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Midget Carbs Question

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importcars

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well... new to mg's.

I have not picked up a Haynes manual...yet.

I am also new to carbs. I know the general idea behind them, but the ones on my 72 MG Midget with stock 1275 are differnt from anything i have seen before.

now from what I read, I think my carbs are SU's. If so is there a link to learn more about them, there is sumthin on the top you can unscrew and it looks like oil is in there or sumthin....

heh i promise i am not as dumb as i sound!! LOL i am just more of a EFI guy...



my car i just bought it and it will start up easily, but die right afterwards, like 3seconds later. the fuel pump clicks and it appears it has filled the fuel filter with fuel.

my dad and I are going to pull the carbs off sometime and clean them and throw a new seal kit in them, but i just want to know more about them before we pull them off.

i am sure he wont have a problem.. he has worked on ol MHs and AHs back in the day...



so basically just would like to find out as much info on them as possible.

thanx for all the help
Adam Z
 
Adam you should have twin SU HS2 late model, meaing emission tubes and poppet valve butterflies. I would suggest a minumum get new shafts and early butterflies without the poppet valve. If you every had a dirt bike and worked on it's carbs, SUs are kinda similar. I would recommend Joe Curto for parts and tech advice if you choose to rebuild yourself, they are not extemely complicated, you can get contact info for Curto at www.joecurto.com. To give you an idea if you bought new shafts, early butterfiles and two rebuild kits you would spend about 100 bucks.
 
And what Hap was too polite to say is that his shop rebuilds carbs also. But then maybe he has more work than he can handle. Ohhhhhhh?
 
[ QUOTE ]
But then maybe he has more work than he can handle.

[/ QUOTE ]

Hope not, though that would be good for him. I'm trying to save up enough money to send the carbs from my 1275 off to him. He needs to get his work load cleared off by spring time so he can fit mine in. /ubbthreads/images/graemlins/grin.gif
 
Guys, I always got time to build carbs, it's one of my favorite jobs. Taking an ole grungy SU and making it work and look brand new is very satifying for me.
 
i appriciate all the links, i am about to begin reading till my eyeballs bleed from looking at a 14" early 90s CRT monitor!! i cant wait /ubbthreads/images/graemlins/laugh.gif

not to sound like an ass at all, because i do appriciate recommending ppl, but i do all my own work. im not a fan of paying someone to do something i need to know... if ya know what i mean. my dad has always done his own work, and used his knowledge to make money, i know for sure he knows how to rebuild them so it will b great to work with him on the carbs together /ubbthreads/images/graemlins/wink.gif


the lil black plastic "plug" i unno what it is, but there is like oil in there. is that oil? if so when i pull the carbs apart, what do i replace it with?

thanx
Adam
 
That is the carb piston damper. Many recommendations for what to fill it with--engine oil, marvel mystery oil, ATF, and the list goes on. Everyone seems to experiment to find what works best. I'm curently running some 10w30 in mine, because that's what I had handy.
 
medium weight engine oil is fine for a street car.
 
what does it change if you put differnt oils in it, like say marvel mystery oil?

you say engine oil is fine for street, what would you use for say racing, and why?
 
Oh my word. Lighter oil allows the pistons to rise and fall faster, heaver oil slows the process down.

Medium oil for the street please.

Is my understanding that light oil gives quicker responce at high RPM but may cause the engine to stumble on acceleration, not a prob when raceing. Heavy oil slows the process down, we need engine oil about 20W will work just fine.
 
i see i see.

thanx alot!


im going to go order some seal kits from oreillys and pull the carbs apart and clean them so it will run decent.
 
Hehe, only one at a time, save the other for guidance. Oh yea, they are a bit different front and rear.
 
Adam, I respect your desire to do it yourself. There are plenty of good SU rebuilding books, and people like Joe Curto who have and will sell you good parts to do it with.
My biggest advice to you with these cars is do not buy the cheapest parts, you'll end up regretting it and spending more in the long run.

Mini Mania website, www.minimania.com has a good selection of Midget/Sprite books, go to the classic Mini area, do and advanced search using car type, plug in Sprite and books, also Moss Motors has a good site www.mossmotors.com and some good books on carbs and such, Winner Circle also has a good selection but not listed on thier website, it's best to give Rob and Dave a call and they can tell you what they have Winner Circle 216-889-4666. I would highly recommend a Bentley shop manual and "Tuning the A Series Engine" by David Vizard. There are several SU books as well. Joe Curto in his carb rebuild kits includes a good exploded view of the carb and specific directions. You can also google up HS4 exploded view and get info free off the net, but that still not a replacment for good literture.
 
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