The Official "What The Heck Is This?" Thread

I think the only way to know for sure is to trace the two wires back to their source/target

 

I have a new question…

I have searched high and low on the forum and the internet and cannot find an answer to this. Can someone tell me what the three holes are in the cylinder head above (front two up and left, back hole up and right) the exhaust header? They are threaded and appear to go all the way into the combustion chamber. Are they for pressure testing? Should I plug them before starting? Any help would be appreciated.

 

Those are for the emissions air injection system. Assuming you are not going to use it, they can just be plugged with a threaded plug.

Tim

 

Could possibly be Pollution control ports for the lines from the air injection pump. If you are not installing them just plug them. Probably will be metric thread. Someone more familiar with the v-6 can better advise you though. My jeep is a intermediate with a v-8. the ports on my 304 are actually in the exhaust manifold.

 

My CJ had the emission crap attached using those holes. I had those plugged on mine.

 

Can you recall what size threads/plug? I can’t seem to find anything that fits.

 

Sorry. I do not. The shop that rebuilt my engine put them in when I ask them to remove the emissions. If you want, I can check my parts manual to see if it tells.

 

No, that’s okay. I have a FSM. Now that I know what they are, I think I can run it down. Thanks for all of the help!

 

Those holes are air injection ports, and go into the exhaust port, not the combustion chamber. You should have them on both heads. Your engine originally had a belt driven air pump and a tubular manifold system that pumped fresh air into the exhaust ports to help combust unburned fuel going out the exhaust, cleaning up emmissions. Without too much effort, you can likely find a bolt to fit those threads. Most people try pipe thread plugs, but many GM engines used standard bolt threads, like 7/16”.
-Donny

 

Reaching back a good ways, but I think those threads may be inverted flare threads. Those plugs should be available at most FLAPS and I know Summit has them but you will need to determine the size.

 

The thread size is a bolt thread, 1/2"X13tpi . That does not do the sealing though. The seal is the shoulder portion just below the nipple end that just blocks
part of the hole in to the exhaust port. A well sealed 1/2"X1/2" bronze bolt or a 1/2" X 13 set screw may work. A picture.

From another site:
Hmmm...just plugged the smog ports on the heads of my 225 OF V6. Bought some 1/2" - 13 x 1/2" stainless set screws. Smeared 'em with some copper Never-Sneeze and cranked 'em in. Worked and looks great

The fun part of the project was removing the tube that runs inside the exhaust port up to the back of the exhaust valve. Those suckers did NOT want to come out.

 

I have now reviewed a few threads on these, to include removing the tubes. Not super excited about it, but I will tackle it when I change out my exhaust headers in a few weeks. Looks like drilling and placing a rag inside the exhaust chamber will be the way to go…and take it slow. I am not driving the Jeep around yet as I am still waiting on my overdrive to come in the mail anyway.

The bigger issue is finding the correct plugs. It doesn’t appear that they are mass produced. I found one (1x plug) for sale individually on eBay (although the picture showed all six), but obviously I will need six, and the listing said that they were custom machined. I scoured Summit last night as @duffer recommended, but didn’t come up with anything. I find it hard to believe that they aren’t produced, so perhaps I am searching for the wrong product name?

“Buick 225 A.I.R. Port Plugs”
“Dauntless emissions port plugs”
“225 air injection plugs”

I also don’t see any AN size conversions that would match. I can go with some short 1/2x13 bolts as stated above, but it appears that turbulence cause by not fully “plugging” the hole could cause some rough running issues. I also read something about using an inverted flare to plug the tube for a Buick V8. Not sure, but could be similar, if not identical to the Buick V6.

Again, thanks for all of the references on this one. I think the 1/2x13 bolts are a temporary fix, but I would like actual plugs in the future as a long term solution.

 

Assuming you can get the lines out, and the "nuts" are in servicable condition, you can do what the PO did on my jeep, cut the tubes, pull the nuts off, and braze the hole closed, and screw them back in.

 

There shouldn't be any more turbulence than when the original tubing was in place. Also, there are these.
https://www.summitracing.com/parts/rnb-785-491?rrec=true
https://www.dormanproducts.com/p-46645-785-491.aspx

 

It’s a late 70 Dana 30 but I don’t know what gear ratio? Can someone help?


https://www.beamingpix.com/image/SifJ6
https://www.beamingpix.com/image/SiVvt
https://www.beamingpix.com/image/Sinqn
https://www.beamingpix.com/image/SivjS

we spun the wheel and it went almost exactly 2x around with the ring gear spinning once. But I don’t think there’s a 2.0 ratio.

 

I think it says 46/13 so that would be 3:54 I believe.

 

Dana p/n 32957 crosses to 3.54.
http://www.canadawideparts.com/downloads/catalogs/danaspicer_generalInfo_XGI.pdf

 

Is 3.54 close enough to 3.73 to run together off-road?

 

Having different ratio axles will cause drive line wrap, and the added strain will eventually cause a failure somewhere in the driveline. Off-road is not the best place for a driveline failure.

The 3.73 axles are fairly common, I just sold the D30 front axle with that ratio out of a 66 Dauntless I am parting out, still have the rear axle but that won't help you.

Used axle assemblies come up on Jeep forum classifieds, Craigslist, Facebook market place, and various other markets sometimes at very low prices, sometimes for free.

 

No way- you can get away with maybe .05 difference, 3.54 & 3.73 would bind up pretty quick.
I had an F100 that came stock with 3.50 rear & 3.54 front.