Air Valves on PI cars

[Davidw]

I have tried searching this topic so as not to bother you all but after two attempts all I got was the same gearbox threads repeated 6 times. My question is this: -

 

I have bought a supplementary Air valve for my 5 in order to fit it at the back end of last pair of throttle bodies as outlined in Roger Williams' excellent book. Are these just a push fit or does one put some sort of sealant around it?

[Red 6]

I have tried searching this topic so as not to bother you all but after two attempts all I got was the same gearbox threads repeated 6 times. My question is this: -

 

I have bought a supplementary Air valve for my 5 in order to fit it at the back end of last pair of throttle bodies as outlined in Roger Williams' excellent book. Are these just a push fit or does one put some sort of sealant around it?

 

 

Hi David, I suggest you use sealant in case it pops out whilst in use.

 

I would be interested in the outcome as I doubt this modification will offer any benefit but it does add another point of failure and something else which has to be twiddled to get a good tickover.

 

My reasons for the scepcism being at idle the air requirement for all cylinders is adequately handled by the existing air valve which in itsself was a modification from the origional design found on the the early TR5's and I have not experienced the rich or difficult tickover running phenominum mentioned in the book either on my road car or full race version. If it does provide a noticably better anything I will give it a try.

 

Hope this helps.

 

PS where do you play I might come along?

[Chris Mountford]

Hi,

 

Did this 20 years ago on my 5 that had no valve fitted from the factory or the dealer fitted retro fit valve.

 

I fitted the OE TR6 valve first and this made a big difference to how the car ticked over, fitting the second valve didn't make a huge difference but it was a noticeable improvement in the lack of plug sooting towards the back of the engine.

 

They are easy to fit, just knock out the small 'core plug', clean both manifold and valve faces up and fit with some adhesive (sorry but cannot remember what I used). You will need to drill the plenum box and weld in another stub pipe unless you intend fitting a small remote filter. Originality wasn't such an issue then!

 

Don't forget to remove the throttle stops on each pair of butterflies thus ensuring the butterflies are closed. Equalise all the linkeages so that they all operate in unison.......fail to do this accurately and it'll never run smoothly. It is difficult to do if the bushes that support the shaft under the throttle bodies are less than perfect.

 

Balance the two valves as you would a pair of SU's, as in, listen to the amount of 'hiss' going through each, and then couple them up to the airbox via the short link pipes. I read somewhere that the valves location in the manifold is best in the '150' position rather than in the later (TR6) '125' spec position if you have the later manifolds. If you have the 5 / early 6 manifolds you will not have that potential for choice.

 

Hope this helps

 

Chris

[Davidw]

Thanks for your replies.

 

Hi Red. Took me a bit of time to work out what you meant. next gig is at the Swan in Thame High Street on Sunday 29th november at around 8.30 pm. We usually play in pubs around Chinnor, Thame & Aylesbury. Returning to your thoughts on PI - I am trying to get the rear pair of cylinders not to run so rich. Throttle spindles are OK & all bodies open in synch. I will post again when I have done this and put some miles on the car to see what the result is.

 

Chris - thanks for your detailed reply. Will take what you say in board.

 

All the best

 

David

[Davidw]

Quick update, chaps. Decided to go the whole hog as per Roger Willimas book and increase the size of the plenum chamber/air box as well and then fit a large K&N at the end, keeping the hose trunking to feed cold air. So i am now on the look out for an air box I can cut open and increase in size.

 

Soon as I have all the bits I will fit it all & post the results.

 

Thanks

 

 

David