H4 float chambers
- johnv
- 1275 Cooper S
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H4 float chambers
Are there any clever people who can convert 20 degree angles H4 float bowls to 30?
.. new they're £100 each!
.. new they're £100 each!
Mk2 1968 Cooper 998 TPL555F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
- MiNiKiN
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Re: H4 float chambers
I think there is no need for clever people - a simple float chamber adaptor from BURLEN shall do the trick.
http://sucarb.co.uk/float-chambers-spar ... ptors.html
http://sucarb.co.uk/float-chambers-spar ... ptors.html
Yes I am a nerd: I am researching the Austrian Mini-racing scene of the 60s and 70s 

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Re: H4 float chambers
I think those are for use with HS carbs only.
I did have the same question as the OP a few years back and some clever people did reply. I never got round to trying it myself and I can't find the thread now. ( not very clever).
As I recall it involved a bit of heat and judicious brute force. Making sure the forces are applied carefully so as not to distort/ break the casting.
There was also use of soap involved by one poster!
Mark F commented he had tried it but wasn't pleased with the result.
Alternatively several people have commented on here that you can run the 20° bowls with no problems.
I'm sure others will add to this.
I did have the same question as the OP a few years back and some clever people did reply. I never got round to trying it myself and I can't find the thread now. ( not very clever).
As I recall it involved a bit of heat and judicious brute force. Making sure the forces are applied carefully so as not to distort/ break the casting.
There was also use of soap involved by one poster!
Mark F commented he had tried it but wasn't pleased with the result.
Alternatively several people have commented on here that you can run the 20° bowls with no problems.
I'm sure others will add to this.
- MiNiKiN
- 1275 Cooper S
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Re: H4 float chambers


Yes I am a nerd: I am researching the Austrian Mini-racing scene of the 60s and 70s 

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Re: H4 float chambers
I tried on my set but they are too brittle and didn’t have much luck, ended up buying new one for the one side and a used Morris minor one for the other, I believe they work ok at 20 deg but didn’t try, unsure of which set you have but I had mga ones and changed choke levers as well. The linkage I modified
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Re: H4 float chambers
Although I have been away from the Metallurgy Dept for decades, I seem to think that if they are made from Mazac, their ductility will be zero. This means that they are brittle and will not deform even when heated. Mazac is a zinc based alloy and Zn has a hexagonal close packed crystal structure which makes it brittle. If they were aluminium it would be a different story. Al is face-centre cubic and deforms easily. (Too much info ?)
I would be impressed to see any Mazac ones that have been successfully altered to 30 deg.
I would be impressed to see any Mazac ones that have been successfully altered to 30 deg.
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Re: H4 float chambers
I have had a few sets of early Alexander H4's that ALL had modified float bowls. This was common practice in the early days, before 30° bowls were widely available.
As has already been said it can be done quite easily, you just need to be careful with the temperature, but when they are done they do "look modified" it's not a flawless modification.
All round it is a MUCH better bet to just use 20° bowls and not worry. There are NO issues at all with using 20° bowls apart from the endless queue of smart alec's who won't be able to control their excitement at being able to tell you that you have the wrong float bowls on your carbs.
As has already been said it can be done quite easily, you just need to be careful with the temperature, but when they are done they do "look modified" it's not a flawless modification.
All round it is a MUCH better bet to just use 20° bowls and not worry. There are NO issues at all with using 20° bowls apart from the endless queue of smart alec's who won't be able to control their excitement at being able to tell you that you have the wrong float bowls on your carbs.
- johnv
- 1275 Cooper S
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Re: H4 float chambers
I don’t think I could live with that .. I may have to bite the bullet ..
Mk2 1968 Cooper 998 TPL555F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
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- 998 Cooper
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Re: H4 float chambers
I have done it by taking 5 degrees off both faces of the manifold, 5 off the head end, and, 5 off the carb end.......
You need to do something fiddly with the manifold mounting washers, but, not too difficult......
And, plug and re tap the mounting studs at 5 deg (to bring them back to 90)............Was about a days work puttering about......
You need to do something fiddly with the manifold mounting washers, but, not too difficult......
And, plug and re tap the mounting studs at 5 deg (to bring them back to 90)............Was about a days work puttering about......
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Re: H4 float chambers
There’s a Morris minor su on ebay with auc4815 bowl and a auc1019 choke lever for £39.95 or best offer, may be worth buying
Also another auc1019 choke lever for £10.
Also another auc1019 choke lever for £10.