24 replies to this topic

[benspray]

Hi all,

Just a quick question, currrently the engine is standard metro 1275 but Im having carb problems (currently its fitted with a single HS4) and the exhaust downpipe needs replacing so Im looking to replace the carb and fit an LCB which means I also need a new inlet manifold.
so I've been looking around and figure I'd like to fit a set of twins - seen a nice set of HS4 twins on a modified AEG573 inlet - would this be too much for the engine at the moment? longer term I'd like a new cam and some porting done on the head but thats a while off yet.

Cheers
Ben

[stardude]

twin hs4's are will be fine on it.

[benspray]

Cheers, Just been scanning through 30 pages of search results from "twin hs4 1275" a bit of helpful info there too, one thing that pops up occasionly is MPG decrease with twins?
Not sure how but on a run I can get abuot 45-50mpg at the moment with the single hs4 but this really runs out of steam up in the higher revs.

Am I really likely to drop to mid 20's with the twins? if thats the case I think I' just look for a single HIF44... I have to admit I was mainly going for twins for the looks of them basically going for a bit of a 60's cooper s style to my car (1983 mayfair) just got hold of a set of 10" mambas, mk1 grill etc..

Cheers
Ben

[liirge]

there's often debate about MPG decrease with Twins, some people actually report an increase in MPG when fitting twins. I think its how you drive, if you put twins you'll be more tempted to rev it higher so therefore will use more fuel.
The increase in MPG that alot of people see is only a couple of MPG, so i say fit them them! they sound brilliant and are really retro!

[Dave33]

As said,as long as its well setup then mpg can be slightly better than a single carb.
It matters not how many carbs are used as the engine only draws from them what is required.
On a decent maniflow manifold with a straight run to the ports,the motor will be more responsive,peak hp wont be much different though.
and as stated twins sound great so promote you to give it a bit more throttle than normal.
Avoid the BL manifold though as its very poor compared to a maniflow.
hth
dave

[benspray]

Cool cheers, Im now the proud owner of a very nice pair of HS4's
Will see what fun they give me when they arrive and I try to fit and tune them then...

Cheers
Ben

[benspray]

Hi all,

Right just got round to fitting these carbs, all on and looking good but I cant figure out how to attach the choke cable, ie I have the "trunion" but how do I secure the cable outer to the carbs so that the cable actually works as I have no bracket or locator that I can see?!?
Does anyone have a pic (these are twin HS4)

Cheers
Ben

[liirge]

What kind of manifold do you have for the twins?

[benspray]

What kind of manifold do you have for the twins?

Just the (apparently naff) cooper s type, I can get a part number tomorrow after work, but its the one used on the HS2 setup normally but the inlets have been opened up to math the HS4's
I'd like to change it for a maniflow when I can warrent another £140

Which leads me to another question, how on earth do I connect the breathers as the new carbs dont have any connection for that, the manifold has a hole which apparently takes a "gulp valve" but I cant find anywhere selling one (and doesnt look like the maniflow manifolds have a conenction either)

Cheers
Ben

[liirge]

Ok, i will write more in bursts, as its late etc.

But first i think you should get a nice few pics of the setup, I believe you have the manfold which will take a bolt, that holds a bracket to take the choke cable.

[liirge]

This is the bracket:

http://minispares.co...ty=pb&pid=34633

Visible here on the manifold:

http://www.minisport...nfo_MS2952.html

The valve you are after is called a clack valve.. they come up on the Bay alot, I also thought minispares sold them...but i cant find it. Would be interesting to see your manifold

Here it is:
http://minispares.co...a...5134&title=

Voila!

This may also help clear things up:

http://www.somerford...x...page&id=170

Edited by liirge, 16 August 2010 - 11:35 PM.

[benspray]

cheers, now I know what Im looking for re the clack valve I'll keep an eye out for one on ebay

I have that bracket on my manifold for the throttle cable, thats all setup and working ok - what I have figured out Im missing for the choke is a little insert which presses into the body of the carb which you can see on this pic:

http://www.sucarb.co...estoFlipped.jpg

on the right hand carb a little gold insert facing upwards - niether of my carbs have these inserts so the choke cable doesnt have anywhere to go...... Im assuming they can be bought just no idea where or what its called....

I'll get a picture of my setup / manifold details tomorrow night and post it up

Cheers
Ben

[benspray]

choke cable holder part also seen on the left hand carb on this auction:

http://cgi.ebay.co.u...les_CarParts_SM

Cheers
Ben

[liirge]

Just seen your point....yup cable tie it in place i reckon!

[benspray]

yep could work, at the moment the hole left in the alloy is bigger than the out on the choke cable so it just slides straight through, cable tie as a temp fix I think then good plan when I get round to it I may just find a bolt that fits and centre drill it out to the right size for the choke cable...
just to try and find a cheaper way to do the breathers now then

Cheers