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"