OKR

Thanks Chris

I found a bit of 1-1/2" copper pipe and attacked it with a hammer to make it flat. I will look for a thicker bit. It worked a treat though on some scrap. Not quite as good penetration as the tile because of conduction, but I think I just needed to up the power a bit on the welder or perhaps I needed slightly more gap. As you said it is much better to clamp to and conducts away the heat so not as easy to warp the weld. The tile worked well but was very fragile unlike the copper. Great tip!

Thanks for the pictures. When you do your plug welds how big a hole do you drill. Its been a while. I did find an optimum power V hole size but can't remember what it was now!

Nick

Thanks Chris

I was going to have a crack at it today. I still have to clean the underside of the repair area of rust and underseal, so I started up and backed out of the garage a bit. Then realised I could smell petrol, looked outside to see a rather large and expanding puddle of petrol under the car! Engine off quick as one of the carbs was flooding! Very odd as I transfered the rubber tipped float valves to this set of carbs. This cured the flooding problem with the old set and not a problem up to today with the replacement set. Its not filling me with confidence!

No welding today!

Spent some time putting back the pressure reduced I had removed while doing the carb swap. It made no difference, putting more fuel all over the diff. Turned it off a bit quicker this time! Pulled the offending float apart for a look, found nothing. Put it back no flooding. Its a brand new filter and the pipes are new! Nothing found inside at all but now working again. Perhaps a small piece of crud in the valve, I hope!

Spent the rest of the time messing up the mixture adjustment and carb ballance! Time to give up as I am supposed to be making it better! Checked the timing with the strobe found it about 15°. Checked later with a colder engine and it was 12°. Thought that was a bit odd. Better leave it for a new day!

Nick

Hi Andrew

A nice Autumn project would be to replace all of the Scotchlock connectors before they cause problems. Easy to say but quite a daunting task. You should become an expert in vehicle wiring by the end of the exercise! At least you can do it a little at the time. I imagine the Bristol has a few more fuses that the crab!

David

I think I need some carb needle advice.

Old set of twins (2x standard carbs on a modified MGB inlet manifold) had TZ needles. Seemed fine no issues with tickover mixture. From memory 30 + years ago these needles were sold to me as standard "S" needles. The replacement RH proper "S" carb seemed very odd. Thought I had it close today but no, sooty plugs! RH carb acting weak but with sooty plugs 1&2 huh?? LH not perfect but ok looking plugs 3&4. So LH carb more normal. Engine runs fine but running on alot! Not happy with it so pulled the needles to find C1 as far as I can see with the RH having a very worn spot in the tickover area. Also the needle step wont go in flush. Bingo! So what needles should I use?

As it stands standard MK3 cam, Low compression MGB pistons fitted by dad and standard MK3 head.

Help appreciated.

So far I have found a good set of TZ and RH needles plus a poor set of C1's. They might say CI not 100%

Nick

Thanks David

I have gone with the TZ needles as it was ok mixture wise in the mgb style carb setup before.

Cleaned the float needle valves so hopfully no more flooding. So far so good.

Tried to check the piston drop time and found that the LH carb piston was not dropping to the bottom but fouling on the new jet. Put a different jet on and same thing. Scratched my head for a while wondering how you center the jet. Took one of the removed carbs apart and tried that one and made that bind in the attempt. Ahh! Then thought I better try with the jet height adjuster nut and spring removed as it was stopping the thing from centering on the jet before tightening. This worked. Found out it is much harder to do with the carbs fitted on the car! After much messing around and a second new jet got it nice and free.

So the spings are identical. Check. The pistons drop with one click as they both hit the bottom at the same time. So piston drop test now a pass.

Thought I better start from scratch with the jet level with the bridge. Screwed it richer as per the book. Start up. Running ok but backfiring when reved. Another Ahhh moment and couple of bad words said but nothing broken! Unscrewed the dampers to see if they were lifting together and found no oil! Idiot! That fixed the backfiring.

Proceeded to adjust the mixture. Found what I thought was a good spot on both carbs with good sucess this time. Took out the plugs all were much better. Still a little rich but much more reasonable.

Happy to leave it until I can go for a drive now.

Thanks again David

Im going to have to check that one and if it is an issue it will be self inflicted! I could not get the TZ needle out of one of the old pistons. I didn't want to damage it so have used the whole piston in the RH 'S' carb. It now does not have its matching piston! I can't use the old carb pair as the old carbs are not handed like the 'S' carbs are! My dodgy set up from years ago! I still have to fine tune the balance so will check them then. If its an issue I will get a new set of TZ's and put the matching piston back.

Thanks for the heads up David. Welding floor next job!

Nick