Hot engine won't start

**rovercare** · 14th December 2008, 09:57 PM

Originally Posted by JDNSW

You are right - there are two kinds of coil, those designed for a (external) ballast resistor and those that are designed to run directly on 12v. But these do not have an internal ballast resistor - they simply use thinner wire on the primary and are designed to not overheat on 12v. (sometimes described as a 8v coil or a 12v coil) One thing that should be added is that the external ballast resistor on many vehicles is not a discreet component, but is simply the wire from the main harness to the coil - not recognising this and replacing it with ordinary wire is a favourite way of killing the coil.

I cannot think of any post war English engine that uses a ballasted coil except perhaps for US derived engines (I have an idea that some Rover V8s do, for example)

And using the wrong coil will always give trouble - use a 12v coil with a ballast resistor, and you will get poor spark, and consequent poor performance. Use a 8v coil designed for use with a ballast directly on 12v, and you will end up with a cooked coil (although modern ones will survive quite a while) and burnt points, but you will have a really good spark while it lasts.

John

8V coil? must be earlier than anything I've touched, as anything with a ballast resistor is 9.6V

Its not thinner wire as such, its merely the number of turns in the windings, this is the current limiting and Voltage output factor

A coil is merely a transformer, that changes 9.6/12V to High tension, 20-40ish KV

And yes, useing the wrong coil is bad, and when a 9.6v coil is used continuously on 12V, the blow up good and oil sprays everywhere...................well I was 13 and it was a Datsun 1600 paddock bomb

**DiscoDave** · 14th December 2008, 10:44 PM

Here are some photos I took when I was dismantling the distributor:

I'm fairly sure that split pin is not meant to be there.

The brown wire was supposed to supply a good earth connection for the points and condenser, unfortunately it also prevented the vacuum advance from working!

Things get a little worn in 50+ years... The condensor didn't fit in the niche in the distributor mechanism and had almost worn through rubbing on the cam.

I found this amongst the sundries in the seat-box. Obviously not a Land Rover spare but possibly useful.

Inside the New Era box was this.

**JDNSW** · 15th December 2008, 05:33 AM

Originally Posted by DiscoDave

I don't have the original fuel pump, it has been replaced in the past by some type of Holden (I was told) electric pump located on the chassis rail near the fuel tank. There is no return line only a single line, heavily modified (butchered) with in-line fuel filters and rubber hoses in places. It has however run fine in this configuration since I bought it.
Today I dismantled and cleaned the carbi, spraying out all the jets. On reassembly I was able to run the engine for a while but there was fuel dribbling into the carbi throat all the time the fuel pump was on which can't be right.

That shows either the pressure is excessive or the needle valve and seat need replacing or the float has a hole in it. Or possibly there is an internal leak in the carburetter.

John

**series1buff** · 15th December 2008, 08:49 AM

hi Dave

My limited experience with the carbies says: they are sensitive to fuel pressure .. you need from, 1.5 to 2.5 psi max . The needle/seat design is a old 1930's Solex thing .. originally set up for gravity feed systems .. they typically used a autovac vacuum sucking tank on the dash and a gravity feed to the carby..on Morris' and such. The needle/seat has two tiny holes that appear to meter the fuel flow into the fuel bowl... I've seen some with larger holes for some reason..possibly for motors with a higher fuel demand..6 cyl. ?

The gasket between the main body and the accelerator pump unit.. tends to weep petrol. I made a new one , but it still weeps very slightly ..
Mike

**series1buff** · 15th December 2008, 09:08 AM

Originally Posted by Aaron IIA

Mike,
it sounds like you were having some problems with your truck (was that the Puddle Jumper?). My Ford Blitz works fine. Dropping the voltage regulator output voltage would result in the battery not being properly charged. It must have had a problem elsewhere. Original Ford coils are known to give problems. The internal wax insulation often breaks down giving shorts, even in NOS coils. If you want to keep running a bell style coil, keep looking until you find a good one. I have a source in Adelaide if you get stuck.

