Dolomite Sprint Ignition Timing

[Tilly]

I’m sorry if this has been asked before but I could not find it easily. What is the dynamic timing with a strobe gun for a standard Sprint with standard carbs and air filter. Using 98 octane fuel here in Oz. Thanks in advance.

[cleverusername]

I think in general the advice is to advance it as much as possible till you get pinking and then retard it a bit. The book figures are for four star, so not much use. I think 10-15 degrees BTDC is a good starting point.

Saying that, I suspect somebody has figured out the exact figure.

[gmsclassics]

Given you've got a strobe, that gives you scope to get your timing set up including distributor mechanical advance.

Best to disconnect the vacuum when checking timing. The static figure, which is okay for a strobe up to about 750rpm, that I have found works well on both my Sprints here in NZ is 10 degrees, which in fact is the factory workshop figure.

With the strobe, you can also check the mechanical advance as revs rise. Factory manual gives figures of 7-10 degrees at 1600rpm and 12-16 at 2000 and above. So maximum advance in total you should be looking for is 22-26 degrees with the static at 10 (the scale next to the crank pulley goes up to 24). I don't think it matters if it advances a little bit more as race engines are usually tuned to about 32 degrees. As stated above though you do need to road test to ensure you are not getting 'pinking'. Don't forget to reconnect the vacuum advance before using on the road!

I did use 98 octane but have found it is no better in my Sprints than the 95 octane we have in NZ, just the latter is cheaper! Neither contains ethanol. When I was racing, that car used 100+ octane Avgas, but there was nothing standard about that engine.

I get about 33mpg (8.5L/100km) consumption on average. The twisty road I live on rises 175m over a distance of 2.5km, so that is a good test for pinking.

Just out of interest, the best way I have found to set up the carb mixtures on a Sprint is using one of those 'Colortune' kits if you can beg, borrow or buy one. That enabled me to lean the mixtures on my cars without concern about being too lean. Result has been better fuel consumption and in my opinion, a more responsive engine.

Hope this helps

Geoff

[soe8m]

Not over 32 degrees max.

You can set the ignition on two way's.

Set it exactly correctly by the book at idle and have 200 revs further a timing what is way off and a curve that looks like nothing. That is the case with Lucas Dizzies 10.000km after when new.

You can set the ignition by driving and when all is ok when cruising/accelerating you will end up with a certain timing at idle but who cares.

Jeroen