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Dizzy Vac and tuning
https://www.ausmini.com/forums/viewtopic.php?f=2&t=25321		 Page 1 of 1
Author:  Shard [ Mon Nov 27, 2006 12:26 pm ]
Post subject:  Dizzy Vac and tuning
So I took my car to link today because yesterday when I fired it up to head down to mt. cooper my clutch decided it was the right time to start playing up. (i'm looking at $650-$700 for labour and parts of worst case scenario the fitting of a clutch kit and possibly primary gear and machining of stuff).

So there goes my christmas savings, but anyway;

When I was there he noticed the vacuum pipe ( I thought it was just a breather pipe) wasn't hooked up the vacuum so he attached it. The car started blowing smoke and running like a dog backfiring etc.

Now it runs beautifully with the pipe not connected but he said letting air into the carby wasn't such a good idea. My question is, if I re-attach the pipe, is it just a matter of getting mixture right or do I need to worry about timing too (and anything else?)?

thanks,

Shard
Author:  Shard [ Tue Nov 28, 2006 9:45 am ]
Post subject: 
29 views and not 1 reply? I thought it was an ok question to ask :(.

Shard
Author:  Mike_Byron [ Tue Nov 28, 2006 10:07 am ]
Post subject: 
Yes it is an okay question. I have been away from the computer for a while.

Probably your vaccuum advsnce mechanism in the dizzy is stuffed. Thats why the pipe is off the dizzy. And yes, sucking air directly into the carby isn't a good idea and the motor will run lean at some point. That could have disasterous results on pistons.

Most likely somebody has adjusted the mixture as a bandaid to cope with the extra air being sucked into the carby but that is not a good fix. its a bandaid fix and its bandaid with not very good adhesive.

Either find a good dizzy that is of the same type as your that has a working vaccuum advance or take yours out and reco it have it reco'ed.

Then connect up the vaccuum pipe, time the engine properly and spend time getting the mixture right again - it may require different needles so that bit might better done by some who have the resources of a variety of needles to play with.

Without actually looking at your motor all i have said is best guess speculation but i think I am not far from the mark.
Author:  feralsprint [ Tue Nov 28, 2006 10:09 am ]
Post subject: 
Shard

If it runs like a dog with the vac line on it would seem that maybe the needle has been adjusted with the hose off, you will need to adjust the height and mixture if you put the hose back on

Sorry Mike we were typing at the same time :D as he said

Jon
Author:  Shard [ Tue Nov 28, 2006 4:50 pm ]
Post subject: 
thanks guys, it was tuned when I got it so the next step is to tune it with the vac connected cheers.

Shard
Author:  Shard [ Tue Nov 28, 2006 6:06 pm ]
Post subject: 
Ok so I played around with the mixture with the vacuum connected and I can get the engine running ok but it's backfiring and missing like crazy under accell so the timing is my next port of call.

I've got a 998A+ rover engine in it, in my mini manuals it says for engines 1974 onwards the timing is static 4deg BTDC and stoboscopic at 1,000RPM is 7deg BTDC.

are these the right figures I should be working with or are the rover engines different?

Shard
Author:  Morris 1100 [ Tue Nov 28, 2006 6:25 pm ]
Post subject: 
Do a test of the vac advance in the dizzy. Take the vaccum hose off the carby end leaving it on the dizzy and suck on it. It should hold a vacuum. If you can keep sucking the vacuum diaphram is stuffed.
Author:  Steve.E [ Tue Nov 28, 2006 6:36 pm ]
Post subject: 
Is the distributor cactus has it been tested are the weights right, has it been running hot at all?

Wind the jet up till it cuts off the air, then wind it down two complete turns and two sides and advance the distributor from there and see how close it gets you

Steve :D
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