Distributor advance curves

[cliftyhanger]

Checked the dizzy on my TR7 powered toledo after the RBRR, as I was disappointed with the 31mpg achieved (flipside the PI chaps would have been ecstatic with that!) but last time in a friends dolly with same spec we got 37, plus we didn't have a 100 mile stretch of average speed cameras.....
First thing was to checkthe timing. Yep, 10 degrees at idle. Rev it and it went to a max of maybe 20.
Anyway, popping the dizzy cap off and then the rotor arm revealed some rather stretched advance springs, meaning the dizzy was getting over half the advance just by taking up the slack. Not a great start.
Then checking the vac advance showed there were no leaks, but it was jammed at max advance. So none available on light load...

Stripping the dizzy (I hate you Spen King!) out the car, and then the dizzy itself showed the van advance was a simple fix, the plate had an oversize washer just touching the case.
The advance baseplate was stamped 16 degrees, which I assume is correct.

Icleanedthe weights up, and borrowed some springs off another delco dizzy. They area bit thinner than the "originals" and have some pre-tension. However, I eckon as a stopgap they are at least a better bet than what was there.

I digress. So here is my point.
I believe Revington TR sell standard TR7 springs. But is there anything more suitable?
And is the 16 degree baseplate correct? or should I swap it for the 25 degree one I have on the spare dizzy?

I don't really want to go to the expense of having it recalibrated, besides finding anybody to work on a delco is tricky.

Any advice?

Cheers chaps.

[Toledo Man]

Clive, have you conidered fitting a Sprint dizzy? The advance curve should be fine for your TR7 lump and you can use a 45D4 cap and rotor arm keeping your existing HT leads. It will make life 10 times easier with the points and gives you more options for electronic ignition.

[cliftyhanger]

Is the sprint advance curve the same? doubtful, it may be close though.
Besides, it may be no better than the delco one I have in terms of condition/springs. And I already have leccy ignition fitted.

I understand the advantages, but once I have the correct/best curve sorted, I am hoping that it won't need touching again!

[Jon Tilson]

Sprint dizzy advance curve is less than a TR7 one.

I have one in my TR7 engined dolly because of the electronic ignition unit it came with. I compensate by going a bit further at static.
It could be better...

I suspect you would have more advance curve option on this type than a TR7 delco one though.

Jonners

[MIG Wielder]

Is the sprint advance curve the same? doubtful, it may be close though.
n!

I did a comparison here.
viewtopic.php?f=4&t=30681&hilit=distrib ... t&start=15

There are graphs about 2/3 of the way down.
HTH,
Tony.

[cliftyhanger]

Not very at all close then.
Saying that, a good sprint will be better than a knackered 1850 type! but unless checked or recurved, just swapping offers no advantages in terms of performance/economy. So I will get some proper std springs for mine....

[Jon Tilson]

Robsport will have them and probably Moss as well.

Jonners