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MG MGB Technical - New Burlen SUs report

Have installed my new Burlen SU carbs. They look great, BUT, there was a disconcerting note included with them regarding complaints about flooding and overflow thru the overflow tube. They put the blame on dirty fuel. I an having that same problem, despite a new fuel tank, new fuel lines and an inline fuel filter about 18" from the carbs. At first only the front fuel bowl flooded. I oened it, saw not the smallest speck of dirt. However the float is now all plastic with no means to adjust and the jet is now mainly plastic, removed and cleaned both wiht compressed computer air. took for a test drive only to return with both bowls flooding. I guess the next step is to install grose jets and the older style float that is adjustable. Any thoughts?? thanks, Kenn
Kenneth von Wolf Lewis

Ken,
I took some fine sandpaper and sanded the edges of the plastic pins...mine were hanging up in the housing. All work good now. Have heard bad things about the new Gross-jets so I didn't go that route..
Robert Dougherty

Robert, Thanks for the input. Exactly where did you sand and with what. Would certainly be glad to give yo.ur approach a try
Kenneth von Wolf Lewis

I put a pressure limiter in line in the end. I think this may be a modern fuel thing. Neoprene tipped float valves also worked.
Stan Best

I also installed a pressure regulator/filter by 'Filter King' and it stopped the flooding,
Ron
R. Algie

A pressure regulator might be worthwhile if you are using an aftermarket fuel pump. Some deliver more output pressure than the OE SU fuel pumps originally used. It takes only a few PSI more than the designed 1-2 PSI for SUs to cause flooding.

Grose Jets sold today are not the answer as too many folks who have bought those made in the last several years have NOT had the consistent luck that those of us who bought ours before the mid 90s have had. Apparently, the manufactuer is NOT the same as they originally had, and product quality has suffered.

My suggestion is to investigate float valves which have the Viton tips (better even than neoprene at resisting modern fuels). Joe Curto, http://www.joecurto.com/ , is an SU resource who should be able to either sell you the Viton tipped valves or at least direct you to who does sell them. They are out there.

I immediately replaced the float valves which came with my new Burlen SUs with the older Grose Jets I had used with good results on the OE carbs I was replacing. I was lucky, and my good performance from those Grose Jets remained stable and well controlled. Today, I would replace them with the Viton tipped valves. Good luck, and when you find a good source for the Viton tipped valves, please let us know from whom you got them. Good luck!
Bob Muenchausen

Thanks to all for your detailed and thoughful input. For the nonse I have removed the grose jets from my old carbs (the jets worked fine and were only a few years old) I had given my old carbs to my friendly local LDC mechanic in trade for a killer deal on the new. He was happy to let me remove the Grose jets. Did a test drive around town doing "honey-do" errands and all seems well Still, I am keeping my fingers crossed. thanks again, Kenn
Kenneth von Wolf Lewis


I got the same problem with my new Burlen SU carbs and I replaced the new grose jets by the old ones.

The main visible difference is in the shape of the needle, the new one has a conical end while the old has a spherical end. The new is 0.42mm longer than the old one.
I can't verify the shape of the seat.

I plan to order a model with a ball design.
http://www.minimania.com/web/Item/AUD9096GR/AddedFrom/CatBrowse-%20FUEL_SYSTEMS/InvDetail.cfm
Does anyone has already installed this part?
Regards
Remi
Remi B

The Viton tipped needles are available from Burlen here in UK. They must have a US agent.
Stan Best

Hi Guys,

Did any of you complain to Burlen that their product was not, in this sense, 'of merchandiseable(? spelling) quality'? They are generally good guys and should provide suitable needle valves in their refurbished carburettors.

Peter
P L Hills

It was difficult to complain directy to Burlen and I didn't know that other people got the same problem.
The carbs were bought to Moss(lower price than Burlen!) and the parts would have been sent back to Moss to complain to Burlen.
Taking into consideration carriage cost and time to wait the problem fixed, I prefer to buy 2 vitton valves (15£) to definitively close this problem and enjoy driving my MGB!
Burlen should add a customer survey form with the carbs, it is a cheap and efficient method to improve the quality.

Regards
Remi B

Peter,

I did complain to my mechanic who got the carbs for me from Moss. Knew of no way to reach Burlen that would be meaningful. Included was a note in the plastic envelope with the new gaskets which addressed this flooding issue by laying the cause to dirty fuel. As my entire system is new to newish and I have an inline fuel filter just before the carbs I felt this was unlikely. Frankly, the note caused me to feel that Burlen, while quite aware of the problem was taking the position that a "good defense is a good offense", rather than correst the problem. I was surprized to learn from this forum how widespread the problem is and that many others have found solutions similar to my own. Seems that Burlen needs to reengineer the float jet unit, perhaps using the Viton tipped jets mentioned in this forum. Perhaps Burlen, Moss and other suppliers need to follow these forums, would be a good quality control and customer service approach.

regards, Kenn
Kenneth von Wolf Lewis

I have discovered another new twist to the new Burlen SU carbs. The jet adjusting nut is no longer 5/16, but is now 17mm. The original jet adjusting tool needs to be replaced by one which cost not about $3.00. but more like $9.00. N ot really abig deal, but it would be nice if instead of describing the carbs as virtualy the same would say similar with changes and/or updates. Wonder if the old SU Tuning manual is really still correct for these carbs? I have found that despite being "set at the factory" mine were way too rich for my BGT.
Kenneth von Wolf Lewis

I have had a flooding problem with my SU's - and also tried the new Grose Jets - never got them to stop flooding. I also had problems with the plastic needle hanging up. Eventually found a needle and seat combination that worked, plus with the new plastic non-adjustable float found that the valve seat needed the fiber washer installed in order to arrive at the correct shut off level. Hope this helps, Don
don scott

Has anyone had experience with fitting the fuel bowls with the older floats with the adjustable metal tab? Am not altogether happy with the non-adjustable all plastic floats!
Kenneth von Wolf Lewis

' Am reminded of the old saying: "If it works, don't fix it." Thanks, guys, for reminding me of that. My old HIFs are working fine, and now, more than ever, I'm convinced that I should leave them alone.

FWIW,
Allen
Allen Bachelder

"Virtually" does actually mean 'similar with changes or updates', or to put it another way 'virtually identical' means they are *not* identical. 'Set at the factory' probably means 'set to the starting point', which should be good enough for starting. If you have to move away from the starting point (two full turns or 12 flats down from being flush with the bridge in the case of mixture) more than 6 flats I'd say there was something wrong, either with the carbs or something else on the engine.

Done right, and not fiddled about with, both HSs and HIFs keep their tune for many tens of thousands of miles. I haven't had to adjust reset in many years, in fact I no longer bother checking the balance even annually as they never altered. The only exception might be that the HSs without the thermally compensated jets *may* need 1/2 a flat or so richening for winter running. Whatever, if you do need to tweak either mixture or idle speed after doing a full and complete setup from scratch, only ever adjust both carbs by the same amount in the same direction. It is fiddling with each carb differently that mucks them up.
Paul Hunt 2

This thread was discussed between 24/07/2006 and 08/08/2006

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