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MG Midget and Sprite Technical - Heat Wrap

I am taking the Frog to Spain in June, Its going to be hot so I was considering using heat wrap around the LCB. I do have a heat shield on the carbs but the fuel pump is also mounted in the engine bay just behind the washer bottle (facet silver top) The pump has been there since the 80's with no problem. However I have noticed with modern fuel a greater tendency to vaporise in hot conditions in traffic.

Any experience of the wrap and if so any recommendations??

Bob Beaumont

Hi Bob

We have recorded many cases of losing power with heat wrap forcing heat back into the head. We have also seen severe warpage of ex manifolds associated with heat wrap. Best bet, I feel, is a bigger heat shield to form a thermal barrier twixt inlet side and ex side.

Peter
Peter Burgess Tuning

Thanks for the advice Peter. The pump seems to be getting quite warm and rattling away more than normal hence my thinking of ways to cool the engine bay. May be better to fabricate a shield around the pump.
Bob Beaumont

Good idea, maybe even use aluminium self adhesive tape to protect pump and any metal fuel lines.

Peter
Peter Burgess Tuning

Bob,

IIRC you would be better with the pump at the back of the car as it'll be lower and so less vacuum on the input side to induce vapour formation, also less of a fluid column to induce vacuum when you accelerate.
David Billington

That's a good plan! I see the facet pump working temp should not exceed 180 degrees F. After a run the pump body is hot to touch so i guess its reaching its max operating temp.

David, Yes that's the best option I agree, I'm trying to find an intermediate solution
Bob Beaumont

180F = 82.2C . IIRC 82C that won't be comfortable to touch except for the briefest period, around 60C you could touch for longer before it became uncomfortable. Best check with a thermometer if possible.
David Billington

The other option is to vent the heat and increase air flow out of the engine bay.
prop

Bob, as you won't need your heater in Spain, disconnect the 4" heater air hose at the heater end and reposition it to direct air onto the pump and fuel lines. The incoming air may be ambient warm in Spain, but unlike the rest of the air under the bonnet it won't have been boosted by passing through a hot radiator!
GuyW

Last year I spend my holiday with the Frogeye in Corsica. I had problems as you expect to have. I managed in the end, but indeed it is good to take some actions to prevent this from happening. It is not nice when you go uphill and lose power.
Jan Willem

When i was experimenting with underbonnet temps a few years ago i had a probe on top of the battery as the highest point under the bonnet.
With an ambient of about 36C it would reach 80C in short order after stopping at lights or in stationary traffic.

For vapor lock issues with SU carbs isnt it the fuel bowls which need to be insulated more than anything?
I remember someone on here having them coated with something.. or maybe wrapping the fuel bowls would help
Andy Phillips (frankenfrog)

Thanks for the comments Very welcome. I think the critical issue is heat building up when stationary and the more volatile fuel. I have been to SW France twice with no issues but over last weekend in London, I experienced a problem with loss of power and hesitancy when the engine temp reached 190F after queing in traffic.(The ambient temp was 27C.) I thought it was the condenser (a distributor doctor one) but after touching the pump I had second thoughts! It was quite hot and as David suggests worth checking with a thermometer. It was not too hot to hold however. The pump is a facet silver top which is admittedly 25 years old so I have ordered a replacement silver top together with some aluminium reflective tape to wrap the pump and fuel line. Guy I don't have the 4" heater pipe as the oil cooler is mounted vertically there and is fed through the intake in the Bonnet.





Bob Beaumont

I would get some foam insulation like used to insulate home plumbing lines for cold ... put thwt around your fuel line then wrap with aluminum tape

the idea is the aluminum tape and must be aluminum not aluminum colored will reflect the heat and the foam insulation will act as a air gap sort of but will take longer for heat to soak into the fuel lines

id probably tempory relocate the fuel pump out of the engine bay maybe inside the car... yeah i know... thus i said tempory and then move it to a safe place when back home

id probably make some kind of air filter inclouser thst would hold both carbs and have it force feed from a funnel and large tube from thr front of the car... agian out of aluminum sheeting ... nothing fsncy just temp for the trip

in a pinch you can also jimmy rig the bonnet hinges with lots of washers and longer bolts so that the bonnet lid sits up high in the back and will exit the hot air... it looks odd but it will let alot of hot air out of the bay.


