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Old 05-04-2016, 09:58 AM   #1
dmjlambert
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carburetor neck

Hi
What is this part properly called? In this picture from jimbosprint's 72 C20 I have added an arrow pointing to it. I am missing this part from my 69 CST/10 with 350 4bbl engine, and when I received the truck it had a piece of pipe and assorted washers on the air cleaner stud to make the wing nut hold the air cleaner top, and the crankcase breather inlet hose was just shoved off to the side taking in air and critters from the engine compartment.
Did this "neck" come in different heights, or were they all pretty much the same? If I want to put this back to stock, is this a part I need to hunt around for used?
Thanks
David
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Old 05-04-2016, 02:13 PM   #2
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Re: carburetor neck

I believe it would be the air cleaner "spacer". Like this?
http://www.ebay.com/itm/1967-1972-CH...-/151794745294
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Old 05-04-2016, 03:03 PM   #3
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Re: carburetor neck

I think I have one of those that I'm not using. If I find it, you can have it... just pay shipping.
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Old 05-04-2016, 03:17 PM   #4
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Re: carburetor neck

Quote:
Originally Posted by crud View Post
I think I have one of those that I'm not using. If I find it, you can have it... just pay shipping.
You are very kind, crud. I'm afraid I was quick and already clicked on the link Alex V. provided, and bought it. So, I supposedly have one on the way. Thank you both for your responses.
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Old 05-04-2016, 03:20 PM   #5
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Re: carburetor neck

No problem. I don't blame you for jumping on it when you found it. Probably hard to find.
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Old 05-04-2016, 07:20 PM   #6
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Re: carburetor neck

Yeah, I did a quick scan of LMC's catalog and didn't find one FWIW.
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Old 05-12-2016, 08:59 PM   #7
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Re: carburetor neck

Ok, folks, it arrived and fits well. Here is a related problem. After doing some research I figured out that the part that fits on the rocker arm cover is called a flame arrester. Then there is a hose that goes to the air cleaner spacer. It all fits together fine, except the guy who rebuilt my engine took the flame arrester and hose off of the rocker arm cover. There is nothing I can do to get the flame arrester back on. It is a simple round peg trying to fit in a round hole, and it just won't go. I even tried removing the flame arrester from the hose, cleaning up the flame arrester, greasing the end and putting a large socket over it and hitting it with a mallet. I do not see any obstruction. The rubber grommet is not soft like the one on the PCV valve side of the engine. Do I need to remove the rocker arm cover and replace the grommet? This one thing is turning out to be a pain in the rear.
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Old 05-12-2016, 10:21 PM   #8
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Re: carburetor neck

Yes. You need a new grommet. You probably can remove it without pulling the valve cover, unless part of it breaks off & falls down into the head.
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Old 05-12-2016, 10:27 PM   #9
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Re: carburetor neck

Are you sure it goes on that side? Does it fit into the grommet on the other valve cover?
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Old 05-12-2016, 11:07 PM   #10
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Re: carburetor neck

I believe it is on the correct side. But now on looking closely at before and after photos, I have different valve covers. It would have been nice if the rebuilder included fresh grommets. I believe the breather grommet is brittle and will likely break apart.
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Old 05-13-2016, 12:30 AM   #11
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Re: carburetor neck

The breather flame arrestor goes to the right valve cover with the hole toward the back. Looks like yours is oriented correctly. I think your local Chevy dealer may have the correct grommet. I have some new GM Performance valve covers that use the same grommet.
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Old 05-13-2016, 12:51 AM   #12
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Re: carburetor neck

Ok, thanks. I will check with the parts department at Chevy, and if that doesn't work out I will check online with some place like Classic Industries.
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Old 05-13-2016, 08:29 AM   #13
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Re: carburetor neck

They don't push in!
Clean the inside of the grommet with a rag, polish the arrester barb with emery cloth, spray inside the grommet and the barb with wd40 and twist it in.
Easy peasey!!
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Old 05-13-2016, 01:25 PM   #14
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Re: carburetor neck

