Room for collector extensions, perhaps? Regardless, it would mean physically relocating the evac/collector connection downstream a bit, so there's be some "cutting & pasting" involved for at least that connection, possibly that and the O2 bung, both. Devon
But the header vac system would be upstream of the collector extensions. Nullifying the point, right? And let’s see....I just blocked the driver side vac system, and installed 84/94 jets. Let’s see where it takes us on a nice cruise
Another possibility would what you tried previously, finding a way to disable the evac system temporarily to tune the carb, then re-enable evac and don't worry about wide-band readings anymore (remove sensors, plug the sensor bungs). Devon
And I didn't consider this, your comment just spurred me. how about O2 sensor on one side only, evac on the other side only? I was thinking you might be running two sensors. Maybe evac on one side is enough? Devon
Tune it with evap plugged on driver side, Then pull sensor , plug bunghole and add race fuel.... Off to the races......JIM
Just thrashed it a little. Plugged on drivers side, with 84/94, still 11.5-12:1 rich at cruise, and approximately 15+ at WOT, and only getting leaner as the rpms climb
Good question Devon, I don't remember seeing that, but I might have missed it. That would explain a lot.
7 psi, and carries 7 psi through the whole run. It’s a very large pump. I can watch it fill my front and rear bowls with sight glass in about 2 seconds
After 2 carbs and the wild tuning without satisfactory results it seems as the constant is your AFR gauge. I know they are a great aid for tuning, I have never had the money to get one. I have tuned the old fashioned way. Is the car breaking up when "going lean"? How long do you pull showing lean, or are are you lifting as soon as you floor it?
I meant to get back earlier. I'm swimming in 2020 Corvette stuff at work, but I have peers with huge experience in all of our gearhead stuff, so I'm sending them over to look at this thread. Not giving up! Devon
John, just talked w/a work fellow, he's racing BBC. I explained all to the best of my ability. He's seen this situation only one time before, and that's 25 years. Intake manifold leak. That's the next place to explore. Devon
And more. The spark plug reading part is still in full swing. BUT... You'll get the usual stuff on the insulator that may show signs of detonation. The better reading is way down inside, near the bottom where the insulator meets the parent metal of the plug. Hard to see without bright light. He (Justin) actually cuts plugs to see what's happening. He says your next full throttle blast needs to be on the way to the garage, less idling, the better. Devon
