Hitchcocks Forum

Hi All. Had a decent run in my recently re commissioned '59 Constellation last week. Not bad considering, (couple of oil leaks which are to be expected, and I can see how to fix those). Biggest issue is that the old girl is running rich. She's running a single Mk1 Concentric with a 240 main jet, 106 needle jet and a 3.5 slide. Can't remember slow-running jet offhand, but tickover is ok. Both plugs black and sooty (dry, not oily) and it 'hunts' a bit when running in the midrange as if choke was 'on' (there is no air slide on the carb). Everything else is standard apart from Pazon ignition. Before I start messing, does anyone have any data to suggest if this is a good starting point, or any suggestions for improvement? If no suggestions I'm going to try replacing jets and needle with the same (the carb was pretty worn and I've had it re-sleeved, so it's possible that the needle and/or needle-jet are worn too). I'll probably replace the float too to ensure correct depth of fuel in float-bowl. All suggestions most welcome!

Hi

I know this is probably not what you want to hear but I'd put a 1 3/16" 389 Monobloc on it.

300 main, 30pilot, 31/2 slide .106 needle jet with needle clip in the middle!

thats what mines got which is std fitment..

Time you've peed about with a worn out unit it'll save allot of heartache and expense.. Just an opinion!.. Good luck with it!

I would try lowering the needle, that should help and might even sort it for you. Cheers, Paul.

Your settings look about right. Concentrics apparently need a 20% main jet reduction on Monobloc settings but otherwise the numbers are transferable. I realise the Connie would normally have 2 carbs but the same year Super Meteor (single carb) settings would be pretty accurate if the increased bore (SM size) carb is used. I used the figures you have quoted on a 59 Super Meteor fitted with a (new) Mk1 Concentric and it ran very well. Paul (Bullet Whisperer) is right about how to proceed in the tuning process but it sounds like you're not far off. I have to say though, that that re-furbing a Concentric is a waste of money unless originality is important. The Monobloc is a much better carb and will last a lot longer and work better than a even a new Conc Mk1. I also have doubts about the quality of new Amal spares so don't rush into replacing needles and jets until you have eliminated the other possibilities!
REgards, Mark

I'd be interested to see how they've re sleeved a Mk1 Concentric. There is so little meat in the body it's hard to Imagine how you could bore it out. I re sleeved a couple of 389 monoblocs in brass and a friend has done 29's and other later separate float bowl versions all with good success. I'm guessing you had the Concentric done in Teflon or similar?

Thanks for the suggestions, Paul & Mark. I'll try lowering the needle first and see what happens. The re-sleeving was done by a guy in Wolverhampton recommended by Mark whose name I've forgotten (age related amnesia...!). He did it by taking a minimal amount out of the body and brass-sleeving the slide. A very professional job! I'm going to persevere with the Conc because I actually prefer them to Monoblocs - I've always had problems with them leaking and the ones I've had have been old & worn. New ones may be better but I'm sticking with what I have! Should I reduce the main-jet by 20% anyway? Thanks again. Stephen

Stephen, I now can't find the recommendation for main jet reduction for Concentrics over Monoblocs so don't take my word for it! In any case your problem is mid range so address that first, once it's sorted you can re-check to see if main jet needs adjustment. Needle position is the first place to start and maybe needle jet as if that is badly worn it can give the same symptoms. REgards, Mark

Hi Mark not all Connies were Twin Carb.

My 59 is single carb as standard!..


Tom

Tom, I know that early Connies were fitted with a single Amal 10TT9 carb but the jetting for these is completely different so not part of this discussion! What might be interesting is to find out the jetting for the Indian Chief which was effectively a single carb (Monobloc) Constellation. REgards, Mark

Hi Mark

Factory supplied Connies with the following set ups.

57-58 Single AMAL TT 1 3/16" Main= 480 Pilot= Adjuster screw Slide= 5 Needle position= 3 Needle Jet= .109
59-62 Single AMAL 389 1 3/16" Main= 300 Pilot= 30 Slide= 3 1/2 Needle position= 2 Needle Jet= .106

Also 59-61 Twin AMAL 376 1 1/16" Main= 320 Pilot= 25 Slide= 4 Needle position= 3 Needle Jet= .106
Also 60-61 Twin AMAL 389 1 3/16" Main= 380 Pilot= 30 Slide= 3 1/2 Needle position= 3 Needle Jet= .106 (High Comp Engines)

Then 62 - 63 on Super Meteor and Connie Single 376 1 1/16" Main= 240 Pilot= 30 Slide= 3 1/2 Needle position= 3 Needle Jet= .106

I don't have specific info on Indians