High rpm breakup

[HalfDozIN]

Dialing things in after getting the car back together, and I'm having a loss of power/breaking up right at 5,000 rpm. It SEEMS to be that the lower the boost, the less aggressive the issue. Today, with 5 more psi, it actually missed like it was hitting the rev limiter, vs just laying over.

Combo as follows:
Ported irons
Comp 212 flat tappet with the springs they sell in the kit
Tr6 in waste spark config with truck coil pack, limiter set at 5900.
Brand new (today) autolites and msd 8.5 wires.

No knock, good afr's.

Last time at the track, it had no issues at all running to 5600+, and nothing has changed.

Car sat in storage for practically a year after, except for the occasional start and move, and keeping old gas out of it.

I'm leaning valve springs or coil packs, is it possible for springs to have gotten weak from sitting? I haven't read of much for issues with these coil packs, but is that a possibility I should take seriously?

 

[SCOOBY DOO]

What spring pressure?

 

[HalfDozIN]

What spring pressure?

They're the comp 980 spring that ships in the cam kit. That's why I'm wondering if they've gotten weak enough to finally cause an issue, I think the 980 is something like 90 lb seat when new? Didn't give me problems last time it was raced, but its done a lot of sitting since then, and it's been over a year...

 

[SCOOBY DOO]

They're the comp 980 spring that ships in the cam kit. That's why I'm wondering if they've gotten weak enough to finally cause an issue, I think the 980 is something like 90 lb seat when new? Didn't give me problems last time it was raced, but its done a lot of sitting since then, and it's been over a year...

980's are stock spring pressure and soften up after a couple of passes. Slap a set of 981's in.

 

[HalfDozIN]

980's are stock spring pressure and soften up after a couple of passes. Slap a set of 981's in.

Probably need replaced by now even if not the culprit. Good a time as any to put the rocker shaft braces on I bought eons ago, eh?

 

[SCOOBY DOO]

Probably need replaced by now even if not the culprit. Good a time as any to put the rocker shaft braces on I bought eons ago, eh?

I ran spring pressures that were off the charts...and I also ran solid shafts.

 

[dynoman]

What spark plugs , resistor or non-resistor ??

 

[HalfDozIN]

What spark plugs , resistor or non-resistor ??

Autolite 25 platinum, because that's what was around. NGK ur5's were doing the same thing, and also NOT doing this before the car sat. Both are resistor if I'm correct in my understanding.

 

[Chuck Leeper]

The truck coils are usually very reliable.
Should have the heat sinks on the top.
I'd do the springs first.

 

[HalfDozIN]

The truck coils are usually very reliable.
Should have the heat sinks on the top.
I'd do the springs first.

No heat sink, it's the v6 truck coil, waste spark setup. Still, I haven't heard of a bunch of issues with them, so I think you're all on the right track. I'm guessing I was 'marginal but getting it done' pressure wise last time I was racing it, but they have since worn in and weakened. The cam was done very shortly before I bought the car 3 years ago, so about 1 season of driving and running it seems believable for those springs.

 

[BEATAV8]

X2 on those 980's being inadequate. Comp should not be recommending those springs for a turbo buick. 981's will do the job.

 

[TIMINATOR]

Might be new corrosion or poor connection to the coil pack power or ground connections. Clean the ground connections on all of them, especially if you are in a back east type location.
The 5 psi more requires more voltage at the plugs, what gap are you running?
The 5 psi higher boost also pushes on the back side of the intake valve, making the effective spring pressure lower. A 1.7" intake valve has right at 2 square inches of area (inner seat diameter area less valve stem area) so your added 5 lbs boost actually dropped your EFFECTIVE intake valve seat pressure by 10 lbs. If you started with 80 lbs, that's a loss of about 12%.
There are a lot of LS beehive springs that will work with your combo, with the added benefit of less inertial weight on the retainer and moving end of the spring. At under 6000 rpm that doesn't make a lot of difference tho.
TIMINATOR

 

[HalfDozIN]

Might be new corrosion or poor connection to the coil pack power or ground connections. Clean the ground connections on all of them, especially if you are in a back east type location.
The 5 psi more requires more voltage at the plugs, what gap are you running?
The 5 psi higher boost also pushes on the back side of the intake valve, making the effective spring pressure lower. A 1.7" intake valve has right at 2 square inches of area (inner seat diameter area less valve stem area) so your added 5 lbs boost actually dropped your EFFECTIVE intake valve seat pressure by 10 lbs. If you started with 80 lbs, that's a loss of about 12%.
There are a lot of LS beehive springs that will work with your combo, with the added benefit of less inertial weight on the retainer and moving end of the spring. At under 6000 rpm that doesn't make a lot of difference tho.
TIMINATOR

Gap is .030", should be no issues with the tr6 and late model 4.3 coil pack jumping that gap until much further than I've gone, haven't been over 20 psi yet. Agree with your analysis of force against the valve, that's why I mentioned it seemingly being worse with more boost.

It does act how it was when my stock module/coil started to go, though. That's what sparks the doubts. I will definitely check all my grounds and the ccci plug, I'm in the Midwest.