Spluttering Spitfire

[oliproctor]

Hello all,

I need your help please!

My 1965 Mk2 Spitfire has begun spluttering and backfiring under acceleration after around 15-20 mins of driving to the point where it has cut out once or twice.

It did this last summer before it was taken off the road for winter for some TLC and bodywork restoration however the problem was foxed after I noticed the vacuum advance tube had split in the middle after adding heat-shields to the carbs as I thought I may have been due to overheating and vapour lock. After turning the advance all the way in it ran like a dream and was smooth and a delight, something it still does until it reaches 20 mins of running.

I have checked the spark plugs and cleaned them, all were in good condition bar number 3 which had carbon fouled (maybe due to the timing being out??), drained and cleaned the fuel tank and replaced with fresh petrol, new fuel filter and tubes and I even added lead additive to see if that may help but to no avail.

The only resulting possible problems I can see now are the fuel vapourising after 20 mins of running and the timing being out. My brother and I thought to maybe add an electric fuel pump to the boot of the car so heat radiation from the engine won't be an issue anymore and keep the original as a 'dummy'. The carb dashpots do not get hot due to the heat-shields but the fuel pump has done over the past few days and I can only touch the pump for about 3 seconds before having to take my hand off it. I did a test today in the midday sun (around 30 degrees, barmy for North Yorkshire I know) and one at 22:00 to see if it was heat related. The dashpot were cool tonight and fuel pump cooler than midday with me able to hold onto it for 8 seconds or so before it being too hot to hold onto but it still started spluttering uncomfortably after 20 mins again. 

Surely if the timing was out it would splutter straight away? Anyone have any words of wisdom please?

Here are a few pics of 'Lockie'.

Thanks Oli

[Pete Lewis]

Back fires  sounds like a typical condenser failure  there are some awful condensers about .

It wont be vapourisation ,  might have fuel blockage with rubber slivers floating and jam behind the float needle valve

Is very common

Check  th e brush in the dizzy cap actually contacts the rotor arm sweep plate

Read the post about manifold leaks , amd fitting heat shields , can alsomhave air leaks 

Squirt some brake cleaner or even petrol along the  gaskets , does it suck it in ?

Timimg will affect all plugs the same and wont be erratic  the vac pipe only helps economy it wont affect how it runs  and any air leak is so small and enters after the throttle plates wont cause much problem.  Do check the small braided wire in the dizzy is intact

Are the dizzy contact  terminals secure ,  also check the coil is wired for correct polarity  if its negative earth at the batery then the coil neg goes to dizzy and pos+  has the ign feed

Do you have std or pancake air filters?

Check the HT coil wire terminal is clean in side  no green corrosion under the plastic seal inside the coil head

I guess this is a delco dizzy they generally dont suffer from rotor arm problems 

Let us knowmwhat you find

 

[oliproctor]

3 hours ago, Pete Lewis said:

Back fires  sounds like a typical condenser failure  there are some awful condensers about .

It wont be vapourisation ,  might have fuel blockage with rubber slivers floating and jam behind the float needle valve

Is very common

Check  th e brush in the dizzy cap actually contacts the rotor arm sweep plate

Read the post about manifold leaks , amd fitting heat shields , can alsomhave air leaks 

Squirt some brake cleaner or even petrol along the  gaskets , does it suck it in ?

Timimg will affect all plugs the same and wont be erratic  the vac pipe only helps economy it wont affect how it runs  and any air leak is so small and enters after the throttle plates wont cause much problem.  Do check the small braided wire in the dizzy is intact

Are the dizzy contact  terminals secure ,  also check the coil is wired for correct polarity  if its negative earth at the batery then the coil neg goes to dizzy and pos+  has the ign feed

Do you have std or pancake air filters?

Check the HT coil wire terminal is clean in side  no green corrosion under the plastic seal inside the coil head

I guess this is a delco dizzy they generally dont suffer from rotor arm problems 

Let us knowmwhat you find

 

Thanks for this, I'll have a look today. I'm not sure of the make of the distributor and they are pancake air filters not standard. Why would that make a difference?

Thanks Oli

[Clive]

Like Pete I reckon ignition related.

My first checks would be rotor arm, condenser and possibly cap. Also the coil... New ones don't seem to be very good, Lucas are not what they were. 

If you have locals, borrow known good bits off their cars....

