846 replies to this topic

[Jared Mk3]

Dual vacuum gauges would be fun to watch 

[mercenary62]

excellent thread and some amazing pictures , ive just bought a 61 mk1 , and will be using a dellorto or weber, keep up the good work

[timmy850]

Dual vacuum gauges would be fun to watch 

They are fun to watch and they have bright colours, what’s not to like?

excellent thread and some amazing pictures , ive just bought a 61 mk1 , and will be using a dellorto or weber, keep up the good work

Yours looks like a good starting point for a project! A Weber or Dellorto is a good choice, the only downside is the standard speedo cable. I used a 90 degree adapter part number BH 2410/10 from a Rover 3500 in order to get it working.

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[timmy850]

This week my new air fuel ratio gauge (O2 sensor) turned up. It's an Innovate MTX-L Plus with the tailpipe adapter

 

I wanted to add it to a portable box with a switch and fuse, and the power comes from the accessory/cigarette lighter port

 

After a  few measurements and some cutting we ended up with this. I got it in the car and ran through the calibration procedure 

 

It works! This will give me a very good idea on how to tune up the SU carbs 

[timmy850]

I drove the car to work yesterday and got to appreciate my fine tuning on the Dellorto! Hopefully I can get it close to this on the SU’s.

Cruise = 14.0 to 15.0
Part throttle = 13.0 to 14.0
Full throttle = 12.0 to 13.0

[timmy850]

I had a bit of time free over the long weekend, so I thought I would get stuck into swapping the carbs 

 

10 minutes later and the Dellorto was off. It's so easy, just fuel line, choke cable, throttle cable and the 4 manifold nuts. 

 

Getting the HS2 carbs on was a bit of a nightmare.. it was really fiddly and not a lot of room to get your hands in. I managed to get it started, but it would idle OK for a couple of seconds and then the RPM would increase to 4000rpm with no throttle input. The pedal was strange too, not returning back properly and a bit sticky 

 

I left it for the day and had a think about what was wrong, so:

Throttle cable was too long and hitting the exhaust manifold

Throttle cable was incorrectly adjusted and had 2cm of slack

Vacuum port was left open

Middle throttle return spring on the wrong way

No dashpot oil

Possibly the PCV was opening too much

 

I fixed all the issues above and bypassed the PCV and got it to run and have a nice consistent idle. The throttle response is really good, and it's a lot quieter than the Dellorto! I hooked up the PCV again and it was idling too high - about 2000rpm. I still need to do a baseline check over the linkage and set the idle mixture, then I can take it for a drive and see what it's like!

[Jared Mk3]

Twin carbs just look the part, don't they? Very nice, especially with that black rocker cover 

[timmy850]

Twin carbs just look the part, don't they? Very nice, especially with that black rocker cover

Thanks Jared! Certainly it all looks nice together with the black rocker cover and air box - I’m slowly getting closer to the idea I had in my head!

I’ve had a little bit of time to work on the SU carbs. After a couple of hours on the weekend messing about with checking for air leaks and setting the linkage and jet height I ordered some new needles as it was running so lean. The initial setup was M needles, red springs and SU damper oil. I’ve got AH2 needles now, so I need to give them a go when I get a chance


In other news, I’ve sourced some mint condition A+ rods for the next engine - still fitted with the factory standard size bearings and pistons!

[timmy850]

I received the AH2 needles a couple of weeks ago and gave them a shot. They were perfect under full throttle but still very lean at cruise and part throttle. I was able to give them a couple of turns richer to make it good enough to drive around, but it made it too rich under throttle. It also just felt a bit weird, especially when cold.

At this point I started to get a bit confused as my engine seemed to want richer needles than the 1275 S “rich” needles recommend by BMC (AH2). A lot of reading about SU carbs followed for the next few days and I came up with a couple of ideas: a needle richer in the bottom end like #3 or perhaps the spring was wrong
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I asked for some ideas and a generous guy Glen offered to send me a couple of sets of needles to try out. He also had a look over some of my engine photos and spotted something not right. I’d suspected a leak somewhere, and previously I’d had the carbs and manifold off to check everything over and not found anything obvious. What I’d missed in the swap to the PCV system was that the only source of intake air to the crankcase should be through the proper filtered oil cap. I’d left the filter breather open to atmosphere on the flywheel housing, which mean that the PCV was now able to suck in a huge amount of air. I’ve since capped this breather off temporarily to check if it’s the problem, if successful I’ll join this to the other breather with a T piece, or possibly to the rocker cover
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Next I gave the car a test drive last weekend with the HV3 needles. It ended up being a lot richer at the bottom end than the AH2, in part to fixing the big air leak at the PCV and also the different profile. I also found an air leak around the catch can, so I bypassed it too.

