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Vacuum Routing Troubles...
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Topic: Vacuum Routing Troubles... (Read 717 times)
JohnnyPopper
Senior Member
Posts: 2560
Old Goof
Vacuum Routing Troubles...
«
on:
November 07, 2023, 08:55:48 PM »
I read extensively through the manual for my '78 K10, trying to figure out the vacuum routing of my engine so as to re-engage the EGR system and Timing vac advance.
BTW, It is a '78 K10, 350, full smog i.e. EGR, Diverter, EFE valve, and the heat/stove riser in the air cleaner (thermAC?), which name escapes me... There is no dashpot at the carb, just a solenoid tied to voltage with the AC compressor.
It doesn't match exactly to any of the diagrams in 6E.
Purple 2 port is in the manifold. A Green 2 port with what looks like it has a filtered port? is in the T-stat housing along with a blue 2 port.
Any help would be greatly appreciated!
Logged
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400 Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction
bd
Global Moderator
Senior Member
Posts: 6455
Re: Vacuum Routing Troubles...
«
Reply #1 on:
November 07, 2023, 10:58:39 PM »
If you don't have the original emissions sticker on the air cleaner housing or radiator support and no one else posts an applicable diagram, do the best you can using Fig 6E-8.
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Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)
JohnnyPopper
Senior Member
Posts: 2560
Old Goof
Re: Vacuum Routing Troubles...
«
Reply #2 on:
November 08, 2023, 11:47:37 AM »
Thanks bd!
Any thoughts on the vac ports? I have a Qjet and my best guess is the left to right ports are correct as far as plumbing the vac lines.
Logged
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400 Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction
VileZambonie
Global Moderator
Senior Member
Posts: 19029
Re: Vacuum Routing Troubles...
«
Reply #3 on:
November 08, 2023, 04:03:59 PM »
Is your VECI label intact? Is the 2 letter code visible? I'm attaching applicable 78 k10 diagrams. Also, the 1980 diagrams are here which should be helpful for references
http://forum.73-87chevytrucks.com/smforum/index.php?topic=37085.0
Logged
, ___
/ _ _ _\_
⌠ŻŻŻŻŻ' [☼===☼]
`()_);-;()_)--o--)_)
74 GMC
,
75 K5
,
84 GMC
,
85 K20
,
86 k20
,
79 K10
JohnnyPopper
Senior Member
Posts: 2560
Old Goof
Re: Vacuum Routing Troubles...
«
Reply #4 on:
November 08, 2023, 07:45:26 PM »
Thanks guys!
No sticker left on the air cleaner.
There is a partial on the top of the core support. Is that the VECI? If yes, where would the code be?
Logged
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400 Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction
JohnnyPopper
Senior Member
Posts: 2560
Old Goof
Re: Vacuum Routing Troubles...
«
Reply #5 on:
November 11, 2023, 07:59:55 PM »
So with the motor at operating temp, I tested the condition of the 3 TVS's.
Purple, in the T-state housing OPEN
Green, also in housing CLOSED
Blue, in manifold OPEN
Assuming the opposite is true when cold, I can try to figure which TVS goes to what VAC circuit...Here's to hoping...
Logged
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400 Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction
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Vacuum Routing Troubles...