Carb Icing - Pancake filter

[markevo30]

After a minor engine strip (top ends) and clean up i've been suffering with some poor running issues.

The engine is a single port 1600 fitted with the dreaded Bocar carb and a 009 with electronic ignition. I've set the valve clearances and the plug gaps and timed it at 30 BTDC.

I've set up the single adjuster screw carb as per instructions found on the net and i thought all was good (if running a little lumpy) but on a run yesterday it kept cutting out at junctions. Looking at the carb there is definitely ice on the manifold under the carb so i'll be checking the temperature on the heat risers later to see if they're blocked.

If they are blocked i know i'll need to try and unblock them using the various methods described elsewhere.

My question is this - I also have a pancake type air filter with a pipe attached to the oil filler as shown in the picture below. Is this adequate to supply the carb with warm air? If not is there an aftermarket alternative arrangement which can supply more warm air. I say aftermarket as the standard air filter stand has been cut out previously.

 

[Happystamps]

In short, no. Someone's been at your engine with a view to "upgrading" it, and they've fitted lots of shiny stuff. Ok for magpies.

Right, your air intake. Underneath the right hand bank of cylinder heads you should have a piece of tinware that looks like a banana, known as a "stove pipe". That's not really the important part, but that should take the hot air to the air filter on the stand that you're missing. Without that filter and stand, you sort of have three options:

1-recommended- find a stand, bolt or weld it on, fit an original air filter. The stands are surprisingly easy to find.
2- fit twin carbs. Budget £300 if you're really being smart, or £500 if you can't be bothered watching out for hidden gems on eBay. Gets rid of the carb icing issue and also is ace.
3- get yourself a length of air ducting and somehow join it to the pancake filter to provide a good feed of warm air, then down to underneath your right hand cylinders. Often relies on duct tape but sorta works.

You'll need to cut a hole in your rear tinware (closest to you) if you're sticking single carb for the tube, and I'm assuming that you do have a rear valance, you're not just driving around with your engine lid flapping about like a loon.

Now your 009 won't be helping matters, especially since your icing issue and the pickup issue are both going to hit you just off throttle. Obviously I'd recommend going SVDA, second hand is fine, or you can muck about 'til the cows come home drilling holes in your carb to compensate for the lack of instant response from your 009- you've got no vacuum telling the dizzy that you've just booted it, only the centrifugal force from the rev increase from increasing the fuel to the engine... Which works OK, but it's not brilliant.
If you do go for another distributor, it's worth going for a cheap electronic ignition set. Points and condensers don't seem to be nearly as good quality as they used to be.

Third- you've got a plastic fuel filter on the high pressure side of the pump. It's a can of worms, but I wouldn't recommend having it in the engine bay at all. At the least, not on the carb side of the pump as those plastic filters can split and these old vans LOVE to catch fire.

Forth- Tinware- you got flaps and a thermostat in that fan housing? If not, it's worth it. Smoother running, faster pickup, no overheating and pulled head studs...

Fifth- last thing, I promise- watch out for that upper pulley. They like to go bang.

Other than all of that business, looks pretty tidy matey.

Good luck

 

[markevo30]

Thanks for the response Happy stamps, loads of good info there.

The engine bay actually looks like this now so that answers a couple of the points you made i.e. the tinware and the fuel filter. I just posted an older photo as it showed the pipe and filter.



Twin carbs are definitely on the wish list but i was just trying to get the best out the current setup. Just for future reference what twin carbs should i be looking out for?

I would also like to go back to a vac advance dizzy, again is there a particular one i need to look for? An SVDA is a dual advance isn't it? Were they standard on a 1600SP?

If i were to fit twin carbs have they got a vacuum take off for the dizzy?

I've gone slightly off the original topic here but it's good to know.

Back to the icing. I've just taken the van out for a run and checked the heat risers. I can feel heat in the small diameter pipework on both sides but it's still cold where it joins the main manifold. I take it this should be warm too so there is a blockage? The manifold under the carb is stone (ice) cold.