846 replies to this topic

[timmy850]

I’ve still been trying to get these dual HS2 carbs together. I’ve run into a few things that have taken some time and messing around to figure out. A bit more ingenuity is needed compared to a Cooper S setup as there isn’t a factory formula to follow

The first thing was the throttle return spring. The standard 850 setup is to run the spring from the throttle clamp on the arm down to a loop on the cast manifold clamp. This wasn’t going to work for an aftermarket manifold, and also seeing as the carb isn’t in the centre anymore. I had a couple of H type SU linkage arms, but unfortunately they fit the larger diameter throttle spindles on 1.5” and up carbs. I then noticed the middle linkage bar was in fact the larger diameter so I was able to make it work. I used an old throttle abutment bracket to make an anchor point, as I didn’t want it hanging down near the exhaust manifold


The next problem I had was when I tightened up the throttle blade screws the spindle would get very tight and hard to turn. A lot of head scratching later I found out the tolerance between the new throttle blade and spindles was way too loose and it was bending the spindles when I tightened up the screws! I have refitted the stock spindles and blades for now (which have a nice tight fit to each other) and they work perfectly. I might try it like this and see how it goes




A mini friend was kind enough to pick up and deliver some ram pipes for me, and they look really cool. If I decide to run these for a while I’ll get some foam socks to try and filter the air




I finally splurged and bought a new boss for my Les Leston steering wheel. I’ve had the steering wheel since 2017, I bought it on eBay with a boss and horn surround but the boss was missing the taper at the back. The taper is essential to lock the boss on the column and not totally rely on the splines. This one came from Nippycars


It bolted up fine


The unusual part is you need a spacer to get the horn button to contact the spring in the column. I’d found this shock spacer in my box of “useful parts” and we've got a working horn.


Off comes the stock wheel


And on goes the Les Leston. It’s one of my absolute favourite designs and it looks awesome and is a good size to drive with too

[Vinay-RS]

That steering wheel is gorgeous and it suits the rest of the car perfectly! Love those carbs too, looking forward to seeing them fitted and getting a video of them running. 

[timmy850]

That steering wheel is gorgeous and it suits the rest of the car perfectly! Love those carbs too, looking forward to seeing them fitted and getting a video of them running.

Thanks Vinay! It’s

I’m hoping to install the carbs soon, in between our next drive in April and annual show in June.

[timmy850]

Here’s the update for April:

We had a Minis in the Gong drive on the 23rd and it turned out to be a nice sunny day. On the way back up through the national park to head home my temp gauge started to rise and by the time I could find somewhere safe to stop it was just over 100C (and continued to rise once I’d stopped)

I did a few quick checks under the bonnet and found that the front centre welch plug had popped out and all the coolant had drained out too

Luckily I still had Phill & Dave along with their cars as I’d stopped in an area with no phone reception. Dave kindly offered to go and pick up his 4x4 and car trailer and we got it back home.

The following Friday I had taken off work already to do some fun jobs to the mini, but I ended up tearing it apart to replace the welch plug. The alternator, distributor, oil feed pipe and coil all needed to come out to make room. While trying to spin the engine over with the fan I also noticed the crank pulley was a little loose so I decided to tackle that at the same time.



The block needed a good clean as there was a lot of rusty scale around the plug hole. It got sealed and punched to retain it.

Getting to the crank pulley is always a fun job as the radiator needs to come out too. At least this time the radiator was nearly empty so I didn’t make too much mess. I decided to add a timing tape to the crank pulley to help with setting timing

Once I got it all back together it fired right up, which is always a relief. I drove it to work a few days later and it all seems fine again regarding the core plug.

I have been doing some more fine tuning of the Dellorto since getting the O2 sensor installed in the manifold. My recent dilemma is:
Lean idle (15-16:1)
Rich cruising - on the highway it's running about 11:1
The rest of the time it seems decent, but on the rich side.
I've checked the fuel bowl level and that was OK, so I decided to remove the carb & manifold to check there are no air leaks and it all looked fine. I've done a review of the jetting and done a bit of research & decided to try some leaner emulsion tubes & bigger chokes. Kev has opened up my 32mm chokes to 34mm and send me a few jets to try, so I'm hoping with a few more tweaks it'll be even better.

[timmy850]

With the Dellorto parts off in the post getting modified and a few spare days off work I decided it was finally time to try the dual HS2 SU carbs. I thought I had them all ready for installation so it was time to see if they fit!

The first issue I ran into was that with the stock alloy carb spacer the fuel bowl was hard up against the centre exhaust runner. The Maniflow Freeflow sticks out a lot more than the stock 850 manifold

I'd bought some thick plastic spacers just in case and they were needed in addition to the standard alloy spacer. The next two issues were that the LH carb was hitting the fuel line bracket on the bulkhead & the manifold studs were now too short.

I had some longer studs, but they were too long and needed to be cut down a little bit. I was happy at this point to keep going and then added the fuel lines

Rather surprisingly it fired right up with no choke or throttle cable connected. It was running quite lean on the initial jet heights I'd used but it was a good start!

