h4 questions

[velopackrat]

and I should mention this one choke arrangement was due to Mark and Rich's sage advice!
Since this pic was snapped, the stock SU throttle return springs have been changed to the method Swiftune uses to solve the return spring challenge.

[smithyrc30]

and I should mention this one choke arrangement was due to Mark and Rich's sage advice!
Since this pic was snapped, the stock SU throttle return springs have been changed to the method Swiftune uses to solve the return spring challenge.

What make/model are the air cleaners on you car please?

They look long enough and big enough to hide the ram pipes under

[velopackrat]

The air filters are K&N brand. Not sure the part number however. See this ebay link, some good pics.
http://www.ebay.com/itm/MGB-MGA-TR-VOLV ... l&vxp=mtr

I made the mounting flange with built in stacks from Delrin stock. It might have been Nylon, can't remember, actually. It hasn't been on a Dyno however, so I can't tell you if it's a good or bad for making power. At least the air is clean!

[abri]

On the topic of H4 carbs...

I have a freshly rebuilt 1275 S with stock AEG510 cam that's running an unmodified 940 head (apart from seats nicely cut), Minispares 1.5 ratio rockers and an Maniflow standard bore LCB. I'm currently using the standard twin HS2 carbs with M needles.

I have recently got hold of a set of H4 carbs. With the setup as described above, would there be any benefit in swapping the HS2s for the H4 carbs? The car will mostly be used on the road (99% of the time) and might do a track day in future. Obviously the H4 carbs are nice to look at but I won't fit them just for that reason. If I can expect a meaningful performance improvement I would. What do you think? Overkill??

[dhenry]

Do it.

[Vegard]

Damn. I didn't know they were rubbish.....

[su_mark]

See below spec sheet for original LHD H4 carb set up. Spec No AUD 165. These carbs had no chokes as they were for competition use.

AUD 165a.jpg

It would be quite possible to choke both carbs using a similar system to that in the pic below (with the inclusion of the fast idle cam arrangement on the carb with the bowl on the outside). You would, however, have to work out how to make the choke cable pull from one side, underneath, which would seem to me to be a bit of a ball ache given you could just choke one carb like Rich says. Not sure if it would fit without touching the bulkhead, but there are shorter levers than those shown....

carbs1.JPG

[mk1]

Thanks Mark,

Always great to hear the facts from the Horses Mouth as they say.

[Vegard]

See below spec sheet for original LHD H4 carb set up. Spec No AUD 165. These carbs had no chokes as they were for competition use.

AUD 165a.jpg

It would be quite possible to choke both carbs using a similar system to that in the pic below (with the inclusion of the fast idle cam arrangement on the carb with the bowl on the outside). You would, however, have to work out how to make the choke cable pull from one side, underneath, which would seem to me to be a bit of a ball ache given you could just choke one carb like Rich says. Not sure if it would fit without touching the bulkhead, but there are shorter levers than those shown....

carbs1.JPG

That'd NEVER fit on a Mini!

[abri]

On the topic of H4 carbs...

I have a freshly rebuilt 1275 S with stock AEG510 cam that's running an unmodified 940 head (apart from seats nicely cut), Minispares 1.5 ratio rockers and an Maniflow standard bore LCB. I'm currently using the standard twin HS2 carbs with M needles.

I have recently got hold of a set of H4 carbs. With the setup as described above, would there be any benefit in swapping the HS2s for the H4 carbs? The car will mostly be used on the road (99% of the time) and might do a track day in future. Obviously the H4 carbs are nice to look at but I won't fit them just for that reason. If I can expect a meaningful performance improvement I would. What do you think? Overkill??

Anyone?

[mk1]

Having run very similar set ups with both HS2 & H4 I would say that you would definitely notice an improvement, particularly in acceleration & top end. Possibly at the cost of slightly rougher low end & tick over.

Personally I would look into getting a decent head sorted before you think about fitting the H4s.

[dhenry]

Yes, fit the H4's. I think you will most likely see an improvement in performance.

[su_mark]

I reckon it's a borderline case. You'd probably see an increase in performance from a straight swap (properly set up), however, don't forget, a decent carb set up will be wasted if the inlet manifold isn't up to the job. If you haven't already, consider fettling the manifold to better suit the carbs. Sounds daft, but make sure all the ports line up and are the same size. For the H4's, see if you can get an original 12A661 casting (AEG 347), they can be improved internally better than others, smoothing out flow paths etc.
It may be worth considering just improving the manifold you already have and keeping the HS2s.....
Swings and roundabouts I reckon...
... but... the H4's look the business!

[sttuning]

Hi,Does anyone have a part no for the Burlen kit to remove one of the chokes as mentioned earlier
in this topic.Cant see anything on their website. Thanks

[su_mark]

The kit (called thermo jet kit) is WZX 997.
You will also need the correct size jet: AUC 8188 - 0.09", AUC 8189 - 0.100"

[sttuning]

Thats great thanks for the info.

[mk1]

Just to clarify, The thermojet Jet is significantly different to the standard H4 Jet. The two are not interchangeable.

[abri]

Great! Thanks for the input.

The manifold I currently have is a slightly "fettled" (smoothed and ported) AEG347. That is what I would used with the H4s.

I hear you about the head as well.

Good, so I will keep the carbs and as a long term project start working on putting the head together that will take most advantage of them.

[Daz1968]

How do h4 carbs effect a 998 cooper, as I noticed the downton touring conversion utilised these along with a modified head and lcb manifold, was contemplating doing this to mine, but when looking into it the h4 is theoretically too big for a 998,

[almondgreen]

See below spec sheet for original LHD H4 carb set up. Spec No AUD 165. These carbs had no chokes as they were for competition use.
Attachment:

Where can I get more infos about this carb setup ?