LS conversion VA heater plumbing
 

I know this has been addressed before, but I'm wondering what the consensus is in terms of maintaining flow through the heater core loop when the heat is off. Basically are you using a flow through type shut off valve or the VA supplied washing machine valve that stops all flow?

VA valve. If not you'll get heat 100% of the time.

I got that. The question is use a valve that shunts the water flow away from the core, or one that just shuts it off.

Shunts it to where?

Back to the water pump, bypassing the core. E.g. 4 vs 2 port heater control valve. Many OEM applications use the 4 port when flow through the heater core ports is desired. I thought I heard that the LS engines require flow for proper thermostat function.

I am in the process of installing my LS with vintage air too. This has been a concern of mine also. From what I read on other forums people haven't been having trouble. But I am interested to hear what you come up with.

I think he means we've always been told not to block off flow from the ls water pump. Most people who don't run heat have to loop the water pump inlet and outlets heater ports. The vintage air heater block off valve effectively blocks the heater flow. Some late model cars have a by pass when the heater is off but I haven't seen people use them. Like I said I am very interested to hear what you guys think on the matter. This is my first big build and I am always learning something new!

I've done 5 LS cars with VA valve. All have worked fine and continue to work to this day.

Thats good to hear! I was going to go this route and hope for the best.

Keep in mind the small 5/8 nipple on the WP goes to the heater valve and the larger 3/4" fitting returns water to the pump.

I use the Dayco 87616 Small Id Hose to run from the 3/4" WP nipple to the 5/8" VA Heater fitting. The hose is a 5/8" hose the has a 3/4" bell on one end. Hose is 60" long.

Better the using adapters and crap. The 3/4" end is about 6" long. I cut off approx 5"

It's a myth that the heater hose needs to be looped back to the pump if your deleting the heater. I run both of our cars with ports completely blocked with no issue.

It is not a myth and is how the thermostat is designed to operate from the factory. Every single LS equipped car used either a 4 port heater valve or in most cases no heater valve and instead air is diverted in the heater box.

That said the engine will run fine you just might see slightly warmer temps at idle. At higher RPM's the bypass in the thermostat opens so hot engine coolant will flow across the back of the thermostat even if the heater port is blocked.

I made a video about the difference I saw in thermostat behavior with and without flow through the heater hose port.

Edit. The video is long and boring but what you see is that with flow I get a normal cycle of the tsat but with it blocked my car idle temp is 207ish.


http://youtu.be/oxg4dICnCwc

Imo the only thing that your video shows is that your heater core is adding efficiency to your cooling system which is dropping the temps slightly. If your car does not stay at the temp of your thermostat your cooling system is lacking the proper efficiency in some fashion whether it be from airflow, water flow, or the size or efficiency of the radiator. The thermostat is nothing more than a bi-metal spring, it only knows temperature and opens and closes based on that.

You seriously think a vintage air heater core adds that amount of efficiency to an idling motor? A motor that runs under 200* in road course situations I might add. I get that this is a controversial topic. I did a lot of internet searches on it myself and came across tons of threads that seemed split down the middle between folks swearing it makes no difference and folks who saw a difference. I'm one of the ones that saw a difference.

The fact of the matter is that the LS thermostat is on the inlet/supply side and when the thermostat is closed and the heater ports are blocked there isn't any coolant flow across the side of the thermostat that senses temperature.

ETA: When I made that video it was after a radiator swap in which I changed the location of the steam vent from the heater hose return to the radiator. This is the whole reason I explored the issue because after the swap I saw a more pronounced difference in behavior at idle. I've since switched back to having the steam vent plumbed into the heater hose return and the difference in having the heater hose valve open or closed is less pronounced now because even when the heater core is closed there is still some coolant flow across the thermostat sensor from the 1/4" steam line.

X2

I build off road sand rails also and none of the engines that I do have any type of heater ports, either welded shut or drilled, tapped and plugged and never any issues
In the off road community, there are alot of quality engine builders/ suppliers (ie. CBM Motorsports, Turn Key, Redline, etc.) that practice the same method, even in their highend engines and sand rails (engines $20k+, sand rails $180k+)
I am sure that a stock application / system will produce less than acceptable results as compared to a custom aftermarket performance setup, like most of us run
http://www.custombuiltmotors.com/


Now back on topic for OP

I have had no issues running the VA heater valve in various installs
I have adopted the plumbing layout as done by Detroit Speed with regards to VA valve placement and converting the o-ring fittings to a "AN" style

here is a couple pics that I have saved and a video:

https://www.youtube.com/watch?v=283BYw2f0Qc

Hope this helps

Jeff

That looks really clean. Are the VA valves failure prone?

How did you convert the fitting to accept -an style fitting? Or did you just use a -an fitting? I can't find a male o-ring to male an fitting?

I used the o-ring to flare adapters
come in various sizes (ie -6AN to -10AN)

http://nostalgicac.com/fittings-hose...g-adapter.html

Here are a couple pics of plumbing layout on VA unit (one from DSE)

hope this helps
Jeff

thanks! ordered