680 (747cc) distributor mountings

[malcolm]

Does anyone know anything about distributor types for early engines? I've bought a 123 distributor (above in photo) but the body is different from the distributor that came out of the engine (below). It'll fit if I remove the bush and seems to be designed for a clamp down fastening rather than a pinch bolt fastening. Wondering if there is another mounting arrangement with a shorter bush and different clamp used on some other engine. Or is I have just bought the wrong distributor. Franzose and 123 say it should fit the 680 engine but I can't see how.

Looks like I should have bought a Dauphine version advertised for the 670 engine. Would any parts from a later engine help it to fit? I could maybe cut the bush down and improvise a mounting, or try to machine the body to the right shape.

 

[Piet]

As long as the bottom collar has enough reach to allow the distributor to go down far enough for the drive dog to fully engage you are OK. Then you just have to fake up a mounting to hold it. Renault tried a variety of dizzy attachments on the early engines. They seemed obsessed with the idea of letting the distributor be able to float or pivot and find its own centre but eventually realised it wasn't necessary. If yours sits down ok and you have a tapped hole in your block you will need to make up a suitable mount. I will post some pics in a while.

 

[malcolm]

I've found a photo of the later distributor mounting. I don't have the enlarged casting for the bolt hole on the top. I only have the bolt hole on the side. But the 123 distributor doesn't need to be rotated so I could pin it in place at TDC and clamp from the side hole.

I think the height is good (I'll measure it) and all I would need is the later bush.

Might be better to use this distributor rather than buying another as I would like to put the 845cc engine in at some point when I find a good one.

 

[Piet]

PR785 is for early 3 speed Spanish cars, PR 808 is sixties French built 3 speed and early 4 speed cars, the last one {PR number 953 but cut off) is early to mid seventies 4 speed cars with various gearboxes. I used a later type clamp down on an earlier block. This required making a piece of angle iron with a stud on the side to attach to the old type block, then have a bolt going down to clamp up onto the angle iron. Anyway, you get the drift, whatever arrangement you have, you can make an adaptor. Make sure the dizzy is engaging well but not being forced axially down onto the drive, if you get what I mean- but I'm telling you to suck eggs I'm sure! A typical problem with older cars is wear in all the rotating arrangements mean the timing isn't held precisely, making tuning a nightmare. Hence throwing it out and clamping.

 

[malcolm]

Thanks for the parts diagrams. I can see which parts I need now. Anyone have any spare?

 

[malcolm]

I ended up cutting down the original sleeve. It's a risky thing to do as I think the length of the sleeve controls the end float on the distributor drive gear which should be around 0.15 to 0.5mm from memory. I measured a lot and found when the original sleeve was slipped onto the old distributor and a flat edge placed on the flat beside the drive pin the sleeve had about 0.2mm float. Not sure if it's a coincidence but the new length worked out very similarly on the new distributor so I adjusted the length so the sleeve was the same distance short of the flat on the distributor. (Thinking about it it must be that which sets the end float). Hopefully that's good as you need a special tool to measure end float with the sleeve installed.



The early engines don't have the extended casting for mounting the distributor clamp. I drilled and tapped some 1 inch bar. The clamp mounting needs to be as close to the edge of the bar as possible.



Finally installed! The clamp isn't foolproof as the mounting stud is a bit too far from the distributor. I used a GTL clamp. The timing of this one is adjusted via USB so it shouldn't ever need adjusting. Thanks for the tips Piet - you've saved me from buying another distributor.