Triumph Repair: 1976 triumph spit 1500, rich stock, leaded gas

Question
QUESTION: i have just had my car krypton tune and it backfires when pressing the gas,it pops through the air filter as well,the plugs were black sooty cleaned them ,i have put unleaded in it ,the car is not unleaded,will that cause it,thanks 1976 triumph spit 1500

ANSWER: Tony,

Not familiar with Kryton tune.. but it doesn't matter.

Your car is running rich. Stock Stromberg CD150?   Checked the diaphram lately?

Not sure where you're located, but leaded gas has been hard to find for the past 20 years, unless you're using leaded racing fuel normally?   

Regardless, unleaded won't cause the symptoms you're seeing.  It's a rich condition, or a timing fault in the ignition.


Cheers,

Jim

---------- FOLLOW-UP ----------

QUESTION: basically its been tuned and timed.and it keeps running like sh))i live in england thanks,tony

Answer
Tony,

If you're in the UK and it's a "home market car" then it should have twin HS4 SU carbs.   From the symptoms you describe it sounds like it's running rich.   Have you checked the choke linkage to make sure the jets aren't sticking in the down position?   Or does your car have the waxstat jets?

If it's not running rich there's a chance the distributor advance isn't working properly.   Still running the original Lucas Opus ignition or something different?

I don't know who did the "tune and timing" but I know that in the US it's tough to find an auto technician that still knows how to tune a carb properly in this age of fuel injection and hi tech engine management.  


Cheers,

Jim