Well after something like being out of commission for 18 months I’m finally in the final stages of getting my 83 GSL back on the road! Since the engine blew I figured I’d upgrade a little bit so I had Daniel at GarageLife (shoutout to that legend) build me a 12a with a streetport. After spending the weekend finally getting the engine all hooked up, I was able to fire it up for the first time and after troubleshooting some bad spark plugs I finally got the engine to fire up reliably and it seems like it wants to run. That being said it is running like absolute crap and I’m struggling to figure out why at this point. Despite having the engine ported, I have yet to change up the induction and I’m still running the stock Nikki carb. I swapped to 130 primary jets and 170 secondary jets but at this point I’m thinking that may have been too much. The engine seems to me to be running very rich. It won’t take up any throttle without protest and no amount of idle mixture adjustment is able to lean it out it seems. What are y’all’s opinions based on the video of how it’s running. For a variety of reasons I don’t believe that the engine is running lean but it may be worth mentioning that I have the rats nest unplugged and none of the plugs for the ACV components hooked up.



Also, for some reason the tachometer reads accurately up to 2000 RPM, but the moment it hit 2k the needle drops to 0 and sits there without moving even though the engine is still revving up. The moment that the RPM drops below 2000 RPM again the needle jumps right back up and starts

Here’s some footage of the car idling at about 1100 RPM. I can’t get it to idle any lower.
https://youtube.com/shorts/YD9q32dUceg?si=XUtHOkIuBKA06nw3

 

You're off the reservation on your carb jetting, so I'd check with the builder to see what they recommend. Your Tachometer dropping out at 2k RPM tells me you need to look more closely at your ignition; probably your Trailing Ignitor going out, a bad distributor Cap or Rotor, or possibly a bad Coil - in that order. Tune up parts will cover most of this, but as you said you traced another problem to faulty spark plugs, you should really be starting your tuning session with all new ignition and fuel components, or you could spend a lot of time chasing your tail. This means new spark plug wires, as well, fresh gas, etc.

Once you get it running and idling, you'll be able to start tuning properly. As a street port, the idle will suffer co pared to stock, anyway. Beyond that, it's about getting to good off-idle acceleration and good mid- and top-end power at WOT. Start with getting the ignition sorted out, though.