Triumph Repair: lean moter, stock air filter, stromberg carbs

Question
I recreantly changed a cracked head on my 1976 triumph spitfire.
I got a 1975 head and had it rebuilt than I found out it did not
have the emission holes in it.I decided to us it anyway. I plugged off the main hose and disconnected the air pump. Now the motor runs lean, I half to run it with the choke out a little. Would the difference in the heads cause this trouble if so can the carburetor be adjusted

Answer
Hi Kevin,
The air pump access holes had nothing to do with the mixture as the holes went into the exhaust ports. Most Stromberg carburetors were adjustable. Remove the top thumb screw and put a long 3mm Allen wrench down into the oil in the top pot to see if there is a Allen screw in there. If there is, that is the jet adjusting screw. Clockwise to rich. Be sure there is oil in the top pot.

However, there are other things you should look at. Check for any vacuum leaks and be sure the stock air filter is in place as many Stromberg carbs will be lean without the factory air cleaner. Also look at the auto trimmer on the side of the carb. (long plastic cover) remove the cover and for a test put something under the cover to hold the valve closed all the time and the brass screw next to the auto trimmer needs to be closed all the way and left that way. It was only used when the car was new and then closed off.

Howard