Is there anyone out there who knows about Mini (engines) lumps and carburetors? I have a standard 1275 that just won't run correctly, i.e., sluggish idling and backfiring issues. The engine seems to be a hodgepodge of different engines and I suspect the carburetor isn’t the right type for the engine.

The current setup is a standard 1275cc (Metro) lump with a HS4 waxstat carburetor. The needle is an ADB needle (slightly bent) along with a RC40 exhaust system.

Does anyone know which carburetor is recommended for a 1275 lump? Also is the ADB needle made for 1275 lump?

Any help is appreciated.

 

I assume you've looked at all the basics, valve adjustment, points, timing etc?

A bent needle can cause the symptom you describe too.....

 

I see no reason you can't make that combination work. When I got my 1275 metro with HIF-6 it also bucked and stumbled. My recommendations

1. Be sure your ignition system is spot on...good plugs and points and the TIMING IS RIGHT. Most 1275 will start at 8 deg BTDC on a static check.... How are the plug and coil wires and the dizzy cap? 5 years playing with mine has re-enforced the rule of 'ignition system FIRST'. You can get a simple timing light from Harbor Freight and the procedure is in Haynes if you've never done it b4. VERY EASY once you find the marks. ANY decent mechanic should be able to do this one for you....no special tools required.

2. Next check for vacuum leaks...that's where my problem was. Old hoses crack, and hoses removed but not properly plugged mess up the system. The automatic vac' advance won't work right if the vac' is off to begin with. Plug the leaks. {other readers may also note: I have a vac servo for my brakes and saw improved performance there when I replaced those lines and the check valve ensuring all was tight....}

3. Needles are cheap - around $20 - and easy to replace. Are you on a stock air filter or a cone? ... the cones require a different needle because of the increased air flow. I'd call Seven and ask for a recommendation. But replace the bent one for sure.....
http://www.7ent.com/sub.cfm?lastfoun...ownum=5&id=351

4. Avoid the temptation to jump to the fuel system first for anything other than leaks or clogs (filter change). If you mess with the carb and later go back to the ignition you just find yourself BACK at the carb to adjust to the correct ignition....


BTW: Lump means 'completely stock'? Sorry, never heard the term ....

 

Hi..Ashley
1) start with timming.......remove rocker cover and take spark plugs out and put in 1st gear pull car forward untill NOs 1-2 rockers are rocking this is the firing stroke.....
2) remove dizzy cap ns rotar arm should be pointing between 1 & 2 o'clock position, put a dot of white paint opp rotar arm on block...
3) now replace dizzy cap and NO 1 lead should be oppisite dot...and lead order is 1-3-4-2 in anticlockwise order.........check spark plug gap...
next job is stripdown carb and clean and reasselble and top up dash pot with compressor oil or sewing machine oil............

As for carb needle you will need to know what cam you've got and if cylinder head has been modded and has block ben rebored .......

hope this helps and don't be afraid to ask for more help............

 

good luck

 

Also check that the vacuum to the dizzy actually advances (i.e. "moves") the plate that points are screwed to. I found in mine that the screw used to mount the points was binding under the plate, causing the plate to be locked in place.

 

Thanks for all the information.

The timing was set (correctly) a couple weeks back, along with the points. The next thing I will have to check will be the hoses for vacuum leaks.

Contacted SEVEN to see which needle they would recommend for my specific engine setup along with a replacement kit for my Waxstat.

British slang clarification: “Lump” = Engine as the “Dizzy” = Distributor. Sorry, I learned to work on cars (Minis) in the UK. So the slang has become part of automotive vocabulary, such as "Bonnet and Boot" instead of "Hood and Trunk".

 

Talked to 7 !! Well done GrassHopper (imho)

Thanks for expanding my Brit Speak dictionary ... had not heard lump for engine b4

Given that information (lump = engine) ... what needle is ideal has a number of other variables to consider. But if you talked to 7 I'm sure you got good joo-joo ....