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mooose
Newbie
Joined: 13 Oct 2008
Posts: 27
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 Posted: Sat Jan 30, 2010 4:52 pm Post subject: Twin Plenum throttle options |
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Hi chaps
I dont know how many of you guys are using these (apart from the sticky above)?
Has anyone come up with an aftermarket throttle assembly for it. I know about the John Eales ones for £6-700, but im thinking more along the diy route.
Im getting throttle hang up with the standard one and its driving me crazy.
Thanks in advance
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4.6 RV8 in a TVR Chimaera |
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ramon alban
Knows His Stuff
Joined: 18 Nov 2006
Posts: 439
Location: Bedford UK
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| Posted: Sat Jan 30, 2010 9:27 pm Post subject: |
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Hello Moose, first of all, have you read my PDF on this subject, available from here:
http://www.vintagemodelairplane.com/pages/Downloads/Rover_Tasters/Idling01.html
I recall from you prior posts you cant read PDF's on your computer. If you have no alternative PC let me know and I will temporarily upload my original WORD document for you to access.
Back to the idle speed hangup. There are many possible causes such as, physical spindle damage, badly worn quadrant boss, poor setup, crud, throttle plate alignment, incorrect spring function, axial alignment, etc.
Any one of the above can croak the mechanism so you have to review all the possibilities. Its best carried out on the workbench. Everything is covered in the PDF.
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Ramon
http://www.vintagemodelairplane.com |
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daxtojeiro
Gold Member
Joined: 25 Nov 2006
Posts: 117
Location: Norwich UK
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| Posted: Sun Jan 31, 2010 11:22 am Post subject: |
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After a bit of polishing:
Cost very little too, but you can't use it on a lucas as it won't connect into one AFM 
Phil
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http://www.extraefi.co.uk/cobra/accobra.htm 5.0L TVR powered Cobra Replica (MSnS-E) |
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mooose
Newbie
Joined: 13 Oct 2008
Posts: 27
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| Posted: Sun Jan 31, 2010 12:59 pm Post subject: |
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thanks Ramon but was hoping for alternatives as i fear my linkage is worn 
Dax nice set up but im on about the twin not siamesed
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daxtojeiro
Gold Member
Joined: 25 Nov 2006
Posts: 117
Location: Norwich UK
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| Posted: Sun Jan 31, 2010 2:25 pm Post subject: |
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Sorry  no idea why youd want to do that though when you can do the above 
Phil
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http://www.extraefi.co.uk/cobra/accobra.htm 5.0L TVR powered Cobra Replica (MSnS-E) |
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mooose
Newbie
Joined: 13 Oct 2008
Posts: 27
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| Posted: Sun Jan 31, 2010 6:29 pm Post subject: |
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| daxtojeiro wrote: | Sorry no idea why youd want to do that though when you can do the above
Phil |
Fair point, still running the lucas at the moment
Phil do you have a close up of the throttle linkage you used on that set up.
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ramon alban
Knows His Stuff
Joined: 18 Nov 2006
Posts: 439
Location: Bedford UK
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| Posted: Sun Jan 31, 2010 10:35 pm Post subject: |
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| mooose wrote: | | was hoping for alternatives as i fear my linkage is worn |
One really needs to know exactly where.
I know from experience that the only insurmountable problem is the throttle spindles being twisted due to abuse. or friction caused by misalignment, gross contamination or badly setup springs.
Some members of this forum have reproduced the spindles, by the way!
As for the external linkages, the most common problem is wear in the central boss of the quadrant, making it impossible to tighten it onto its spindle. This is addressed in detail in my article, thus:
• Check the hub area of quadrant for distortion and undue wear preventing it from securely gripping the jackshaft. If damaged, it would normally be discarded and a new one fitted.
• New items may be difficult to obtain but it is possible for the quadrant hub to be dressed and adjusted to restore its grip. This requires careful use of a small hacksaw to open the hub slot and a small file to reshape the seats for the securing set-screw, nut and washers.
So, please dont overlook this simple solution. Other common issues surround centralising both discs in their respective tunnels because, if not, it is doubly likely that one or the other will bind.
• Upon re-assembly, smooth operation without friction in the intake tunnels is paramount. This depends upon axial location of the discs in their slots after the retaining screws are tightened. If a disc interferes with its tunnel, slacken the fixing screws with the throttle closed to allow the disc to centralise itself before retightening the screws. Incorrect axial or radial alignment will also result in unwanted air ingress around the discs. Use a thin blade screwdriver to lock the fixing screws by slightly opening their split threads.
The whole article is in the same vein, in specific detail and every point has to be addressed, nothing missed, otherwise these systems cannot be properly adjusted. Sure, your system will be worn, they all are at this age but that does not preclude successful repair and adjustment.
I appreciate you may have your heart set on an alternative but, I have to say, apart from the substitution of a couple of poorly engineered and expensive central pull systems I have not come across anything else using the conventional layout.