Prop


prop

I think the ambient in Spain combined with high exhaust temperatures will require moving large amounts of heat way, and bigger heat shields or strategically placed bits of foil are unlikely to have huge effect. Drastic maybe but I would consider louvres,vents or both. Spanish petrol too only be available in 95 RON so tweaking the ignition might be wise,as would taking some octane booster with you.


Fergus

Fergus

please show more of that last / bottom pick... very nice sim to carls

prop
prop

Aluminium into a timber former


Fergus

Reverse the pitch on the fan blades so that it draws air from the engine bay and blows it forward through the radiator. (NOTE putting the fan on the wrong way won't do that).
Modern cars do this. I know it sounds illogical, but at speed it makes little impact on the air being forced through the radiator due to the cars speed, but in traffic it stops the heat build up inside the engine bay.

I think Mini fans do this IIRC?

Rob
Rob aka MG Moneypit

The position of a Mini's radiator, not the mpi versions though, is why the fan blows air from the engine bay out via the wing. MPI Mini's use a conventional system.
J White

Having slept on it and read all the helpful comments, I am going to relocate the pump under the rear wheel arch like the later Spridget. At least I know it won't get too hot there. I have ordered some ally foil so will also wrap the fuel lines for added peace of mind.
Hopefully it will stand the rigours of Spain in June!!
Thanks eveyone
Bob Beaumont

Bob,

Maybe you'll be lucky and it'll be one of those years when it's hotter in the UK than Spain ;) .
David Billington

Bob...

your fuel pump idea may not work... there are 2 kinds of fuel pumps

pushers and suckers

if yours is in the engine bay it maybe a sucker and may not be able to push the fuel forword as well


is that true ?... i dont know...its been debated here before and was concluded to be true

id look long before the night your supposed to depart the next morning to find out
prop

Bob,

I would disregard Props comment as IIRC it applies to SU pumps where they did apparently have some minor differences between pullers and pushers. If this is the pump you have http://www.demon-tweeks.co.uk/performance/fuel-pumps/facet-interrupter-electronic-fuel-pump-kit then maybe it'll be pushing out a higher pressure than what SU carbs like so maybe a pressure regulator would be nice at the front but it has worked for you up till now so is likely to stay doing so when at the back. A higher pressure in the line to the carbs will make vaporisation less likely in the fuel line and I think rubber fuel lines would conduct less heat than metal ones so the last bit of the run from the rear pump might be crucial. Regarding shielding fuel lines and the pump, the fuel lines are going to be heated by radiation or conduction and so will benefit from shielding/insulation but the pump is a different matter as it is generating heat from the electro magnetic coil and so wrapping it could trap heat in if wrapping it traps heat in the pump. Shiny surfaces have far lower emmisivity, ability to radiate heat, than weathered oxidised surfaces so if the heat is generated in the pump rather than taken in from the surroundings than a wrap could be detrimental.
David Billington

Failed to add this comment at the end in time.

Fitting the pump at the back in the standard position should get rid of that last concern as it is out of the hot engine bay and in relatively benign surroundings.
David Billington

Thanks David
It is the same pump as you highlighted. It pushes out up to 5psi and the SU's have coped ok so far. All the fuel line apart from the connection to the carbs is metal tubing beneath the car until it pops up by the nearside engine mounting. its only that last bit which is in the engine bay so yes hopefully that will be ok. It seems Mini's which have a mechanical pump mounted on the block right next to the exhaust pipe at the 'back' of the engine do not have any problems!!
Bob Beaumont

David

how did you deduce be had that perticular pump

thats one heck of a jedi mind trick

Am I thinking about tacos right this moment ?


Prop
prop

Prop,

If you bothered to read Bob's first post you would see he mentions it is a Facet silver top pump.
David Billington

regarding the mini fan idea.

It doesn't work. Cools beautifully at idle.

At about 15 to 20 mph it'll overheat off the scale in very short order. Zero airflow through the rad when you need it when pulling slowly up hills.

Going faster makes massive fan racket and starts flexing the blades off, stress cracks round the bases.

I had a mini fan fitted on mine...
Rob Armstrong


Bob Beaumont, Greater London, United Kingdom


I am taking the Frog to Spain in June, Its going to be hot so I was considering using heat wrap around the LCB. I do have a heat shield on the carbs but the fuel pump is also mounted in the engine bay just behind the washer bottle (facet silver top) The pump has been there since the 80's with no problem. However I have noticed with modern fuel a greater tendency to vaporise in hot conditions in traffic.

