Poor starting when hot.

[Tony Fearn]

This subject was aired in 'Natter' under the heading 'Tufnol', and for clarity I thought I would type a resume of the answer-posts to keep them all together for reference in case anyone searches for some such detail in the future.

The car in question was a 1962 Sunbeam Rapier, but I suppose the suggestions could well be applied to the Javelin and the Jupiter, if not the earlier vehicles.

They're in no particular order, and you will have to 'suck them and see'

1. Supermarket petrol is of varying quality and classics are more susceptible to variations in the composition of the various brands.

2. Un-leaded fuel burns hotter--increases under bonnet temperature--consider ceramic coating of exhaust manifold. Under bonnet temperature may be allied to
modern petrol.

3. Rubbish in fuel tank, petrol pump, fuel lines and float chambers. "New un-leaded has more methanol in it and it can act as a 'paint stripper".

4. Change the coil and check the polarity.

5. Invest in a new rotor arm (Distributor Doctor website) and condenser.

6. Use heat resistant gasket material between inlet manifold and carburettor base, eg 'Tufnol'-- hence the original post.

7. Fabricate thin aluminium or stainless steel sheet to form heat shields.

8. The mixture is too rich.

9. Dizzy too advanced.

10. Blocked radiator, or water channels in engine block and cylinder head.

11. Stale petrol!! Read David Mason's post in 'Tufnol' below. If car not used enough, the petrol goes off in the tank.

12. There could be a broken, or almost broken wire inside the distributor - either CB or earth wire.

13. The distributor plate may not be correctly earthed - needs deposits cleaning off it.

14. There could be a bad earth on the engine to chassis. This might raise the voltage on the engine when starting, giving less voltage across the contact breaker.

15. Check the points gap and replace or clean the points as necessary.

If any more suggestions are added to this post, or the 'Tufnol' post, I'll edit this post sometime, to include them.

Tony.

[Keith Andrews]

Many of these I woulds consider non issues.
By group
These are simple issues that one would assume any car enthuistist keeps maintained and has checked if anything goes wrong anyway... and most will cause other obviuos and serious running issues such as mis firing ,well before hard hot start becomes one, if effects at all.
4. Change the coil and check the polarity
5. Invest in a new rotor arm (Distributor Doctor website) and condenser
8. The mixture is too rich.
9. Dizzy too advanced.
10. Blocked radiator, or water channels in engine block and cylinder head.
12. There could be a broken, or almost broken wire inside the distributor - either CB or earth wire.
13. The distributor plate may not be correctly earthed - needs deposits cleaning off it.
14. There could be a bad earth on the engine to chassis. This might raise the voltage on the engine when starting, giving less voltage across the contact breaker.
15. Check the points gap and replace or clean the points as necessary.

These may/ can have an effect and come down to fuel perculation in the carb.. and issue not just related to modern fuels, but one that many manufactures consided as possible reflection on the reliablity of their 'product'
For decades now, many, could be most, classices no longer have heat sheilds installed and have no issues, be it modern or old fuel types. fuel peculation can be checked simply with an elcheapo mechanics stethoscope.
2. Un-leaded fuel burns hotter--increases under bonnet temperature--consider ceramic coating of exhaust manifold. Under bonnet temperature may be allied to
modern petrol.
6. Use heat resistant gasket material between inlet manifold and carburettor base, eg 'Tufnol'-- hence the original post
7. Fabricate thin aluminium or stainless steel sheet to form heat shields.

I throw another routine maintance in here...corrodied battery/ starter terminals
and wires/ cables that have aged or sometime in there life time been shorted out causing surface corrosion inside the insulation.
These will cause hard starting , not just hot hard starting.

This...our old classics used to run on crap fuels like the British pool fuels, kero has been used in the past...so to crasp at straws (assume) on bad QC of discounted fuels is very unlikely.
1. Supermarket petrol is of varying quality and classics are more susceptible to variations in the composition of the various brands.
And this..we do check , maintain our fuel filters, we do have filters right? The only way is occurs or could be put to hard starting is we have run the car, its picked up crap..go to re start and doesnt... and still will not when cold...
3. Rubbish in fuel tank, petrol pump, fuel lines and float chambers. "New un-leaded has more methanol in it and it can act as a 'paint stripper".

This gruop are the most likely and the normal things to look at for hard hot start
11. Stale petrol!! ..... If car not used enough, the petrol goes off in the tank.
And not listed but prevuoisly mentioned, the starter armiture winding faulty, and /or solenoid contact/windings.
Also a vaccuum leak in the inlet side of the engine, opens up when engine heat expands metals....usually also causes hot engine coolant temps

[Tony Fearn]

Hello Keith, and thanks for categorising the rather random list I posted.

It's good to have another's comments on the subject, although perhaps there are quite a number of members that don't have your wide experience and knowledge, so might just check all the points mentioned just in case 'something rings a bell'.

