Classic cars forum & vehicle restoration.

[Ray White]

I have been looking for a new or refurbished SU carb; in particular the H4... but Burlen, my first port of call, seems to be out of stock and I have had no luck in searching the 'net at all.

I want to find a single 1 1/2" H4 with the original style choke and a banjo type fitting to the float chamber.

The reason I am looking for this particular carb is that the Eaton M45 supercharger that I have fitted to the MG TC has a 1 3/4" H6 which, at the time , I was advised by the supplier would be ideal for my engine.

I have since discovered that for a 1300cc engine - even modified with the fast road cam and tuned head with bigger inlet valves, like mine - the 1 1/2" carb - which it would normally have had - would still be the better option.

What concerns me is that I have been told by a hot rod supercharger guy in the States that the bigger carb could both reduce torque and MPG... but I don't know if that is the case or not.

I thought perhaps if I had a choice of carbs and experimented with different needles I might stand a chance of getting optimum performance from the engine.

Any ideas??

[lowdrag]

Not sure if this is exactly what you seek but I found it on Google:-

https://www.ebay.co.uk/itm/NEW-H4-SU-CARBURETTOR-MINI-COOPER-SEBRING-SPRITE-MG-/353645646614?var=0&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338268676&toolid=10044&customid=CjwKCAjw2P-KBhByEiwADBYWCrLLVyt3umodOOG4FYDDvv9nOY6b6tdJ2TXSl4jUc3lAyyX53I2GVxoCnfgQAvD_BwE

[Ray White]

I looked at that one. It's quite close but I think that would be a HS4 rather than an H4. I don't know what it does (presumably it must do something) but there is an extension built in to the design.



If the HS4 is a direct replacement then I expect the one you have suggested would polish up O.K.

(Unlike some on here, I prefer shiny.... but I wouldn't be put off by it's tarnished condition!)

Thanks for trying.

[Bitumen Boy]

I'm no expert at all but I think the HS carbs were simply updated versions of the H models - essentially advances in materials had made it possible to simplify the jet and its feed from the float chamber, which could be a source of trouble on the older models.

[peter scott]

I don't know but does the S mean sloping? The eBay one is canted at an angle but I think you want a vertical one. I think the canted ones just have a twisted "bracket" on the bottom of the float bowel. I suspect there is no difference in the main carb body.

Apart from Burlen the other major supplier is Midel in Australia but looking at their website they don't appear to have H4 or HS4 in stock either.

Peter
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https://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[Ray White]

[Ray White]

[Bitumen Boy]

I rather think that where SU carbs are mounted at an angle it's down to the manifold rather than the carb flanges. Seem to recall that uneven wear can be a problem when they're mounted that way, and it's probably just a dodge for squeezing them into a cramped engine bay.

[Ray White]

[Bitumen Boy]

[Ray White]

There is certainly no harm is giving the guy a call. It's the wrong carb for my supercharger but like you say he may be able to help.

[alastairq]

http://sucarb.co.uk/float-chambers-spares/float-bowl-chambers.html

The Old H-type float chambers coul dbe had in angled[either plane] or vertical.
Plus with a choice of 'angles'....[20 & 30 degree, I think?}
The HS types had the flexible fuel supply pipe.
With The H-type, I think care needs to be taken with the material used for the top hat grommets [rubber gaskets] used on the banjo under the jet?
In today's fuel-age, it may be prudent to buy guaranteed ethanol-resistant material, eh?
Burlen were non-committal about the materials they used regarding ethanol, when I emailed them not long ago.

Of course, if used with a blower, then I doubt 95 octane petrol of any description will be the fuel of choice, eh?
More likely needing to use 98 octane [which, at the worst, is currently E5]...??
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Dellow Mk2, 1951 built, reg 1952.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
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Ford Pop chassis, Ashley 1172 bodyshell, in pieces.

[Ray White]

All the information is gradually coming together. Thanks, Alastair. That the f/c angle could be adjusted would account for some of the spare parts that I have seen advertised.

Burlen is no longer stocking ANY grommets!

(At least that is what their website says)

As to petrol.... Who knows what will be available by the time I have finished this car ?. I sometimes wonder if it will EVER get done and that's despite doing something almost every day.

[alastairq]

[Ray White]