11 replies to this topic

[CityEPete]

I know this topic has been done to death but that advice has always been to set the engine to rev as fast and smooth as possible then back off a tad at a time if it pinks or pings, the thing is santa is bringing me a proper timing light with both a digital rpm counter and the digital advance setting.

I have read that the optimum setting for my car (1987 city e 998 early unleaded) is 32 degrees btdc at 4000 rpm which I can accurately set now, my mini has no rev counter so it was guesswork for a start before!

Any advice or better suggestions welcome, thanks.

[lrostoke]

sounds like you've covered it there....us 32 as a starting point then back off in 2 degree increments if you get pinking.

 

I keep the vac advance connected,  my thinking is at 4000 rpm you should have full mechanical advance so the vac won't be doing anything.

[CityEPete]

Thanks, sounds like I have understood it then, basically adjust the throttle to give me 4000 rpm, set the gun to 32 btdc, point and shoot until I can get the dizzy adjustment to show 0 degrees on the pulley and the rpm steady at 4000. Neighbours will love me, lol. Im interested to see exactly what rpm I have at tickover and what timing at 1500 rpm is now and again after.

[lrostoke]

depends what weights you have in the dizzy

 

If you have 10 degree weights, this gives 20 degrees of advance, so with a max of 32 @ 4000, at 1000rpm you may be seeing 12 degrees.

[CityEPete]

I will check it first and make a note of the rpm and the advance as it is now because its pretty good as is but I think it has a little bit more to give, then wizz it up to 4000 rpm and adjust it to 32 btdc, reset the tickover to about 950 do you think? I will see what degrees I am getting again at tickover in comparison to see if I have effectively gone more or less advancedto where it is now then take it for a spin!

 

I have no idea what weights it has, its all pretty standard stuff for an 87 CityE I think, It was only by chance that I discovered that I am fairly sure its unleaded as I found a link that backed up the previous owners claims, it has engine number 99H581P on the engine 99HB81P on the documents, clearly a mistake and now I cant find the page that listed it as unleaded so maybe its not or maybe it has a recon head, who knows, lol.

 

Thanks again though, I will report back.

[lrostoke]

87 wouldn't have been unleaded as standard, I think late 88 is about earliest.

 

So possible engine swap or head work / swap if it is

[CityEPete]

That was my initial thought so I text the owner as I forget to even ask when I bought it and they told me unleaded, I have a leaded Minor that I use additive in, I was tempted to put some in the mini from time to time just in case?

[CityEPete]

Just had a play with the new timing light, it was running at about 850rpm at tickover and 17 degrees btdc! set the gun to 32 degrees and switched it over to rpm, held the throttle to get a steady as possible 4000rpm, switched back to degrees and shot the crank pulley, bang on 0 degrees!!! decided I must have been about right with the run it up the bypass and keep pulling in to adjust it until it feels best then nip up the pinch bolt method, Lol.

 

Good fun though, I am looking forward to future setups with this light, so nice to have an rpm counter as I mostly tinker on older cars without one

[dklawson]

For future reference, rather than trying to hold the throttle at 4000 RPM, use the idle speed screw.  Bring the engine RPM up by changing the idle screw position, then adjust the timing.  When you are done, re-adjust the screw to give the idle speed you want.

[lrostoke]

whats she start like sometimes with a high tickover advance you can get a bit of kickback when starting..

[CityEPete]

For future reference, rather than trying to hold the throttle at 4000 RPM, use the idle speed screw.  Bring the engine RPM up by changing the idle screw position, then adjust the timing.  When you are done, re-adjust the screw to give the idle speed you want.

Its a pig to get at with the standard airbox on :-(

[CityEPete]

whats she start like sometimes with a high tickover advance you can get a bit of kickback when starting..

Starts well, one in 50 times you get a tiny run on when switching off but mainly if its quite hot after a long run

 

When I first got it I checked the timing before and after fitting the electronic igntion kit, it was already set off the fixed comb scale at 1500 rpm (estimated rpm) with my standard timing light but went well, now we know why as it was probably at about the same place as it is now 17 btdc.

 

I set it to about 10 degrees as the haynes manual said and it felt like it was out of puff so I kept advancing it trial and error almost certainly back to where it was before on standard points, it was the only reason I needed to mess with the timing at all really.

Edited by CityEPete, 24 December 2013 - 01:34 PM.