Pontiac renovations, part 27.

With the engine and transmission back together, I decided to finish up doing the things that are difficult to do with the engine installed.

Looming tape

I wrapped the wires that are now in place (lights and such) and tidied up under the hood.

Delco 10si alternator ident

I undid the clamp bolt and cleaned up the body of the alternator. 1100542 shows it’s a Delco 10SI, 63 Amp remanufactured unit.

Alternator in pieces

I stripped the alternator down, thankfully Delco have the manuals online for their older models. There are 4 individual parts inside the end case; the rectifier bridge (silver finned heat sink), a capacitor, the voltage regulator (white plastic) and diode trio (orange).

The principle of the alternator is moderately simple. A magnetic field in the armature, created by passing an electrical current through a couple wound around it, rs rotated by the engine next to a series of wound coils (stator). As it moves past each coil winding, the change in magnetic flux generates an electrical current in the coil winding. As the magnetic field moves towards the coil, a positive field is created, as it moves away, a negative one is created. There are usually 3 windings (either in a Y or Delta configuration) so an alternator creates 3-phase alternating current. This is no good for a car battery which is direct current, so it is rectified through a bridge rectifier set of diodes before it’s connected to the battery.

This output is connected through the diode trio to the voltage regulator. The voltage regulator changes how much current passes through the winding in the armature, making the magnetic field stronger or weaker depending on how much voltage the stator coil windings produce.

The diode trio tested bad- two of the diodes are open circuit (do not conduct at all) and one doesn’t diode any more so that should be the root cause of the alternator not charging. The voltage regulator isn’t getting the voltage it needs from the output so isn’t applying voltage to the armature winding and the alternator is producing very little charge.

Valve lash adjustment.

I readjusted all the valves. The manual states to make sure they are all set correctly.

Installing engine

I bought some new bolts for the rear engine cradle, rated 8 (strong for shear force) with the correct fine pitch thread. That was cleaned and reinstalled and the engine wired in temporarily.

Securely mounted

It was good to see it back in. I set about reinstalling the ancillary parts and started to look at the manifold, which has never sealed well. It is made in two parts, with a “hotspot” flap in the exhaust that directs the exhaust around the outside of the intake by the carburetor before letting it escape though the downpipe.

Heating bolts

It was suggested that I split the two parts and re-settle them to allow them to seat square against the engine. Easier said than done, as all four bolts were seized and all four broke upon attempting to undo them, despite heat and releasing oil.

Drilling out old bolt

I carefully center punched the remains of the bolts and started to drill them out.

Cleaning threads

I then used a thread tap to clean the last of the bolt from the threads.

Original threads

The two most accessible bolt holes were straightforward, but the two at the back are obscured by the casting of the manifold and proved impossible to drill out straight. I ended up drilling them oversize and tapping the holes with a new thread.

Reassembled manifold

I made a temporary gasket and reassembled the manifold, which allowed me to put it back on the engine. It leaks but the correct gaskets are many times thicker and take up a lot of the gap.

Radiator hose

The original lower radiator hose was so badly rusted to the spigots I had to cut it to remove it. I took the old hose to the auto parts store and a replacement with the correct bend in was sourced. I cut it down to length and put the anti-kink spring inside.

Engine plumbing

I finished putting everything into the engine compartment that was required to make the engine run. I filled the radiator up with water and connected the fuel.


The three gauges that are currently connected all worked. Fuel gauge reads a quantity of fuel in the tank, engine temperature reads as it warms up and the ammeter reads a discharge.

First time outside in a while

I connected up the propeller shaft and took it for an experimental drive. The gears changed, it went forwards and backwards and overall worked.

Throttle linkage and spring

The throttle linkage was very sloppy and had a lot of free play. This was causing the gas pedal to move the gearbox modulator lever quite a distance before the throttle began to open, with the net result the gears were holding until high speed before changing and under light throttle were quite harsh.

Tight connection

I added some springs to the connections to hold them all in line, peened the bar of the throttle down to remove the slack and readjusted eveything as per spec. The result was as hoped for; gears that change gently under light throttle and more positively and at higher speed with heavier application of the gas pedal.

Testing wires

I started to track down a misfire under light load, I checked the spark wires for continuity. They are all good, but the insulation is poor so I think new ignition parts are required (cap, arm, coil, wires, plugs).

Water, soap and 2000 grit paper

I turned my attention to the cosmetics of the car because the weather had turned fine. I started to wet-flat the paint with dish soap, plenty of water and 2000 grit paper.


After finishing with the paper, I started to polish the paint with scratch remover cutting compound, then a finer grade polish, and finally wax.

Regaining a shine

The day became too hot to continue, as the polish was just flashing off, so I stopped. The improvement is noticeable.


I also masked up and painted the driver’s side hubcap with red lacquer. That made an improvement also.

Shiny paint

I loaded the car back up into the garage, and looking across the hood, I was able to smile. It is beginning to look nice. Much more yet needed, but this is a good start.

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