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MG TD TF 1500 - Carb Tune Kit

Hi, anyone use the SU carb centering tool for $34.95 from Moss and if so how were your results? Is it just as easy to center using the John Twist method?

Steve
SD Denham

I bought the tool and it makes the job much easier in my opinion. I thought it was money well spent and I use it quite a bit so I feel I’ve gotten my money’s worth out of it.

Bill. Chasser
TD-4834
W A Chasser

With care completely rebuilt my twin SUs on my 1250 TF. Re-bushing the shaft was the one thing that really had to be done with great caution to ensure drilling the old ush out and ensuring I'd still left the necessary ridge to prevent leaks.Following John Twists method centreing jets wasn't that difficult I found. Just takes time and care. Good Luck
JK Mazgaj

This method works well for me. I copied it from the Burlen web site.

Tim

Timothy Burchfield

Thanks for the feedback all, I did buy the centering tool and it was worth the investment. My carbs are by all means not perfect and I get just a little wiggle room when setting up the carbs and one piston I could not keep from sticking. The tool goes straight through the top and into the jet assembly (minus the jet) so when you tighten everything up it stays in place. If you have a metal lathe you could make one of these pretty easy I think and save $35.

Cheers and for those of you stateside Happy 4th of July

Steve
SD Denham

I know some people are proud of their comprehensive tool kits, keep everything clean and shiny, have a shadow board on the wall to store them and their spanners probably all match. My spanners are kept in a tool box and given a wipe with an oily rag now and then. Some of them have been cut short to fit into difficult places and one has been ground down to fit the jet adjusting nuts without taking the springs off. I was told to buy the cheapest possible hand tools and if one wears out or breaks within a year replace it with the very best you can afford. That means the tools you use the most are of top quality. I suspect that unless you tune SUs every day a jet centering tool would remain in a closed drawer for a long time.

Jan T
J Targosz

Jan, many hand tool manufacture/sellers here in the US provide a lifetime warranty with their tools. Buying cheap and then buying quality seems like a wasteful exercise. I know from many, many years of experience that buying the best tool you can afford will save you money in the long run. That's what I tell any young person with whom I discuss restoration and repair. I also bought the jet centering tool that Steve describes. Annnddd... I promptly lost it. I found it a quick and effective method for centering the jet while I had it. Unlike some here I'm always fiddling with the jets, and it seems, everything else on the car. I think I'm mentioned in the Moss and LBC profit reports.

Regards

Tim
Timothy Burchfield

I bought the kit and used it once. Honestly, for me, if the piston goes up easily and drops with a thunk, it is centered and runs great.
efh Haskell

Hi Tim,

What I was trying to get across is that I believe many people buy tools that they will never use. You will have seen the shiny 150 piece socket set advertised when apart from the 3/16, 1/4, and 5/16 no others are ever used. OK it may be a bit of an exaggeration but I hope you see my point. Many of the hand tools I have were inherited from my father, who was also an engineer, or bought second hand at autojumbles where top quality, branded, items can be found. One of the worst buys has to be comprehensive sets of twist drills. I have seen 1/4" ones bend rather than cut a hole. Trouble is though unlike spanners you do need a good range of sizes.

Cheers

Jan
J Targosz

Jan, understood. If you look up "too many tools" in the dictionary my garage will be shown. My kids are dreading the day when they have clear out the garage of tools and spare parts. Another point on which I'm sure we can agree is that modern hand tools generally, are not the same quality as those of our fathers' time. Now here is a tool I bought that I have found to be indispensable. Indispensable in reminding me that I buy way too many tools. :-)

Regards

Tim

Timothy Burchfield

My dad always said “Buy the best tools you can afford - you’ll never regret it”, and IMHO he was right. Poor quality (or the improper) tools leave you frustrated and result in time wasted. Like you, Tim, I’ve got a ton of specialty tools, some bought, some made, but at least I’ve labeled them to make my survivor’s job easier! :D

As to the jet centering tool, I’ve turned several aluminum ones in my lathe for friends - they’re quite easy to make and they make the job infinitely easier and more accurate.
Kevin McLemore

Hi Tim and Kevin,

We could start up a new thread titled "Tools we have inherited or bought second hand"!

I have a pair of "Gas Pliers" which belonged to my father. They are excellent for tightening the large brass nuts on the speedo and rev counter cables.

Cheers


Jan
J Targosz

If I knew what the jet centering tool looked like, I might make one myself. Anyone have a pic please?
Dave H
Dave Hill

Dave,

Here is a picture of one.

https://www.angloparts.com/en/catalogues/part/155887/200.699

If you want dimensions, let me know I can give them to you later this afternoon.

John


J Scragg

Thanks. Don't think I'll need the dimensions as I should be able to take them from a carb.
Dave H
Dave Hill

Yes, I was going to suggest this. The tool needs to be a tight sliding fit in the dashpot and both the upper and lower jet bearings. You don't need to machine the knurl in the top section.

John
J Scragg

I wanted to add that you can improve the design by adding a very small undercut between the small and large diameters. This will ensure that the tool sits squarely on the upper jet bearing.

John
J Scragg

When I made mine I made it to fit inside the jet itself, not inside the jet bearings. I insert it while the jet bearings are loose, then tighten the bearings and remove it. Works very well. (Since it’s made of aluminum it can’t harm the harder brass jet orifice.)
Kevin McLemore

What's the difference between setting the centralisation with a custom made tool or the piston and needle? Surely with both you have to loosen the jet bearing, rotate it until everything is concentric and the tighten the nut.

Jañ T
J Targosz

Yes, I've always done it the traditional way, but it can move a bit when tightening up. I think with the tool it should be kept in position more positively.
Dave .H
Dave Hill

Using my type of tool, since the tool fits snugly in the jet orifice, it is more accurate than using the needle, since the needle has limited play in the jet by its very nature. Thus the jet is better centered.
Kevin McLemore

Jan,

The differences between using the centering tool and the "clunk" method are, the tool is correct first time whereas the clunk is trial and error. More importantly the tool assures that both upper and lower bearings are perfectly aligned. Misalignment of the bearings is one of the causes of stiff choke movement.

John


J Scragg

I used to use the ‘clunk’ method, but then I began to think about every time I tried the ‘clunk’ drop during the setup process, but it wasn’t in alignment, I was rubbing the needle against the jet, and possibly wearing down both (and therefore altering the mixture at that place on the needle). Of particular concern to me was the possibility that in the end I was getting the ‘clunk’ but the needle was still slightly rubbing the jet (i.e. imperceptible interference), and that after bajillions of such rubbings during normal operation the idle position on the needle, and the jet hole itself, would become badly worn and impossible to tune.

Hence my use if the centering tool. No wear during setup (aluminum is softer than brass) and absolute centralization in service.
Kevin McLemore

Is this correct for H type carburetors? The description on the Moss website says it’s for Jag 120, 140 and 150.

https://mossmotors.com/su-jet-centering-tool

Stuart

S Grimm

This thread was discussed between 28/06/2019 and 06/07/2019

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