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Alternative carbs to the SU HIF44

Posted: Thu Dec 04, 2014 11:39 pm
by Brrok_lands
Coming to the end of a refurb of a standard Samurai which has the original carb which seems to be the most unnecessarily complicated and complex piece of kit ever created. The engine is now running (just) rougher than a rough thing, even though it was running ok when I first got it.

Compression is good, fuel is fresh and although I've had a problem with a faulty (new) plug I coming round to the conclusion that it's probably a fueling problem.

I know the SU HIF44 is the favoured replacement choice but what about other SU models. The HS6 is a 1.75" carb like the HIF44 and can be picked up considerably cheaper. Other than the horrible wax stat choke on the later versions (had a pair on a Dolomite Sprint I had 20 odd years ago) and the separate float chamber they are basically the same.

Is a carb change a better option (time and effort) than trying to do battle with the original carb to get it set up properly?

Brook

Re: Alternative carbs to the SU HIF44

Posted: Fri Dec 05, 2014 12:08 am
by ScottieJ
HIF SU carbs are the best to go for tbh, the older ones with the external float bowl arnt as good in my opinion.

There's a few other options though. Weber, Nikki carbs and I've seen a subaru carb used before as well.

Re: Alternative carbs to the SU HIF44

Posted: Fri Dec 05, 2014 8:54 am
by Brrok_lands
Scottie

Thanks for the reply. Is it a fuel supply problem when off road with the external float chamber that is the problem, or are there other reasons? I could imagine that the float bobbing about on rough ground could play havoc with the needle valve that controls flow into the float chamber.

As cash it tight at the moment and I'm just wanting to get it running properly rather than looking for a performance improvement as it will probably have to be sold once it's up and running and MOT'd, I may have to do battle with current one. The Weber 32/36 should be more common but still seems to command a good price, a bit of patience on my part may turn up a bargain eventually.

Brook

Re: Alternative carbs to the SU HIF44

Posted: Sat Dec 06, 2014 9:55 pm
by twiss
You could get an external float bowl carb.. But you should provably stay clear of the h carbs. They have the float bowl attached rigidly to the carb body and the fuel flows through the cast arm. The hs carbs are similar but the float bowl is removable. It has an extra seal and bolts holding it on so more to go wrong ;)
I've been told that the HD is the best of the bunch. Easily identifiable by the fuel hose connecting the float bowl to the carb. If you have a Google around the problem is often a simple one and can be resolved by adjusting the float slightly. At least with the HD carb its easy ;)

Re: Alternative carbs to the SU HIF44

Posted: Thu Dec 18, 2014 10:21 pm
by Brrok_lands
Just to complete this.

I have managed to get my engine running sweetly again with the original carb. Not quite sure why but a plug swop from NGK BPR5E to BCR6ES made a big improvement as well.

Re: Alternative carbs to the SU HIF44

Posted: Mon Dec 22, 2014 1:18 am
by 3VILC
For what its worth, my theory on why the HIF works best, the jet is directly in the middle of the float bowl, tipping the carb on an angle doesn't really have a huge effect on the level of fuel in the centre where the jet is