Any experience of the wrap and if so any recommendations??


Nope... Sorry David... he never mentioed it !!!

Your Psychic dude simple as that.... whats next weeks lotto numbers


the jedi force is strong with this one....haha



prop
prop

Wtf?
Rob Armstrong

Prop,

Are you able to read? as that quote of Bob's first post you just posted contains the words "(facet silver top)" QED.
David Billington

Prop,

I suppose, depending on your knowledge of English grammar, that from Bob's post you assumed he had a Facet silver top washer bottle from the way he worded the post.
David Billington

I recalling seeing a perfectly conserved/restored MGC that had a factory installed squirrel cage fan and duct work to the carburetor bowls, complete with an electric switch to engage the bowl cooling fan when required.

The C compartment was tight and outside air was also drawn into the air intake from outside the engine compartment.

Both my midget and the B suffer from alcohol related vapor locking at temperatures over 35°C (especially at idle). They get very testy and can die in traffic while the fuel pump clicks away. It has occurred to me that this factory solution for the C, no doubt and afterthought even in times when alcohol wasn't an issue, might be a solution for the Bs and Midgets struck with modern fuels on hot days.

The Kenlow type radiator fan doesn't help. If anything it seems to blow more hot air into the engine compartment perhaps aggravating the carb bowl overheating.
Glenn Mallory

For further information regarding the MGC U.S. spec carb bowl overheating solution see:

http://www2.mg-cars.org.uk/cgi-bin/gen5?runprog=mgbbs&mode=archiveth&archiveyear=5_2010.dat&access=&subject=5&subjectar=5&source=T&thread=2010071822405210309
Glenn Mallory

Thanks Glenn for the post. As you say the engine bay of a 'C' is really cramped and the big engine will push out quite a bit of heat so the fan seems sensible approach.

I am rather hoping temperatures in Spain will not get into the over 30's too much. The engine bay of the Frogeye is less cramped than the 'C' and possibly the Spridget so may vent slightly better. I don't use a thermostat either to help keeps things cool. As I have mentioned I have been to middle/south of France with no problems in recent years. The increase in ethanol content is the culprit it seems!!

Bob

Bob Beaumont

This proved to be effective with 10 % ethanol in the south of France: double spacers, one on ever side of the insulated heat shield. re routing the fuel ili away from the heat. See photo.

Flip


Flip Brühl

I recall that Alan Anstead was sorting exactly this problem out with another MASC member's frog. They moved the pump to the back -problem solved.
Graeme Williams

Moved the pump to the rear by the OS wheel yesterday. Pump seems much happier there and 'ticks' much less slowly than before. Installed a pressure regulator to bring the pressure from 5 PSI to 3.5 PSI. No difference in the performance of the car but yesterday was quite cool.
Interesting I was doing the work at Orchard Restorations who let me use their lift. Apart from the big healeys they restore and maintain they had a Frog in for a service. The owner had recently purchased it from a dealer for almost £12K. The car was in an appalling state with seized wheel cylinders, leaking fuel line (rubber tube run inside the transmission tunnel)leaking carbs (H1's) leaking diff and very amateur welding. There was a fair bit of 'pudding' in all the usual places. It was clearly going to cost quite a bit to put right:(
Bob Beaumont

I would definitely run the car with a thermostat, or at least a blanking sleeve. The engine will run hot anyway when the ambient temperature is high and running cold increases cylinder wall and piston ring wear.
Glenn Mallory

Thanks Glenn, I use the blanking sleeve so the flow is even. It has the bypass also blanked off. It usually runs around 165 degrees F although can get a bit cool in cold weather then I use some cardboard to partly blank the rad!
Bob Beaumont

reactivate please
Bob Beaumont

Hi
I thought i would reactivate the thread as I have now returned from Spain. The frog did 1000 miles in 12 days travelling over the Picos mountains to Ponteverdra then via Leon back to Santander. No fuelling problems at all. Got a bit hot on some twisty mountain passes (190F) but no misfires or starvation. Used almost no oil and averaged 34MPG. Thanks for everyones help.
Bob Beaumont

This thread was discussed between 14/05/2016 and 29/06/2016

MG Midget and Sprite Technical index

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