Aaron.

Aaron,

I sold the Ford years ago ( to a movie company..it was used in a local movie, "The nun and the bandit" ) ..but I've still got 3 Ford coils ( divers bell type ) . One is brand new , made in Australia, a aftermarket brand ! If you need them .. your welcome to them.

**DiscoDave** · 15th December 2008, 01:49 PM

The float seems fine with no sign of a hole or fluid inside. The needle and seat looks new and has two comparatively large holes feeding fuel to the bowl. The lever which raises the needle seems worn so I'll fiddle with that for a bit...

**JDNSW** · 15th December 2008, 03:48 PM

Originally Posted by DiscoDave

The float seems fine with no sign of a hole or fluid inside. The needle and seat looks new and has two comparatively large holes feeding fuel to the bowl. The lever which raises the needle seems worn so I'll fiddle with that for a bit...

Looking at the manuals I have on this carburetter, it seems that the accelerator pump actually contains two diaphragms. The outer one is the accelerator pump one, but the inner one is referred to as the "economy action membrane", and has the note that if it is perforated you will have a rich mixture at all times, especially at small throttle openings. Perhaps this is the problem.

But excessive wear on the lever that operates the needle valve will result in too high a petrol level, which will also cause a rich mixture.

John

**Aaron IIA** · 15th December 2008, 08:59 PM

Originally Posted by DiscoDave

Today I dismantled and cleaned the carbi, spraying out all the jets. On reassembly I was able to run the engine for a while but there was fuel dribbling into the carbi throat all the time the fuel pump was on which can't be right.

Did you re-assemble the carburettor with all new gaskets, seals and accelerator pump diaphrams? What did you clean it with? Use either proper carburettor cleaner, or I have been told methylethylketone (MEK, PVC priming fluid). It does make a big difference when the carburettor is clean with new seals.

Aaron.

**DiscoDave** · 15th December 2008, 09:08 PM

John - both diaphragms in the accelerator pump seemed in good condition. I couldn't follow it's operation though, when you press the accelerator the linkage seems to prevent the lever on the end of the pump from working???

Aaron - I just dismantled and cleaned with "Carburettor and Throttle Body Cleaner" then reassembled. I have no 'carbi-kit' as yet. Can you tell me a good place to source one?

**LOVEMYRANGIE** · 15th December 2008, 10:57 PM

Originally Posted by JDNSW

The original SU pump did not have a return line (they give a fixed pressure regardless of flow rate), so this does not apply to all electric pumps. If fitted with the original SU, or a near copy, there should be no problem. But if it is another type of electric pump, then there is a very good chance that the pressure is excessive (the persistent leak from the fuel inlet to the carburetter certainly supports this).

The ideal thing would be to fit a more suitable pump. I can't find delivery pressure data - probably because it is fixed by the spring in the pump, not adjustable, and never a problem! But it would help when assessing whether it is a problem. It is worth noting that the SU pump was always installed close to the carburetter and at about the same height, but many more modern electric pumps are designed to be installed close to the fuel tank, and hence need to deliver higher pressure. Installing them where the SU was may well cause problems from excessive pressure.

John

The intank pump fitted to V8s with Solex 175 carbs is an AC Delco CD600.
Fuel pressure is 4-6 psi. This is about the maximum for any non performance carby setup.
Holley Reds are internally regulated to this pressure and the Blue is regulated to 15psi, but is usually accompanied by a regulator at the carby and a return line off the regulator back to the tank.
The thing with carbies is that you only need fuel pressure that will provide enough fuel at W.O.T. The most important thing is the volume. It doesnt matter if you only have 1psi at the needle, as long as it can provide the volume to keep the seat loaded by the float at full noise.

Cheers

Andrew.

Thread: Hot engine won't start

Thread Tools

pressure

coils

Bookmarks

Bookmarks

Posting Permissions