I just replaced my groumet with one I got at my local speed shop, like new now
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Old 05-14-2016, 11:50 AM   #15
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Re: carburetor neck

Quote:
Originally Posted by crud View Post
I think I have one of those that I'm not using. If I find it, you can have it... just pay shipping.
I could use a spacer upgrade as mine is in bad shape, if you find it let me know what you want for it
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Old 06-25-2016, 03:41 PM   #16
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Re: carburetor neck

Ok folks this is what I ended up doing. I searched high and low and made several trips to parts stores, speed shop, and to the Chevrolet dealer. I went to AutoZone, O'Reilly, Advance, and nobody could help me with grommets for the valve covers. A guy at the speed shop said to go to O'Reilly and buy a couple of breather covers, open the packages and chuck the new breathers in the trash and get the grommet out of the package, and that was the only way I was getting a grommet. I thought that sounded like something I didn't want to do. I became acquainted with a guy in the parts department at the Chevy dealer that had been around since the days of 67-72. He ordered me some that did not turn out to be the right size, but he researched further and ordered some that fit. 3 trips to the Chevy dealer and now I have some that fit. Perfectly.

I carefully clipped and removed the old grommets a piece at a time and made sure nothing fell down inside. Inserted the grommets and the PCV valve and flame arrester.

With the new grommet, inserting the flame arrester was extremely difficult. I used a little white grease and pushed and twisted, crawled up on top of the engine and put all my weight on it and pushed and twisted some more. Halfway through the process I removed the grommet and put it on the flame arrester and tried to work the grommet into the hole on the valve cover. That didn't work. I decided since this was going to be hard as hell, I would stop, take a break and do some good cleanup on the flame arrester and give it a shot of gloss black paint and work more to insert it after a couple of days. I put the grommet back on the valve cover and was eventually able to insert the flame arrester into it. It was not easy at all, it was hard as hell. But it did eventually pop in. Looks great now, and I won't be re-visiting that job for years (I hope).

I measured the valve cover holes at 15/16 inch.
Breather/flame arrester grommet part number 14091870
PCV valve grommet part number 3989350
PCV valve part number 6487779 (right angle elbow)

The PCV valve is the one with right angle elbow, I know that is not stock for 1969, but I like it. The one from Chevy is more solid built than the one I got at O'Reilly and I decided since I would just get the right part right there right now. The PCV valve grommet with the slant is probably also not stock for 1969 according to the parts guy, and the breather/flame arrester grommet would also work for the PCV valve just fine. But I like the slanted one.
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Old 06-25-2016, 03:54 PM   #17
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Re: carburetor neck

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Old 06-25-2016, 04:37 PM   #18
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Re: carburetor neck

Well now I know that that thing is a flame arrestor!! But flame from what - carb to valve cover? I'm not sure I get the point of it. I understand something being there to help not suck up oil but flames?

And dang, $40 shipped for the thing!!! At least you have it and are done, but I might go sell mine now, lol.

If anyone is interested, I bought the open cleaner setup that was used on the muscle cars back then along with the cross flag 396 and turbo jet decals.

http://www.classicindustries.com/pro...s/6423907.html

It is also designed to plumb into the same flame arrestor thing, but since it is a drop base I also ordered a plastic air cleaner spacer that was the same height. Just had to trim it a touch to get it to fit to the GM lid circle. The port moves from teh factory spacer to the lid itself on these. The rubber hose is different hose, modified my stock one to fit.

I can snap a pic if anyone cares to see how it looks in a pretty stock truck. More "performance" looking while being period correct. I just though that the nozzle is sooo small on our factory air cleaners. Necks down to like 1.5 inches.
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Old 06-25-2016, 05:03 PM   #19
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Re: carburetor neck

This is how I understand it.

The stock setup is: Air flows into the snorkel of the air cleaner housing, goes through the air filter and down into the spacer between the air cleaner housing and the carburetor (shown in the picture in the top message of this thread). Most of the air goes down into the carburetor, but there is a hose connector on the spacer to send some of the filtered air to the passenger side valve cover. During a backfire situation, you don't really want flames going down that path and into the valve cover, so you put a flame arrester there at the valve cover.

