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MG MGA - SU Carburetor Gromet

Hi folks,

It's been a while since I've been on the BBS -- many, many years.. I see Dominic Clancy and Art Pearse continue as active participants over the past 25 years.

Any way...

After 22 years the float bowl gaskets finally dried out and blew out, gasoline dripping all over my garage. This event occurred in early April, just about the time that Moss Motors shuttered for the next two months.

The original replacement grommets, Moss part number, 370-021, that I installed in 1997 were poor replacements to the original SU part. Those grommets were a squishy, gummy-bear type that leak fuel if screwed up too loose or too tight. The grommets that Moss now offers are infinitely superior as stiffer viton rubber, albeit thicker. The plot also thickens.

The lazy man works twice as hard.

I thought I could replace the grommets with the carbs in situ, just dropping the float bowls from the carbs, replacing the grommets, then screwing the float bowl into the carbs. It didn't work. Don't try it. The thicker grommet don't leave enough bolt thread to catch the carburetor to continue screwing.

Angry and impatient, I removed both carburetors - still attached to one another - from the manifold - with the fuel line still attached to both carbs. Don't do this. It didn't work. I replaced the grommets, mounted the carbs, started the car, only to hear and then watch fuel spewing out of the braided fuel line like a severed artery from a low-budget horror film. While the stainless steel braided exterior was still shiny, the dried out plastic fuel line was dried, losing is elasticity, and fractured.

*******IMPORTANT*******
Don't forget to unscrew/remove the distributor vacuum line from the rear carb before removing the carb. I say this because ... why....?

OK. Lessoned learned.

Now on the third Moss order, I combed through any and all parts that I may need, ordering more parts than I need. This afternoon, I spent the morning and early afternoon preparing the carbs, removing one at a time, cleaning it, inspecting it, and replacing parts, then reinstalling.

Much to my surprise and delight the car started, idled, and otherwise ran great.

This post is intended for the archives should anyone query this before attempting the same job.

Cheers.
Arthur DiLello

Hey Art - Good to have you back! Sorry it was to document a less than perfect repair experience but at least it appears you still have your sense of humor!

- Ken
KR Doris

Welcome back. - Have I really been here that long???

I always remove the carbs from the engine as a pair attached to the manifold. To do this I remove the air filter covers and filters, bend the top of the heat shield just a little away from the engine and then use a 1/4" drive ratchet to remove the nuts securing the inlet manifold to the head. I unscrew the fuel supply from the carb too, and unplug the hose from the vacuum advance. There is then just enough space to remove the carbs as a set, which means parts can be replaced without having to reset the carbs and synchronise them.

Art's story also reinforces my dislike of braided lines as it shows that they can look excellent but are rotten inside. Braided lines are a service item like any other, whether fuel line or brake lines. Rubber hoses are chepaer, have the same lifetime and can be inspected much more easily. Braided hoses have no effect on the pedals either if the brake system is in good order.

The 52000 km (32'000 mile) MGA MkII that is sitting in my workshop is a case in point. All the brake hoses had been recently renewed, but the clutch hose is original and shot. Al the heater hoses snapped while being removed. The fuel supply line between body and carb had been replaced with with a piece of plastic line with a fuel filter (this is illegal in Europe and dangerous to use none fuel rated line....). All will be replaced with new. The carb grommets are rotten and weeping (not been touched yet but I think will crumble when I undo the bolts) and the braided fuel line between the carbs LOOKS ok, but will be removed and checked / replaced.

Unfortunately the original radiator has been used as a jacking point and will have to be replaced (refurbishment is three time the price of new here) but I will take a photo of the core for Barney's page.

All the rear suspension rubbers will come out today and a huge Moss order has been placed for just about every rubber part on the car and a complete NEW braking system including discs.
Dominic Clancy

Arthur
I enjoyed reading your post, thank you. Not because I took any pleasure from your misfortune, but I guess, because as is often the case with humour, I am really laughing at myself, having been in similar situations.
During our lockdown I also had a leak from the float bowl seals. And also a similar leak from the jets. Because of my own ridiculous need to double check things retrospectively, I removed and replaced the carbs three times, they were probably ok at the first attempt, but being lockdown, I had plenty of time on my hands to play about in the garage.

As I had replaced the seals only two or three years ago, this time I replaced the cork jet seals with Viton O rings that I found on eBay. I am hoping they last longer in the battle against modern fuel.
It came in a pack of 10 O rings, 5 for each carb. Two are used in tandem to replace each of the four cork jet seals (AUC 2120), so that’s 8 in total. Then a single larger O ring at the bottom to replace each AUC2118 (x2).

Time will tell if they last longer, but I am hopeful.
Graham V

This thread was discussed between 10/07/2020 and 11/07/2020

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