Re: A-series distributors

Can't you just change the driveshaft from the cam?

Yes I have the A+ drive shaft so that's not the problem. The A+ block is cast differently to cater for the forked retainer, so I'm wondering what's the best way to adapt the A-series block

For what I remember of the A+ distributor the means of locking the unit's body to the engine was different, the normal A series distrib' mounting pinched in from the sides, the A+ clamped down from above IYSWIM - the drive dog might well be different, but that is not the real problem AISI.

Yes if it's the same but I wasn't sure about that.

Why not buy the right distributor? I got one recently for £25 at a show

- new bankrupt stock. Alternatively just use the A-series clamp and retain the existing flange.

Richard

Would you really risk the A series over 6000 RPM for very long? Well!!!!

Converting Hitachi distributors for use in BMC A and B series may help out if you can't fit the A+

rm

Can't you find some points that will do better than that? Not all makers of replacement points used the same strength spring and ISTR that an outfit called Commercial Ignition (or some such) used to make ones that would run to 8,000 or so. Finding them now might be a bit tricky though. . .

As for changing to an A+ Metro unit, are the advance curves the same?

Ron Robinson

There are various reasons to change to the A+ dizzy. One is the stronger points spring, another is the longer-lasting points (wiping action), then there's the assymmetric cam which delays points bounce. Yes the advance curve is different but I'll be changing that anyway to match the camshaft. Actually most of these benefits are available just pre-A+, but it's the one I happen to have. This engine is designed to rev to 7,000 - the standard dizzy, as I know from having tried it, bounces at about 6,300. Also it's worn out! So I might as well change to a better, later one if possible.

Thanks for your useful links. I'm a lot more confident about the rpm capability of the A-series than you are. Racing units regularly go to 8,500 or more.

Yes it it's properly set up, particularly the smaller engines. But you can fit contactless ignition such as Lumenition or the Pertronics Ignitor (marketed by Aldon over here).

Richard

Because he says that the original is unsuitable for his 'tuned' engine and secondly the body of the distributor at the clamping point is different and thus the two types of locking clamp / pinch plate can't be exchanged with each other.

A series engines don't last long over 6000 rpm

Ah, right. Must confess I'm not familiar with the A+ dizzy, but I know from experience that the standard Lucas 4 cylinder unit from the late 50's / early 60's will, when in good nick and fitted with a good set of points, cope with over 8,000 rpm. It wasn't until the Formula 3 screamers started running at over 10,000 rpm that Lucas had to go to something rather more special - first a black box system that used to suddenly stop working for no discernable reason, then a conventional distributor with lightweight points that would, if you were lucky, last for just about one race. However if you have the chance of something with wiping points then go for it, especially if it is anything like the Ducellier ones where you can set the dwell angle with the engine running.

Ron Robinson

Thanks everyone for this plethora of interesting answers. Special mention to ops for the fascinating link re Hitachi dizzies. May not fit though as greater length may not clear steering column - not a problem with transverse engines. That's why they usually fit a side entry cap on RHD Sprites. Still not quite sure what to do, but all good food for thought.