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<  Workshop  ~  HS6 Conversion

PostPosted: Fri Jan 05, 2007 10:14 pm
User avatarItsukiPosts: 4790Location: TeanJoined: Sat Jun 05, 2004 4:00 am
Shamelessly pulled from my blog, but over Christmas I swapped the carbs on the 2000 over from the evil CD150s (equal to HS4s, thats 1.5" carbs on a 2.5!) to a pair of HS6s as would have been standard fitment...

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[I]HS6s as purchased just before Christmas...[/I]


Over Christmas I decided to do the first major work to the 2000 and so set about ringing up a nice bill with Chris Witor (very helpful and known to be “the man” for saloon stuff) who built up a kit of hoses, pins and the like for the conversion from Strombergs to HS6s. He also persuaded me to drop the manifold the HS6s had come on – the water pipes had been cut off – for a more standard (and piped!) item. In all fairness I didn’t need much persuading, as I did think having a lot of rubber piping draped over the manifold would look a bit untidy and he said the car would run better anyway (I know there is lots of debate over putting hot water through an inlet manifold , but as I say Chris knows his onions so I didn’t quibble).
With all the parts arriving just before last post and James scheduled in for a New Years arrival – obviously because I hadn’t seen him for a while, not because he can tune SUs a thousand times better than me *cough* - I was ready to go…


I have to say I was quite worried about how I would adjust to life in an enclosed engine bay rather than the openness of the Spitfire, but there’s a surprising amount of room to work with and with the engine being a six pot it did all feel a bit more spaced out. Dismantling the current setup was a very quick and easy business – taking things apart is always nice and easy given the liberal use of WD40 – and the Strombergs and manifold came off in one lump, closely followed by the exhaust manifold.

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[I]Nakey inlet/exhaust side...[/I]


While my dad got with cleaning up that side of the engine I got on with cleaning up the 2nd hand manifold from Chris Witor and then swapping the HS6s over to this new manifold. I’m quite a clumsy person and also a bit forgetful so to simplify the changeover I whipped off the old airbox backing from the Stromberg setup, bolted the HS6s to that (the outside holes match up quite nicely) and with all that secure swapped the manifolds round in no time; saves worrying about dropping the spindles and all that…

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[I]Sorting out the manifold swap...[/I]


We then popped a new gasket onto the top of the downpipe (it was blowing terribly before the conversion) and a new inlet/exhaust gasket onto the head and proceeded to put everything back together. Aside from the fiddliness of the pins and nuts in this area everything went back together nicely and the preformed hoses included in the kit from Witor were very handy for quickly connecting the new waterways and return pipe up. All that was left on the assembly side was to sort out the changeover from a levered throttle to a cable one. I’d bought a 2nd hand pedal & new cable in the Witor kit and it was actually quite a simple task – although placement of the pedal “somewhere” in the footwell can be slightly daunting once the old pedal is off it becomes clear that various curves and protrusions leave little choice as to where to attach the new one… which is actually quite useful!

You might imagine the job was all but over by now but unfortunately nothing is ever that simple, and when James and myself got down to tuning the engine we found that one of the carbs was doing absolutely nothing in its current state. Luckily my dad is in the process of converting his 1275 Midget to a single HS6 and so a quick scavenging of the jet assembly from my dad’s carb had the car finally running on 6 cylinders. James then worked his SU magic to tune the car properly, and aside from a small intermission when the plugs had to be cleaned to stop it running on 5 cylinders it was a relatively simple process.

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[I]SUs sans airbox etc...[/I]


James had also been kind enough, upstanding Southerner that he is, to pick up a 2500S airbox and filter that happened to be for sale 10 minutes from him and so once the preliminary tuning had been done the airbox was manoeuvred into place (put all the bolts in the airbox before you offer it up the SUs, there just isn’t room to push bolts in afterwards!) and a few tweaks were made to the mixture to compensate for the new restrictions.

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[I]Now with blingy 2500S airbox/filter on...[/I]


The result? The car actually feels like the thumper I imagined. There’s still tweaking to do in a few places, but it’s actually nice to punch the throttle in 4th and feel the car actually move. It’s also nice to have it do it in such a refined manner – with the clattering downpipe silenced and the airbox on it just emits a low growl and surges onwards. The only thing I have to do now is to find out why I can’t get overdrive anymore!!

Edit: A loose wire was to blame for the inactive OD; now I have all 6 gears for powah and terminal velocity testing :D

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PostPosted: Sat Jan 06, 2007 7:21 pm
User avatarHulkaruthersPosts: 5017Location: London, The SouthJoined: Wed Jun 23, 2004 4:00 am
Indeed - it was fun tuning the car. Going from "it's got potential" to "it's gone sideways entering Tean high street"

Slowly rotating the advance - 50mph... 60mph... 70mph...

Still more to come too...!



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PostPosted: Tue Jan 09, 2007 8:59 pm
User avatarL33t n3rdPosts: 765Location: O-townJoined: Mon May 31, 2004 4:00 am
6pot on carbs ft1337w!

Good work chaps, what's the plan next? any vids / audio snippets?

Was it hard finding carbs for such an old car or is there more to life than Webers and Dellortos!
:cry:

I need more updates.... Daws has a project and it doesn't involve self-grooming! :drink: :drink:


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PostPosted: Wed Jan 10, 2007 12:42 pm
User avatarItsukiPosts: 4790Location: TeanJoined: Sat Jun 05, 2004 4:00 am
Just a tiny rather crap video snippet of James "testing" (or rather thrashing and using as an excuse to get my estate sideways) his tuning skillzorzz.

http://www.methinksperchance.com/temp/2k_tuning.wmv

Sounds far too quiet at the moment, but I have a plan! The car has 2 centreboxes under the car and one long pipe out the back, but the 2nd of these two boxes catches on the prop quite a lot (nasty noise!) so I am thinking of utilising a bit of bendy exhaust piping I have lying around and whipping the 2nd box off until I can work out a full system some time...

