TR6 Carb rebuilding/assessment 69 TR6

[ichthos]

Hello,
One thing I am guilty of periodically is repairing things that don't need to be fixed. Part of this comes from not being able to accurately assess what the real problem is to begin with. One thing I wanted to do but avoided is rebuilding the carbs. I have an extra set, so if it takes me a while, I will still be able to drive. After reading a couple of articles and information on the forum, it seems time consuming, but possible for me. Most of what I read never seems to mention the throttle shaft. It seems like that would be a prime candidate for wear after 38 years. I am trying to decide just how much I should do myself. I am hoping someone can help me out with a few questions I still have. 1) How do you know if the throttle shaft is worn enough that it needs to be rebushed? 2) Is it possible to rebush the carb myself? If not, what is a reasonable price to have it done? 3) Is the throttle disk normally replaced when you replace the throttle shaft? 4) Before I even get started, TRF, and others on the forum have mention using a "colortune kit". How useful is this in assessing my carbs to begin with and is it easy for a novice to use?

Thanks, Kevin

 

[Tinster]

Kevin-

Yes, replace the throttle shaft bushings- they make a
world of difference. Paul Rego has come up with a new
re-bushing concept that even a non-mechanic like myself
can install. You can find my photos on Paul's how-to:

https://www.britishcarforum.com/tikiwiki/tiki-index.php?page=Throttle+Bushing+Repair

I had my carbs professionally refurbished by Jeff Palya.

I bought the carb sync gauge but not the colortune.

Hope this helps a little.

dale

 

[DougF]

It is easy to determine if the carb is on the car by shooting ether in the location of the possible leak. If your idle speed varies, it should probably be rebushed. Same method can be used in finding vaccuum leaks.
With the carb off the car, if there is any noticable wobble in the shaft at the carb body connection, then rebushing should be considered.
Rebushing can be performed at home, but the proper tools are necessary. A good drill press, the proper sized reamer, and a small press would probably do most of the job.
Don't know the prices, but there are several shops that could quote the work for you.
The butterfly would need replaced only if it is worn. But if you do the shaft, it has to come out. At that point you might as well replace it.
Colortune is very helpfull in getting the fuel mixture right. It allows you to see what color the mixture is burning. White is too lean, yellow too rich, and a blue colored flame is just right.
When you rebuild, take time to clean everything thoroughly. You might be amazed what you'll find in there. I found several dead insects lodged in mine. Probably caused a little breathing problem for the carb and the bugs.
You may find that after rebuilding, the idle won't fall below 1,500 rpm regardless of what you may try. This is an emissions problem that is very fixable.

 

[YankeeTR]

Most carb rebuilders will rebush or ream your carb bodies for oversize throttle shafts which would allow you finish the rebuid yourself. I have a local, car friendly machine shop that has rebushed/reamed carb bodies for me for $40.00 a pair. This is pretty straight forward stuff for these guys.

SU's are a simple carburetor...don't be intimidated as most anyone with patience can do these carbs quite easily. The toughest part is synchronizing the carbs and getting the final tuning done right...and you can do it. I've never used a Colortune although I have heard they are EZ to work with and do a good job. I still synchronize mine with a rubber hose...I'm a glutten for punishment!

Buy a QUALITY, FRESH carb kit. I like Joe Curto's stuff as has much of it made exclusivly for him. Many of the "other guys" buy Joe's kits when they rebuild carbs for customers.

 

[TR3driver]

The ZS carbs use seals on the throttle shaft, which are normally replaced as part of a rebuild. Because of the seals, wear in the shaft or bushing is not as critical and usually doesn't cause an air leak. However, at some point, the butterfly starts dragging on the carb throat, which can cause erratic idle rpm.

If memory serves, original carbs did not have separate bushings for the shaft to ride in; so a proper repair involves drilling and reaming the carb body to take new bushings. Can be done at home, but a bit tricky and a mistake may ruin the carb body.

 

[ichthos]

Randall, It is funny you should mention eratic RPM. I tried spraying starter fluid around the vacuum lines. I could find no jump in RPM when I did it and yet I find myself having to pull out the choke at a stop light most of the time. I have tried a number of things to get the engine to idle low enough. The engine will continue to rev a little high (most of the time) and then suddenly drop back down. Are you saying that because of the seal, it is possible for the shaft to be worn and not hear any increase in rpm when I spray starter fluid around it?

I am hoping not to have to rebuild the carbs for a while when I finish. (I think this car has become my hobby and I have so many other things to do on my car at this point.) It seems like replacing the shaft, bushings, seals, and butterfly are important, but it doesn't sound like something I want to undertake. I am going to read article by Paul, but if there is a chance to ruin the body, I would be the one to do it. Most people mention TRF and Joe Curto for parts. Has anyone ever had either one of these places put in new shafts and bushings? If so, were you happy with their work? What did it end up costing?

Kevin

 

[TR3driver]

Are you saying that because of the seal, it is possible for the shaft to be worn and not hear any increase in rpm when I spray starter fluid around it?

Yes, that's my point exactly. But you should still be able to tell if they're badly worn, by grabbing the exposed shaft and trying to move it against the bushings.

Has anyone ever had either one of these places put in new shafts and bushings?

I haven't. TRF currently has rebuilt carbs on sale for $400/pair (plus a core charge). I'd guess Joe is a little above that price.