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Hey everyone! I heard there was a magical and mystical exhaust manifold for 292 chevy's that have a 3-bolt flange and a larger diameter of 2 1/4" (instead of the leaky 2", 2-bolt with garbage doughnut ring on my 250). Is there any truth to this? Anyone know where I can look to find one?

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They do indeed exist. The diameter maybe 2.5, but in any case larger. They show up on that auction site occasionally. They are more common on the larger trucks C40, C50. Good luck

Larry


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I seem to recall seeing a 3 bolt flange manifold with the smaller pipe size. If that's true then 3 bolts is not a sure indicator of the larger head pipe connection.

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For what its worth....

I am not an expert in the English language, but I believe "Infamous" is not the correct word choice. "Infamous" basically refers to being famous for the wrong reasons, such as notorious, disreputable, disgraceful, etc. I have used the word incorrectly myself in the past.

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I have a 292 Exhaust that is 3-bolt and a 2" outlet.
Actually it is 1-15/16" or 1-7/8" hole, depending on how measured.

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 Originally Posted By: DeuceCoupe
I have a 292 Exhaust that is 3-bolt and a 2" outlet.
Actually it is 1-15/16" or 1-7/8" hole, depending on how measured.


How big could you possibly open it up to?
2.250" or less?
Just asking.

MBHD


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Big truck 292 (C50 and C60) engines had the 2 1/2 " 3 bolt manifold. I have a few of them.
250's also had a 3 bolt version with a smaller output. Have to measure it but it is probably 2 1/4". Tom


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Tom,
My 2"outlet 3-bolt does not look like it would safely punch out much past a true 2". The casting is pretty thin in a couple spots and being an exhaust manifold I'd hate to thin it down any more, so taking out 1/16 to 1/8 would be about all as it looks. I wish they were all 2-1/2 outlets. That is a lot of cubic inches to push out of a 2" outlet.

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An especially bad in pulses of 49" each...

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If you would turbo a L6 w/the stock exhaust manifold., I think it would be better to use the larger outlet.

I never seen anyone use the 2.5" one being used for a turbo yet.

I have a coulple 2 bolt flange manifolds & I am pretty sure they could be opened up to 2" w/out much fuss.

MBHD


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I'll measure both exhaust flanges that I took off of the C-20s. I don't think they were all that large in diameter. They were obviously very restrictive as my 292 runs a whole lot better with the long tube headers.


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My 292 3 bolt exhaust manifold measures 2 1/2" ID.


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Both of my exhaust flanges measure a little over 2" ID. I thought they looked small. They also have a rectangular space under the intake that heats up the carb for the colder weather. I can't help but think that was where most of the restriction was coming from (also the ports running into one common tube).


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My 292 3 bolt is 2 1/2" also. I know it came from a early 60's dump truck. 1 OL REDNECK


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Thought I'd update this thread on my watched topics with some current sources for the 292 tractor replacement part for this:

http://www.ebay.com/itm/250-4-1-292-4-8-GMC-Chevrolet-New-Exhaust-Manifold-/272464327253?hash=item3f7023b255:g:9scAAOSwB09YOfye
http://www.ebay.com/usr/specialtyengineparts

http://www.ebay.com/itm/400750523442?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
http://www.ebay.com/usr/reliableaftermarketpartsinc?_trksid=p2047675.l2559

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I have had a few guy's complain to me about the quality of the aftermarket 292 manifolds.


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Originally Posted By: tlowe #1716
I have had a few guy's complain to me about the quality of the aftermarket 292 manifolds.


I know people who put it on, but had to grind it down to fit it to the Offy. Any other issues on the fit?

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Well, keep in mind its designed to fit a tractor, not a car or truck. And the quality is probably fine when its used in the correct application it was designed for.



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The 292's were used in John Deere combines, New Idea pickers, many irrigation pumps. Not in tractors that I know of. All the exhaust manifolds were the same 3 bolt one used in pickups- C50-60 big trucks.
The problem complained to me was poor casting. Cores that were not centered.


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I was just reposting the terminology that Lifeguard mentioned in his last post where he said "tractor". More specifically would have been industrial or farm applicable. As for the centering of the cores, maybe they're cast overseas or just due to incompetence. The price didn't really reflect something made in the US either, so maybe they were.



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Originally Posted By: Lifeguard
Thought I'd update this thread on my watched topics with some current sources for the 292 tractor replacement part for this:

http://www.ebay.com/itm/250-4-1-292-4-8-GMC-Chevrolet-New-Exhaust-Manifold-/272464327253?hash=item3f7023b255:g:9scAAOSwB09YOfye
http://www.ebay.com/usr/specialtyengineparts

http://www.ebay.com/itm/400750523442?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
http://www.ebay.com/usr/reliableaftermarketpartsinc?_trksid=p2047675.l2559


The second supplier lists it as a John Deere part, and people had referred to it as for agricultural equipment. Just assumed tractors and other field equipment. Hadn't thought about it being used for stationary equipment, but that makes sense. Water pump, generator, etc.

The first supplier just lists it as a truck part. I'm not sure if they are two different casting suppliers, or if they are just selling the same part. Used to be available through The-Co.com real cheap, but they don't seem to carry it anymore and the eBay prices have been steadily rising closer to the cost of a pair of Langdon cast headers. Cheaper of the two is $202.98 compared to $307 for the Langdon exhaust with heat plate. Unless you can find an original HD 292 exhaust, those are the two cheapest options.

http://www.langdonsstovebolt.com/store/#!/Stovebolt-Cast-Exhaust-Headers-for-GM194-230-250-292-engines/p/1395980/category=18665955


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