Not Running on 1 and 3

[Sparky]

O.K. so out with the single carb and in with the twin carb. While this was happening all of the HT leads came off. Now it's all back together she's not running on No.1 or 3 cylinder. I've worked this out by pulling of the HT leads, removing 2 or 4 the engine slows and runs even rougher, removing 1 or 3 (or both) no change. By connecting 1 HT lead to 3 position and giving a bit of a rev will induce a bit of a pop from the exhaust. I've swapped spark plugs between 2 and 3 with no change.
Before this work the engine was running sort of OK but the single carb was way past its best hence the upgrade to twins. The only other thing is the bus has been parked on a slope of about 15 deg (nose down) could the oil sitting at the front of the engine be a problem? When the spark plugs were removed to swap them over they both looked the same (a bit black from running rich with the single carb).

Over to you dudes, I'm sure one of you will have more of an idea than me.

Arran.

 

[Frankie]

I had this and I remember it being the carb balancing sync the carbs and see what happens good luck hope I'm correct forgive me if not good luck.Frankie

 

[Sparky]

Hmmm. I could understand it being a balance thing if it was one side not working, but it is the front two cylinders. i.e. each carb is supplying one cylinder OK but not the other on that side. There seems to be unburnt petrol coming from the exhaust (wet patch on the tarmac) that could be from No. 1 and 3 cylinder or from 2 and 4 being too rich! Ahhh it's driving me nuts.

Arran

 

[Loxy]

Hmmm. I could understand it being a balance thing if it was one side not working, but it is the front two cylinders. i.e. each carb is supplying one cylinder OK but not the other on that side. There seems to be unburnt petrol coming from the exhaust (wet patch on the tarmac) that could be from No. 1 and 3 cylinder or from 2 and 4 being too rich! Ahhh it's driving me nuts.

Arran

What type of twin carbs did you fit? if they are twin barrel e.g. Dellorto DRLA, Webber IDF etc then they will have seperate idle screws to balance each barrel - so you could get one on each side not set up right - hence the need to balance them.

On a more basic note have you set up the firing order correctly? 1-4-3-2 ? getting that wrong would make it run badly.

 

[Sparky]

The carbs are ICT34's.

As to the running order I think I've got that right. I've spent ages going from the Haynes book to the bus and back again. Is it possible to have the HT leads for 2 and 4 in the wrong place and it still run? ie 90 degrees out on the dizzy cap? I've just been out again and the bus runs exactly the same with both 1 and 3 completely disconnected. When I disconnect them there is a good spark from the cap to the lead so a guess there is a complete path there.

Arran

 

[Frankie]

have you timed the van .

 

[Sparky]

No, not checked the timing yet, but it shouldn't have changed from before the strip down I hope. I'll try and check the timing tomorrow as I'm unpopular enough with the neighbours as it is.
Thanks for all your help so for dudes I just know I've done something stupid (again)!

Arran

 

[Frankie]

http://www.aircooledtech.com" onclick="window.open(this.href);return false;

then look for 34ict set up.Frankie.

 

[noddy]

Sound like ht leads in wrong order done this myself several times.

You should see a small mark on the top edge of the dizzy body just a line less than .5mm wide this is the number one cylinder position firing order then going clock wise goes 1,4,3,2.

Have you checked for air leaks at the head to manifold might be that back cylinders are drawing a really lean mixture, have you checked for a spark from each plug, plug out of head and earthed on case.

 

[Sparky]

Yep. I thought I had the leads in the wrong place so I took then off and checked, put them back on and exactly the same.
I'm afraid to say I've given up on it now ...........










but I have taken it to our local early bay specialist just have to call them tonight to find out what i did wrong. I'll report back when I know.

Arran

 

[our bus 68]

Hey Arran

What's the verdict ? Do we need a black armband ? :?

Rob

 

[Sparky]

She lives
All Luke did was a complete setup and tune and she now runs like a dream all for a bargain price. Curiously I can still remove No.1 or No.3 spark plug without making any difference at tick over :? She must be working OK as Luke took her for a test drive and went up to 65 with no problem :shock: It must have been a shock for the old girl as I only take her up to 55 max.

So a big thanks to Luke of Garry Angel Racing for sorting it out, and as a side note thanks to his brother Simon of NOSVW for getting it through the MOT the other day and the cool new sticker

Arran

ps Rob if you're calling us try a mobile as the land line rings when you call it but not at our end.

 

[richbaker78]

are you running them with a 009 - ie no vac takeoff? if so have you fitted a balance pipe between the vacuum take of ports on the carbs. IF you have blocked off the vac pipe ports it can give this exact symptom. You can even tune them up fairly effectively without it in place...if you dont have a balance pipe fit one!!! just join the port on one side to the other

you will then need to retune the carbs with the BP in place.