I ended up driving it to work twice this week and it runs really well, the only negative is slightly too rich at cruise now (previously too lean). I’ll give the AJ needles a go, maybe they’ll be a good overall balance (or perhaps the AH2 will now be fine after fixing all the air leaks)
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I also hooked up the twin vacuum gauges - one to each carb. Just because I can!
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Here’s a video of driving around

[KTS]

nice video - certainly looks and sounds like its going ok !!

 

i do think your AFR gauge install could do with a bit of work though  

[Jared Mk3]

Nice video. Car sounds good  I do like the new style of driving shoes though!

[timmy850]

nice video - certainly looks and sounds like its going ok !!
 
i do think your AFR gauge install could do with a bit of work though  

Thanks! Once it’s tuned up properly I can give it a decent drive on some nice roads and not just around the neighbourhood. It’s hard to tell if it’s faster or slower than with the Dellorto, but it’s definitely a lot quieter, and easier to get off the line. I’d also forgotten how smooth the SU’s are compared to the Dellorto, it’s not as snappy, but will take full throttle at any time without any hesitation

My wife wasn’t a fan of the AFR sensor install either for some reason... it’s in the exhaust tip and then the cable runs in through the rear window

Nice video. Car sounds good  I do like the new style of driving shoes though!

Thanks Jared! It’s been cold enough to wear socks!

[timmy850]

Nothing major has happened in the last month or so as I've been trying to sort out a bunch of little jobs. First up was the SU tuning. When I left off I had HV3 needles and the gauge was showing it was pretty rich, but it drove perfectly. I swapped for the AJ needles, but they were too lean, so back to the HV3.

 

I raised the jet a couple of flats and the AFR's were nearly spot on, although now I was getting a lot of pinging - particularly at 2-3000rpm. I reduced the timing in that area with the blackbox and no more pinging. I have to say SU tuning is much easier with an AFR gauge and a good selection to choose from, thanks again to Glenn as its saved me a bunch of time and money in picking the right needle. I'm yet to work out the fuel economy thanks to the speedo...

 

Another long term project is nearly complete - the ROH Contessa/Contesta wheel caps. I was lucky enough to get 5 of them, but they needed some TLC. I gave them a clean up and polish as they were all tarnished.

 

My wife was able to help and redo the red lettering with some red modelling paint and they came up really nice! The next step is to clean up the wheels and two of them will need the centrebore to be opened out by a couple of mm to suit these caps. I also got some new A008 tyres as the old ones were almost gone

 

As always I look out for parts for sale, and I bought a crusty old Sports rocker cover for a good price. I decided to try the Dremel for polishing as I had bought a polishing kit for it and it has turned out pretty good so far! Hopefully with a little more time it'll turn out even better. I'm still trying to decide whether to paint the fins at the top or leave it bare.

 

 

Here's a few photos of the car all washed and clean for a change 

 

[Vinay-RS]

The rocker cover looks really good after the polish and the restoration of those centre caps is awesome! Nicely done! 

[timmy850]

I was reading up on how to stop the gear stick buzzing and there was a couple of good ideas, one being to add the lower boot to the gear stick (the round one). It fits over the retaining plate on the end of the gearbox, but turned out to be a loose fit and didn't help with the vibration. At least it'll keep the dirt out of the mechanism

 

The next idea was to add a rubber bush to the end of the gearstick. This adds a tiny amount of preload to the shifting rod and has completely stopped all the buzzing 

 

I got a new vented oil cap which is supposed to work better with the PCV system. That was a nice 30 second job

 

Another long term project has been to make up a set of the original type spark plug leads. I think these Champion WC548 are the right ones for my car, regardless they look much better than the modern generic ones. A friend gave me a set of caps years ago, and I found a dissy cap complete with leads and caps at a parts sale. I got a length of new ignition lead, all I need now is to cut them to length and put the caps on

 

I dropped the speedo off for repair on Tuesday morning and I got the call Friday morning to say it's good to go! He replaced the tenth's number wheel on the right as it was stuck on 11700. I've got it back in the car soon just in time for our first mini run in a couple of months!

 

Finally I've managed to find a wood Maxrob steering wheel rim after looking for a couple of years. It looks to have been recently refurbished and is nicely polished and stained. The wood is a little on the red side for my taste, I'd prefer a bit more brown, but I definitely can't complain for the price. I'll have to see how it looks on the car when I get some time on the weekend.