What - so far - have you seen on your system that you know is worn.
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Ramon
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mooose
Newbie
Joined: 13 Oct 2008
Posts: 27
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| Posted: Sun Jan 31, 2010 10:56 pm Post subject: |
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| ramon alban wrote: | | mooose wrote: | | was hoping for alternatives as i fear my linkage is worn |
One really needs to know exactly where.
I know from experience that the only insurmountable problem is the throttle spindles being twisted due to abuse. or friction caused by misalignment, gross contamination or badly setup springs.
Some members of this forum have reproduced the spindles, by the way!
As for the external linkages, the most common problem is wear in the central boss of the quadrant, making it impossible to tighten it onto its spindle. This is addressed in detail in my article, thus:
• Check the hub area of quadrant for distortion and undue wear preventing it from securely gripping the jackshaft. If damaged, it would normally be discarded and a new one fitted.
• New items may be difficult to obtain but it is possible for the quadrant hub to be dressed and adjusted to restore its grip. This requires careful use of a small hacksaw to open the hub slot and a small file to reshape the seats for the securing set-screw, nut and washers.
So, please dont overlook this simple solution. Other common issues surround centralising both discs in their respective tunnels because, if not, it is doubly likely that one or the other will bind.
• Upon re-assembly, smooth operation without friction in the intake tunnels is paramount. This depends upon axial location of the discs in their slots after the retaining screws are tightened. If a disc interferes with its tunnel, slacken the fixing screws with the throttle closed to allow the disc to centralise itself before retightening the screws. Incorrect axial or radial alignment will also result in unwanted air ingress around the discs. Use a thin blade screwdriver to lock the fixing screws by slightly opening their split threads.
The whole article is in the same vein, in specific detail and every point has to be addressed, nothing missed, otherwise these systems cannot be properly adjusted. Sure, your system will be worn, they all are at this age but that does not preclude successful repair and adjustment.
I appreciate you may have your heart set on an alternative but, I have to say, apart from the substitution of a couple of poorly engineered and expensive central pull systems I have not come across anything else using the conventional layout.
What - so far - have you seen on your system that you know is worn. |
Hi Ramon
This is the little sucker causing the hang up
Its badly worn, i had go at welding some new material to re shape it which has helped but its not perfect.
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ramon alban
Knows His Stuff
Joined: 18 Nov 2006
Posts: 439
Location: Bedford UK
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| Posted: Mon Feb 01, 2010 12:52 am Post subject: |
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I enlarged and sharpened your image thro photoshop to get a good look at the detail and I have to say, that slot in your reversing lever looks bluddy good with no reason to think it would not work.
Its possible the bearing that runs inside the slot is wobbly and the broached rectangular hole in the lever may be loose on its shaft.
For the latter, reduce the hole size by careful use of a ball-pein hammer on an anvil until is snugs the shaft. May need a thin washer to make it tight.
From my previous notes, what is the state of play with your quadrant boss?
Also I forgot to ask if you have the OE throttle return spring from the quadrant leading edge down to the fuel pipe retaining bracket.
Further, I made a small mod on my quadrant throttle stop bar to allow the quadrant to go back only so far to close the discs, and no farther. It consists of two rubber tubes over the bar, the outer one shaped like a cam and the inner one used to turn the cam.
You can see the leading edge of the quadrant lying on the outer tube here.
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Ramon
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mooose
Newbie
Joined: 13 Oct 2008
Posts: 27
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| Posted: Thu Feb 04, 2010 8:13 pm Post subject: |
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Both the reverse link arm and bearing were both badly worn causing the throttle to snag and leave gaps in pedal pressure.
Since the last picture ive had the oval slot straightened and a larger bearing fitted to take away the play. The pulley is now both smoother and sharper with no gaps in pedal operation. 
Ive also had the quadrant re conditioned ( lower section removed and new clamp welded in)
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ramon alban
Knows His Stuff
Joined: 18 Nov 2006
Posts: 439
Location: Bedford UK
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| Posted: Fri Feb 05, 2010 1:45 am Post subject: |
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| mooose wrote: | Both the reverse link arm and bearing were both badly worn causing the throttle to snag and leave gaps in pedal pressure.
Since the last picture ive had the oval slot straightened and a larger bearing fitted to take away the play. The pulley is now both smoother and sharper with no gaps in pedal operation.
Ive also had the quadrant re conditioned ( lower section removed and new clamp welded in) |
I'm not quite clear if you did those improvements since my last post and you a now a happy Moose or do we still have Idle speed hang-up? I'm hoping your rotating smiley says its fixed?
Please dont overlook the subtle adjustment instructions regarding centalising discs and using minimum central spring pressure in my article along with getting the best return spring pressure and my innovative quadrant stop idea?
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Ramon
http://www.vintagemodelairplane.com |
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