77 fresh air duct

[Royal Sierra 454]

I'll take some pictures. Wide/round I believe.

 

[Turbo4whl]

Old post revival, @Craig 85 mentioned two snorkels.

So in an effort to make my BB engine run better when it was still cold, I reinstalled the heat stove air cleaner. Then what I found was when the engine was still cold and you nailed the throttle, I had a hesitation, you could hear the air horn door snap open, then the engine would roar and go. The vacuum created inside the air cleaner housing was enough to pull open the door because not enough air was entering from the heat stove.

I found that on a Dodge van they used two snorkels. The second snorkel, without a heat stove, had the vacuum door plumbed straight to manifold. So when manifold vacuum drops, when you punch the throttle, the second door opens.

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I blocked off the small heat stove port on my second snorkel. Yes, this fixed my cold run, mash the throttle hesitation.

By the way, the other cold weather system I added back on was the 'Trapped Vacuum Spark'. The heat stove and the TVS made this a start and go engine.

Oil pressure is up? Yes, then we're ready to go..

 

[Royal Sierra 454]

Took some picture of the two-snorkel setups. First 2 pics. are of my 1976 GMC C15 factory 454. The last 3 pics. are from my 1976 K5 Blazer factory 400. Both from Ca.

 

[Craig 85]

Both of my 1976 C-15 454 and K5 400 came with snorkels. Both from CA. Maybe an emission thing? Both still have their original Flex duct.

It may just be an 81-86 issue with the different snorkel tubes. This is the correct one for my 454. There is more of a bend near the air cleaner snorkel opening (also longer smooth area). I had an 1980 C20 3+3 years ago with a 454, but I don't have any photos of the engine, so I can't recall if there was a difference.

I just saw you photos after I posted the first paragraph. GM must have changed the snorkel set up for the 400 K5's in '77. My '77 K5 was always a CA truck and had the wide mouth air cleaner snorkel like your 454 has.

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[SquareRoot]

Wide or narrow snouts? Impressive tho.

 

[AuroraGirl]

It may just be an 81-86 issue with the different snorkel tubes. This is the correct one for my 454. There is more of a bend near the air cleaner snorkel opening (also longer smooth area). I had an 1980 C20 3+3 years ago with a 454, but I don't have any photos of the engine, so I can't recall if there was a difference.

I just saw you photos after I posted the first paragraph. GM must have changed the snorkel set up for the 400 K5's in '77. My '77 K5 was always a CA truck and had the wide mouth air cleaner snorkel like your 454 has.

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i have a 350 or maybe it was a 400 air cleaner for a 77 that had the wide mouth, at least the lid was matched to one that was. It could technically be different I guess

 

[Craig 85]

i have a 350 or maybe it was a 400 air cleaner for a 77 that had the wide mouth, at least the lid was matched to one that was. It could technically be different I guess

It could be a California thing. I've had 5 carbureted Square bodies over the years with small and big blocks from 77-85. They all had the wider mouth air cleaner snorkels. This was my '79 GMC K15 (photo #1). The only thing I did to this was add the taller lid.

I had three 87-88's TBIs, both small and big block with HD emissions, those had the same TBI air cleaner/snorkel set ups (photo #2).

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