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Mk3 Spitfire engine and gearbox rebuild


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Just for reference, here's a homemade chart of some carb needles of interest. I videoed the last rolling-road run on the BR needle and can see it goes rich from about 3000 to 4200rpm, then a bit lean from 5000ish to 6000.  I would guess the rich-to-lean crossover might be happening around needle station 7 or 8, which tallies with the BR curve and the 'operating ranges' shown in the bottom image. But it's guesswork when you don't know where the carb piston is. Ho hum. 

I'm going to have to fit an AFR gauge. And some cameras to watch what's going on everywhere. Am beginning to understand the appeal of EFI... 

image.png.ef55b45bbaabb223876ca4cbdf14fbb1.png

Graph below taken from Burlen website 'technical' page:

tech

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or.... take it to someone who knows how to set these carbs up.
Mine was a revelation after a proper rolling road set up.  Not much was changed but it meant (in order of priority):

- I could run full throttle with no concerns on engine durability

- the engine pulled throughout the rev. range

- more hp.......

It's a dying art setting up SUs - I have a great recommendation in Cambridge........

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I'm a lover of making a mechanical system work - that's art.  EFI / megasquirt are beautiful too - but in a different way.

You could always graft in a Honda VTEC engine - lots of screaming hp - but that's a different game.  Decide what you're after.
.......neither is wrong, it's what suits you.

 

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1 hour ago, flatter4 said:

or.... take it to someone who knows how to set these carbs up.

Yes, this, and I am not one of them.  But hurry up as they are retiring / dying off.  There are a couple down this way who are pretty good

 

4 hours ago, PeteStupps said:

Am beginning to understand the appeal of EFI... 

Yeah.  It's kind of cheating, but life is short.

 

1 hour ago, flatter4 said:

I'm a lover of making a mechanical system work - that's art.  EFI / megasquirt are beautiful too - but in a different way.

Yes......  CD carbs are pretty amazing things.  Apparently simple.....

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1 hour ago, flatter4 said:

or.... take it to someone who knows how to set these carbs up.

Well yes that's a better idea!

I pass Cambridge fairly often, if you don't mind sharing your recommendation..? I remember hearing of a carburettor guru somewhere round there now you mention it

 

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I truely can't recommend Regency Autos enough.

Peter Baldwin (Mini racer, SU guru) was going in 2 days a week to help / train on their rolling road - this was 2019, so phone and try and book a day he's in.

Lee Deegan runs the rolling road and is damn good too - he's picked up plenty from Peter.  I would (and did) trust him with my car.

Their website doesn't give much detail, but if you scroll back through the facebook posts you'll see that plenty of classics pass over the rolling road.

     https://www.regency-autos.co.uk/contact-us

     01223 324 050

     enquiries@regency-autos.co.uk

     Regency Autos,120 Church End, Cherry Hinton, Cambridge, CB1 3LB

 

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Argh.. flipping radiator is leaking.

Thought I had a leak from the top hose but can see water bubbling through the brazed joint, which must be cracking. Bloody thing has only done about 3000 miles since I fitted it. It's a recon one from James Paddock. I'll give them a call in the morning.

 

_20210922_232946.JPG

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9 hours ago, PeteStupps said:

... a little Googling tells me this would be soldered, not brazed. Which I might be able to achieve

Bugger! Yes the joint is soldered and probably fixable relatively easily.

Radiator needs to come out and laid flat to do this.

Needs a bit of heat so you will need a propane torch, the type for doing plumbing is perfect. Also plumbers solder and flux. A soldering iron and cored flux won't do the job.

Get rid of all the paint round the joint and mechanically clean everything. Fine grit paper and wire wool is best. Then clean with flux and some heat and repeat before starting. 

Flux the joint heat and add the solder from the coil. 

This is the tricky bit as you want te solder to flow but not get too runny so heat control is critical. Might take a couple of goes to get the hang of it but should be fine. 

Just avoid getting too much heat into the whole radiator to protect the rest of the solder. 

 

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Thanks @Escadrille Ecosse, I'll give it a go at the weekend if my neighbour will lend me his blowtorch! Then if it goes seriously pear shaped I've got one week before the RBRR to get hold of a new rad... 

Laid flat - that's interesting cos I'd probably have tried to do it with the rad in situ (drained and hoses disconnected of course!).

