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914World.com _ 914World Garage _ late model heads

Posted by: vsg914 Mar 31 2004, 07:05 AM

What is the best method to block the air injection ports on the late model heads? All I have is two holes. I know there is susposed to be tubes in the holes, but they aren't there.

Thanks in advance, Curt

Posted by: SLITS Mar 31 2004, 07:17 AM

Some say with a pipe plug, don't remember which size (actually whatever fits).

My preference would be to heliarc them shut from the port side.

And then there's JB weld.............,

Posted by: vsg914 Mar 31 2004, 07:54 AM

Motor is out of car and I don't want to take the head back off if I don't have to, so the heliarc from the inside would be my last choice.

A long threaded pipe nipple with a plug on one end might work, but wouldn't the head have to be threaded below the fins? If I have to thread it, couldn't I just use a long bolt with thread sealer?

JB weld is woncerful stuff, but don't think this is the right application

Any other sugesstions? Anyone? Brad? Jake? Mark?

Posted by: vsg914 Mar 31 2004, 08:06 AM

Ok, after putting new batteries in my scorpion light, I can see that the head is threaded above the exaust valve. Looks like a 10 mm. Maybe a bolt of the right length would work?

Posted by: 2-OH! Mar 31 2004, 08:17 AM

Plug with a 55mm length bolt of the correct thread and some high temp locktite...

The only problem is the bolt head might interfere with the intake manifold flange when you try to bolt it on...It's a pretty tight fit but after the bolt is in, you could carefully grind it off a little bit for the desired clearance... don't get the debris in the intake port...

2-OH!

Posted by: nebreitling Mar 31 2004, 09:36 AM

there's a comprehensive thread on this very thing if you search for it. me having the old tubes, i just blocked them off with a ball bearing and caps -- works great, except...

one (which was never very tight) came out the other day. i DID use JB weld to help support it back in place , and it's holding so far. head temps run, what, <400? JB weld is good for 500+? not much "headroom".

one thing i wonder about the late heads -- when blocking them, are we not letting them ventilate enough? earlier heads have a vaccuum tube for this purpose...

Posted by: vsg914 Mar 31 2004, 10:11 AM

Nathan, I'm talking about the air injection tubes, not the head vent tubes. These go directly to the exhaust port.

2-0H, m10X55 worked perfect.

Thanks, guys

Posted by: nebreitling Mar 31 2004, 12:13 PM

my bad -- got mixed up. glad it worked!

Posted by: RustyWa Mar 31 2004, 02:31 PM

I thought I used a 50mm length on mine, I can't remember but, it is listed in that comprehensive thread.

I do remember though that when I took my exhaust off and looked up into the port, the 50mm (if that is what I used) was just perfect for length. I think a 55mm would stick into the exhaust port.

Posted by: vsg914 Mar 31 2004, 07:39 PM

Rusty, When the guy's got back from the bolt store(yes, we have a place that sells nothing but nuts and bolts), I put the bolts in dry, then turned the motor by hand. No problem. I then removed them, saw that there was about half an inch of threads making contact, dropped on some red loctite and reinstalled them. Later, they told me, "oh, by the way, they didn't have 55mm, just 50mm"

The best part of this story is, we installed the motor this afternoon. It cranked three revs, fired and ran. I wish I had the means to run the motors on the bench first.