18rg gurus, your help is needed.

[maurice c]

Hi Guys,
I have just taken my slightly mangled dizzy from my 250 head 18RG to clean and prep it and have made a discovery, I think what I'm running is a 18r dizzy. Heres a pic comparing it to a 18r-c dizzy.


I think that their the same the one from the RG is on the left, Rc right. Anyway I'll be using one of them, is their any point in trying to change the ignition advance map in the future? Thanks Maurice.

[airfireman1]

I would not be too concerned, I have just found out that the 18rgeu that I bought a while ago was running an 18rc dizzy the clamping set up was a bit of an abortion and did not secure the dizzy very well. That was converted to electronic at some stage. fortunately I had a spare 18rgu dizzy that had the correct body so that it could be clamped to the timing cover properly. It ran well with the 18rc dizzy anyway.
Cheers.

[maurice c]

Apparently there is no oil pump drive on a true RG dizzy, does anybody have an idea if theres an advance difference?

[Steve M]

Apparently there is no oil pump drive on a true RG dizzy, does anybody have an idea if theres an advance difference?

That's not entirely correct.
Different models had different things.
8823something 18RG distributors had the oil pump drive on them, also 18RGEU and 18RGU dissies did.
Some of the earlier models did not, so I've been told.

The best way to tell, other than reading the yellow label on the dissy body is to look for wear marks where the oil pump drive section of the distributor shaft is. If there has never been any wear on that part of the shaft from driving an oil pump, then chances are that it is an original twincam dissy.

From the angle of the photo it is hard to tell but I think I can make out some wear on both distributors you've shot there, so both would be single cam distributors, or both have been used in single cam engines.

[Rodger]

Maurice

Toyota like most makers try to use common parts across their range. The dizzy is one place they do and it can be set up to suit either motor.

Remove the vacuum/points plate and check the mechanical advance system of weights and springs. The advance plate will have two slots one marked say 8 another say 13. Pick the higher number of the two and assemble with the post into that one. A number of 13 equates to 26 degrees of mechanical advance. The lower number has usually been used in the 18R-C as part of the anti-polution attempts by Toyota.

The aim is to set around 32-34 degrees maximum advance with the above mechanical plus static. IE for the above 26 mech + 6 static.

Regards

Rodger