John S's Journal

Thanks to a fellow member, the mystery of excessive jet depth on my newly rebuilt HS4’s is now solved. I have been trying to get my GT lined out since I swapped the fresh carbs over and it’s been a hair pulling trial. I could get the car to run well enough for some drives in the country but knew all was not well. Little did I know that the PO had cut off the end of the air inlet pipe on the valve cover, thereby eliminating the restrictor and consequently over-diluting the mixture. Clay Johnston was kind enough to mention a couple things and it dawned on me that I hadn’t checked that piece of the equation. I wound up making a restrictor out of a tapered plastic cap from a small bottle of Loctite by drilling a 5/64” hole in the end and trimming the other end so that it would slip into the part of the way and then slipping the canister hose back onto the pipe with the restrictor inside. Set the jets 2 full turns down and the car started right up and ran smoothly. Raised the jets up 2 flats to see if I could lean it out some and took it for a long drive out in the countryside. Pulled the plugs and they look pretty good. There is a bit of a slight surge/hesitation at a light/moderate throttle so there is more to do but the car ran as good as it ever has in the short time that I’ve had it back on the road. I always attributed the earlier issues that I had when I was using my old carbs as being due to worn throttle shafts and that the fresh carbs would solve that. Now I know why the excessive jet depth was also present in my old carbs.