Jetting suggestions for DG carb setup on 2.1DJ

Post by **autocamp** » 17 Apr 2007, 21:53

I'm going to fit 2.1 DJ engine in place of the awful DF currently fitted and use a pierburd DG setup, any suggestions on jetting changes?

Many thanks in advance

Post by **Fritz** » 17 Apr 2007, 22:42

A quiet word or PM to IOM Si (Toomanytoys) who now resides in central France may be able to help with your question, as he did a similar engine carb swap at least 4 years ago and is still running the same set up with the assistance of an LPG kit.

Regards

Fritz,,,,,,

Post by **HarryMann** » 18 Apr 2007, 05:11

No, other than to have a range of main jets maybe 5 units below and 5 or 10 units above what the 1.9 DG has to hand, as you don't want it wrong when pulling hard at full throttle for long. And if progression doesn't feel right when pulling up onto the main jet, think emulsion tube (air correction)... you'll find less and less peeps have any experience of carb tuning these days, but Simon TMT should have a good idea what's needed as Fritz says.

And as with that choke size you'll be strangling it a tad, make sure your air filter is 100% good, as you don't want additional restriction there. The DG one is probably quite large enough.

Post by **toomanytoys** » 18 Apr 2007, 07:25

If the truth be known.. it possibly would benefit from running some smaller jets. as the engine should give a bigger vacuum..
in reality the standard jets in a 2E3 work very well and give the same or better than DG mpg (I used to get same mpg but travelling faster) as the cam timing is longer so allows for the charge to get into the engine.

One thing with the DJ is you will have to consider what timing and fuel to use.. UL95 use 5 deg BTDC, or with UL98 you could go a bit higher maybe 8 deg BTDC but I would be a little wary of runnng 10 deg on UL98.. the Fi has better control over the fueling than a carb.. unless anyone has put a lot of miles on a "DJ'd" DG.. I have but on LPG which is a different kettle of fish..

Air filter.. if an early square type then dont worry, same as in Audi 5 cyl turbo's so flow plenty of air..
but I would make sure you rebiuld the carb before using it and set it up properly
If you can stretch to a rolling road session with someone that knows carbs, then you could fine tune the timing and carb settings/jets, but it will cost you.. but you would know whats going on..

Its a great conversion, lots of usefull torque, without compromising the mpg..
Oh and think about using the oil cooler from the DJ as the extra heat needs to go somewhere, plumb it in to the coolant return from the carb heating..
make sure the cooling system is in good nick and fit a new genuine thermostat (been some problems with some aftermarket ones.)

Post by **T'Onion** » 18 Apr 2007, 08:13

Cheers for that info Si , I was just about to pm you about the air filter .. I got the older square one

Mine is running a 2E3 that came with the 2.1 when i bought it , i have no idea if its been re-jetted , but *oh-my* when it hits 3K it picks up the front and its smiles all round ,
i also need to sort the oil cooler plumbing out ,before the bashtie ,(thanks m0cki for the info)

Up to now , i well happy with the 2.1 , not cos its quicker/faster but because of the torque , i can now whistle up the hills in third rather than 1st/2nd

as for mpg , it's much better , time will tell and i need to tweak it a little , power against mpg , will let peeps know later on in the year

Post by **HarryMann** » 18 Apr 2007, 08:16

There ya go, some excellent pointers, def. agree about the 'extra suck' the DJ has...

This may help too (or hinder

) Comparative advance curves

Wikied that simon: http://wiki.80-90.co.uk/index.php/Fuel_ ... ting_carbs

Post by **toomanytoys** » 18 Apr 2007, 10:16

Mmm.. would like to see what the power differances would be on a dyno.. the DJ dist advances quicker but doesnt advance as far.. the DG should give better mpg over the DJ dist in a 2.1 dg... if the DG curve is correct? where did that come from?

Post by **HarryMann** » 18 Apr 2007, 10:43

Bentley figures... but I don't necessarily trust them - one would really have to whizz both distributors up a Sun Tuner thingy to see what they gave in practice - and then there's the vac adv/ret to take into account for part-throttle cases.

The centrif. curve of the DJ does sort of imply it's breathing a lot more low down, either that or it has poor combustion.

Some look at it as if an engine 'can take more advance' (a good thing) but others that ' it needs more advance', implying poor combustion. I take the latter view, but beraing in mind if the cylinder is filling a lot better, then it will need a bit more advance... but we're getting into semantics a bit there!

Post by **toomanytoys** » 18 Apr 2007, 14:50

Mmm.. The MV/DJ cam timing suggest better filling and the way I understand it the 2.1 cam would work better (than a DG cam) with the long inlet tracts of the DG manifold, maybe thats why the 2.1 works so well like this...
I am having a job finding a different cam that will improve much on the stock 2.1 cam.. and because nobody has really done much work with these engines there is little info to be found..

Post by **autocamp** » 27 Apr 2007, 00:20

thanks for the info

time to start amassing some bits and some jets