I fully realise that this subject has been covered many times but I just want to ask you guys if there is anything REALLY important to watch for when removing all the air injection stuff? Or is it as straightforward as it looks? Any help would of course be really appreciated

 

Make sure you spray the injectors with Kroil or another penetrating oil before removal. Otherwise the injector threads will gall and strip out the threads in the head.

 

It's pretty straightforward. I'll echo Paul's comments about the injectors themselves - take it easy as they (and the 'spider' pipework) can be really quite fragile (especially on our UK cars). Put plenty of release oil on them over a few days and have some heat on hand if you find any are difficult to turn. Have you got the emissions plugs to go in their place? Type-911.co.uk sell them if you haven't already got a set.

You'll want to take the drive belt off the rear of the left hand camshaft (easiest way is to slice through the belt). You can remove the big air pump, the two diverter valves in the left and right corners of the engine bay and several miles of assorted pipework (well, a lot, anyway!). If you've got a standard airbox and not a simple filter on top of your intake you'll also want to block off the several returns back into the airbox. A short section of host, a bolt and a jubilee clip short sort them out.

There are several smaller diameter pipes around the throttle that will need to be blanked off in order to stop a vacuum leak - they're pretty easy to spot as they all connect to one or the other of the diverter valves.

Don't forget about the air intake pipe that bolts in to the side of the catalytic converter; you'll want to pull that out too. It's a big diameter, so you'll need to find a big nut or something similar to affix on the cat.

 

Thanks John.Thats great and I'll manage from there.Its just dawned on me that there are 2 cats, a small one at the wastegate and a large one which needs blanked off.Is it the large one we remove to fit the bypass pipe?

 

That's correct. The small one on the wastegate stays on, unless you want to remove the internal matrix for extra sound when on boost (no performance gain, just noise). The large one running across the back of the car is the one directly attached to the turbocharger and needs the air port blocking when you remove the air injection system; aftermarket bypass pipes will usually have the air port too, so if you fit one you'll find it easier to plug it while it's off the car.

 

Im going to have a bypass pipe made so Ill get him to make it without the outlet for the air injection.You never know,if he makes a good job there may be other guys who would want one.Thanks again

 

Got shot of all the air injection stuff,pretty simple job thanks to the forum.Instead of buying plugs for the heads I used brake pipe nuts and spot welded the hole in the end of the nut.The threads are the same(10x1.0mm) and they dont protrude into the chamber once theyre tightened up.

 

Neat idea, Jock.
What did you torque them to?

 

I havent yet as Im not sure whether to,a: torque them to a normal M10 fine thread torque,b: use a compressable washer and tighten by feel or c: use locktite or similar. Im consious that these nuts are hollow so Ill probably tighten them by feel the way I tightened them into the calipers when I made up the brake pipes.

 

My $.02
I would not tighten to full M10 spec into an aluminum head, not even if it is brand new. You want to put as little stress on the threads as possible or you might end up helicoiling the threads (a good idea if you want to put the torque to it, but no need in this application).
A side note on compressable washers. Im not sure as to the extent of application on our cars, but I never recommend them in any application. They have been proven to assist in backing fasteners out.
Chemical locking is always, IMHO, the best way to go, but I'm not sure the temperature ranges of Loctite products (internet search yields no results, and the bottles I have here in the shop have Korean writing all over them...dont ask). If its rated to 1500* or higher, I say use that and torque to around 20 ft/lb. Full yield is around 42 lb/ft (for a cap screw anyway).
Good thing is that it is something you can experiment with, cause its somewhat accessable, ie. check torque in both directions after a few heat cycles.
I know we arent cutting diamonds here, but thats how I would attack it.

 

I think Ill go for the 'tighten as if this might strip' theory.The way I'm thinking is a few bursts up the road and they'll be carboned up anyway.What made me think of the compressable washers was there was some behind the barrel nuts on the heat exchangers(the nuts you access up thro the heat exchanger).They seem to be aluminium but hey,they may not have been original.Now that I think about it,is there some sort of non return valve in the air injection systerm? If not,why does the compression not blow back up the injectors?Not that Im worried now,that s..ts well gone!

 

FYI, I tightened my plugs with copper washers to 20 ft-lb.

 

I should have said Im going to tighten 4.Ive got 2 broken injectors to deal with also.The joys