Herald Alternator Kit and Control Box

[PeteStupps]

18 hours ago, Adrian Girling said:

Now to drill and tap the hole in the block which has no thread in it...

Good luck on that. I found drilling & tapping cast iron to be surprisingly awkward. Surprising because I hadn't done any research beforehand, of course. 

[RobPearce]

1 hour ago, Adrian Girling said:

So when I've determined the correct belt length I'll report the pulley diameters too.

The cars with dynamos had a smaller crank pulley than the ones built with alternators, particularly the 1500 Spitfire. It doesn't matter much but the larger that pulley the better it charges at idle. You do need to match the water pump pulley, though, and be aware that a large pulley may overspeed a dynamo at max engine speed. Alternators are less bothered by being spun fast.

So the diameters are of interest for knowing which belt matches them, but there's no reason to worry about changing any of them.

[PeteStupps]

Good info that @RobPearce. Not directly relevant but I noticed a while ago that my 1300fwd had a larger dynamo pulley than my mk3 Spitfire. Wasn't sure why so did some calcs and found that the smaller-pulley dynamo would exceed its speed limit (10k rpm) at 6,300rpm engine speed. Didn't note what the larger pulley maxed out at, but I swapped them over on the basis that the Spitfire might actually see 6,300rpm once in a blue moon, whereas the 1300fwd probably never will.

[Adrian Girling]

4 hours ago, PeteStupps said:

Good luck on that. I found drilling & tapping cast iron to be surprisingly awkward. Surprising because I hadn't done any research beforehand, of course. 

Thanks.  I'm hoping not to break the tap in the hole.  I have to go out to M10 and going for 1.0 thead on the theory that it's a deep hole so it can be a shallower cut which should need less torque to cut. I believe the pilot drill needs to be 9.1mm and it doesn't need lubrication as cast iron has carbon in it.  But any further advice would be welcome!  I believe there is a type of Loctite which virtually does away with the need for a thread...

[standardthread]

According to Zues (screw size charts etc.) a 10mmx 1.25mm pitch (metric fine) needs an 8.75mm drill, a metric course 10mm x 1.5mm pitch needs an 8.5mm hole.

On the subject of pulleys I fitted a larger pulley on the alternator to 'pull' the alternator closer to the block thus giving me some adjustment on the bracket. Because the pulley is larger it will reduce the rpm of the alternator.

An alternative to get everything to fit, try to find a bracket and pulley from a 1300 Dolomite, same engine block as Heralds and Standards

[Adrian Girling]

3 hours ago, standardthread said:

According to Zues (screw size charts etc.) a 10mmx 1.25mm pitch (metric fine) needs an 8.75mm drill, a metric course 10mm x 1.5mm pitch needs an 8.5mm hole.

That tracks with 1.0 pitch needing a 9.1mm drill bit - can't recall where I found this.  Thanks also for the pulley/bracket suggestions - somewhere to go if the change in fan belt length is not adequate.

[Adrian Girling]

Successfully installed the Rimmer Bros Alternator kit using a 1050 mm fan belt in place of the 1063 mm belt sent with the kit, which was too long.  Belt is "Medway" AVX 10X1050La "OIL AND HERT(sic) RESISTANT".

Managed to drill out and tap the corroded hole where the bracket is bolted to the cylinder head.  Used an M10 1.0 bolt. Can give full details if anyone interested.

Pulley diameters (roughly) 4 1/8 fan, 4 5/8 crank, 2 1/2 alternator - difficult to measure accurately as I didn't have calipers with me - I'd be interested to learn if these are the standard pulleys and what other diameters are available?

[PeteStupps]

6 hours ago, Adrian Girling said:

"OIL AND HERT(sic) RESISTANT"

That's reassuring! Won't break up in Hertfordshire. 

Good work getting it on. Your crank pulley measurement is the same as my Spitfire (117mm - metric calipers). My dynamo pulley is about 74mm, so just shy of 3". 

[standardthread]

My 'Y' reg 1300 Dolomite has a 72mm alternator pulley. My 1970 Herald estate has a 62mm diameter pulley with a belt marked 1092 (1092mm long?). I re-built it with a new short Mk IV Spitfire block and haven't measured the crank diameter. One of my spare alternators has a 62mm pulley.

Moral of the story, mix & match?

Edited May 27, 2022 by standardthread
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