John S's Journal

I can move on to something other than fiddling with my HS4’s. It’s been a frustrating experience since receiving my freshly rebuilt carbs. All my efforts to follow the manual to the letter resulted in having to turn the jets way down from the bridge and the front carb wanting more fuel vs. the rear carb. Countless jet depth checks, adjusting, driving, pulling plugs, etc. I decided to check where my old HS4’s were when I swapped in the fresh rebuilds. They too were way down which made me think about the common denominator which was the intake manifold. I cleaned the original one that came with my GT but didn’t check for flatness of the flanges so the plan today was to get the spare from my ‘70 parts and check it with the thought that I could resurface it and have it ready to swap over.

I’ve got some heavy granite tiles leftover from a project so I glued a sheet of 320 grit wet/dry paper to it and got every flange surface smooth and flat after removing the studs.Maybe a half hours worth of sanding. Removed all of the HS4 hardware from the GT, put some #2 Permatex on all of the gasket surfaces and buttoned everything back up. Went through the whole procedure, synched the carbs, mixture, idle, etc. , rechecked the timing and backed it off a bit, quick test drive and was pleasantly surprised at how it performed. I still feel as though I really had to lower the jets quite a bit but didn’t pull the dash pots. Didn’t have much gas in the tank and not much time either so there is more testing to do and analyzing plugs, and probably pull the dash pots to see where I wind up. Maybe the old girl just needs the jets lower than most of the other cars Inread about. Time will tell.