springs are supposed to be good to .620", which my cam comes no where near, but it seemed like I was running out of spring. I'm not sure at this point. If the car kept pulling the way it was and peaked where it should (~6500), it would probably make a ton more power.

EDIT: Here's the graph.

 

Damn nice torque. What valve springs are you running?

 

Sounds like valve float, but I'm no expert. Your numbers I'd expect to be slightly higher, but that 9" is a robber as well. Did they check the spring pressures at max lift and on the seat?

 

I'm not sure on the brand. I bought the assembled heads off of someone and took the springs to a machine shop to verify whether they were good or not. They told me they were good to .620" lift and I went with it. I'm already pricing some 918's. I'll wait until you guys can see the graph to confirm whether it's the springs or not.

 

This project has been years in the making, so I don't remember exactly what they checked when they had the heads.

 

I'd say either valve float or you're hitting coil bind, which can sound like hitting the rev limiter I think.

 

No one has mentioned rocker adjustment, but you should not be running much preload. I only run my stockers to 1/4 turn.

 

I thought about that, too. The last time I adjusted them, I adjusted them to a 1/4 turn of preload (stock replacement Crane lifters). I'm not sure how the car would act if the preload wasn't correct, but I didn't think it would hit a wall like it was.

 

The effects of too much preload would be seen throughout the powerband. I did that and it didn't have power anywhere.

 

Get the beehives, their great springs. They helped my small Joe O. cam big time.

 

Where did you have your heads ported? I am from just across the river and am looking at my options for a H/C package.

 

The dyno graph will tell you where the valve float is. It will look like a cliff dive. Did they have a wideband on it? It's a good idea to at least run Datamaster while you dyno. It can at least tell you if timing is being pulled, and what the duty cycles are etc...Be careful of the dyno tune. Most people end up with too much timing, and lean a/f under load.

 

He didn't have the tuning done on a dyno. Nice numbers especially through a 9 inch.

 

It's a guy named Rob that used to own a shop called Peak Performance in Fenton, MO. He has since sold the shop and is now doing machine work for SCP in High Ridge, MO. If you need me to get his number, let me know.

It does look like a cliff dive at 6500 rpm. It drops about 30 rwhp in about a 100 rpm span. I have a LM1 Wideband on my car, and I kept an eye on it. They have a wideband but it was reading some funky numbers that were no where near what I was getting with my wideband, so I had them cut the a/f graph off of the chart. DC is at about 85% @ 6800, but that is with it hitting the wall it's hitting. I'm going to log the car here soon to make sure all the sensors are behaving correctly when it's losing power up top. Graph is now up top.

 

it definetly looks like valve float to me. since you are unsure what valve springs they are i would start there. you might even be loosing some TQ because it should peak higher too.