12 replies to this topic

[jpw1275]

Hi all, im fitting twin hs2 carbs and at the moment im running a hif44 but i have a faset red top electric fuel pump, so i wanted to know what pressure should it be running for the twins? I have a filter king regulator so i can alter the pressure

Cheers james

[jaydee]

Try 4/5 psi, keep an eye for fuel starvation, but it should be fine.

[jpw1275]

Yea cheers for that, I had the fuel starvation with the hif44 as the previous owner just ran the faset without a regulator so it was over fueling so I fitted one and it kept stalling every block

Cheers james

[dklawson]

What? You exceeded the output of the Facet pump? Are you sure that was the cause of your problem?

Twin HS2s normally run at 2-3 PSI (at the carbs). Their fuel consumption is way below what every Facet pump I have seen can deliver.

Consider some quick and boring math. According to the Facet literature for the "top" pumps
(http://www.facet-pur... flyer 2011.pdf)
These flow 20 to 45 gallons (U.S.) per hour. Now consider you pushing your engine to its max. Maybe your fuel mileage drops to 8 miles per gallon (U.S.) At 100 miles per hour you would need to pump 12.5 gallons per hour... well below the smallest Facet pump's capability.

That begs the question how/where did you mount the Facet. If you mount it high and the pump has to suck the fuel "up" that will make it work harder and effectively lower its capabilities.

[bmcecosse]

Why are you wanting to reduce the power from your engine ? The HIF 44 is FAR better than tiny twin HS2 carbs !!

[jpw1275]

Why are you wanting to reduce the power from your engine ? The HIF 44 is FAR better than tiny twin HS2 carbs !!

Im wanting to have the option of running either carb set up, twins look the dogs and sound nice too!!!!

[bmcecosse]

Dear oh dear....

[jpw1275]

Dear oh dear....

I dont really know what the problem is running twin hs2's..... I do believe they used them on the 1275 cooper s? So why is it stupid using them on my 1275? Can you please enlighten me?

Cheers james

[dklawson]

Roy just feels twin carbs are more effort than they are worth. From a tuning and adjustment standpoint, a large single carb on a good manifold will work equally well without all the fuss. However, it is clearly your choice what you want to use.

Returning to the fuel pump issue though... the twin HS2 carbs were supplied more than well enough by the SU electric pump. Both the electric and mechanical SU pumps supply 2-3 PSI.

[jpw1275]

Cheers for that DK, going back to my original post of my hif carb over fueling with the faset, it felt really boggy and absolutely stunk of fuel without the regulator on so when i turned the pressure down it seemed to resolve the problem , so i guessed it was pumping to much fuel in? But maybe it was something else as you said the faset pumps dont pump that much threw

Cheers for the heads up

James

[dklawson]

The Facet pumps will move more fuel than most A-series engines will ever need. However, they are available in different pressure ratings. If you did NOT install a regulator and installed a Facet pump that delivers more than 4 PSI there is a VERY good chance the excess fuel pressure was causing your running problems. You can use a higher pressure pump in combination with a regulator to provide the SUs with their desired 2-3 PSI. It sounds like that is where you are now so all should be well if you dialed the pressure down a bit.

[jpw1275]

Yea it was the previous owner that installed the faset with no regulator so i bought and fitted a filter king one and never looked back....;)

Cheers james

[Jacko]

Hi everyone, i know this is an old topic but need something clarified, i had a 67mm filter king regulator running with my hif44 but changed it to a 87mm v8 model filter king one, had some flooding problems which ive put down to high psi, had to put a new spring in the regulator as it wouldnt drop down past 3psi (specs say it will drop down to 1-1.5psi) got it at 2psi now so hopefully will be fine now, but my question is, that it is a high flow model for v8 engines (the only difference i can see from the standard 87mm regulator is that it has bigger pipe tail ends which i have reduced for 6mm bore pipes) will high flow of fuel cause a problem or is it just high pressure thats causing my problems? p.s. only bought it because it was black and could fit the blue and red annodised fuel line fittings i negated the saying if its broke dont fix it! lol. any help would be ace.