I am having a high rpm miss and I have done just about everything to try and get rid of it. I was curious what springs you guys run for FI motors. I am running beehive springs and was told that they would be fine with the Cam 224/236 116LSA XE 3192 3196 lobes, .606/.628 lift with a 1.6 rr that I'm running. Is this neough spring or do I need a swap??? What springs are you guys running??

 

how high is the miss and is it really a miss or is it just going flat?

 

Well, actually it feels like its hitting the rev limiter. But I have checked the tune and the rev limiter is set to 7K and the rev on the mallory box is set to 6800. The miss or whatever it is comes in about 5800-6000 and I dont push it any harder and shift out of the miss. I do want to run a datalog and see if there is any knock because the engine start to go lean about that time too. Would that cause it as well??

 

check your knock sensor activity on a scan tool and look at your retard to see if it retards the timing, (note) new knock sensors are cheap and should be torqued to less than 10 ftlbs.will the car go any higher or does it stay there no matter what, make sure the springs are matched to the camshaft, just because they are behive don,t mean they have enough pressure for your cam, check the fuel pressure under load, fuel pumps are not gms strongpoint

 

I'm running the same cam, but with 20+ psi boost up past 6500 rpm. I set up my valvesprings at 155 - 160 lb seat pressure.

Mike

 

Was the mystery rev limiter a little higher when you first noticed it? I had a similar problem I was fighting, mine started around 6200 then dropped to around 5800 after a while. it turned out I killed some lifters. I would adjust your valves take it out and hammer it come back pop the valve covers and check the valves again. What lifters are you running?

 

If it's valve springs it'll start to break up at that RPM even free-revving in neutral. Valve springs don't know if the engine is under load or not.

 

Could it be valve float @ high rpm??? I've been running the AFR rev kit over dual springs. The rev kit has an additional spring which helps to load the lifter to the cam. Some of these roller profiles have alot of slope change, and, this is a cause for the lifter leaving the cam profile @ high rpm. The 3rd derivative if acceleration (da/dt). So far, I am satisfied with the rev ability of my 383/ D1 w/ AFR heads.

 

Derivative of position is velocity.
Derivative of velocity is acceleration.
Derivative of acceleration is jerk.

Of course, there are limits on acceleration based on mass of the valvetrain and spring pressure, but the only limit on jerk is that it is finite. There is no need to go any further and derive jerk.

Mike