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1 hour ago, PeteStupps said:

Thanks @Escadrille Ecosse, I'll give it a go at the weekend if my neighbour will lend me his blowtorch! Then if it goes seriously pear shaped I've got one week before the RBRR to get hold of a new rad... 

Laid flat - that's interesting cos I'd probably have tried to do it with the rad in situ (drained and hoses disconnected of course!).

The solder is quite dense with very little surface tension so you want to minimise the effects if gravity dragging it away from the joint. Especially differentially. 

Good luck and hope you get it all sorted in time for RBRR. 

Edited by Escadrille Ecosse
Auto- bloody correct on phone
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My experiences with soldering radiators and heater matrices is that modern plumbing solder has a higher melting point than that used in rad making (though possibly because old radiators). 
 

I had all kinds of trouble with the Vitesse heater matrix and eventually took it to our local rad shop where they sorted it in 10 minutes flat. He advised me to use body solder as it has a lower melting point and slower transition from solid to liquid.

Your mileage may vary but bear it in mind….. may the force be with you!!

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17 minutes ago, Nick Jones said:

My experiences with soldering radiators and heater matrices is that modern plumbing solder has a higher melting point than that used in rad making (though possibly because old radiators).

This is true, however if you are careful it works fine and it's available at the local diy shop. It also comes on a coil whereas body solder usually comes in bars and is much harder to work in small areas and control heat into the solder. I have tried :mad:

I had exactly the same leak problem on my rad as Pete and fixed that along with adding a drain boss and temp sensor boss to the Spit rad. Done a few others as well. What you can't do this way is solder up the matrix. And the join of the matrix to the header tank is pot luck.

These took me minutes as well.

20191114_174457.thumb.jpg.ddb62f4e8dd498a23953cc08724907af.jpg

20191114_174450.thumb.jpg.f4b2b85f9fefac0181aef14e137ed8ac.jpg

Meant to add Pete that I think the reading my rad leaked at that point was because it wasn't quite lined up with the hose properly. Don't know of yours is the same but sorted that at the same time 

Edited by Escadrille Ecosse
Fit with hose
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I'll heed your warning Nick but hope for results like Colin's! 

1 hour ago, Escadrille Ecosse said:

my rad leaked at that point was because it wasn't quite lined up with the hose properly. Don't know of yours is the same but sorted that at the same time 

This is a good point. My top hose is very old and hard as rock (but it didn't leak!), and now I'm wondering whether that might have contributed. If it's slightly misaligned since being put back together that could have put extra stress on it. I'll check alignment and fit a new hose when I get this crack sorted. 

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Hello Pete

                Be very gentle with the heat(you are not cooking a Steak!)

And try and keep the solder just over pastey (this were body solder is better a more pasty stage) pipesolder is to designed to flow!

And as said get it very clean

But do not worry it is not Rocket Science! just do not rush but keep the flame moving!

Roger

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16 minutes ago, rogerguzzi said:

Hello Pete

                Be very gentle with the heat(you are not cooking a Steak!)

And try and keep the solder just over pastey (this were body solder is better a more pasty stage) pipesolder is to designed to flow!

And as said get it very clean

But do not worry it is not Rocket Science! just do not rush but keep the flame moving!

Roger

This....

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Good luck Pete.  Let us know how it goes.

Be careful with your choice of top hose.  I bought a brand new one and the first time the car got hot it ballooned out and sprang a leak:

image.png.ad7b75cea115c39e27c4e218f7a2120c.png

..and it wasn't overpressurised.  All is fine now with a NOS hose fitted.

 

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29 minutes ago, rogerguzzi said:

Hello All

             I fitted a set of silicone ones to Spitty about 10 years ago(before they were so expensive!)

They have done 40,000 miles and still just the same and been on and off a few times.

Roger

I got some good ones for the Scimitar which have done the job superbly.

I got one for the Spitfire that lasted barely five minutes. When I cut it up there was not fabric reinforcement in it. The replacement was much better quality.

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14 hours ago, rogerguzzi said:

Be very gentle with the heat(you are not cooking a Steak!)

And try and keep the solder just over pastey (this were body solder is better a more pasty stage) pipesolder is to designed to flow!

And as said get it very clean

But do not worry it is not Rocket Science! just do not rush but keep the flame moving!

Thanks for the tips Roger. I will also try cooking steak with a blowtorch if the radiator repair is successful :biggrin:

Edited by PeteStupps
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