Special tuning H4 carbs

[AndyPen]

...and Somerford's info here:


https://www.somerfordmini.co.uk/carbure ... ial-tuning

[Roadrunner]

H4's were the works choice for a very specific reason.
Group 2 Rally regs in the 60's (I think also in racing) allowed the carbs to be changed, but not the inlet manifold, which had to remain standard to the car.
HS4 carbs have a diagonal bolt pattern, as opposed to vertical like the H4, and the 1.5" H4 would be a straight replacement for the 1.25" Hs2 carb fitted as standard to the Cooper S.
In the early days they were in fact straight off the MGA, including the wrong float chambers, necessitating the fitment of extensions to get the float level correct.

Well I though it would be something like that to get around the rules, they used stuff easy at hand that came off the line or was in the stores which would have had the parts

[251 ENG]

Also H4 will produce more power and torque on a correctly set up engine compared to HS4,s

[johnv]

Also H4 will produce more power and torque on a correctly set up engine compared to HS4,s

I wish you hadn’t said that as I’ve just changed mine for HS4’s

[MiNiKiN]

Thank you all, very helpful and informative.

[Herbert]

H4's have a longer choke tube and the butterflies turn the other way to an HS4. This gives a better mixture. On my S running H4's gave me 12hp more than the HS4's. More revs, and a better torque curve. Only a Weber will give you better figures. I would always recommend H4

[mk1]

Most points have already been covered comprehensively.

The C-AHT-1 & C-AHT-2 brackets will all be available again very soon. I am working with Catmint Gordon to get these sorted.

They will be available through Gordon very shortly.

M

[MiNiKiN]

H4's have a longer choke tube and the butterflies turn the other way to an HS4. This gives a better mixture. On my S running H4's gave me 12hp more than the HS4's. More revs, and a better torque curve. Only a Weber will give you better figures. I would always recommend H4

12HP is massive

[johnv]

Most points have already been covered comprehensively.

The C-AHT-1 & C-AHT-2 brackets will all be available again very soon. I am working with Catmint Gordon to get these sorted.

They will be available through Gordon very shortly.

M

Is there a bracket available for the throttle cable / manifold Mark?

[johnv]

H4's have a longer choke tube and the butterflies turn the other way to an HS4. This gives a better mixture. On my S running H4's gave me 12hp more than the HS4's. More revs, and a better torque curve. Only a Weber will give you better figures. I would always recommend H4

12HP is massive

It is. I had mine on the RR at RACE recently with the H4s, I'll leave the HS4s on when I go again at the beginning of December and see what the difference is. 12HP will persuade me to put them back on! (The only other difference is that I have changed to a 123 distributor)

[mk1]

The throttle cable bracket is available from the likes of Minispares.

[johnv]

The throttle cable bracket is available from the likes of Minispares.

This one
http://www.minispares.com/product/Class ... 0to%20shop

I must have something else wrong then as that one doesn't have the right angles

[Ronnie]

This ad seems to be pretty much what my sets look like - hope it helps? I see the two spring extensions in your box of bits.


https://www.ebay.co.uk/itm/295339019106 ... gKpSvD_BwE

Those ebay carb's they appear to have an odd set of pistons one appears to have been flowed and the other is standard.

[AndyPen]

This ad seems to be pretty much what my sets look like - hope it helps? I see the two spring extensions in your box of bits.


https://www.ebay.co.uk/itm/295339019106 ... gKpSvD_BwE

Those ebay carb's they appear to have an odd set of pistons one appears to have been flowed and the other is standard.

Oh yeah - looks that way - well spotted!

[NicholasUpton]

Are these the correct float bowls for the carb tags listed. Finally pulled everything out of the cleaner and can now read the part numbers on the castings.

[TECH396]

Are these the correct float bowls for the carb tags listed. Finally pulled everything out of the cleaner and can now read the part numbers on the castings.

Nick. I believe the correct number is AUC4814 and they would use 2 of the RH floats for the LHD setup. The other float is AUD4815 & also 30deg.

[NicholasUpton]

I assume they are correct, no AUC but cast with 4814

[quote=NicholasUpton post_id=313207 time=<a href="tel:1668789785">1668789785</a> user_id=4160]
Are these the correct float bowls for the carb tags listed. Finally pulled everything out of the cleaner and can now read the part numbers on the castings.

Nick. I believe the correct number is AUC4814 and they would use 2 of the RH floats for the LHD setup. The other float is AUD4815 & also 30deg.
[/quote]

[TECH396]

I assume they are correct, no AUC but cast with 4814

[quote=NicholasUpton post_id=313207 time=<a href="tel:1668789785">1668789785</a> user_id=4160]
Are these the correct float bowls for the carb tags listed. Finally pulled everything out of the cleaner and can now read the part numbers on the castings.

Nick. I believe the correct number is AUC4814 and they would use 2 of the RH floats for the LHD setup. The other float is AUD4815 & also 30deg.

[/quote]

Yup, those are them. You can see they're 30deg and not the more common 20deg ones. The omission of the "AUC" may be reproduction ones?. (Burlen sell some), but I'm not 100% sure. I'm sure someone else here can confirm that..

[251 ENG]

They are original SU bowls not burlen ones .

The most difficult item to find to build up a set of H4,s with 30 degree bowels

[timmy201]

My 4814 is cast with the number only and no “AUC”

But the 4815 is cast with AUC