Early 1.9 to 2.1 conversion - stop me if I'm being stupid!

[CJH]

I meant the other edge - the one that pushes past the seal lip. I wondered if the leading edge, the one you created by dremeling off the excess, could damage the seal lip during installation.

[itchyfeet]

Ah yes I can't really remember but I think I would have tickled it with wet and dry at 45 degrees to remove any sharp edge

[itchyfeet]

its here...
http://forum.club8090.co.uk/viewtopic.p ... 0#p8162794" onclick="window.open(this.href);return false;
used wet and dry to clean it up

[CJH]

Yes, thank you, saw that. I guess I was still concerned that sanding the sleeve against a flat surface wouldn't take the sharp corner off. But I'll assess that once it's on and smooth the corner if necessary.

I cleaned up the DG flywheel last night and measured the depth of the parallel sided section that the sleeve needs to cover - seems to be about 9mm. But I can't see that it's that critical. The seal will run roughly in the middle of that area, with a tolerance of about 1.5mm depending how far in the seal is pushed. So as long as the sleeve goes almost to the end of the parallel section, and is under flush at the top, then it should do the job. It could be under flush by at least 1mm before it becomes a problem I reckon. Obviously I'll aim to make a neat and accurate job, but I don't think it's that critical.

[itchyfeet]

whats critical is that it does not stick out, mine was only just underflush and I had to beat it on to get it there, next time I will take a bit more off

[Neil74]

Hi Cjh
Are you running with the Dj distributor with the carburettor? If so how do you connect the two vacuum ports?
Or is it on the Dg distributor?
Thanks for any help
Neil

[CJH]

Hi Neil

I'm using a DG distributor, set at 10º BTDC (for super unleaded), and with a new genuine vacuum advance unit. I don't know how different the timing advance curve is from a genuine DJ distributor, but it seems to run very well. I'll be having the carb re-jetted on a rolling road at the end of October. One of the things they did the last time I had it on the rolling road (with the stock DG) was to adjust my distributor timing - it was optimised for about 4000rpm I think, and I never did check what that did to the idle timing I'm afraid. I'm hoping they'll be able to tell me something about the timing curve the next time I go.

[itchyfeet]

Hi Neil

I'm using a DG distributor, set at 10º BTDC (for super unleaded), and with a new genuine vacuum advance unit. I don't know how different the timing advance curve is from a genuine DJ distributor, but it seems to run very well. I'll be having the carb re-jetted on a rolling road at the end of October. One of the things they did the last time I had it on the rolling road (with the stock DG) was to adjust my distributor timing - it was optimised for about 4000rpm I think, and I never did check what that did to the idle timing I'm afraid. I'm hoping they'll be able to tell me something about the timing curve the next time I go.

Lots of peole running DJ dizzys, who knows how they behave with just one vac connection.
CJH if by chance you want to test a DJ dizzy on the rolling road let me know I have a spare I can lend.

[CJH]

That's an interesting idea - could be worth having it with me in case they tell me something like "that timing curve looks awful - are you sure this is the right distributor for this engine?". But I think I'd like to find out a little more about the differences before going down this path. Do you have a part number for the DJ distributor? Is it just the vacuum unit that's different, or are the internals (e.g. the weights etc) different as well? I wonder if it's possible to dig up the timing curves for these two units - I think I remember seeing one for the DG distributor somewhere, maybe.....

[itchyfeet]

Timing curves in wiki

[itchyfeet]

P1080416 by Paul_Barr, on Flickr

[CJH]

Timing curves in wiki

So they are.



Those are the mechanical advance curves - the vacuum advance adds 12º-16º for both apparently. The DG curve looks a bit flatter at the start, i.e. a proper DJ distributor will advance the ignition more rapidly over the first 1000 rpm or so, which then gives it about 3º extra over the entire rev range - compare the DG curve with the DJ@5º curve. So there may be merit in using the proper DJ distributor, but perhaps with the single vacuum advance unit, assuming it will physically fit, to avoid plumbing problems. Or maybe you could just give the DG distributor a few degrees more advance (say 13º) at idle so that the curve matches better at higher speeds.

Maybe I'll have a go at digitising those curves to have a play.

[Neil74]

Thanks for the info Cjh.
I am looking forward to seeing how you get on with the rolling road as I am fitting a 2.1 Dj in place of my tired 1.9 Dg over the winter.
I will be using the Dg carb to start with.
Cheers Neil

[CJH]

Don't take any of this as advice - it's just ramblings, for discussion.

If the timing curves given in the wiki can be taken as the truth, then here's a plot of the DG and DJ distributors both set up with 10ºBTDC at 800 rpm. The DJ has gained 3º advance over the DG by about 1250 rpm, growing to 5º by 1500 rpm. The DG then catches up a bit, closing the gap to about 2º by 2200 rpm, but it remains 2º behind for the rest of the available data.

.

And here's a plot of what the curves would look like if the DG was set to 12º at 800 rpm. Those extra 2º would disappear by about 1150 rpm, the DG would then lag the DJ by a maximum of about 2.5º at 1500 rpm, and the gap would be gone by 2200 rpm.



When my van was on the rolling road, and it was the same for my mate's beach buggy, they were much more concerned about the timing at 4000 rpm than at idle, so I'm going to guess that making the DG distributor behave like the DJ distributor from 2200 rpm is preferable to making them match at 800 rpm. So maybe setting the DG distributor to 12ºBTDC at 800 rpm would be better. That's assuming the vacuum advance is the same for both - no evidence of that though, other than the statement that both add 12º-16º of advance. I'd be surprised if this 2º adjustment would make a noticeable difference though.

Discuss.

[itchyfeet]

vac has to be more influential which is why I say who knows how a Twin vac behaves with just one connected
DG vac is under throttle
DJ is plenum and throttle body ( will look later exactly where)