What have you done to your square lately??

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Joined
Jul 20, 2021
Posts
925
Reaction score
3,371
Location
Tennessee
First Name
Matt
Truck Year
1979
Truck Model
C10
Engine Size
6.17775926 liters, 3L80, 228.6mm axle
I just kept the wiring to the relay, blower motor and the resistor. I cut out everything else back to their main harnesses, put heatshrink on the ends and taped them back in. Kept the plugs and wiring for "just in case"

Also if you bought the fiberglass box theres no hole for the resistor so you can put it wherever you want as long as its got a little airflow. I put mine up top and relocated the vacuum ball inside on top of the heater box.

Some of this is ignition box and coil wiring but came out decent enough.
You must be registered for see images attach
 

WFarm

Full Access Member
Joined
Jan 11, 2023
Posts
1,200
Reaction score
7,637
Location
Central Virginia
First Name
Paul
Truck Year
1975
Truck Model
K5 Blazer
Engine Size
454
I just kept the wiring to the relay, blower motor and the resistor. I cut out everything else back to their main harnesses, put heatshrink on the ends and taped them back in. Kept the plugs and wiring for "just in case"

Also if you bought the fiberglass box theres no hole for the resistor so you can put it wherever you want as long as its got a little airflow. I put mine up top and relocated the vacuum ball inside on top of the heater box.

Some of this is ignition box and coil wiring but came out decent enough.
You must be registered for see images attach
That looks great! Really like that sleeving. Thanks for the info, realized I need to remove the resistor from the old evaporator box.

That is the same cover I bought too, btw.
 

WFarm

Full Access Member
Joined
Jan 11, 2023
Posts
1,200
Reaction score
7,637
Location
Central Virginia
First Name
Paul
Truck Year
1975
Truck Model
K5 Blazer
Engine Size
454
And so it begins…..

Noticed today that as soon as I started loosening the heater hose hose clamp it started to drip. Now I wonder how it ever didn’t drip!!

So now I need to replace the heater core. Not looking forward to it, as I think the first thing that came down the assembly line was the heater core, and GM built a truck around it, lol.

You must be registered for see images attach
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
9,940
Reaction score
19,065
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
Well, I had a flash of inspiration on the way in regarding the vacuum for the distributor advance at WOT. When using manifold vacuum, it disappears. Hmmm. What happens if you put a check valve in ?

So, I tried it. Had to reinstall the valve as I had it backwards the 1st time. :anitoof:

Interesting - it did not have the TA DA !!! effect at WOT I thought it would. It probably is a little better, and seems to be eliminating to puff of something ( raw fuel , maybe ? ) I was seeing out the tail pipe in car headlights at night.

Testing will continue.
Test it,engine hot,going up a long hill,preferably pulling a trailer. If your check valve works,your vacuum advance can works,your centrifugal advance works,total is set correctly,you should be rewarded with tons of piston and rod bearing destroying predetonation. The reason for hooking the vacuum advance to manifold or ported vacuum is the timing drops out under heavy load to prevent detonation. If they wanted vacuum advance to rise with engine speed and not retard with throttle opening,they'd have used venturi vacuum,not ported or manifold vacuum. They used to do that about 100 years ago,venturi vacuum and manifold vacuum working at the same time. I think Ford called it loadomatic ignition. Kicker is you still had to have the manifold vacuum so ignition would retard in high load situations. I found an article that explains all this.

 
Last edited:

WFarm

Full Access Member
Joined
Jan 11, 2023
Posts
1,200
Reaction score
7,637
Location
Central Virginia
First Name
Paul
Truck Year
1975
Truck Model
K5 Blazer
Engine Size
454
Removed the old heater core. I don’t usually time myself when doing things, but probably because I was dreading this particular task I made note of when I started. Turns out the job wasn’t that bad at all. Had the heater box out of the truck in 45 minutes, and had the heater core out and on the bench in another 15 minutes. Nothing else was broken so should be good to go tomorrow when O’Reilly will have the new core.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach
 
Last edited:

Chevrolado

Full Access Member
Joined
Dec 13, 2012
Posts
903
Reaction score
1,905
Location
McKinney, TX
First Name
Dave
Truck Year
1977|2006
Truck Model
K10|1500
Engine Size
5.7|5.3
I was about to say, I think "heater core" jobs are universally spoken about being the worst. But from what I've seen so far under these dashes - its all hanging right there and somewhat easy to get to. I think its the later model trucks (90's plus) that maybe start to get more difficult when you start adding airbags and modern HVAC tech.. hah. :D

Looks good man! Lookin forward to seeing a fresh core going back in.
 

