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| what is this? https://slantsix.org/forum/viewtopic.php?t=9734 |
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| Author: | Slantosis [ Sat Jul 03, 2004 1:51 pm ] |
| Post subject: | what is this? |
I posted this at .com earlier... It has been a while since I have had a full motor together and I was looking at my head today. What is that hole and stud for at the back of the head? I put my intake and exaust on and it is still not covered. Is it a coolent passage or something that should be plugged? This is a 74' head I beleive and my 66' head doesn't have it. What am I missing here?  Can anyone help me out here? Thanks |
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| Author: | Guest [ Sat Jul 03, 2004 1:54 pm ] |
| Post subject: | |
That hole is for air injection, it leads right into all the exhaust ports. Plug the hole or you will have a big exhaust leak. |
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| Author: | Dennis Weaver [ Sat Jul 03, 2004 2:52 pm ] |
| Post subject: | |
Here's one for you... My mid-seventies head had that same hole, machined, threaded bolt hole tapped, etc. Now I've had a brain fart or two in the past  , but I spent hour upon hour porting, polishing, and otherwise carressing this head, looked at it up down and sideways and got to know it pretty intimately including hour after hour in the exhaust ports, and that particular hole in this particular head appeared to have a bottom and sides and go nowhere. Nor could I find any passages or unusual openings in any exhaust ports. I knocked a steel plug in the hole anyway, just for my sanity and to keep folks from asking questions... Anybody else encounter one that led to nowhere before? I got this head from the junkyard loose, so I have no idea if it ever had any smog trash hooked up to it. Perhaps a truck head?D/W |
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| Author: | DusterIdiot [ Sat Jul 03, 2004 4:41 pm ] |
| Post subject: | Heh... |
Gotta love those union auto workers on Fridays before leaving the plant...eh, Dennis? The best one by far would be my aunt's early 80's Toronado... the plant finished the driver's side in SAE Inch, and the passenger side in SAE Metric.... (even the intake manifold was metric/inch...) I've got two of those heads in the garage now, waiting for a day when I can clean up the work bench and assess which will be a good core for the O/S valve head... -D.Idiot |
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| Author: | Craig [ Sun Jul 04, 2004 7:40 am ] |
| Post subject: | |
Yep, I have one of those heads with that pretty extra hole in it that leads nowhere. I think it came off of a 1976 model year (made 1975) engine/car.  My belief is that as they changed head castings to incorporate air injection, they set up parts of the assembly/machining line to test and prove out the new operations, such as drilling this big hole in the back of the head for air injection. None of the other holes to the ports are drilled.
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| Author: | Slant6RamTruck [ Tue Jul 06, 2004 8:58 am ] |
| Post subject: | Just to be sure |
The air injection hole in the exhaust port is not very hard to see with a valve removed. If it exists, you won't have to strain to find it. That "doesn't have all the holes drilled" anomally has got to be a real kicker for someone trying to make an air injection system work. Does anybody actually keep those things attached? I hate pollution inspection time. It's not the sniffer that gets me, but the VISUAL  inspection is a kicker. I gotta find a blind inspection crew. LOL
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