It's interesting to hear that you support David Morris' statement about stale petrol. I suppose this can affect the cars all year round if they're not used regularly, but of course more so in the winter months.

I wonder if you could expand a little on the comment below with regard to a twin Zenith carb on the 1592cc Sunbeam Rapier engine that's giving me trouble?

Also a vacuum leak in the inlet side of the engine

Regards,

Tony.

[Keith Andrews]

It's interesting to hear that you support David Morris' statement about stale petrol.

look, there is only one way I can put this.
Hell yeah.
And several threads here on hard start......after winter storage.
Im not around just jowetts, but hot roads, classic Aussie and American cars, and also on such forums world wide...multi ply these forums by...several 100 even thousand in size...
And have chain saws , line trimers, and still use vintage roller lawn mower.
The compenets in modern fuels have a low boiling piont, and also have the ablity to permiate many materials that hold them.
Hence why I do not have issues, I keep my petrols for impliments in a sealled aluminium container and that last fill ias just enough to finish the job leaving stuff all in the tank....If the tank doesnt need to be filled for a job dont.

I wonder if you could expand a little on the comment below with regard to a twin Zenith carb on the 1592cc Sunbeam Rapier engine that's giving me trouble?
Keith wrote:
Also a vacuum leak in the inlet side of the engine

OK the 1st thing is to forget nit is a certain car...it is a 4 stroke, interal combustion engine....
Not only do the have around 36 degs total advance under loads in common but the things that make them misbehave in common.
Vaccum leak....that simply means a leak to the atmosphrer before the valves...causes lean mixtures, which causes running hot (depending on the cooling system design, maitance and condition) runnng , burnt and resesesed valves / detonation in extreme cases , with inbetween a pop or back fire when let off the throttle.
Causes can be a a mis adjusted secondaries on a 4 barral holley , dirty or faulty or incorrect spec of a pvc valve, hair crack in a inlet manfold from not using a torque wrench to the same in a carb base plate, leaking gaskets worn butterfly bushes, mixture screws that have at sometime been abused ( not uncommon when some one is trying to adjust idle with mis adjusted sec butterflies and/ or worn bushes.)
For gaskets , cracks, bushes I use a pen lpg torch unlit and float it around parts and places...a change in rpms and/ vaccuum says u have found a leak.

Now if the carb is giving u trouble then that could also be the hard hot start.
So what "trouble" is the carb giving.....
Think of the carb as an inanimate object that operates 3 fuel ciruits (idle, power and cruise) independantly of each other each presion circuit calibrated in microns of an inch.
It is common for old / worn carbs to have a couple circuits effected by a single worn issue...say a butterfly bush.
idle mixture and speed scews way out of spec. then run lean at cruise, but no effect power, just lean enough to give a shade more hp...espec if the power circuits are worn.
When it comes to a carb, and if some enjoys reliable driving, dont mess around replace new or full rebuild.
If the carb is in good working order simply jet/adjust it to give the correct mixtures in each circuit.
If it will not do so , either it is worn or been messed with, or there is somthing else wrong.

[David Morris]

Hi Tony,

Drained the Javelin's tank yesterday, there was only about a gallon in there, put some fresh fuel in and she started first try.

However, I know that Lloyd Steel tried his Javelin on his return from New Zealand and she started first time after several weeks standing in the garage with the fuel untouched.

So, I don't know if the fuel does 'go off' but it certainly does seem to be my experience, particularily when re-starting with a hot engine and 'old' fuel in the tank. Perhaps I should try buying a top of the range fuel, rather than the cheaper brands? I should add that I use an additive to reduce valve recession. I have stuck with Morris Lubricants additive ( well you have to stay loyal to your name's heritage, don't you! ), as recommended by the FBHVC. Perhaps there is some chemical problem at work here?

Perhaps the additive doesn't like ethanol?

All the best,

David

[Keith Andrews]

Perhaps I should try buying a top of the range fuel, rather than the cheaper brands?

Well u could try that, maybe go to the States, try their fuel, or Aussie... end of the day, it is the volitile parts of the modern fuel that permiate and evaporate , and it it those that the engine relies on to fire up, amonst other things.
As I meanted above, doesnt matter if a chainsaw, lawm mower, American muscle car or a jap import thats been in storage a long time.....even petrol kept in most portabe containers are prone over long periods.

I should add that I use an additive to reduce valve recession.

Why.. the leaded fuel thing was one of the biggest roots of the 20th centry..all from 1 company.
Before the 2nd world war , we didnt have lead, then they had issues wioth the supercharges spitfires, lead fixed, and the root went on from there.
Keep in mind u are running modern octane fuels and persiphic gravity with very different flame times across the chamber than what was orginally around when the car was made... throw into that that your engine is most likely oversized, heads skimed and a few other things changing the compression ratio.....which means the engine needs different jetting and timing curves, Both together and individually these are what cause valve resssision NOT modern fuels.