Originally Posted By: tlowe #1716
Which wide band are you using? They can be very good reference tools, but sometimes lead you a stray with tuning if you are glued to the readings.

From my experience.
For idle, aim for 13.5
Cruise 12.75-13
WO throttle 12.5

These chambers are very lazy and seem to like fuel.

Does your carb have a secondary PV?

I have the AEM UGEO wideband (Bosch 4.9 LSU sensor) with 52mm Analog style gauge. It seems accurate but yeah, I'm pretty OCD about things and could easily see myself buying every cam and spring to make it exactly how I want, instead of how it needs to be.

I went to pull my PCV today (Spectre chrome cap style) and sure enough, the PCV housing broke right off the valve. I had to somewhat mangle the valve to get it out as it was pressed in there good. The valve was stuck closed upon testing, but I can't say for sure if it was before I mangled it. Luckily I kept the original one and it works fine, I cleaned it and may attach the chrome housing to it for looks.

Float bowls are both still set to spec. I didn't change them. Both accelerator pumps are solid and respond to the throttle.

I ended up putting a small piece of wire in each idle restriction port on the primary metering block. First thicker wire I chose leaned it out so bad it would only start with the throttle partially down. I ended up with a very fine strand that worked perfectly. Now it idles around 13.5 and cruises to 3000 or so RPM between 12.5-13.5. I may need to increase primary jets after all but I'll get the turbo on before I go further.

That's all good news, but it still dogs it up hills or any kind of low speed load. I was too distracted by the lean wideband (16-17) and trying not to stall on the hill to think about the vacuum. I suspect my "under load" vacuum is closer to 8-10" so my 6.5 power valve isn't opening when needed.

This carb does not have a secondary PV.

Bought the 3" VBand clamp, flange and a 3" U-J mandrel bent pipe today. I have to go up a ferry ramp tomorrow to get to the welder... if it makes it, the turbo should be on tomorrow.

Thanks!


67' Camaro - Performance 250 build - www.TurboCamaro.ca