Which Weber Carburetor?

[billjackson54]

I have the Ford 8 valve DOHC engine fitted to my Cabrio. It is one of the carburated ones....NOT the more common EFi version...and it isn't running very well. It over-runs badly on switch off and doesn't seem to go as well as it should either....so I asked my local garage to "set it up". It's had new plugs and new oil.
To cut a long story short, a new Weber was fitted...not the same type, quite, as the new one has an automatic choke..but a brand new one I bought a year or two ago for another project (a 1600 CVH engine in a Quantum Saloon). This strategy has been successful in that the car has more power....but the over-running persists and the car is pretty smelly (petrol) at switch-off.
My car has an electric fuel pump. Can anyone tell me which particular model of Weber was fitted to the Ford i4 8 valve DOHC engine? I've tried Google and while the information is available for cars produced up to 1985 (Pinto Engines) there is simply no information for the later DOHC engines. I would consider moving over to EFi, except I believe the cylinder heads are different so I'd need a lot of extra parts. We considered fitting a Nikki carb (I've used them before on Pinto engines successfully, but the Nikki I have, NOS, wouldn't fit the I4 manifold...so we fitted the Weber. SO what I need to know is a) the actual model of Weber Ford fitted to this engine, b) Any thoughts forum members may have on the over-running issue and c) would a 2 litre 16 valve head (from a later Ford Galaxy) fit?
Thanks!

[philcoyle]

Re: Which Weber Carburetor?

Hi, could it be the Ford N8A engine also known as Ford DL20 DOHC carburetted engine, and I think there is some reference to Ford 14 DOHC.

[milliemarlin]

Re: Which Weber Carburetor?

The Webber carb fitted to my Pinto engine had an ant-dieseling valve. I think several other Sierra configurations had similar valves. I guess you have already checked the Haynes manual for your configuration if not the Sierra manual 0903 '82 to '93 is available on line.

My understanding is that dieseling is caused by the engine momentum sucking fuel (vapour) through the carb and igniting it through the heat and compression of the engine. I distinctly remember my dad’s old Ford Anglia continuing to run as we opened the house door.

I believe it can be caused by worn spark plugs thinning at the business end and retaining their heat. You have checked this one off. Also carbon build-up allowing localised hotspots. Engines that run hot because of clogged waterways, poor coolant condition, misadjusted timing or mixture will be more prone to the condition.

Older cars do smell more of petrol than modern ones so that might not be a problem.

Hope this helps, Paul

[Cameron F]

Re: Which Weber Carburetor?

Sounds like it is the N8A engine as Phil says. These are pretty rare (weren't common back in the day). From around 85 the EFi DOHC was in production so there was very little time for a carb'd version to be sold. THe DOHC was the successor to the pinto (but is a completely different engine in every respect). The original carb would likely have been most likely a weber 2V (The 2V TLD had an antidieseling valve fitted as Paul says) but the ordinary 2V didnt (the 2V and 2V TLD dont look alike). Here are the diagrams of the carbs if it helps...
2v.JPG

2v1985.JPG

2vtld.JPG

[philcoyle]

Re: Which Weber Carburetor?

Hi Bill,
You could try retarding the ignition if it is at all possible on that engine.
The OHC Pinto engine had a wiring system that fitted into ignition to coil loom via a 3 pin plug this gave a choice of 3 timing settings when earthed. This system allowed you to choose your fuel octane rating and timing. This may not be of any use at all to you, but it might help if you decide to retard the timing and weaken the idle speed and mixture adjustment screws.
Nothing seems to run right since the fuel has been mucked about with, but cutting back the advance may help with the overrun.

[chris_cussen]

Re: Which Weber Carburetor?

Bill
Remeber I said I also had a 2.0l DOHC carb engine before I destroyed it? Well I have a Weber 28/36 TLDM carb on a shelf in my garage. If you want it just come over and take it away.

If you decide to go fuel injected you will have to change the head, get a hi pressure fuel pump, engine bay wiring loom and ECU. Not so easy to obtain, I know having been there... Which accounts for my very slow Zetec transplant.

Chris

[ggrum]

Re: Which Weber Carburetor?

According to the trusty Haynes Manual the N8A engine was fitted with a Weber 2V(TLD) carb which had an anti dieseling valve fitted in the same housing as the jets and emulsion tubes. I don't know about this carb but I believe the ant dieseling or fuel cut-off valve on some other carbs was solenoid operated, possibly held open when the ignition was on and closing when the ignition was turned off. Perhaps this valve is faulty and sticking open - just a thought.

[ggrum]

Re: Which Weber Carburetor?

Just realised all this is shown in a previous post. Should have looked more thoroughly.

[philcoyle]

Re: Which Weber Carburetor?

Just a thought, but have you tested the feed wire to the anti dieseling solenoid. Does it turn on and off as it should with the ignition, possibly it's live when you turn on the ignition (solenoid retracts the plunger) and as dead as a dodo when switched off, the solenoid will then stop any fuel passing through the carb.

[dogoncrazy]

Re: Which Weber Carburetor?

Unless you have a fuel pressure regulator in the system I would suggest that the electric fuel pump is over pressurising the carb.