Tufnol

[Tony Fearn]

One of my other cars, a 1962 Sunbeam Rapier IIIA, is experiencing problems re-starting when hot. Most embarrasing at times, as it takes 20 - 30 minutes to cool down, bonnet open, in the most ridiculous places - usually with a line of traffic behind!
Tonight, at my 'Classic Car Maintenance Course' at the local college I have started to fabricate a heat shield to fit between the inlet and exhaust manifolds which are extremely close to each other, but a colleague suggested that I also include Tufnol carburettor spacers for the twin Zeniths, - belt and braces comes to mind.
I've heard of Tufnol, but has anyone used this product for a similar application? If I bought a sheet to make a couple of spacers, is it sufficiently heat-resistant to be used for this purpose.
I think that another name for it is 'Bakelite', but remember rather obnoxious smells when a light bulb overheated it in the living room, as some older bulb holders were made of it.

Tony.

[Keith Clements]

Bakelite was the first plastic; but being made with asbestos is probably now banned. Like all plastics it depends on the composition and manufacture as to its properties, including melting point or flammable temp.
Melting lamp holders were caused by the arc created by a poor connection, so temps could be very high. I would say that something that can withstand 150deg C should be OK between the carb and the head. What you want is something with low thermal conductivity for summer and high thermal conductivity for winter (otherwise you will experience icing)!

The actual problem is that petrols are now of diffrent composition having been designed for petrol injection (and probably recirculating pumps). But sure, getting the heat out of the engine compartment and away from petrol delivery is a good idea.

Tufnol is about the same resin as Bakelite but has cotton as a binder.

You could try some electric circuit board material . Maplins?

[StevenGray]

Tony
Tufnol tec data here http://www.tufnol.com/tufnol/default.asp?id=100
If you decide to use some I may be able to help, I have a number of off cuts which are 6mm thick either Whale or Carp brand
most probably Whale,(been on the shelf a long time so cannot remember which one)

Steve Gray

[george garside]

not sure about this but wasn't the carb flange packing (part 50880) on the Jav made of some sort of ''plastic''. Similar packings or spacers were used under the carb on various makes and may have been to reduce the amount of heat transmitted from the manifold or whatever the carb was bolted to. They may still be availble from classic spares outfits or autojumbles .

george.

[george garside]

Curiosity aroused I googled tufnol carburettor spacers and low & behold amongst several were hitchcocks motorcycle services who stock them in a veriety of venturi sizes and 2 thicknesses - so there's no need to make them Tony

george

[Keith Andrews]

One of my other cars, a 1962 Sunbeam Rapier IIIA, is experiencing problems re-starting when hot.

This is a classic symtom of a starter armiture having a high resistance in its feilds due to old/ poor contacts joins.
Many older starters had soldered joints ...and tuning by ear in the old days that advanced the intial.
Increase intial , incresaesintial loads on starters(armitures) that increases current draw dramatically.. over time this causes dry joints in the armiture...
All this Assumes that there are not other issues such as dirty / loose grounds, terminals etc....which can also be related in some instances to clamping tight when cold and 'open' when warm.
The other cause could be the contacts in the solenoid to the coils..
Worn bushes bearings, brushes, comuntator usually a combination on older starters

Starters with armiture failure as described above can have the armiture tested on a growler at the local auto sparkie... down side most modern auto sparkies dont have one now, and/ or the young guys never heard of one, even it it is in a dark back cnr of the workshop.
The other alternative is put the armiture in an oven, get it hot enough that can hold, for a few seconds only, then check the continuity of the windings, re solder any suspect joints,
Or have a hoist and tools ready set up drive the car, when warmed up enough, onto the hoist , drop the starter and do a bench test ....

Bottom line, good working starters and electrical systems did not have these issues, adding a heat sheild is ineffect treating a symtom not the cause, which usually ends up Murphy stepping in at the worst possible time long way from home, a complete starting system failure.

[george garside]

Tony , there is something in what Keith is saying but before investigating the starter it may be worth just changing the coil. I have had similer breakdowns on both cars and motorbikes where a good cooling off period restores everything to normal until it happens again and in every case it has been a buggered coil which is sparking enough to keep the engine running but which has reduced capacity when very hot . Both the carb and the coil will also tend to heat up more AFTER the engine has stopped as the underbonnet temperature generally increases in the short term due to lack of fanned or natural passage of cool air under the bonnet and obviously around the manifold and coil.. I think that is one of teh reasons for the tufnol spacers.

george

[Tony Fearn]

Thanks everyone for the replies. Together with the ones from the Rapier Club, I could be a bit busy when the weather warms up a bit, although the spray-painting of 'Mary Ellen' will take precedence if we get a good dry spell.
To Keith A:- This is something that I have no idea about, so thanks for the input. I must say though, when trying to re-start the hot engine, the starter whirrs away merrily, turning the engine. I even used the starter, with the ignition key and first gear to exit the traffic line into a convenient side street where I could let the car cool down.

The SROC members have suggested, a failing dizzy rotor, ceramic coating of the exhaust manifold (£300-ish), exhaust wrap, gunge in the petrol tank and system, gunge in the rad and waterways and replacing all fuel pipes with ones of larger bore.

