Parts Catalog Accessories Catalog Tech Info Tech Forums
 
  Search our site:    
 Cart  | Project List | Order Status | Help    
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Apr 2012
Location: Portland, Oregon
Posts: 16
re-bush throttle valve

My throttle valve leaks and the flap rattles. It's a vacuum leak. Does anyone have a how-to (with pics) for changing the bushings out? Or is there anyone who does this professionally? I seem to remember reading long ago about about bronze retrofits?

I called Eurometrix in Massachusetts, but they don't work on 914 throttle bodies. I have a 1973 1.7 liter engine with the throttle body on the side of the plenum.

Thanks,
Marcus
Old 05-04-2012, 11:53 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #1 (permalink)
Registered User
 
Join Date: May 2012
Location: Virginia
Posts: 2
Garage
I had the same problem with the throttle on my '70 1.7L. My throttle had no bushings and seals like the later engines. I simply removed the screws from the throttle plate (butterfly), buffed down the rough spots on the throttle shaft and then removed the shaft. Fortunately, I have access to a machine shop so I had the throttle "bearings" milled out and bronze "oil lite" type bushings pressed into place, reamed to size and then the old shaft placed back in.

You will need to machine this carefully as the machined holes are placed from opposite sides of the throttle body. I guess you could machine directly through both sides in one set-up, but I wanted "pocket holes" for the bushings to sit in.

The results were tremendous. Smooth operation and air leakage was greatly reduced, my idle is now controllable down below 1000rpm. The whole process took about 20 minutes plus reinstalling the throttle body.

If you can find someone to do the milling you're better than half way there. You could order bronze bushings from McMaster Carr. OK to order INCH bushings and drill/ream to the metric shaft size.

Side note...the largest leak I had was the idle bypass screw. There was so much junk on the threads that I could not close the valve enough to slow the idle down. the junk was so bad that it felt as if the screw had bottomed out. After removing the idle screw and cleaning both the internal and external threads for the idle screw I was able to slow idle down substantially.

Sorry, I didn't take pictures.

Good luck,

Brian
Old 05-04-2012, 12:28 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #2 (permalink)
Registered User
 
Join Date: Apr 2012
Location: Portland, Oregon
Posts: 16
I'll have to hunt for a machinist. Most around here don't do small project stuff anymore. Do you remember which bearings you obtained from McMaster-Carr?

Thanks for the info!

-marcus
Old 05-04-2012, 08:08 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #3 (permalink)
Registered User
 
Join Date: Nov 2004
Location: Vancouver, BC
Posts: 60
I did a mod to add spring loaded oil seals to replace the NLA seals. The thread is on the world site which is down right now.
Old 05-05-2012, 06:21 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Apr 2012
Location: Portland, Oregon
Posts: 16
Where did you find the lip seals? I've been googling for a half-hour and have found nothing.

I found this though:

Carburetor Throttle Shaft Repair Kit 5/16" ZA-01

But, you know, not metric and $200.
Old 05-05-2012, 10:00 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #5 (permalink)
Registered User
 
Join Date: Nov 2004
Location: Vancouver, BC
Posts: 60
I went to my local seals and o-rings shop. I can't recall the sizes, but I have a bill somewhere and can check. I ended up having to bore out the throttle body a bit to get them to fit.
Old 05-05-2012, 02:39 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #6 (permalink)
Registered User
 
Join Date: May 2012
Location: Virginia
Posts: 2
Garage
I don't recall since we just pulled them out of our stock bins.

Here's my thought process though:

As I recall, the shaft is 8mm in diameter. That equals about 0.3149 inches. The closest shaft that McMaster has(without being too large) is an INCH bushing with an inside diameter of 5/16" (.3125") that's 0.0025" undersized. Great, you'll want to be able to ream this out to size AFTER you have pressed the bearing into place in the throttle body.

Now you need to measure and see how much space you have around the shaft to drill out a larger hole. Compare this to the OD's available for a 5/16" sleeve bushing. I'd go with the 3/8" OD by 1/4" long or even 3/8" long if there is enough material there. Use the SAE 841, you want the bearing to wear before the shaft does.

Here's the link to the McMaster-Carr page McMaster-Carr The bushings are dirt cheap you can probably even find bits and tools you need in McMaster somewhere. I know they have metric hand reamers, probably run about $50 for one of those.

Hope that helps. You should get better than 40 years out of that with a bushing in place instead of metal to metal.

Good luck,
Brian


Quote:
Originally Posted by r3dplanet View Post
I'll have to hunt for a machinist. Most around here don't do small project stuff anymore. Do you remember which bearings you obtained from McMaster-Carr?

Thanks for the info!

-marcus
Old 05-07-2012, 10:42 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #7 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 07:43 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 


DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.