Stumbled on some HS6s for a nice price almost straight after I got the car which was rather fortuitous, there seems to be a few sets around :D Have turned away from Webers and Dellortos for the saloons though... 7r1umph PI FTW!! :bow: :bow: :bow:

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PostPosted: Wed Jan 10, 2007 1:10 pm
User avatarCridaperPosts: 13970Location: WolverhamptonJoined: Mon May 31, 2004 4:00 am
Dawson wrote:
Sounds far too quiet at the moment, but I have a plan! The car has 2 centreboxes under the car and one long pipe out the back, but the 2nd of these two boxes catches on the prop quite a lot (nasty noise!) so I am thinking of utilising a bit of bendy exhaust piping I have lying around and whipping the 2nd box off until I can work out a full system some time...


Have you tried taking the lid off the air box at all? Mikes Sportrak had a similar affair and I suggested taking the lid off, induction noise was incredible. But then the whole routing of the intake was long and complex which sort of made it like a trombone.

As you know this made a big difference on my 4i too. But I suspect may suck a lot of hot air in during the summer months if you are bothered about that sort of thing.

Shame the engine position makes fitting K&N's (or similar) a bit of a chore. Although you could whack a K&N cone straight on the end of that flexi-tube I bet. In fact I think I have one (in my shed) you're welcome to try if you want, it was the one I used on the Volvo. With a cold air feed it might do the trick. Or it might just flap around, suck hot air in, look odd, make no decent induction noise and just screw your finely tuned mixture up.

Loosing one of the exhaust boxes sounds like a experiment worth conducting. But as you well know, exhaust notes can be a bit hit and miss.



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PostPosted: Wed Jan 10, 2007 3:12 pm
User avatarItsukiPosts: 4790Location: TeanJoined: Sat Jun 05, 2004 4:00 am
Those videos were when we had no airbox on at all; I think the huge piston in the way really kills off induction roar in SU's, from what I've noticed you just tend to get the sound of air hiss and thats about it! Not too bothered about the K&N's either, thats the hot side of the engine so it wouldn't be doing much good sucking air around there anyway, especially as its much more enclosed than a similar SU setup on a Spit/GT6/Herald/Vitesse... Am going to do the K&N cone at some point, but I was penny pinching and as the airbox came with filter box I just used that for now...

The thing I'm most concerned about in the estate visavis exhausts is boom inside the car. The standard Witor system comprises of a straight through pipe from the front of the car and a backbox at the back, but I'm not that keen on the backbox on the estate anyway and the straight through pipe isn't recommended on estates either. They do a "semi sports" especially for estates which comprises a single centre box underneath the car and a backbox at the back, but as I said I don't really like the idea of the backbox on the estate, so I may see how good it is with just one centre box and keep the nice long tailpipe. I don't mind it being loud as long as it doesn't detract from being in the car, its so relaxing to be in it at the moment.



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PostPosted: Wed Jan 10, 2007 3:35 pm
User avatarCridaperPosts: 13970Location: WolverhamptonJoined: Mon May 31, 2004 4:00 am
Bah you'd have those pancake filters on if they just bolted straight in and you know it. Although it does seem pretty illogical to have air filters directly above the exhaust. A lot of modified Mini's are run like that. The 2500S set up looks a great solution.

Certainly worth trying the exhaust thing, I mean you can always barn the old box back in if it turns out horrid. Personally I think it may be a bit raspy but that's pure speculation.



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PostPosted: Wed Jan 10, 2007 3:51 pm
User avatarItsukiPosts: 4790Location: TeanJoined: Sat Jun 05, 2004 4:00 am
LoL, not sure I would after having the sock over the DHLA in the Spit, you could feel the car get fluffier and fluffier as you cooked the engine bay in a traffic jam. Until you got going again it felt like you'd sucked two hamsters into the trumpets!
Best time for that car was at night, it was as crisp as a morning frost then... One reason why my s00pa tougé time was at some godforsaken hour in the early morn... SHHNORT! :drink:

Will be interesting to see what taking the 2nd box out does to the sound... once its out there's got to be 6 foot or so of uninterrupted pipe from the 1st centre box to the tailpipe... should smooth stuff out a treat you'd imagine! As you say, if it doesn't work I'll whip the whole pipe off and have to bed someone to weld it back again :cry:

Just got to check that bendy exhaust is the right diameter now...



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PostPosted: Wed Jan 10, 2007 4:06 pm
User avatarCridaperPosts: 13970Location: WolverhamptonJoined: Mon May 31, 2004 4:00 am
Cold air induction FTW.

If you cut the current box out and leave a few inches of pipe either end then you can just sleeve it to refit it. Hell you can even use steel bean tins and jubilee clips if you have to.



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PostPosted: Wed Jan 10, 2007 9:38 pm
User avatarItsukiPosts: 4790Location: TeanJoined: Sat Jun 05, 2004 4:00 am
Would using bean tins go past barn and into the new rally cry "CANTEEN!!"? :cry:



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PostPosted: Wed Jan 10, 2007 10:40 pm
User avatarHulkaruthersPosts: 5017Location: London, The SouthJoined: Wed Jun 23, 2004 4:00 am
There is a perfect square hole in front of the air filter housing - where the current air filter pokes through.

A bit of ally with a hot hat glued to it would make a perfect place for a cone filter to get all the fresh air it wants.



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PostPosted: Thu Jan 11, 2007 2:33 am
User avatarL33t n3rdPosts: 765Location: O-townJoined: Mon May 31, 2004 4:00 am
JC FRESSSSSHHHH

That's how I roll too...


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