TR4 misfiring under load, fouling plugs

[GTP1960]

SMG,

That point gap is of course really off, so fix that first. Some around here say the gap can really be horribly off, and yet the car will run, but, still, fix that. Be sure all your wires in the distributor are intact. Good shape. The wire from the Terminal Bush to the points must not be shorted.

I wouldn't time it with a strobe. Instead, just static time it. If you have a test light (or care to buy a bulb of just pull a bulb out of the front turn signal and get some spare wire), just connect one line from the light to a good ground, and the other line to the side of the coil that goes to the distributor. Be sure you're at TDC with the rotor pointing at piston number one. Loosen the clamp nut on the distributor base, and with the ignition key turned on, slightly rotate the distributor so the light just comes on as the points just begin to open. Be careful of course not to yank the distributor upward. After the test light just begins to glow, stop, re-tighten the distributor and you're done--except that to be 4 degrees BTDC you must now turn the vernier adjustment dial so one more notch line on the vacuum body shows. Each notch is apparently 4 degrees.

Check the contact and spring up in the "underside" of the distributor cap. Be sure it's there, and clean. Replace that rotor. Sometimes a rotor is just manufactured wrong and you may not see it.

Granted, none of this may fix your problem but you need to rule them out. Look at those plug wires. Be sure you do have the correct plugs. A good condenser. Don't drop any little screws or anything down into your distributor. Then, for me, I'd look at those SUs last.

Finally, if your TDC mark on the pulley is gone, I'd wonder how your shop used a strobe. Others here know better, but to find TDC I think you're looking for when piston #1 is at its highest point on the compression stroke (each piston has two strokes, compression and exhaust) and without the mark on the pulley you'd probably have to determine that point and mark it with a white marker. You'd do that by removing the valve cover and watching the #1 piston valve reach its highest point, when the distributor rotor is pointing to #1. You can pull the crank fan slowly by hand to get to the right point. I pull mine with a rag 'cause it's really difficult with the plugs still in.