Since getting my 1954 GMC w/Hydramatic a couple of months ago (my first experience with a stovebolt), I have been driving it and addressing things that were not handled by the prior owner who used it for sunny day driving only (ex: get the wipers working; tighten up steering box; etc.) in prep for this to be my daily driver. I am pretty much there now . The truck has always (for a couple of months now) felt a bit lethargic/low-powered, but, I attributed that to it simply being "an old truck with only 115 bhp". It would cruise at 60-65mph no problem, but going up steep hills would require downshifting to 3rd and it typically required more throttle than I would have liked (often flooring it to get over 40 mph). I decided to run a few tanks of fuel thru it to get used to it (getting a good baseline of experience) before tuning it at all. Well, after putting about 1000 miles on it, I decided to check out the ignition dwell and timing. Lo and behold - it was running only 18 degrees of dwell!! (I'm mystified it was running at all) and the timing was somewhere off the scale - most likely a function of the horrible point gap. It was also idling around 700 rpm (should be 400 rpm) - which meant the vacuum advance was perpetually engaged. However - no pinging under load and started fine when cold (seemed a bit cranky/slow when hot indicating advanced timing). Well- I reset/adjusted everything this past weekend. Now, with the dwell at 35 degrees (low end of the allowable range per the manual) and the timing set per the book - I have a new truck! Goes up hills with power to spare, needs very little throttle to drive and idles like a sewing machine at 400 rpm (book value for hydramatic trucks). Also, it is substantially quieter in the cab now that I don't have nearly so much intake noise - most of the noise is coming out the tail pipe . With the proper idle setting it isn't fighting transmission drag at stoplights anymore either! Just really nice now!!! Can't wait to see what my fuel economy has moved up to (was running about 11 mpg). Oh - I totally lucked out on the rebuilt motor that came with it: so far only used about 1/8 quart of oil in 1200 miles! Anyway - I am amazed that the 248 could run reasonably well being SO FAR out of tune - then again, my basis of comparison is smaller european engines which wouldn't even come close to running under such conditions. As of right now I am totally smitten with this truck - it is truly a pleasure to drive!
Getting There Roland ; Now go look up and perform a HOT VALVE ADJUSTMENT and be flabber gasted at how well it runs !