If you don't have a stock setup and you get filtered air from somewhere else, such as from a stand-alone breather filter getting air from the engine compartment, then you would not need a flame arrester. If you're getting air from the air cleaner that is attached to the carburetor, that is when you better use a flame arrester. The fumes in the crankcase include blow-by and are flammable.

To continue the journey (for either stock or non-stock setup), the air that goes in the passenger side valve cover goes through the crankcase (to give it some positive crankcase ventilation) and gets sucked out of the driver's side valve cover via the PCV valve, and into the large vacuum port at the front of the carburetor.

Last edited by dmjlambert; 06-25-2016 at 05:25 PM.
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Old 06-26-2016, 05:57 PM   #20
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Re: carburetor neck

You would think....well I would.... that the fire would pretty much blast right through the air cleaner. My open, factory setup has the same general connector but is....open. then again, I suppose that if the system is sucking air through that valve cover igniting oil inside. And it would then be supplying a solid stream of fresh air so long as the engine was turning. Seems unlikely but hey, you never know. I resisted the urge to just cap the port on my new air cleaner.
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Old 06-26-2016, 06:25 PM   #21
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Re: carburetor neck

I don't get what you are saying. How does your valve cover breather hole accept air? From open air immediately surrounding the valve cover, or does it suck air through a hose from the carburetor air cleaner housing? If it sucks air through a hose from the carburetor air cleaner housing and goes down into the breather hole with just a plain open pipe, then you may want that spark arrester. I think the spark arrester also doubles as a way to connect the grommet to a hose.
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Old 06-27-2016, 11:46 AM   #22
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Re: carburetor neck

Sucks it from the air cleaner housing, essentially like the factory setup. I reused the factory flame arrestor.
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Old 06-27-2016, 07:16 PM   #23
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Re: carburetor neck

In that case it seems your setup is just fine.
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Old 07-05-2018, 04:32 PM   #24
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Re: carburetor neck

Quote:
Originally Posted by dmjlambert View Post
This is how I understand it.

The stock setup is: Air flows into the snorkel of the air cleaner housing, goes through the air filter and down into the spacer between the air cleaner housing and the carburetor (shown in the picture in the top message of this thread). Most of the air goes down into the carburetor, but there is a hose connector on the spacer to send some of the filtered air to the passenger side valve cover. During a backfire situation, you don't really want flames going down that path and into the valve cover, so you put a flame arrester there at the valve cover.

If you don't have a stock setup and you get filtered air from somewhere else, such as from a stand-alone breather filter getting air from the engine compartment, then you would not need a flame arrester. If you're getting air from the air cleaner that is attached to the carburetor, that is when you better use a flame arrester. The fumes in the crankcase include blow-by and are flammable.

To continue the journey (for either stock or non-stock setup), the air that goes in the passenger side valve cover goes through the crankcase (to give it some positive crankcase ventilation) and gets sucked out of the driver's side valve cover via the PCV valve, and into the large vacuum port at the front of the carburetor.
Not to bring an ancient thread back from the grave, but I've been pondering what to do with this hose that is sticking up connected to nothing. I just found this thread while browsing another another.

I have a hose that just sticks up from my passenger side valve cover that looks like it has one of these flame arresters. Reading this post is it safe to say it is not needed with the air cleaner I have? If not should I just leave it sticking up as is, put a breather over the passenger side cover or just remove it and plug the hole? I'm guessing plugging the hole is unwise. There also appears to be a place on the bottom of my air cleaner the I could attach run this hose to, but I would need to find a molded hose to make the 2 bends.

Suggestions?
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Old 07-05-2018, 04:54 PM   #25
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Re: carburetor neck

I think this might go to the piece on the carb the air cleaner is on top off? The thing with the red arrow pointing to it in the first post.

Last edited by ncpetersc; 07-05-2018 at 04:56 PM. Reason: referenced 1st post
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