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Hello, I am new to the site which I am very impressed with (thx to all) so I thought I would check to see if anyone could assist with suggestions in initiating a DST tune. I will paste in the engine build specs below but I am haunted by a high rpm WOT misfire. Seems I’ve replaced everything at least once that was suspect and am on my third OPTI so I think we can safely rule that out. I did read one of the post here that someone had been a bit too lean and not enough spark advance that caused this situation. Anyway, thought I would ask for anyone who thinks they may be able to assist with thoughts on this situation ahead of my initial try at tuning it DYI.

LT4 with Scat 383 Street/Strip Rotating assembly. Hardened ARP crank, rod and head bolts.

Mildly ported LT4 heads - ( Valves I 2” E 1.55”) - matched to LT4 intake - ports also opened up to mirror head ports. Bowls - removed material to reduce CR and increase combustion efficiency - polished -CR: 10.9.

Holley High volume fuel pump, K&N fuel filter.

Accel 30lb fuel injectors

BBK 52mm throttle body, K&N filter.

Hydraulic Compcam. 305-8
Duration In276 Ex290
Duration @ .050 In220 Ex230
Lift In 545 Ex 545 (Jegs 1.6 Roller Rockers). LDA 114 Degrees

Compcam Valve Springs #26915
Seat load: 105, Rate 313lb per in. Coil bind 1.100 inch.

Compcams hydraulic roller lifters

Underdrive pulleys. 160* Thermostat.

Dougs Shorty Headers, Flowmaster cats, 3” Corsa cat-back w/ H pipe

High Volume Oil Pump

MSD ignition box, Blaster coil, 8mm Taylor wires. NGK 4177 (TR6) spark plugs. (One step colder than stock LT4 plugs)

MSD Optispark Distributor (no noticed improvement over GM Opti)
 

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I would troubleshoot the ignition system. I ditched my Taylor’s along time ago. Found a set of factory LT4 corvette plug wires, just had to swap one boot. Maybe bypass the MSD. And a AC/Delco Optispark?
 

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Discussion Starter #3
Thanks for your input. I plan to start with your suggestion to replace the wires. I’ll try one thing at a time. And as far as the OPTi spark it is an MSD unit, after installing a second aftermarket acting and the problem still plagued me I pulled out the wallet and got the MSD unit. And when you mentioned circumventing the MSD unit I assume you meant the ignition box is that correct? I’ll try the new wires, if no improvement I will disconnect ignition boxAs a next step.
Thanks again for your assistance, what year Z 28 do you have? My last one was a 92. Alan
 

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1993-6speed!!! My last two digits of my VIN is 28!!! Nice meeting you!! Solomon tuned mine it runs perfect!!!
 
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