• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!

    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

SU carbs and the Oxygen Sensor

martx-5

Yoda
Country flag
Offline
I have an O2 sensor mounted into my TR3 exhaust manifold that's hooked up to an analog O2 gauge that I have mounted in the glove box. I've modified the TR's engine by increasing the compression ratio and installing a 282° cam along with 87mm pistons and liners.

With this combination, when I got on it hard, according to the O2 gauge, I was running pretty lean. I called Joe Curto, told him what mods I did, and he sent me a pair of RH needles to replace the original SM's. Well, I installed them yesterday, went out for a drive, and carefully watched the gauge under various conditions. When I stomped on the gas, there was an initial lean tip-in, quickly followed by a nice rich mixture. (AFR in the 13-12 range) At cruising, it leaned out a bit...fairly close to stoimetric. It does run a bit rich at idle, but being that all the other readings are exactly where they should be, I'll leave things alone, as the car runs better then it has since the resto was done.

Ah, the wonders of technology that can applied to an engine using carbs to set the mixture.
 
martx-5 said:
When I stomped on the gas, there was an initial lean tip-in,

Heavier juice in the dampers will fix that without affecting anything else.
 
Thanks Randall. I'll give it a shot.
 
Back
Top