BT7 Choke Assembly

[Deamaker 5]

Hey guys, the choke assembly had a bracket that mounts to the one carburetors on a BT7 - dual carb - set up . Question is on the large trinnion that goes into that bracket - it has 2 pieces, 2 washers, and a nut - how does this trinnion clamp down on the choke cable coming through it?

I have tightened the nut on the trunnion, however, you can still pull the cable loose or the cable will move once u pull the choke out. Maybe I am looking at this too hard, but perhaps I don’t understand how this trunnion works. Thanks.

 

[red57]

If there are no burrs or restrictions, the inner piece should slide inside the outer piece as the nut is tightened and thereby pinching the cable housing as the holes for the cable mis-align. Check for burs or other things that limit the sliding of the two pieces. Moss

 

[Deamaker 5]

If there are no burrs or restrictions, the inner piece should slide inside the outer piece as the nut is tightened and thereby pinching the cable housing as the holes for the cable mis-align. Check for burs or other things that limit the sliding of the two pieces. Moss

Apparently I did not make myself clear enough - there are no burrs or restrictions- these are brand new parts . So , I am assuming that when u put the cable through this trinnion and line up the inner hole and outer holes the cable would go right through until you cinch up the little bolt on the trinnion and that prevents it from moving any further or where u would want it set . I have no problem with this ( if this is the correct way ) , the issue I have is when u tighten the little nut in the inner trinnion piece it’s cranked all the way and nothing happens - meaning u can still grab a hold of the choke cable and pull it right back out . This is the issue I have . Thanks .

 

[Deamaker 5]

Apparently I did not make myself clear enough - there are no burrs or restrictions- these are brand new parts . So , I am assuming that when u put the cable through this trinnion and line up the inner hole and outer holes the cable would go right through until you cinch up the little bolt on the trinnion and that prevents it from moving any further or where u would want it set . I have no problem with this ( if this is the correct way ) , the issue I have is when u tighten the little nut in the inner trinnion piece it’s cranked all the way and nothing happens - meaning u can still grab a hold of the choke cable and pull it right back out . This is the issue I have . Thanks .

Could the washer on the outside of the trinnion be too large ?? How big is that washer ? Should it overlap the bracket entrance? Sorry - I just want my choke to work !!! Lol !

 

[red57]

OK, It's good to know they are new parts and no burr or other problems. My car is currently wrapped up in masking getting ready to paint the shrouds so I can't get at mine and I don't happen to have a spare one to look at but....

I've never had a problem with this type clamp but looking at the design, some possibilities come to mind. It sounds as if the inner piece is bottoming against the washer before adequate 'pinch' happens on the cable. Is the hole in the outer tube piece equidistant from both ends? Could it need to be turned around? If you remove it from the car, can you try tightening the nut to see how small the opening closes before bottoming out the nut? The inner trunnion shown in the Moss picture looks to be tapered towards the stud so possibly you could use a washer with a larger hole to allow it to draw further? I don't remember a taper on mine, but I can't get at it to check.

If you bought it from Moss, call them and ask if they have had any issues - not unheard of for the suppliers to send poor quality parts to Moss and others.

 

[Deamaker 5]

OK, It's good to know they are new parts and no burr or other problems. My car is currently wrapped up in masking getting ready to paint the shrouds so I can't get at mine and I don't happen to have a spare one to look at but....

I've never had a problem with this type clamp but looking at the design, some possibilities come to mind. It sounds as if the inner piece is bottoming against the washer before adequate 'pinch' happens on the cable. Is the hole in the outer tube piece equidistant from both ends? Could it need to be turned around? If you remove it from the car, can you try tightening the nut to see how small the opening closes before bottoming out the nut? The inner trunnion shown in the Moss picture looks to be tapered towards the stud so possibly you could use a washer with a larger hole to allow it to draw further? I don't remember a taper on mine, but I can't get at it to check.

If you bought it from Moss, call them and ask if they have had any issues - not unheard of for the suppliers to send poor quality parts to Moss and others.

