Question: Throttle Bodies

[dskeller]

I received this note from the mechanic who is rebuilding the engine for my 69 911S. Thoughts? I will be the first to admit that I love old porsches but am not mechanically inclined in the slightest. Any words will be greatly appreciated.

I need to you to consider and decide on how far you want us to go with a few things. These are items that are mostly for visual effect. The first thing is the throttle bodies; One has more wear than the other and they appear to be from 2 different engines. They will work fine, but one has moderate play in the throttle shaft bushings. I have attached a web site you can go to where they give as full description of how the throttle bodies work and what their company offers to make them like new. The engine could have a slightly erratic idle and there could be a faint clicking sound as a result of the worn bushings if nothing is done. Beyond idle there would be no issue and even at idle it won't be too bad. On the website you can see how they re-plate and anodize all the parts to make them look new. They also can re-plate the crossbar and throttle linkages. All this is great but it costs over $2K to do it. If you elect not to do throttle body reconditioning, we would clean and paint them so they looked fresh, but we won't be able to plate anything - We can clean and apply clear to the throttle linkages, but they would appear dull silver not the gold they were when new or in Eurometrixs photos. Please look at the Website when you have a chance and let me know as we would need to send them out - turn around is 2 months.

The site is http://www.eurometrix.ws/ click on Eurometrix Porsche Carburetor MFI Remanufacturing

[edmayo]

Your mechanic is giving you the straight story. My advice would be to do the throttle bodies now. You will be amazed at how nice it will idle.

[Alan.uk]

Hello,

In case it helps we charge around $1000 to completly overhaul both your throttle bodies. So a lot less than $2k.

http://www.canfordclassics.com/gallery/1350/

Thanks

Alan

[210bhp]

Alan

In the interests of accuracy for your excellent service I think that should be headed up 'taper' and not 'tapper'. Same within the script half way down.

HTH

Regards
Mike

[Alan.uk]

Done, thanks Mike

Alan

[dskeller]

I appreciate your responses . . . I just needed some confirmation to support my financially ever expanding project!!!

[edmayo]

Yeah, I know, they all do that!!

[geshaghi]

Not to stray too far off topic, but is there an independent source for throttle body bushings and seals? Eurometrix certainly does beautiful work, but I'm wondering if the parts are generally available (they don't show up as standalone parts in my copy of the PET), or they are producing them in-house.

[Alan.uk]

Hi, I am not sure how others do it but we make it, including new butterflies with the correct chamfer, the plastic seals, bushes, throttle linkage etc. I am actually having the springs also re-made. With regards to weber carbs we also make an entire oversized throttle shaft, a nice touch is we make and install a bush for the accl pump linkage.







HTH

Alan

[chris_seven]

Bronze bushes with an OD of either 9mm or 10mm are readily available. They have a 5mm bore and are available in 8mm or 10mm lengths. They cost about $1 each

The boss on the throttle body is 15mm OD and 15mm deep on one side and 18mm OD and 15mm deep on the other side.

It is possible to bore the boss and press fit a new bronze bush. I would do this by boring the boss from each side and only to the minimum depth to fit a 10mm long bush. I think 8mm is a bit too short and may allow the shaft to swash even in a small clearance. I would also use the 10mm OD as being a bit more substantial after fitting.

Press in the bushes and then bore both inserts from a single side and ream for an exact fit.

I have been considering using Iglidur X6 which is a modern Polymer Bearing that can operate up to 250deg C and has excellent chemical reistance to gasoline and ethanol and virtually zero moisture absorbtion but I just haven't managed to persuade myself yet.

In small quantities these bushes are abou $6.00 each and would need less work to fit.

I don't think there is enough depth in the boss to fit a proper rotary shaft seal as these parts would have an OD of 12mm and a depth of 3mm so would need a bore of around 3.25mm to work correctly and this would leave no clean up allownace if you needed to re-bore the throttle valve area to remove the damage that is commonly found.

If you make the shaft a good fit there will be little or no issue with leaks.

We are just making a batch of MFI throttle shafts which will be hard electroless Nickel plated for wear and corrosion resistance and centreless ground to size. We will also make some slightly oversize throttle valves.



We will have an end plate 'spin riveted' into place as on the original shaft.