Help! Plenum questions
Discussion
I need to tap into your infinite wealth of knowledge again.
I've removed the plenum to send off for powder coating. I reckon butterflys and rubber seals will really hate 190 C so I need to remove the butterfly and spindle before I send off so here's a few questions:
- I have to detach the butterfly from the spindle - it's attached by two very small brass screws that have their ends splayed to prevent them unscrewing in service. Anyone know a place where I can get replacement splayed screws and any rubber seals?
- I assume after the butterfly is removed the spindle just slides out - correct?
- When I come to replace the butterfly are there any considerations in getting the butterfly into the correct position with respect to keeping the right position for the throttle pot?
.....and finally a puzzler for me (well frankly that aint difficult). When I move the butterfly from shut to fully open the butterfly is able to continue to past the fully open position by 5 to 10 degrees. In other words the throttle lever doesn't have a stop to prevent going past the fully open position and when the lever runs out of movement by bumping against the plenum casting it's gone past the wide open position. It seems strange to me if you push the loud pedal too far the engine will get strangled.... Is that meant to happen? See piccy below
I've removed the plenum to send off for powder coating. I reckon butterflys and rubber seals will really hate 190 C so I need to remove the butterfly and spindle before I send off so here's a few questions:
- I have to detach the butterfly from the spindle - it's attached by two very small brass screws that have their ends splayed to prevent them unscrewing in service. Anyone know a place where I can get replacement splayed screws and any rubber seals?
- I assume after the butterfly is removed the spindle just slides out - correct?
- When I come to replace the butterfly are there any considerations in getting the butterfly into the correct position with respect to keeping the right position for the throttle pot?
.....and finally a puzzler for me (well frankly that aint difficult). When I move the butterfly from shut to fully open the butterfly is able to continue to past the fully open position by 5 to 10 degrees. In other words the throttle lever doesn't have a stop to prevent going past the fully open position and when the lever runs out of movement by bumping against the plenum casting it's gone past the wide open position. It seems strange to me if you push the loud pedal too far the engine will get strangled.... Is that meant to happen? See piccy below
TVR Beaver said:
On your last bit... No.. it needs setting so it's exactly flat when open.. or it obviously starts to restrict the flow... I did it on mine I think by adjusting the cable?... 
I'm just puzzled why the throttle stop doesn't stop at the right position when the butterfly is fully open. It seems quite arbitrary to use whenever the arm catches on the casting to determine the end of its travel. I don't think the Germans would do it like that. 
Mike - I like the idea of reducing the length of the butterfly retaining screws - that means I can use the existing screws with the splayed ends removed - that's good because I'm at a bit of a loss to know what to buy to replace them (UNF 4-48/UNC 4-44/or 3mm fine????)cos my thread gauge is unusable down at that size.
However with using thread locker instead of splaying the screw ends how secure will those screws be? I'm just a bit worried they'll shake loose with vibration and you know where the shrapnel will end up. Is the firmer hold thread locker (like loctite 266) or whatever up to the job of securing such a small dia screw? I know this is trivial detail but I just want to make sure
carsy said:
Not sure on the 2 screws on the butterfly as i`ve never removed mine.
Re the throttle stop, there is a stop on the plenum itself and also you should have one at the throttle pedal. Its just a bolt that screws in and out to get the stop in the correct position.
That's not very clear / precise?Re the throttle stop, there is a stop on the plenum itself and also you should have one at the throttle pedal. Its just a bolt that screws in and out to get the stop in the correct position.
There is a screw in / out stop for throttle closing on the plenum.
Throttle opening limit has a small collar on the end of the shaft linkage (near the cable gland) which can be rotated slightly by loosening 2 screws to adjust the the travel (common as the 'stops' grind away over time).
spend said:
That's not very clear / precise?
There is a screw in / out stop for throttle closing on the plenum.
Throttle opening limit has a small collar on the end of the shaft linkage (near the cable gland) which can be rotated slightly by loosening 2 screws to adjust the the travel (common as the 'stops' grind away over time).
Thanks for that - all much clearer now There is a screw in / out stop for throttle closing on the plenum.
Throttle opening limit has a small collar on the end of the shaft linkage (near the cable gland) which can be rotated slightly by loosening 2 screws to adjust the the travel (common as the 'stops' grind away over time).
spend said:
That's not very clear / precise?
There is a screw in / out stop for throttle closing on the plenum.
Throttle opening limit has a small collar on the end of the shaft linkage (near the cable gland) which can be rotated slightly by loosening 2 screws to adjust the the travel (common as the 'stops' grind away over time).
Thanks for that - all much clearer now There is a screw in / out stop for throttle closing on the plenum.
Throttle opening limit has a small collar on the end of the shaft linkage (near the cable gland) which can be rotated slightly by loosening 2 screws to adjust the the travel (common as the 'stops' grind away over time).
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