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MG MGB GT V8 Factory Originals Technical - SU Carburetters & air filters.......
|I just changed the air filters on my fatory V8 for the K&N filters. I removed the 'Cooper Cans' and replaced them with the much smaller K&N units. Problem is the thing's just broke down after about 5-miles :o(|
I am not too fantastic with the V8 so I called out the AA. The guy checked the spark plugs and fuel pump etc and all was OK, the thing he said was causing the problem was the Carburetters, he managed to start it by blocking the brass overflow pipe but it wasn't happy. The AA guy said it needed the carburetters taking off and looking at(??), probably no parts needed but it wasn't a side of the road job.
Anyway the thing is now sat outside a local mechanics garage and I'll call him tomorrow morning to see if he can take a look. Any ideas? is it likely to be my fault for replacing the Air Filters? I thought the K&N filters were a direct swap.
|I have a similar setup and it will not be the fault of the aircleaners. |
If you are going to have the carburettors looked at and they have been untouched for some time, then now is the time to have them completely serviced. Find someone nearby who is familiar with SUs or an mg specialist. That way it will be a once only job.
|On a factory V8 each carb feeds four of the cylinders, and if one stops feeding fuel the engine will start and run - after a fashion. The engine will also run relatively normally if one of the floats or float valves have failed and it is flooding, albeit pouring petrol onto the floor. So, in what way did it break down?|
|Cheers for the replies. I have had it looked at and it is now back on the road thankfully.|
In answer to the questions:
It stalled once about 2.5 miles after I had fitted the air filters, it re-started immediately after a quick turn of the key, about 20-yards down the road (max 15mph) it stopped again and wouldn't start. The AA towed me to a local mechanic's garage who had a look at it this afternoon. He said there was some crud in the carburettors and they needed cleaning out (maybe I disturbed something when I replaced the air filters?). He also said the points needed adjusting slightly. One thing that is a little worrying is there are no float chamber vent hoses connected to either side of the carburettor (the protruding small brass pipes on either side) and another V8 owner has frightened me as this is a potential fire-hazard.........
I am a little worried as I keep finding little problems with the car and the 3-month warranty I got is rapidly coming to an end. Does anyone know if there is anywhere local (I am near Rochdale, Lancashire) where I can get the car FULLY checked out?
|You certainly need to fit something so that any overflow clears the engine and exhaust, mine came without too and I fabricated a T-piece so I only have one down-pipe (fuel/emissions hose from Halfords) but I dare say you could have two seperate ones, but directing the LH one to the RH side to clear the exhaust. It's possible that removing the original filters disturbed something, but IMHO this would be unlikely to affect both carbs simultaneously, and as I mentioned above the V8 will run with only one carb feeding fuel. But if you disturbed something in the filter or fuel line feeding the LH carb it could affect both.|
I'd be tempted to notify the seller in writing, sent recorded delivery, that you are finding missing parts that are a safety hazard and as such you would expect them to put things like this right beyond the warranty. Did you have an MOT done before purchase? Having said that mine didn't pick up on the missing overflows.
|Cheers Paul, I'll take a trip down to Halford tomorrow and see what I can do. Where is the overflow pipe(s) supposed to go? I have ordered a copy of the V8 CD's from the V8 Register so I may have some more info next week (or whenever it arrives....).|
With regards to an MOT, it had one the day I picked it up..... I will give the guy at the garage a call and let him know about the problems so far.
|Pass on the 'correct' location, I teed mine by the right-hand carb and dropped the hose straight down from there, clear of the exhaust.|
The V8 Workshop notes don't really detail it, but the text is:
"These pipes should exit from the outer sides of both carburettors and meet behind the air box in a tee-piece before passing down the side of the gearbox tunnel to allow overflowing fuel to discharge safely."
I used some 6mm fuel hose, jubilee clipped it to the brass pipes either side of the carbs, ran the hose behind, to the left and down slightly from the airbox, used a 'T-piece' (more of a 'Y-piece') to join them to another short length of hose that just dropped at the left side of the gearbox bell-housing, clear of the exhaust and engine.
The 'T-piece' I used was a bit crap as I couldn't source any metal ones; I ended up using a plastic one and some more jubilee clips. I will try and replace this when I find a metal one.......
This thread was discussed between 04/06/2003 and 12/06/2003
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