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79' GMC C15 - Spruce Caboose

79 GMC 1500
Overview Gallery Discussion
mrk5 said:
I remember my 64 C10 in high school had a flapper valve in the exhaust, a little piece between the manifold and pipe. It had the thermo coil like a choke. Damn thing got installed the wrong way and was forced closed. Took me over a year to figure out the cause of my engine overhearing.
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This 79 has that same thing .
IMG_20200417_120039.jpg

Since I've removed the smog stuff this is now just freeballin down there without any vacuum to orientate it. I'm assuming the way I have it is open.. the pipe after is hot so It must be letting air past, id assume it'd run poor like you mentioned ,if it couldn't let the gas escape. Having one of those installed backwards must have been a tail chasing nightmare


Chevy305 said:
I thought the flapper worked off of a temperature controlled vacuum switch in the thermostat housing? As in run vacuum from carb to switch, then to the flapper valve so that the switch is closed under a certain coolant temp and closes the flapper valve. Then as the coolant temp comes up the switch opens as the flapper swings open.
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Ahh I was talking about the flapper valve in the air cleaner. If you are too mine went from the top of the intake about where the stove pipe vacuum thingy is, to the underside of the air cleaner, and then a vacuum line was attached to another port right beside it and that one went and T'd in-between the manifold vacuum source for the secondaries.
 
Do any Edelbrock carb guys know what this hole that draws in air, located at 5 o'clock to the electric choke housing does? Seems to be a part of the choke circuit.. The truck runs way better with it covered up.. IMG_20200419_115832.jpg
 
Tinkered with the truck today. Painted my door pannels and buttoned up a few things. Took the door jam plastic and checked for any bad rust and cleaned out all the gunk... There's some rust where the kick pannel overlaps the rocker pannels and it's seam sealed, but other then that they are solid still. Could use a wire brushing and paint for sure though.

IMG_20200419_091328.jpg IMG_20200419_103557.jpg IMG_20200419_112233.jpg IMG_20200419_115532.jpg IMG_20200419_121111.jpg IMG_20200419_155908.jpg IMG_20200419_160503.jpg IMG_20200419_113137.jpg IMG_20200419_113202.jpg
 
bix said:
This 79 has that same thing .
View attachment 336869

Since I've removed the smog stuff this is now just freeballin down there without any vacuum to orientate it. I'm assuming the way I have it is open.. the pipe after is hot so It must be letting air past, id assume it'd run poor like you mentioned ,if it couldn't let the gas escape. Having one of those installed backwards must have been a tail chasing nightmare




Ahh I was talking about the flapper valve in the air cleaner. If you are too mine went from the top of the intake about where the stove pipe vacuum thingy is, to the underside of the air cleaner, and then a vacuum line was attached to another port right beside it and that one went and T'd in-between the manifold vacuum source for the secondaries.
Click to expand...
The exhaust flapper valve is completely different than what I was referring to. I was talking about the flapper in the air filter housing. That is for pulling air from around the exhaust manifold to heat the intake air charge to prevent the throttle blades from freezing while the engine warms up.

The exhaust flapper valve is to close off the passenger side manifold and force all the passenger side exhaust through the exhaust cross over in the heads and intake and out the driver side. Again this helps with faster warm ups but it will cost some performance while it's closed.
 
Chevy305 said:
The exhaust flapper valve is completely different than what I was referring to. I was talking about the flapper in the air filter housing. That is for pulling air from around the exhaust manifold to heat the intake air charge to prevent the throttle blades from freezing while the engine warms up.

The exhaust flapper valve is to close off the passenger side manifold and force all the passenger side exhaust through the exhaust cross over in the heads and intake and out the driver side. Again this helps with faster warm ups but it will cost some performance while it's closed.
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Atleast we were talking about the same thing. So in this photo, the vacuum line I had plugged with my air cleaner rod is the one that tees into the vacuum for the secondaries into the bottom of the air cleaner, where the valve cover vent tube area is located. Then another vacuum line beside that one , ran to the top of the air cleaner intake duct, right above the heat stove. It's been starting just fine without any of that stuff hooked up , knock on wood. Might just have to play with the choke as seasons change.

IMG_20200410_115956.jpg
 
bix said:
Tinkered with the truck today. Painted my door pannels and buttoned up a few things. Took the door jam plastic and checked for any bad rust and cleaned out all the gunk... There's some rust where the kick pannel overlaps the rocker pannels and it's seam sealed, but other then that they are solid still. Could use a wire brushing and paint for sure though.