DoubleDingo

Full Access Member
Joined
Jul 3, 2012
Posts
13,896
Reaction score
23,744
Location
Right where I am
First Name
Bagoomba
Truck Year
1981
Truck Model
81-C20 Silverado Camper Special-TH400-4.10s
Engine Size
Carb'ed Vortec 350
Removed the old heater core. I don’t usually time myself when doing things, but probably because I was dreading this particular task I made note of when I started. Turns out the job wasn’t that bad at all. Had the heater box out of the truck in 45 minutes, and had the heater core out and on the bench in another 15 minutes. Nothing else was broken so should be good to go tomorrow when O’Reilly will have the new core.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach
I bought a new heater core around Christmas, it's on my to-do list along with many other things going on.
 

YakkoWarner

Full Access Member
Joined
May 29, 2024
Posts
643
Reaction score
1,049
Location
Central Texas
First Name
Wolf
Truck Year
1989
Truck Model
R2500 Suburban
Engine Size
454
The most recent thing I've done with my square is arrange to get it towed.....again. I'm pretty sure it is simply cursed at this point. A car wash with holy water might be the next step....or it might just dissolve away.
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
9,940
Reaction score
19,065
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
I was about to say, I think "heater core" jobs are universally spoken about being the worst. But from what I've seen so far under these dashes - its all hanging right there and somewhat easy to get to. I think its the later model trucks (90's plus) that maybe start to get more difficult when you start adding airbags and modern HVAC tech.. hah. :D

Looks good man! Lookin forward to seeing a fresh core going back in.
2nd generation Taurus,Nissan trucks,Chrysler town and country,and actually a bunch of others,cars you have to remove the entire dash. Just set them on fire and call your insurance company.
 

Blue Ox

Turning Diesel Fuel Into Fun
Joined
Mar 27, 2018
Posts
5,874
Reaction score
14,629
Location
LI-NY
First Name
Derek
Truck Year
MCMLXXXV
Truck Model
K20HD
Engine Size
6.2L
I was about to say, I think "heater core" jobs are universally spoken about being the worst. But from what I've seen so far under these dashes - its all hanging right there and somewhat easy to get to. I think its the later model trucks (90's plus) that maybe start to get more difficult when you start adding airbags and modern HVAC tech.. hah. :D

Most people speak as if heater cores are apocalyptic, but I'd agree that the GMs of the era are nowhere near that bad. For me, the biggest issue is them bolting it through from the other side. The Volvo I had was an absolute horror by comparison.
 

bucket

Super Moderator
Staff member
Moderator
Joined
Aug 3, 2010
Posts
35,095
Reaction score
43,609
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
2nd generation Taurus,Nissan trucks,Chrysler town and country,and actually a bunch of others,cars you have to remove the entire dash. Just set them on fire and call your insurance company.

I've had literally hundreds of '96+ Chrysler minivan dashboards out. I think I had it down to 4.5 hours, including yanking the HVAC box and "fitting" aftermarket evaporators and then putting it all back together.
 

Catbox

Full Access Member
Joined
Jul 12, 2018
Posts
4,874
Reaction score
19,038
Location
Just Outside of Portland Oregon
First Name
Peter
Truck Year
1979
Truck Model
C20 Silverado Camper Special
Engine Size
461
We moved a bunch of my sons large items out of storage and into his new house.
Truck Gang stuff.
What is fun is we just parked randomly.
Instead it looks like we organized ourselves in order of height.
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
 

Radiohead

That guy on the Columbia
Joined
Mar 17, 2022
Posts
3,054
Reaction score
9,901
Location
Low Earth Orbit where it's safer
First Name
Eric
Truck Year
MCMLXXIX
Truck Model
C-20 Silverado Camper Special
Engine Size
454 crazy cubes, or 7.4 luscious litres
We moved a bunch of my sons large items out of storage and into his new house.
Truck Gang stuff.
What is fun is we just parked randomly.
Instead it looks like we organized ourselves in order of height.
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
I see the two I won't be loading/unloading.... even if they're parked in the white zone, which is for loading and unloading only.
 

78C10BigTen

Full Access Member
Joined
Apr 12, 2017
Posts
18,029
Reaction score
32,781
Location
pennsylvannia
First Name
Ted
Truck Year
1978
Truck Model
C10 BIG TEN
Engine Size
350
We moved a bunch of my sons large items out of storage and into his new house.
Truck Gang stuff.
What is fun is we just parked randomly.
Instead it looks like we organized ourselves in order of height.
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
Burb looks like it has a drivers side lean...
 
Top