All,

At wits end. Car hesitates heavily above 6K RPM when the coolant gets above 210. WTF? You name it, I have done it to try and solve this problem.

Your goal: to get me to think of something I have not done so fire away with suggestions. Throw them out there but be unique in your approach. obviously simple things like fuel filter and plug wires have been tried. Help me look at it in a different way.

Thanks!

 

valve float?
ICM?
what's your spark gap?
Stock coil?
MSD ignition?
good coil/ICM gound?
What's your fuel pressure?
Does a datalog show spark retard?

 

Detonation?

 

Thanks much for the input.

Springs changed 155lb seat pressure now.
ICM changed
Gapped 0.40 currently and was told to try 0.20 or 25
issue both with stock and MSD coil
Need MSD 6A....possibly won't discount
VERY good ground. This has been reworked to be as good as possible
Pressure rock solid 42 all the way to 6500
I have disabled spark retard but does show lean up top..miss?

going to move the coil away from the block to keep it cooler and retry this. After that, I will go with smaller plug gap.

 

Try adding fuel and pulling lots of timing up top, this way you can quickly see if it's a detonation/spark retard issue.
I wouldn't even bother relocating the ICM/coil, they get just as hot on every other LT1 out there.
I would regap to .025" - .030", it's very possible that your spark is blowing out.

 

What size are the injectors?

 

Next step is to try 0.20 gap currently at 0.40...really get that son bitch small...

Yeah coil relocation did nothing as I tried it last night.

 

Confirmed by bench test at 43 lb/hr. all withing a couple % of each other.

Thanks.

 

After 2 years of trying to solve this issue, it seems done! Tested at high temps, high RPM and full load, a plug gap of 0.20 solved the issue. Car is glass smooth in power all the way up to 6600 RPM.

Always thought that only blown or boosted cars had this problem but I now understand that high compression cars also can have this issue.

Thanks for the help.