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Q & A: 48 TC

My friends Art & Yvonne Lewis and Jerry & Shirley Niemi tell me your the best, so here goes.

I bought my 48 TC from Jerry Goegen a few years ago. Because it had been sitting in his barn/museum for quite some time, it needed quite a bit of work to make it a reliable driver.

Took car to Chuck Troast at New England Classic MG in Freedom, NH, about an hour away.

He had a great deal of difficulty getting engine in tune. Turns out distributor was pumping oil from the crankcase into the distributor. After rebuilding distributor, still couldn't get tuned properly. Also starter acting up - kicking back.

Pulled engine and checked timing chain - was installed out-of-phase!

Dropped crankcase and checked internals. Connecting rods ground down severely - looked unsafe, so decided to do an engine rebuild.

One of the mechanics who worked for Chuck at the time rebuilt the engine (2-years ago this month). Crank was ok. Bored .120 over and balanced by machine shop in Portsmouth, NH. Installed new 3/4 cam, connecting rods, hardened valves, lifters, timing chain, chain tensioner, pistons, ring gear, freeze plugs, motor mounts, clutch, pressure plate, throw-out bearing. Rebuilt oil pump.

After finally getting back on the road, still didn't feel right. Turns out Glen, the mechanic, installed the timing chain out-of-phase and installed rocker shaft backward. So installed new rocker shaft and repositioned the timing chain.

Car finally running well.

This summer, TC seems a bit sluggish, so I decided to tune it up.

Adjusted valves (as specified for the new cam), installed new plugs and checked Point gap. Then adjusted timing (using a 12 volt test lamp). To my surprise, if I adjusted timing to TDC or a few degrees before TDC, car had no pulling power. Repeated this a few times to make sure I hadn't made a mistake. Same results. Only way I can get the engine to run reasonably well (but not optimally) is to advance the timing to the point that the starter begins to kick, and then back off a bit. Timing has to be advanced 20 degrees or so.

Also adjusted carbs (balanced the two carbs) but can't get the mixture on the rear carb right. If I adjust leaner, engine slow and if I adjust richer engine slows and if I raise the piston a hair, engine wants to die.

Finally, the engine seems to run much rougher than my wife's TD. At about 2500 rpm (driving or sitting still) quite a bit of vibration evident. Chuck Troast says that TC motor mounts are much stiffer than TD, so nothing unusual about vibration. However, I am convinced that the engine was much smoother before the rebuild.

Question # 1: How do I tune this engine given the circumstances I have related?

Question # 2: Any thoughts about the vibration?

Question # 3: Will you be offering a workshop on TC transmission rebuild any time soon?


Elliot

Elliott!

A couple of notes. I think the 3/4 cam was an error. Usually 3/4 means 3/4 race and that gives a very, very rough idle because of the valve overlap. The stock cam is so very much better. Would it make sense to change now?... read more