1973 LS4 M40 ECS/EGR/TCS/TCS Vacuum Hose hoses

[Gary C.]

Hi,
A friend is restoring his 1973 LS4, manual transmission and is trying to work out the layout and connections for ECS/EGR/TCS/TCS Vacuum Hose hoses and wiring. Does anyone have a layout schematic for this or a detailed photo?

Also his thermostat housing does not have a fitting for the temperature switch. I think it should have one?
Are the switch and correct housing available?
Any help will be greatly appreciated,
Gary
Perth West Australia

[Joe L.]

Re: 1973 LS4 M40 ECS/EGR/TCS/TCS Vacuum Hose hoses

Hi,
A friend is restoring his 1973 LS4, manual transmission and is trying to work out the layout and connections for ECS/EGR/TCS/TCS Vacuum Hose hoses and wiring. Does anyone have a layout schematic for this or a detailed photo?

Also his thermostat housing does not have a fitting for the temperature switch. I think it should have one?
Are the switch and correct housing available?
Any help will be greatly appreciated,
Gary
Perth West Australia

Gary------


All I could suggest with respect to the vacuum hoses would be to refer to the 1973 AIM. Also, Dr. Rebuild's catalogs usually have excellent drawings. Others might have more info.

As far as the thermostat outlet goes, 1973 had no fittings for switches. That began for 1974.

[Gary C.]

Re: 1973 LS4 M40 ECS/EGR/TCS/TCS Vacuum Hose hoses

The JG, 3rd Edition says it should have switch, 6490453 but does not say where it is located and there are no 73 pictures.

[Jimmy P.]

Re: 1973 LS4 M40 ECS/EGR/TCS/TCS Vacuum Hose hoses

Hi Gary,
Here is the expanded view of the close up pic used on page 159 of the 3rd edition. Showing the 73 LS4 Thermostat housing 3972128. The 73's don't have any switch in the housings. Joe is correct. I just sent you a PM with my email address, I'd be more than happy to help you and your friend with photos. If I can't help I'll be happy to put you in touch with a couple 73 LS4 original owners.

Part # 6490453 is the Temperature Switch and it is located in the block on the passenger side on both the small blocks and the LS4's for 73. Here is a photo showing where its located on the 73 LS4. (Green wires attached).

[Gary C.]

Re: 1973 LS4 M40 ECS/EGR/TCS/TCS Vacuum Hose hoses

Thanks very much Jimmy, most appreciated.

[Edward J.]

Re: 1973 LS4 M40 ECS/EGR/TCS/TCS Vacuum Hose hoses

Gary, does the emission label have a vacuum diagram on it for 73?

[Gary C.]

Re: 1973 LS4 M40 ECS/EGR/TCS/TCS Vacuum Hose hoses

Hi Edward,
It has the sticker. Hopefully its correct?
20201009_103039.jpg

[Edward J.]

Re: 1973 LS4 M40 ECS/EGR/TCS/TCS Vacuum Hose hoses

Gary I was thinking that the vacuum routing where on the decal, it must be later.how about googling that engine and year there maybe something that will come up.

[Joe L.]

Re: 1973 LS4 M40 ECS/EGR/TCS/TCS Vacuum Hose hoses

Hi Edward,
It has the sticker. Hopefully its correct?
[ATTACH=CONFIG]101615[/ATTACH]

Gary------


It is the correct emissions label for the application. In fact, it is the only emissions label used for any 1973 with LS-4.

[Joe L.]

Re: 1973 LS4 M40 ECS/EGR/TCS/TCS Vacuum Hose hoses

Gary I was thinking that the vacuum routing where on the decal, it must be later.how about googling that engine and year there maybe something that will come up.

Edward------

Vacuum routing diagram began for 1979. However, it is only a schematic so it does not actually show the actual routing of the various lines.

[Gary C.]

Re: 1973 LS4 M40 ECS/EGR/TCS/TCS Vacuum Hose hoses

No worries thanks Edward, Jimmy is helping us sort it all out.