Some people have been asking how to remove and or plug up the air injection ports on '75 and '76 2.0 motors.

A few different methods can be done:

1)Welding of the holes, this is only practical if you know you will never need the air injection holes again. It is also only practical if you have the heads already removed from the motor.

2)Threading in a 10mm valve adjusting screw or allen head screw. I don't like this route since there is a good chance of the screw becoming loose down the road. (Jon Watts just had this happen not too long ago)

3)Using a bolt to plug the hole...this is shown in the first picture. The advantage of this route is that you can use the bolt to secure the sheetmetal to the motor and you can remove the bolt in the future if need be in case you must once again have the air injection ports fuctional.
I have had the bolts work themselves loose...so I made a little bracket which uses the intake stud to make sure it cannot come loose.

4)Keep the air injector in the head and plug the top of the injector.The last few pictures show this. I used a ball bearing to get a better seal, this acts just like the valves in the head to create a better seal. The cap is from the local hardware store...I believe it is for a 1/4" pipe
Like #3, this can be benificial in the future since it can be taken apart and easily put back into service.

(IMG:http://members.rennlist.com/mueller/air_injector_bolt.jpg)
(IMG:http://members.rennlist.com/mueller/cap_on_injector.jpg)
(IMG:http://members.rennlist.com/mueller/ball_in_tube.jpg)
(IMG:http://members.rennlist.com/mueller/exploded_view_injector_plug_parts.jpg)

I welcome other ideas so that we can expand the knowledge (IMG:style_emoticons/default/mueba.gif)

Disclaimer: Disconnecting smog equipment might be illegal in your area, check local and state laws first....... (IMG:style_emoticons/default/mueba.gif)

Cram a banana in the hole. It won't plug it but it makes a good banana launcher.

Thanks again for the pics Mike.

Question about the bolts. Are they just a fine thread metric bolt?

Also, do the tips of the injector stick into the exhaust port? I want to use the old injectors to get the correct length bolt...but I don't want them to stick in to the exhaust stream. By the way, engine is still in the car and exhaust is still bolted up to the heads.

If Performance Products will finally do there 20% off sale, again, I'll be able to buy my new Dansk OEM muffler and verify the length while I'm backdating my exhaust.

The bolts I used I think are M10's with a 1.25 pitch
(I'll have to verify this tonight)

The tips do not protrude into the exhaust port, it looks like you can go another 3mm-6mm longer with the bolt before you started to distrupt flow.

Call Performance and ask for a better price...the worst to happen is for them to laugh (IMG:style_emoticons/default/smile.gif)

Jon,

"I'm not falling for the banana in the tailpipe trick again" (IMG:style_emoticons/default/mueba.gif)

Did you use Loctight on the treads? I know it comes in various grades, from easy to never come out.

This is a topic near and dear to my heart. I've been asking peoples' opinions about this for a while now. I even brought it up last Saturday at our "tech session" at Munk Motors here in MI. There are 2 objectives: #1, plug the hole preventing exhaust from coming into the engine compartment; and, B, prevent whatever you use from backing out. Most people I've talked to agree that no type of loctight will hold up to the extremes in temp. there. For sealing the threads, the mechanic at Munks recommended using a product called Nissan PBC Grease - available at Nissan dealers. He says it will hold up (seal) forever regardless of temperatures. It's a bit pricey, though, at $30.00 for 16 oz. (IMG:style_emoticons/default/ohmy.gif) As far as preventing the plugs from backing out, I like your idea about building a bracket off the intake studs. On my car I currently have bolts in the holes with loctight (IMG:style_emoticons/default/sad.gif) and I've painted one corner of each bolt head to be able to see if they're loosening, but I don't want to have to constantly check the bolts and worry if they're coming loose. I plugged my injector holes in Nov. when I got the car back from CA and I haven't driven it since so as to check for exhaust leaks or bolt loosening but I'm not real happy about my set-up. I also like the ballbearing/pipe end method and may switch to that. I'm anxious to here what others have to say about this topic.

I just went out to take a look at the car and realised that the intake studs aren't long enough to accomodate a bracket like Muellers. I was also thinking about drilling holes in the bolt heads and using safety wire but that would be a bitch to do and it would look cheesey. The ballbearing/pipe end fix is looking better all the time.

I just measured the air injection tube....the threads are 10mm with a 1.0 pitch.......
A bolt 50mm long will be perfect.

Tom, instead of making a bracket to capture the top of the bolt, make a washer that will fold up around the side of the bolt on two sides....make it so that part of the washer will rest up against the gasket...this will prevent the bolt from turning...you'll have to unbend the tabs on the washer to remove the bolt.

Mueller,

Check the threads at the top of the air tube. I personally dont beleive that they are standard threads. You may have "forced" a pipe thread setup on there, but I have always used 944 fuel rail caps (they are metric).


B

No forcing at all......these caps spun on like they had been made for this application....hey, what time are you going to be at the shop in the morning??

I get there at 8am on most days. I'm home early this evening..so I should be on time. Al is there at 8am.

I spent a lot of time at OSH with them in hand and never found anything that fit correctly. The rumor I was told: They didnt want anybody "capping" them easily.


B

One of the reasons for the ball bearing was to insure a good seal...I'll bring an extra set I have for you to check out, not that you do this kind of thing on a regualr basis...

Soon.. my "regular thing" will be production of stainless products and 1 or 2 6 conversions or 6 swaps.

Not much interested in 4cyl cars (injection is another subject) Lengthy talks about getting the dyno running again are paving the way.


B

If you're a PCA member Performance will give you 25% off all the time.

thanks for the tip kevin...that is something that needs to be added to the vendor list

actually, the PCA discount at Perf Prod number changes. I've had several different amounts 15% - 25% depending on the item. I used to go in about once every 2 weeks or so.

You also have to ASK for the discount.

I drilled the head of my bolt with a .064 drill bit and ran safety wire thru it.

[QUOTE]Most people I've talked to agree that no type of loctight will hold up to the extremes in temp.

JB Weld!!!

LOL

Jeff

OK, with the help of SMOG's BS Chairman, I've come up with the plan that I'm going to use, based on many suggestions from many people. To plug the holes I'm going to use Allen head bolts. There are 2 reasons: First, wrench access is very tight there, especially because of the close proximity to the manifold flange, and getting an allen wrench in there will be a piece of cake. Second, an allen bolt will be the easiest to drill for safety wire as you only have to drill from the outside of the head to the hole for the wrench. To seal the threads, I'm going to use anti-seize, as this will certainly hold up to the temperatures there (thanks, Bob "I know what I'm talking about" Freeman). Loctight's 400 degrees F isn't enough. I'm sure the temps get higher than that there. I'm also going to use a lock washer for added protection to keep the bolt from backing out. I've spent alot of time thinking about this issue and sought alot of people's advice on this and I think this is the best solution for me. HTH

Eric, Lowe's still might carry them. Hardwick's in the U-District has tons of oddball bolts, and there is TacomaScrew which should have them. Oh, yeah, try McLendons in Renton closer to your house.
Geoff :flower: (IMG:style_emoticons/default/fighting19.gif)