If it is the coil, I would buy a bosch one

[Pete Lewis]

pancakes offer less resistance to the incoming air and as such this lowered depression in air vacuum   cant suck as much fuel from around the needle and its jet so they often require a needle change away from std.  f it also has a 4-2-1- tubular extractor manifold the problem gets bigger and even more of a needle change and damper springs can be needed to richen the running mixture

thats why its often best to stick with what triumph designed ....it worked   unless you are into much twiddling

Pete

[oliproctor]

Hi Pete and Clive,

I'm pretty new to ignition systems so you'll have to bare with me! 

Distributor was changed last year by the last owner and looks clean and all in working order inside (see first pics) and seems to be a Delco dizzy like you said. All connections seem secure and rotor arm seems to be contacting the contacts nicely as they're all marked, does this answer your comment below?  (see pic 2). If so where is the brush you mention?

4 hours ago, oliproctor said:

Check  th e brush in the dizzy cap actually contacts the rotor arm sweep plate

3 hours ago, oliproctor said:

also check the coil is wired for correct polarity  if its negative earth at the batery then the coil neg goes to dizzy and pos+  has the ign feed

With regard to this sentence above, my car is positively earthed at the battery (not negatively as you said) with the coil positive going to dizzy and negative going to the ignition feed back through the bulkhead, is this correct? (see pics 3 and 4)

All terminals are clean with no green corrosion. 

What is the best way to make sure the condenser is working too, just double checking to make sure its the silver small cylinder (like a AA battery) in the dizzy (see first pic).

Thanks and sorry for asking so many questions, very keen to learn!

Oli

 

 

[DerekS]

Just a thought here. The other problem with pancakes is that they tend to draw hot air from the engine and exhaust manifold rather than cooler air from the front of the car. I had problems with this a few years ago using K+N filters, going back to standard sorted it. 

[oliproctor]

17 minutes ago, derekskill said:

Just a thought here. The other problem with pancakes is that they tend to draw hot air from the engine and exhaust manifold rather than cooler air from the front of the car. I had problems with this a few years ago using K+N filters, going back to standard sorted it. 

By going 'back to standard' do you mean the pancake filters within an air filter box? I didn't think that was standard on a Mk2?

Thanks Oli

[Pete Lewis]

that all looks ok 

there is no diy easy test for a condenser,  if the contacts get burnt badly then expect a condenser fault  there are some terrible ones on sale with little inside the can.

brush contact with the sweep plate is shown on top of the rotor arm  the springy contact must touch the carbon brush in the top of the cap , you cant see this , but a nice light rub mark on the springy bit shows its in contact, if there is a etched burnt mark then theres a gap and the spark is having to jump this and the cap contacts and the plugs .

do  have squirt test on the carb heat shields and manifold gaskets , dont use brake fluid it burst into flames staright oil works but will smoke on the exhaust,  then  if its all sound  have you ever  re set the mixtures   

it may just be set very lean ,

pete 

 

[oliproctor]

33 minutes ago, Pete Lewis said:

that all looks ok 

there is no diy easy test for a condenser,  if the contacts get burnt badly then expect a condenser fault  there are some terrible ones on sale with little inside the can.

brush contact with the sweep plate is shown on top of the rotor arm  the springy contact must touch the carbon brush in the top of the cap , you cant see this , but a nice light rub mark on the springy bit shows its in contact, if there is a etched burnt mark then theres a gap and the spark is having to jump this and the cap contacts and the plugs .

do  have squirt test on the carb heat shields and manifold gaskets , dont use brake fluid it burst into flames staright oil works but will smoke on the exhaust,  then  if its all sound  have you ever  re set the mixtures   

it may just be set very lean ,

pete 

 

Hi Pete,

Video attached shows the Easy Start spray noticeably  increasing revs under idle when sprayed onto the heat shield/manifold gasket. Maybe not completely noticeable from the video but is this the source of all my problems? If so, why is it not spluttering straight away and only after 15-20 mins?

Thanks Oli

[Pete Lewis]

i would think heat is opening the gaps and helping loose  sealing and clamping is  probably defective  

air leaks will cause backfires 

[oliproctor]

So would you suggest taking the carbs off with the heatshields, clean up the gasket areas and make sure each surface is smooth, replace gaskets???, add gasket sealant and new gaskets and then do up the bolts nice and tight to see if that makes a difference? 

Is it worth changing the fuel line that runs around the carbs whilst I'm at it?

