fitting an 1inch and 3/4 su

Post by **lionellength** » Thu Jan 09, 2003 9:07 pm

Does anyone know what needle size and type(colour);of spring to use on an 1" and 3/4 SU. The engine is an untuned 1275 and the car is used for normal road running.Thanks

Post by **Cam** » Fri Jan 10, 2003 9:31 pm

Do you have a HIF44, HIF6 or HS6 carb?

Also what year and vehicle is the 1275cc engine from?

These things will determine the exact spec of needle and spring for your car.

Having said that, using the standard spring (AUD4355) and the BCZ needle should do for normal road use on an unmodified engine. Failing that the BER needle.

To be honest, if you go down to the scrapyard and find pretty much any 1275cc A-series with the same carb as you have, then the needle and spring out of that should suffice.

Post by **lionellength** » Sat Jan 11, 2003 7:23 pm

Thanks Cam, the engine a a Midget engine from, I would guess the late 1960's. The carb is an HS6 that came off an Austin 1800, which is why I suspect the needle and spring needs adjusting.

Post by **Cam** » Sat Jan 11, 2003 8:34 pm

That is an unusual combination nowadays, 1275 and HS6.

The needle I specified should do the trick, but the spring I specified is the large diameter type for the HIF carbs, yours should be the smaller diameter type.

The one you have may be OK, but as the HS6 was never fitted to a 1275 engine (to my knowledge) as standard, I am not sure as to which HS6 spring is suitable.

You could try looking for equivalents by searching:

http://www.burlen.co.uk/

They will also be able to supply pretty much any parts you need.

It's a shame you don't have a HIF44 as the parts for these for a 1275 engine are plentiful (and cheap) if you go to scrap yards and look for 1300 Maestros, Itals, Metros, Montegos, etc.

If you want exact results you could always have the car rolling road tuned, but that could work out expensive.

Post by **lionellength** » Sun Jan 12, 2003 3:10 pm

I'll try the needle you suggest and get advice on the spring. The 1275 engine was never available with an SU6 (1" and 3/4) but it was an option on the Midget (although I've never seen one fitted). The advantage of the carb from the 1800 range is the air filter is small and sits quite neatly on the engine as, on the 1800 it was fitted almost vertically at the back of the engine.

Post by **Innovator** » Mon Jan 13, 2003 10:57 am

The only way to get the correct jetting is on a rolling road with a good operator. Any other method is pure guess work.<BR><BR>Get the car on a rolling road, you will not be dissapointed.<BR><BR>John

Post by **Cam** » Tue Jan 14, 2003 5:50 pm

John,

I completely agree with the rolling road tune, but you have to have a needle & spring to start with!

Could you give me a bit of advice on the subject of rolling roads, as my 1380 needs setting up properly.
Can you tell me how much a basic session would cost (on average) and who is a good tuner (Stoke/Midlands area)?

I suspect that I will need the Aldon yellow dizzy, but I was toying with the idea of getting the engine profiled to find the optimum advance curve and then getting a dizzy built (or building one), but that might work out very expensive.

Thanks,

Post by **Innovator** » Tue Jan 14, 2003 8:54 pm

Sorry about my previous post with the funny letters, do not know what happened there.

Expect to pay around £50 for a rolling road session.

I have always driven my cars (40 miles) to the rolling road with what ever needle was in the carb.

Finding a good rolling road operator is down to personal recommendations. Mine is near Rochdale. Try to find a Mini website with a forum and ask on there.

I have not had much experience of dizzy`s on the A series. First you have to determine what advance you want at what revs, then they should have a machine where they can tweak the springs to get it close.

John

Post by **Cam** » Wed Jan 15, 2003 8:20 pm

Thanks for the tips, John.

My setup is close (as close as I can get it anyway - with no equipment!) but it's always better to have it tuned properly.

Nice to see your project Minor coming along nicely, should be a work of art when it's finished.

Just had a look at your 'how to' section and I like the Tracking Gauge - what a good simple idea - I'll be making one of those soon!

Post by **Innovator** » Sat Jan 18, 2003 7:32 pm

I made the tracking gauge because I could not trust the local auto centre / garage.

I also have one of the proper Dunlop look down the eye glass with mirrors gauge but prefer my home made one.

The new Minor should be at Knebworth.

John

Morris Minor Owners Club

fitting an 1inch and 3/4 su

fitting an 1inch and 3/4 su

SU Carb Jetting

Rooling Roads

Tracking Gauge