Dellorto adv and retard

Post by **stom** » 20 Aug 2007, 16:37

Hi all,

Not been on here as late. me and the camper have been off sick due to injury. all is well now though the van is having a few problems.

the 2lt ac is running the dell drla 36s after and expencive MOT to get the emissions right. it has stopped popping (valve problems), runs for more that 10mins (fuel starved).

running probs start with a very high hydro carbon count, and loss of power in the lower revs. I am not confident that the vacume tubes are in the correct places.

is there a left and right carb? the vac conections are on my left carb.
Jason, how are yours arranged?
could there be a more sutible dizzy for the job?
Mayb someone in the sheffield area has a known to be functioning dizzy to try?

Hope you can make sence of this, and we can get this show on the road.

Cheers

Tom

Post by **jason k** » 20 Aug 2007, 20:30

as you look at the engine the vacc advance (rhs of dizzy vac can) goes to left hand bank of carbs. choose one to connect to
blank off the other vacc connection on the dizzy.
the stock dizzy is fine for the job.
have you checked your vac can is working??

Post by **toomanytoys** » 20 Aug 2007, 20:41

Have you got an electric fuel pump? has it got too much fuel pressure..?

Dizzy.. DONT fit a 009.. these are rubbish on a Type4.. the original electronic dizzy is good if working correctly.. (vac and mech advance not broke)

Post by **HarryMann** » 20 Aug 2007, 23:57

Presume you've read both of these Wiki entries...

http://wiki.80-90.co.uk/index.php/Petro ... gnition_01

http://wiki.80-90.co.uk/index.php/Petro ... gnition_02

First things first, take the 4 compressions to ensure you're starting with an engine that's still holding its compressions, that they're high enough and within spec. across the engine

You might do this both hot as well as cold, if in any doubt...

Then if all OK, check the mech advance with a strobe (see Wiki plot) and check that the vac advance (and vac retard if fitted) is also working correctly (see Wiki for expected values)

Are the spindles/bushes on the dellortos worn, no air leaks in inlet tract or exhaust system.

If all else fails, a good (time-served) mechanic with experience on these aircooleds should be able to troubleshoot with the right equpt. though they are quite few and far between now.

Post by **stom** » 20 Aug 2007, 23:59

left hand bank of carbs. choose one to connect to

I assumed i would conect to the one that isnt on the other carb. Are you meaning the pair that is at the base of each carb.

Testing the vac unit, from wiki

(suck on it - arm/plate should move. Then stick your tongue in the hole at end of a good suck (!) It should stay put and shouldn't hiss)

I do all this and see what the score is.

Garage installed an electric pump, now both carbs get the fuel, unshore of the preasure though.

Cheers
(what are they called these pipe fitting stuby things)

Post by **HarryMann** » 21 Aug 2007, 00:36

Testing the vac unit, from wiki

(suck on it - arm/plate should move. Then stick your tongue in the hole at end of a good suck (!) It should stay put and shouldn't hiss)

Methinks the article I referred to talks about the proper way to check the vac advance and retard (extent thereof)

Maybe you should quote your actual engine code, and whether the dizzie has vac retard as well as vac advance, as later ones and Cali models did, or that was my understanding when all this cropped up about a year ago... (a lot of which is now in the Wiki)

Post by **jason k** » 21 Aug 2007, 10:39

if you got a eleccy pump you may well need a regulator to control flow as these carbs dont like too much pressure. im running a stock pump (new but stock)

Post by **stom** » 21 Aug 2007, 10:41

the engine is a CU and the vac unit has 2 take off points, one of on outer cone shaped bit and the other on the inside pointing towards the dizzy. It is the electrical system, not the conventional points type.

Checked the vacunit, there is movment and my toung sticks with no hissing from the unit. Should i feel any thing when the engine is revd?

I take it for a drive with the adv on the other conections on the carbs. will let you know.

If i need a regulator, what would you recomend?

Post by **stom** » 21 Aug 2007, 12:19

found out the pump puts out 2-3 psi.

What is your float setting on the dells?

Post by **HarryMann** » 21 Aug 2007, 18:21

the engine is a CU and the vac unit has 2 take off points, one of on outer cone shaped bit and the other on the inside pointing towards the dizzy. It is the electrical system, not the conventional points type.

SDo that is the same as Cumbriankeith's I think, featured in the Wiki, with all the correct connections detailed - you shouldn't really eb guessing which is the adv or retard take-off, the need to be right before you move and connected to the correct places (the retard connection is normally very close to the butterfly, as its only spposed to get a vacuum at idle or just off it)

Most of the theory behind these vac adv + vac ret dizzies is layed out in that Wiki article...