View attachment 336896 View attachment 336897 View attachment 336898 View attachment 336899 View attachment 336900 View attachment 336901 View attachment 336902 View attachment 336903 View attachment 336904
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Sweet on the non rust!!

And the door panels looks great from here!

The ones in Gangrene were green from the factory.

How’s your sun visors?
I think I still have the grean ones from mine.
 
max 02 said:
Sweet on the non rust!!

And the door panels looks great from here!

The ones in Gangrene were green from the factory.

How’s your sun visors?
I think I still have the grean ones from mine.
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Yea I was super stoked to see that that area isn't just toasted with rust under those plastic pieces. Def quite a bit of exterior rust, but the bones are continuing to be very good.

The door pannels aren't great but everything in this truck is green. Green bench seat, green door pannels, green visors.. the black just tones it down a bit and matches the dash cluster plastic so it looks decent and they did clean up pretty good. No cracks or anything so I'm happy. Once the smell of paint is gone from truck too.. that'll be nice

As for the sun visors they are pretty dinked. The driver one had a clip/ slide on mirror glued to it. Not sure if that's factory or not.

I'm going to look into getting the bench re-foamed and maybe just wrapped in some black fabric since mine is destroyed in the driver's quarters.

Trucks running pretty good. Still not sure about this hole in the carb and if I should epoxy it shut or not, but the tape over it is fine for now. I may ditch the factory air cleaner because it doesn't fit very well on this carb, the area I had to dent it in to clear the banjo fuel fitting, now makes the air filter sit higher , so the wing nut has to get cranked down quite a bit. I do like the look of it better than the new ones though so maybe I can figure something out.
 
Going to start making up the parts list for front suspension/steering parts. All my tie rods and ball joints are pretty shot. Might just order new control arms for the uppers and re do the lowers as it seems they can't be ordered... Unless I go QA1 and start spending money I really don't need to.
 
Amazon has cheap plastic air filter spacers if you're looking for a cheap solution. I also got a scratch and dent Amazon warehouse deal on a chrome 14" round filter housing for probably 50% off.
 
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Chevy305 said:
Amazon has cheap plastic air filter spacers if you're looking for a cheap solution. I also got a scratch and dent Amazon warehouse deal on a chrome 14" round filter housing for probably 50% off.
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Didn't even think of that, sucks that if I go any higher my valve cover air filter connection will be too high, so maybe a cheapy chrome air cleaner and a vent in my valve cover is the way to go..
 
Back to the exhaust flapper.

You can pull that whole mess and do without. If you need it as a spacer, pull it out and gut it, I also used a tap and ran a set screw in the sides where the pivot was. It will likely turn into a project, pulling the manifold as well...
 
My old '79 had some kind of air filter spacer and an air filter housing that took a lot taller air filter than your standard truck one. I had to just weld in a piece of tube to extend the breather tube to reach it from the valve cover.
Man I wish i would've kept that truck looking back at pics now.
chevy-8-jpg.174686
 
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Bent77 said:
Back to the exhaust flapper.

You can pull that whole mess and do without. If you need it as a spacer, pull it out and gut it, I also used a tap and ran a set screw in the sides where the pivot was. It will likely turn into a project, pulling the manifold as well...
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Yea I need exhaust anyway, it's filled with holes and held up with nine wire anyway, if I do pull the manifolds to tackle that stupid flapper, I'll be junking the whole set up and putting headers on.. but I don't know about putting that kinda money into an exhaust system i might not be able to use down the road if I go ls or big block. Althoughh it'll probably end up happening anyway.. :whistle:

Truckman4life said:
My old '79 had some kind of air filter spacer and an air filter housing that took a lot taller air filter than your standard truck one. I had to just weld in a piece of tube to extend the breather tube to reach it from the valve cover.
Man I wish i would've kept that truck looking back at pics now.
chevy-8-jpg.174686
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Ah man that filter housing is the tits. I'm gonna try and hunt down one like that. I've seen the spacers but didn't want to buy one of I was gonna end up throwing a chromie one on there anyway. Thanks for letting me know those exist.
 
I have no clue what it came off originally. It had a taller but still factory style spacer between it and the carb and it took a lot taller air filter than a factory housing.
 
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Reminds me of the one that was on the 6.2L in my old K5.
 
Interesting, I had one like that on my K5 and coulda swore it was on the 6.2 and I just moved it over to the 350 when I swapped it in.
 
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