The most I can get is 400# and that’s close to coil bind and far beyond my cam lift.

 

That's a baby cam, can you get a good measurement at max lift? I would look for evidence of valve float before suspecting springs.

 

No matter what I do motor will not rev past 5500 to 5700. Valves need adjusting constantly. There’s no rev limiter. I’ve messed with fuel and ignition and never saw any better.
I wondering if the springs and high back pressure is causing it to stop reving and start popping and sputtering.

 

It's definitely possible. Look at the wear pattern on the valve stem tips, if it's showing a star type pattern you have some pretty good float.

 

I’ve had afrs from 11 to 12.6 and boost from 2 to 14lbs. Tried timing up and down.
With more boost it may start a little earlier.
I just don’t know what else it could be.
Brendan

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Is a cam that conservative supposed to rev higher than 5500? Honest question. The specs are similar to the hydraulic roller in my 302 and it doesn't like to either.

What does the log look like when it breaks up?

FYI: MegaLog Viewer will spit out a nice graph capture by going to File > Save Graph as PNG or jpeg.

Okay, but what is the drive pressure at a given boost pressure? The ratio is what matters because actual pressure varies with boost and RPM.

 

Why is TPS falling off before the RPM? Right where your mark is looks like max TPS, and it falls off from there yet RPM continues to climb.

 

A buddy of mine just had something similar with a n/a combo. The thing that stands out between the two is lash kept changing.
After a bunch of struggle he found the retainers where hitting the top of the guide.
Might be something to investigate very closely.

 

I believe as load decreases the problem starts to subside so rpm increases slightly before decaying.
I will ask cam manufacturer what it should be good for.
I pretty sure I let off when it started to break up. I will look for a log that shows it more clearly.

 

Here is an earlier run before I put the EBP sensor in. Tps is at 100% and engine just flat lines.

And thanks for all the suggestions this is driving me crazy.

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Care to post your msq?

 

That cam is ridiculously mild, I can tell you im running a 240/240, 550 lift, 114 lca on a 383, and it signs off at 5800 on the dyno. I ended up going to bigger turbos to create more power, and shot myself in the foot, by loosing bottom end, and having the boost come in a Lil later, so I now have a shorter PowerBand. I talked to cam motion when looking at getting a new cam, and they recommended an even smaller cam, and were very lackadaisical about valve spring pressure. Crower recommended a good grind(and basically hit it on the nail as to what the engine was currently doing with looking at the cam card before I even told them what the problem was). Keep in mind comparing a solid roller to hydraulic, minus roughly 10° of duration off the solid to compare it to a hydraulic. Also, brodix told me after doing some math, that 16 psi boost added to the backside of the intake valve is roughly 40 lbs, which should be added to the spring pressure (2.06 valve).

 

I get the cam is small but there is something else going on. There is a difference in the engine no longer pulling or making power and sputtering- coughing. The log isn't accurately showing what engine is doing. I may have to get video some how.

here is last tune for anyone interested.

 

Why does the lash need frequent adjustment? Could be a sign of float.

 

I’m waiting on parts. My valve springs on head measured lower than I would like. Install hieght is 1.8 and max is 1.1. My lift is only .525 so I have room to shim the springs. I’m hoping to get another 250ishb on the seat and 450 open.