Non runner, massive backfire. (CU) HELP!

[Zomerzet]

Right then,

Just taken delivery of my first ever camper this week. It's an '82 (Aircooled 2.0 CU engine) with unserviceable engine. Just spent the last day or so trying to get the beast running again. It's running a single Weber carb (A few hundered miles old I'm told). When I looked at the engine bay, the dizzy was removed with random white dots on the dizzy and tinware (Not related to actual piston numbers). I was told that the engine had been ran until it overheated due to a dirty clogged oil cooler. There is a white dot on the fan, but it's not quite lined up to the slot in the centre of the fan..

I got a battery in her and ran a compression test, all cylinders were at least 150psi. Found the electric fuel pump not working, so stripped it, cleaned it up and was working fine. Next was initial setting of the ignition. I got the engine to TDC by feeling the no.1 spark plug hole and then lining the slot in the middle of the fan as best I could with 0 degrees by turning the engine slightly. I then checked the dizzy drive was in the correct position (12 degrees as per the manual). Got the dizzy installed after spotting the TINY mark on the edge of the ridge. All spark plugs in and HT leads connected up (With rotor arm pointing to no.1 cylinder). Turned her over with fresh fuel directly to the fuel pump and no firing until a backfire from the exhaust. I've gone through everything loads of times now, but the backfire is the best result I can get.

Is there anything I'm missing or is it summat seriously wrong with the engine?

[BOXY]

Did you make sure No1 was at TDC on compression and not on exhuast?

[Zomerzet]

I felt for compression being generated on piston 1 with 4th engaged pushing the bus forward. How can I tell it's the compression stroke, not the exhaust stroke That would explain the backfire!

[BOXY]

A cork lightly screwed in the spark plug hole will pop out on the compression stroke.

[Zomerzet]

I was using my compression guage and watching for when the needle moved. I think I'll take off the RH rocker cover and check for the no.1 inlet valve just closing to be 100% (as stated in Haynes for the dizzy drive setup).

I'm still unsure how well placed the tippex mark is on the fan. When it says the 'notch in the crankshaft pulley' does that mean the chuffing big notch on the centre of the fan mount, or is there some tiny mark on the fan I should be looking for?

[BOXY]

The timing mark on my pulley was a tiny die-stamped mark on the back of the rim. I only found it with a LED torch and a mirror. I'm not sure what you mean by the "chuffing big notch" unless you mean the key-way the pulley is mounted on? If you've got the cylinder at TDC the mark should be somewhere close to the 0 on the timing scale.

[billy739]

just for luck try the timing 180 degrees out.


have you got a good spark at the plug end of the leads?


set all the timing to tdc for basic fire up

[Zomerzet]

BOXY; Yeah I'm referring to the giant notch in the middle. I want to make sure the fan is on correctly oriented on the crank. I'm assuming it's 'keyway-ed' but is it possible to pop it on incorrectly? If so how do I get the bloody thing off whilst on the vehicle as I've removed the 3 bolts but it's still on solid! Took me a while before finding the tiny mark on the dizzy edge too!

Billy; I think that's the basic issue. I'm not setting the initial timing up correctly because I was using the large notch in the centre of the fan as the reference point for setting TDC. I have a spark at all four leads, which I've confirmed with illuminating spark detectors.

The main thing is finding that timing mark, but I need to confirm that is correct on the fan. I think the best thing to do is try to get the fan off to see the mark on the pulley behind it?

Thanks for the info so far everyone.

[billy739]

you have and are using the plastic timing scale thats bolted to the fan housing about 11 oclock around the fan?

if it dosent look like the engines been apart recently there is no way the fan will move/slip

the timing mark is on one of the ribs for the grove of the fan belt cant remember if its the inner or outer.

if you figure your best tdc for piston 1 ( right rear looking from the rear) then the timing mark will be on the scale , around 11 oclock

[faggie]

the timing mark is on the rear metal section of the pulley where the fan belt runs on nearest to engine case , are you using the correct timing mark on timing scale, and are you still using electronic ignition or has it been converted to points

[Zomerzet]

Thanks for the replys guys. I'm running electronic ignition still, and it's sending a spark to all four spark plugs ok.

I've been pointed here http://www.ratwell.com/technical/FindTimingMark.html by someone and it's got all I need to make sure I'm starting with a clean slate. I'm away for a month now with work, but can't wait to get cracking when I get back. I'll make sure I publish my finings on here

[dugcati]

being as there are so many marks all over things I'd clean off all the larks/ignore the lot and set it all up by feel.

- rocker cover off
- set cylinder 1 to compression
- set dizzy with cap off ( if the dizzy drive is in the right place the rotor should line up with a notch on the dizzy body)
- dizzy cap back on, king lead in and set ignition on cylinder1 by turning dizzy anti-clockwise a small amount then clockwise to hear the spark
- put other leads in (remember the firing order on these vans is 1432 NOT 1342)
- check carb settings - jets, initial setting, autochoke etc
- give it a whirl and see if it wants to cough



when you do get it running find a way to feed the crank case vent (short pipe sticking up next to the dizzy) into the carb top/filter top as this will cover the whole engine bay/lid and ancillaries with oil - it's already started doing that looking at your pics

[Zomerzet]

Thanks Dugcati. I've dropped the engine out for an inspection and rebuild now I've got back, but after some careful examination of the fan I think it looks like everything's orientated correctly. Here is the fan with a white mark where the (Tiny) timing notch is. Also on the fan is a '0' in the position shown by the WD40. I believe this is supposed to line up with where the case halves join together?



I'm still suspicious that the dizzy drive is wrong as the dizzy wasn't fitted when I got the Wedge. I have this diagram but is this looking from the flywheel end OR to it? i.e. is this looking at the engine from the rear of the vehicle? Also, it is the right one I should be looking at (Type 4)?