So you see there's quite a lot to contemplate.

Tony.

[Keith Andrews]

I must say though, when trying to re-start the hot engine, the starter whirrs away merrily, turning the engine

That info makes a huge difference.. forget the armiture etc... even tne starter...If u can move the car on the starter the uissue lays else where...
Years ago when we would grab the nearest SB checy and throw in a boat .. most engines...it was not uncommon to grab a different coil....get 10 or 20 mins out into the open water and engine dies... change plugs, mess around then the engine would fire straight back up....then repeat.
Most of the old engines where on ballast resistor... be it a ceramic resistor or a resistance wire from the ign.
These where (varied between car manfactures) between 6 and 9 Volts to the coil, and most brnd coils had somewher on the base.. in the part number what ever a 6 or a 12.....6 for balist ign and 12 for non balast... or what what we called 'sports coils' back then...which required by passing the ballist resistor....
put a 12v coil on a balast or visa versa a 6v coil on a on a non balast and theresult is the same... coil gets hot, engine dies, coil cools, engine runs.

[george garside]

Tony, thinking about it you can probably discount a fault with the starter fro 2 reasons. 1 It is wroking well. 2. It would not go dead for half an hour and then come back to life. Also things like the manifold needing coating and/or fuel lines needing replacing ?! with larger diameter ones doesn't ring true either as presumably the fault has occured '' all of a sudden'' and the aforesaid components have been happily functioning in their present form for some time.

The reason I suspect the coil is because 1. I have come accross it being faulty with similer symptoms to yours on a number of vehicles & 2 . It will fail if overheated but will come back to life when cooled down after say 1/2 hour standing.

If my guess is wrong trying another coil (off another vehicle) wont have cost anything and is dead easy to do.

a faulty condenser can also throw up similar symptoms
george

[Keith Andrews]

Crossed posts above... basically both saying the same thing..
When was the last time stuff like pionts, condeser, coils where treated to any maintance?
If a while, maybe worth following up on Georges suggestions, even simply replace new if old.

[Tony Fearn]

Hello again.

Thanks for the follow-up comments. I'm really chuffed that you've all taken the time to help me along, even if what we're discussing isn't a Jowett!!

I put new points and plugs in, in early December (2012). The condenser and coil were new about 12 months ago when I had 'Hometune' come to set the whole thing up including balancing the carburettors. I'm going to talk to 'The Distributor Doctor's' outfit shortly (http://distributordoctor.com/) regarding their red rotor arms, as perhaps the rotor that Hometune put in was inadvertantly of lesser quality than necessary.

George: they also do condensers so I'll get them to send me one of those also, and I'll buy another coil after checking the spec with the Series Registrar.

The next bit needs an apology first, and it's a bit 'tongue in cheek'!

Instead of using the superfast all singing and dancing Internet and Web, and wasting time typing questions to 'Splitpin' as a PM, as Jack and Chris and even Keith would expect, I actually used the old-fashioned BT telephone service to talk to Gary, and his wife Judith who answered the phone.

Gary and I had a good 20 minute chat about various things, and sometime soon I should receive a package with a bit of Tufnol in it, although it will have to be sent by snailmail, and might cost 50p as we can't yet do a 'beam me up'.

Regards,

Tony.

[Keith Clements]

I have received many reports of 'new' rotor arms and points failing, probably because of Oriental manufacture. I had the same overheating problem with an ignition coil, Also coils are sensitive to polarity so check, particularly if you have changed battery polarity.

Underbonnet temperature (allied with modern petrol) is the most likely. I fitted an oil cooler with electric fan on the Javelin under the wing and have a powerful electric fan on the rad that comes on in traffic. If the head is not crossflow then keeping the exhaust radiation from the carbs is very important. Chris had his exhaust on his Rover coated and says it reduced underbonnet temps considerably.

Does the car idle OK when hot? It maybe the mixture is too rich. I had this problem and it was a loose jet. Started fine but would not when hot. Once again this may be the modern petrol problem and smaller jets might be the answer. Colourtune or CO check might show this.

When I was having overheating problems (eventually found to be a blocked rad), I carried a temperature gun around. Pointing this at the carb would tell you if it was overheating. A good amount of throttle should cool the carb quickly.

[george garside]

I presume the reason modern electric radiator fans carry on fanning after switch off is to prevent the sudden short term increase in underbonnet temperature immediately after switch off. So on the rapier a change to a modern elec fan may help . It is possible that Tony's underbonnet temprature has gradualy increased over the years due to gradual increase ofcrud not only in the rad but also in the block and head.

george

[Keith Clements]

I came up with an easy way to check that your rad is gummed up. Weigh it! Ok that does mean taking it out but having a new one in the other hand certainly tells you which one is the old one. Back flushing and caustic soda steeping had no effect on removing the crud. So yes the bad starting could simply be a blocked rad. Once again the temp gun will tell you. A high temperature gradient , say more than 10deg C between top and bottom of rad (depending on pump) will indicate a blocked rad. You may think this counter intuitive as cooler water is entering the engine with a blocked rad; but there is less of it to cool the engine , hence it overheats. Anyway that is my theory. If the water coming out of the engine is over 87 deg C I would suspect a blockage.