I think I just figured it out - the outer larger trunnion was manufactured too wide, so a bit on the grinding wheel should do the job.

 

[vette]

I may be completely misunderstanding your issue but here goes. The outer housing of the cable isn’t meant to be clamped there. The outer housing of the cable just sits in a recess of that inner collar. If you were to pull up on the cable housing it will come up and away from that collar. But when you pull on the coke knob the choke cable is pulled between the lower choke lever and the cable housing which is stopped by the inner collar of this “clamp”. It is not really a clamp it is just a fixture to stop the cable housing there by giving a reaction to the inner cable. Also I believe that fixture nut should not be tightened completely. When loose it allows the angle of pull to stay in alinement with the lower choke lever as the lever moves thru it’s radius.
Also are they HD Type carburetors? I didnt know that HD carbs where original to a BT7.

 

[Deamaker 5]

Well I appreciate your comment and I know it’s difficult sometimes to explain precisely as to whats going wrong with an operation in these cars so let me say that maybe clamped is the wrong word to use in this case - perhaps “ stop “ is a better description to use . In order for the cable to operate properly the outer cable has to “ stop” at some point while anyone pulls on the Choke cable ,otherwise the outer choke cable would continue to slide thus not operating the choke at all , does this make sense ??

 

[vette]

That would be a good way to describe it.

 

[Deamaker 5]

Can someone give me a pic or part number of the carb linkage that attaches to the choke cable - I believe it’s a swivel trinnion of some sort as moss does not have a part number for it in their catalog for a BT7.

 

[red57]

Your picture in post #1 of this thread shows the correct choke set-up for BT7.

Top center of this page shows the parts you pictured: Moss, BT7 engine controls

In post #2 in this thread, is a link to Moss detail of the pieces that make up the trunnion: Moss, choke trunnion pieces All pieces together is part # 378-618

 

[Deamaker 5]

I thank you for the clarification so far , however if we move to the carburetor choke level there is also a trinnion / screw there also and Moss does not give a part number for this trinnion / screw ( for a BT7 ) just for the dual choke system . Are these trinnions the same part ?

 

[red57]

Yes, they are the same - on the engine controls page for BJ7 & BJ8, they are referred to as "cable stop" and the BN4-BT7 page referred to as 'trunnion & screw' (but if you hover over the number 106 in the system picture, it says 'cable stop'), part # 378-648 $7.99

 

[Deamaker 5]

That’s interesting, so on page 41 of the moss catalog in the diagram there is a part number of 106 which lists as a trinnion and screw- is this the same part that goes into the choke lever just below the diagram for the part # 100 on the same page ? Thank u I want to confirm this because I have talked to several people now and they are all saying it’s different or moss has even indicated that if there is no part number next to the item in the diagram then we do not carry it - so I don’t know who to believe now - please confirm- thanks

 

[red57]

First of all, Moss and their part drawings are a great resource but they are not always infallible. You can try calling their tech line and asking but usually you will get someone who is simply able to look up and read whatever the computer tells them (as opposed to a gear head who wrenches on these cars). I'm relatively certain that part number 378-648 would be the right one. They list another part number for a similar cable end for the tri-carb models, but I think they are shorter and would not reach thru the brass lever you have on your HD6 carbs. BTW, this same part number is listed for the BN1, BN2, and BN4 as well as the BJ7 which all use the same thickness brass lever witht he same sized hole on the carb - I suspect the omission of mentioning the BT7 is a simple typo/mistake in creating the catalogue.

 

[vette]

Call Healey Surgeons. You’ll get Inan on the phone. Couldn’t have a better resource.

 

[Deamaker 5]

Thanks for all the responses as Moss never got back to me and it’s not the first time that Moss failed to follow up. I don’t think I will deal with them anymore.

 

[Deamaker 5]

Just for clarification, 678-648 is the correct Moss part number for the screw trunnion. Thanks all!

 

[Deamaker 5]

Sorry part # 378-648 for the correct lower trunnion and screw ( cable stop).

[Deamaker 5, it's trunnion, with a U.]