I started off with a similar spec I'd used a few years ago with the Cooper S HS2 carbs - HV3 needles, yellow springs, Penrite damper oil, but brass top dampers. This ended up being much too rich pretty much everywhere. I changed the easy things first - lighter springs and to the usual black plastic dampers and this helped a little but not enough.

I swapped to leaner AH2 needles and it was better, but still a bit on the rich side. I also had a pair of M needles, so I tried those next. The M needles ended up being pretty much spot on, they are a bit on the rich side during full throttle (about 11.5:1 on the gauge) so I'd like to try a different damper oil to see if I can get it a little leaner there.

I also swapped to Ramflo air filters with little stub stacks inside. I added the choke to the LH carb, a new throttle cable, vacuum advance hose, breather hose

The plugs look good after a few days of driving & it's starting up fine with only one choke connected.

[KTS]

a nice bit of tinkering going on there - very satisfying i imagine 

 

out of interest; how does the car drive on the SU's compared to the dellorto?

[timmy850]

a nice bit of tinkering going on there - very satisfying i imagine

out of interest; how does the car drive on the SU's compared to the dellorto?

It was a bit of a frustrating job to get the carbs and manifold bolted up properly! The tuning experience was rewarding as all the changes I made translated to actual results on the afr gauge

In terms of driving the SU carbs are smoother, quieter and a bit less snappy to respond. It’s hard to tell overall on the performance as they sound a lot quieter and less fast!

[timmy850]

I received a parcel after a few weeks in the post from Denmark. It's a genuine Moto Lita boss to suit a Mk1 mini column and horn button. The previous boss kit I had also fit a mini column, but it took the generic Moto Lita horn button and it was also about 1" taller

 

The retaining screw for the horn is accessed from the underside

 

The driving position is much nicer now as the steering wheel isn't so close. It's also much easier to reach the indicator stalk

 

I drove to work last week and it’s been running really well. With the SU carbs and the bulkhead blanket it’s actually quite nice to cruise along the highway compared to the Dellorto. It’s so much smoother and quieter, although this can make it feel a bit slower too. Hopefully with a little more time dialing them in it’ll be even better. The recent cold weather has convinced me to put my heater back in too, having fresh cold air directed at your feet isn't too pleasant!

It’s rekindled my interest in SU carbs and made me keen to get the bigger H4 carbs on in the next year. I’ve also got another SU carb in the post 

The Dellorto parts came back in the post, with the chokes being opened up from 32mm to 34mm. I’ve also got a #5 emulsion tube to try and some larger idle and main jets. Since having the o2 sensor installed in the manifold I was getting actual numbers at idle and it made me realise it wasn’t running to the full potential, my main issue being too rich at cruise despite having very lean idle and main jets. I had been running a #6 emulsion tube, which is the richest one, with some lean idle and main jets. I’m hoping going to a leaner emulsion tube and richer jets will get me a bit closer to ideal.

 IMG_6644.jpeg   71.13K   0 downloads

 

I’m still trying to figure out the balance of looking good/sounding good/nice for long trips/economical/easy to tune/performance/driveability in regard to the carb(s). The current status is:
Twin HS2 on the engine - running about 95%, a little rich under full throttle but otherwise very good. I need to come up with a better return spring as it's very soft on the pedal and occasionally won't return to idle
Twin H4 carbs - rebuild kit purchased and I've picked out a pair to rebuild. I've decided to go with shaft mounted concentric return springs and I'll have to figure out a choke cable solution.
Dellorto DHLA40 - needs to be reassembled with new chokes & existing jets and work my way from there.
New carb - TBA

[70K1100]

Is that different from the SUs and the Dellorto?

[timmy850]

Is that different from the SUs and the Dellorto?

Sorry is what different?

[stuart bowes]

Presumably referring to your sign off with new carbs tba ?

Edited by stuart bowes, 03 June 2023 - 12:13 PM.

[70K1100]

Asking if you are going to run something other than the SU carbs or the Dellorto.

[johnR]

If you fit a heat guard between the manifold and the carbs you will have extra return spring mounting points as well as cooler fuel?

[timmy850]

Asking if you are going to run something other than the SU carbs or the Dellorto.

I’m planning on running all of them at some point! The HS2 have been decent so far but need some final tweaking. The H4 carbs are a few months off at least, but I love the look and they should perform better than the HS2. The Dellorto sounds and drives so nice. I just wish I had a few different minis so I could keep them all on!

And I have another carb on the way which I will try too. More on that when it arrives..

If you fit a heat guard between the manifold and the carbs you will have extra return spring mounting points as well as cooler fuel?

My problem with the heat shields is that I’ve got 2 x LH carbs, so I’d need to buy 2 kits to get the correct sides. It also means I haven’t got the connecting bar that is usually used for the return springs. This was my first attempt, I’ve added one since, but I need a short & strong spring which I haven’t been able to find yet. On the drive home on the weekend the idle kept creeping up and by the time I got home it was idling at 3000rpm! If I pushed it close it’d get back down to 1000

Edited by timmy850, 06 June 2023 - 10:25 AM.

[johnR]

I see your problem - my heat shield came with the connecting bar  but I'm not sure how it would fit with two left hand carbs - I think it would be OK?