Fitting a Hi Torque starter.

[jonnyb]

A few caveats at the beginning of this post.

I am not connected to Powerlite I have just had good service from them so happy to say so.

I am not an auto electrician but have simply reproduced the circuits shown later from other more knowledgeable sources (the Powerlite Fitting Instructions and MGB Electrical Systems by Rick Astley)

As the MGA 1622 engine I am about to put in my Riley has a compression ratio of 10.5:1 and the current starter is a bit lazy I decided to replace it with a Powerlite RAC 401 starter from the MGOC which fits the MGA and early MGB engines.

I am recording this change because it is also applicable to the stock Riley engine and may be of interest to other members.

Before I remove the Riley engine I am trying to make sure everything will fit and work in situ, hoping to avoid surprises later.

When the starter arrived a test fit on the MGA engine looked very nice. As you can see in the pic it is a pre-engagement starter with the dog engaging from the front of the flywheel unlike the original inertia starter which engages from the rear. Also in the pic you can see the link wire between the power contact and spade connection which triggers the internal solenoid. More of that later.

However, as you can see, the motor sits beside the gearbox and projects towards the offside of the engine bay.

In the Riley engine bay this area is cluttered by pipes and a part of the engine bay structure.

As a result the starter will not fit!

Looking at Powerlites' website I wondered whether one of their other models might fit so gave them a ring. They suggested I remove the mounting plate bolts which hold the mounting plate to the starter body, rotate the body to clear the obstructions, and mark the desired relative positions. If I marked the new holes required they would redrill the mounting plate for me F.O.C. Wow what service!

The redrilled plate arrived back in a few days. The plate was redone on their CNC machine and actually had a full set of holes which are positioned on the PCD at 20degree intervals, but one pair was almost exactly where I had marked.

Now when remounted the motor body sat much closer to the engine.

[jonnyb]

And it now fits on the Riley engine, in the bay, without fouling!

In the picture below you can see the lower distributor cap clip which is now much easier to detach and refit with the extra space available. It looks close to the power feed terminal but in fact it can't touch it. I will be putting a rubber cover on that terminal though.

Before the modification was made both starter mounting bolts were free but afterwards the lower bolt was effectively captive.

So this makes mounting the starter a little more fiddly. The top bolt needs to be longer than the bottom one, say 1/4" and engaged first, then the bottom bolt can be used to draw the starter back into position and the the top bolt tightened before both are nipped up tight.

I am having a break for my dinner now but will detail the electrical options later.

[vue from the north]

have you put a larger battery on as well ? im running a 096 lucas heavy duty to throw the standard starter round quicker, had to buy the longer threaded bar for the battery clamp, i thought about the Powerlite but the £220 kept my hands in my pockets, its good write up thanks for doing it

[jonnyb]

The starter has a main power connector and a spade to trigger the internal solenoid. For cars like the MGA and our Rileys which have a bulkhead solenoid Powerlite recommend leaving the link wire in place (see first pic). In this case the bulkhead solenoid is triggered by the starter button as usual. This feeds power to the starter and because the link is in place the internal solenoid is triggered which pre-engages the starter and then the motor and gearbox spin the flywheel. Retaining the bulkhead solenoid has the advantage that the engine can be turned over for compression testing, dwell measurement etc. from inside the engine bay.

A second option would be to remove the link wire and feed power to the starter direct from the battery and then trigger the internal solenoid by using a wire from the starter button direct. This would take the bulkhead solenoid out of the system so the benefits listed above would be lost. Also provision would need to be made to feed power to the loom either by retaining a live feed to the bulkhead solenoid to feed the brown wire connected there or by some other means. It may be advantageous to use the internal solenoid only, as there are reports of new bulkhead solenoids being of dubious quality, your experience may differ?! In this option the bulkhead

solenoid simply becomes a terminal block.

A third option retains the advantage of being able to operate the starter using the button on the bulkhead relay, but without it being required to carry the heavy starting current. To do this the power lead to the starter is connected to the same terminal as the battery lead on the bulkhead solenoid so the starter motor is effectively permanently connected to the battery. The link wire is then removed from the starter motor. A wire is then connected from the spade terminal on the starter back to the switched terminal on the bulkhead solenoid (previously vacated by the original power lead from the bulkhead solenoid to the starter). This new red/white trigger wire can be seen in the 1st picture in my 2nd post above. Now when the starter button is pressed the bulkhead solenoid operates and feeds current to the spade on the starter motor which triggers the internal solenoid thus operating the starter. The same result is produced by manually operating the button on the bulkhead solenoid. The bulkhead solenoid has now simply become a low current relay. The internal solenoid alone switches the heavy starter current but the benefits of the under bonnet starter button is still available. I am planning to use this last approach.

Whoops I forgot to label the box on the RHS of the circuit diagrams. It is the Hi Torque starter.

[jonnyb]

Nov 20, 2023 19:01:15 GMT vue from the north said:

have you put a larger battery on as well ? im running a 096 lucas heavy duty to throw the standard starter round quicker, had to buy the longer threaded bar for the battery clamp, i thought about the Powerlite but the £220 kept my hands in my pockets, its good write up thanks for doing it

No the battery is very young and healthy!

[canuck]

Well done Jonathan,
Nice to read you chose a sympathetic vendor.  

This Hi Torque or Gear Reduction starter motor is a popular upgrade this side of the pond for MGB and the like.

Some of these starter motors comes with an 'indexable' mounting flange.  

I watch with envy from my garage, apparently you are doing everything correctly.

B

[jonnyb]

Yesterday I finally fitted the new starter and road tested it today. All works fine and fairly whirls the engine over. So I know this will be fine when I fit the MGA engine as well.