When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Need a definitive answer to a question that the internet has conflicting info on: The car I’m helping to build is a 67 Camaro with a LS3 based stoker. The HVAC system is a vintage air direct fit unit that uses a single Servo Motor controlled shut off valve for the hot coolant input to the heater core. I’ve read in numerous places that the LS engines require constant flow across the heater circuit in the water pump for proper warmup and operation and I’ve also seen people just put caps on the pump inlet/outlet nipples.... If I use the vintage air shutoff valve, I am stopping flow through the heater circuit as the valve has no provision for bypass flow back into the pump.
Given that the valve is a Servo controlled setup that tells me that Vintage is using it to “throttle” the coolant flow to control heater temp (vs just a blend door position) so using some generic bypass valve isn’t going to work as the heat would be all or nothing...
So what’s the bottom line here? Can LS engines have the heater circuit blocked out in real world driving conditions and operate properly?
I have heard that too, but I personally have done it on many occasions with no problems at all. Both my Nova and my '33 Ford have VA units in them and they both have over 100k miles on the swaps, so I'd say it wont be a problem for you.
This topic came up on Pro-Touring.com or Lateral G I can't remember. There are a ton of guys running VA with the solenoid and I haven't heard of any problems. I haven't reached the point to first start-up on my LS3 swap but I have the VA and solenoid as well. Check out also Team Camaro.net
Seems like mountainous/hilly driving needs the constant flow while us low-load flat-landers can get by with a blocked heater circuit. A couple years ago, Stu-Cool had problems over-heating going up long hills where the engine was seeing constant load. IIRC, the thought was the extra loading was causing issues that us flat-landers never see.
I'm using a similar Classic Auto Air (started by ex-V.A. employees I think) set up with an LS3. I simply plumbed a "T" into those heater hoses -- provides a small 1/8" crossover between them. This allows a small amount of flow across the pump at all times as it was designed for. The "T" is small enough that it doesn't interfere with heater operation. It's plumbed into the heater hoses about 6"-8" inches after they leave the t'stat/pump housing. You can see the 4 clamps just to the left of the motor on the passenger side up against the strut tower in the engine shot below.
Thx Jimbo - I scratched my head for a while until I realized that if the "T" was small enough on the bypass, it wouldn't affect the heater operation. Car warms up just like OEM, and heater control is perfect. Footnote thanks to Brian Baskin at Delta Current Control who thought the approach would work too.
Thanks to all that replied! I presented the issue to the car’s owner and he wants to integrate a bypass similar to what Mr. Yount came up with. I found the following and he is getting it ordered for me:
That’s a nice piece! BTW, the tees I used were Dorman bits at Advance Auto - about $6. But they certainly don’t look as elegant.
Well, if it was my car I would have followed you exactly but this is a near six figure Pro-Touring 67 Camaro and the owner expects the parts and workmanship to match. Much higher end than my typical builds.
For anyone else..this will most likely be plug and play if the control systems in the aftermarket AC kit uses servo motors vs steppers. Or you can mount whatever motor on it you need.
I talked to folks at Classic Auto Air about a second htr control valve programmed to work opposite of the main valve. Figured I could plumb into a crossover - when heater valve was closed, the crossover valve would open, and vice versa. But they seemed either unable to comprehend or disinterested.
I talked to folks at Classic Auto Air about a second htr control valve programmed to work opposite of the main valve. Figured I could plumb into a crossover - when heater valve was closed, the crossover valve would open, and vice versa. But they seemed either unable to comprehend or disinterested.
yep...any ideas that are not on a vendors shelf..your pretty much on your own. we used just this single 4-port bypass to satisfy LS requirements, as well as to emulate the temp mixer function on the system we put together. we mounted the air mixer door stepper motor from our control system to that valve. certainly not as efficient/quick as a chambered evap/heater, but functions none the less.
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.
7 Most Reliable High-Performance Engines GM Has Ever Built
Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...
67 Camaro w/LS3 vs vintage air heater valve... 