 

Thanks Oli

[Pete Lewis]

have you had a read of the troubles we had on twiddle day and  the post i made about manifold studs 

all to do with air leaks 

Pete

[Colin Lindsay]

1 hour ago, oliproctor said:

By going 'back to standard' do you mean the pancake filters within an air filter box? I didn't think that was standard on a Mk2?

Thanks Oli

Mk2 had the very nifty black pancake filters, no box. However:  Fitting a box may help, if you can find one with the correct spacing for the carbs, or else make one.

[Ben Caswell]

In the close up pic of the coil it looks like a yellow wire is chafing against the neg terminal worth moving anyway.

Ben

[Casper]

51 minutes ago, Colin Lindsay said:

Mk2 had the very nifty black pancake filters, no box. However:  Fitting a box may help, if you can find one with the correct spacing for the carbs, or else make one.

I'm not sure you are right, Colin.  My Herald has a Mk 2 Spit manifold/carbs and airbox.  Mk 1, however - I think that originally had open pancakes, and perhaps changed to airbox.  The spacing is different on a Mk 3.

Con

[oliproctor]

1 hour ago, Pete Lewis said:

have you had a read of the troubles we had on twiddle day and  the post i made about manifold studs 

all to do with air leaks 

Pete

Yes I've had a read, luckily my threads and nuts are all okay. But is what I said the correct thing to do as below?

Thanks

 

1 hour ago, oliproctor said:

So would you suggest taking the carbs off with the heatshields, clean up the gasket areas and make sure each surface is smooth, replace gaskets???, add gasket sealant and new gaskets and then do up the bolts nice and tight to see if that makes a difference? 

Is it worth changing the fuel line that runs around the carbs whilst I'm at it?

 

[oliproctor]

1 hour ago, Colin Lindsay said:

Mk2 had the very nifty black pancake filters, no box. However:  Fitting a box may help, if you can find one with the correct spacing for the carbs, or else make one.

ANyone have one of these spare or willing to sell?

 

Thanks Oli

[Pete Lewis]

its not good  to use sealer on manifolds there's a lot of panting where heat and vibrations in the engine make faces shift about more than you imagine   many sealers have a long term hate with petrol and it can get dissolved in time 

however with the multiple faces to seal with gaskets manifolds heat shields and carbs  the use of a non setting high viscous sealer may solve some of your problems ,    needs must rules apply.

once all is airtight you can readjust the needles to get the mixture and idle speeds under control and see how she runs 

pete

 

[oliproctor]

13 minutes ago, Pete Lewis said:

its not good  to use sealer on manifolds there's a lot of panting where heat and vibrations in the engine make faces shift about more than you imagine   many sealers have a long term hate with petrol and it can get dissolved in time 

however with the multiple faces to seal with gaskets manifolds heat shields and carbs  the use of a non setting high viscous sealer may solve some of your problems ,    needs must rules apply.

once all is airtight you can readjust the needles to get the mixture and idle speeds under control and see how she runs 

pete

 

Is there a sealant you would recommend? And what about new gaskets?

Thanks Oli

[Pete Lewis]

always best to use new gaskets , as for sealer  blue  hylomar  or similar 

i use loctite 574 but thats a setting sealer ok  on carbs faces but not manifold to head ...really that needs to remain dry fit

Pete

[Anglefire]

RTV is the other type of sealant that is often used - has a very high temperature tolerance - 300'C is some cases.

[Colin Lindsay]

On 6/27/2018 at 5:43 PM, Casper said:

I'm not sure you are right, Colin.  My Herald has a Mk 2 Spit manifold/carbs and airbox.  Mk 1, however - I think that originally had open pancakes, and perhaps changed to airbox.  The spacing is different on a Mk 3.

Con

You're right! It was the MK1 with two filters and the Mk2 with the black-painted airbox.

Well, it was a long time ago

[daverclasper]

Hi. According to a experienced member. If you remove the condenser, as suspect, then car will run ok, though will burn our points if left like this.

Dave  

[Pete Lewis]

if it runs it wont be very happy

condensers also buffer the coil to aid it discharge cleanly,  a failing condenser can cause backfires if it discharges when you dont want  it

i found a local last week where the heel had worn down so far there was no adjustment left and the points were all but closed 

without a spare,  remedy was to grind the end which now fouled the condenser mount and slot the adj screw hole  the points faces  were as flat as new so  it had a brilliant condenser fitted ,    we need more like that .

if you get a duff one cut it open should have around 9ft of  waxed insulated foil wound up inside .

Pete