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MG MGB Technical - HIF vs HS

I've read that the HIF is a better carb for performance use because of the internal float. I recently spoke with a fellow who raced midgets and he commented that the su had a problem of fuel foaming in the float bowls at a particular rpm. Sounds related.

I've also read that the HIF with it's bi-metal fuel adjustment is a point of concern for reliability.

I happen to have a set of HIF-4 carbs.

Any comments?
Fred H

Fred,

I had a set of HIFs fitted to my B that I vintage race and I absolutely loved them. I did not encounter any problems whatsoever. Once bolted on, I did not touch the carbs (besides the idle) for two race seasons.

According to Mike Brown of Sevenshop (who modified the carbs for me)...The beauty of these carbs is the float chamber design ensures the float is centrally located and almost completely devoid of tendencies to change fuel level during even the most severe cornering. This is definitely NOT the case with the HS 4's. Thus, fuel metering is vastly more consistent than with the HS 4's. Also, these carbs flow better than the HS4's. We have bushing kits which I've designed for these carbs that allows exchange of the biased emissions needle which is spring loaded and rubs against the side of the jet for the older needles which were developed for maximum power as opposed to maximum emissions control and which run concentrically in the jet. This alone transforms the carb into a little sweetheart for performance. We then modify the existing throttle plates and throttle shafts to improve gas flow in that area and with these modifications alone, you now have a carb which will outperform any HS 4 and will meter fuel within a hair's breadth of a well set-up Weber at a fraction of the cost. Also, you now have a carb system which can be tuned quickly at trackside without needing a suitcase full of jets and other metering devices
and a brain full of years of trackside knowledge.

Just thought I'd pass his comments on.

Mark
Mark W

The performance advantage is well taken. For the same reason the HIF 44 is the recommended replacement for the Strombergs (instead of the HS-6)for the dual carbed non-Federal Range Rover, because they work better off-road.
That said, having owned all of the above at one point or another, I find the HS-4 easier to live with as street carb. The bi-metallic temperature compensator is a PITA. Plus, I prefer the yes-I-can-see-it-working choke arangement of the HS-4.
Andrew Blackley

Mark - Would you send me more information on the bushing kit you designed to use fixed needles with the HIF carbs, along with the price for the bushings. Thank you - Dave
David DuBois

Mark-
Do you have a website where people can order the kit? This information would be a good thing to have in the Archives.
Steve S.

Sorry David and Steve, I think I misled you guys. Mike Brown is the designer and seller of these bushings, I was just posting his comments that he exchanged in an email with me.

His email address is: sevenshop@terragon.com

Sorry for the confusion. Definitely email Mike or Sean for more info, they were very willing to help and offer advice.
Mark W.

Mark, I wonder if you'd mind fielding a few questions about vintage racing. If you're interested, shoot me an email. Thanks

Andrew, what kind of experiences has the PITA HIFs caused. I live in Wisconsin, yet I rarely use the choke, and then ONLY to get started when very cold.

Steve, my apologies to you. I just looked over your article again and you DO address the performance issues of the HIF, although the feedback here is very interesting.
Fred H

This thread was discussed on 08/10/2003

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.