Help! Trying to identify modifications done to my Corvette

[skalskirj]

'86 data sheet indicates Z51 option it's a manual,but has 6 speed from a later model,has 3.73 rear gear s/s long tube headers now here's where I get lost, the intake/plenum does not look like other '86's I think later as the aftermarket air filter assy has 3 K&N s that then go to an oval throttle body 86's had a round tube connector ? and here's the puzzler The is a board between the oem Ecm and the oem connector ? I bought it back in '03 it runs damn near perfectly and damn quick but seems to run rich though doesn't stumble on itself or choke black but tailpipes have soot and exhaust smells rich and although it's an early production it does have aluminum heads The guy I bought it from says he sent it to Lingenfelter to be tuned back in the early 2000's and it did 297 rwh on the dyno but he didn't have the sheet there was also a mention of Accel DFI could that be the board ? It'll go sideways in 3 of the 6 The last thing I owned that went like this was my "66 427/390 Coupe

 

[KANE]

'86 data sheet indicates Z51 option it's a manual,but has 6 speed from a later model,has 3.73 rear gear s/s long tube headers now here's where I get lost, the intake/plenum does not look like other '86's I think later as the aftermarket air filter assy has 3 K&N s that then go to an oval throttle body 86's had a round tube connector ? and here's the puzzler The is a board between the oem Ecm and the oem connector ? I bought it back in '03 it runs damn near perfectly and damn quick but seems to run rich though doesn't stumble on itself or choke black but tailpipes have soot and exhaust smells rich and although it's an early production it does have aluminum heads The guy I bought it from says he sent it to Lingenfelter to be tuned back in the early 2000's and it did 297 rwh on the dyno but he didn't have the sheet there was also a mention of Accel DFI could that be the board ? It'll go sideways in 3 of the 6 The last thing I owned that went like this was my "66 427/390 Coupe

WELCOME TO THE CAC!


Wow- sounds like it's a lot of fun!!



Can you link some pictures or show us what the ECM and the engine look like?


If you drive the car at about 70mph and have it in 4th gear, your rpms should be around 3,700rpm. 4th gear is a 1:1 ratio and that should tell you what gear you have by the rpms.