mjls1

iTrader: (1)

I'm in the process of running heater hoses. I read that a "H" pipe should be put in before the heater vavle so that there is always coolant moving around the t-stat when heater vavle is closed. What is everybody else doing, "H" pipe or no "H" pipe? Issues with or without "H" pipe? Thanks

G-Body

iTrader: (4)

No H pipe in my setup. I drive it everyday and have 11,000+ miles so far. The only thing I have noticed is that the heater does not throw as much heat out as when I had the 305 SBC.

mjls1

iTrader: (1)

Thanks, I read on another forum where someone would close the heater valve so no coolant was flowing through the hoses and motor would start to over heat.

Schitzo

iTrader: (6)

Hi mjls1, how i your camaro coming?
I did not use a H pipe either and never had any problem with my setup. I think I remember seeing the thread where someone was having the problem you described and he cured it with a H pipe. He had the problem because of the HVAC unit he was using.

mjls1

iTrader: (1)

Hi schitzo, I think he had installed a classic auto air unit. I'm using the same a/c set up. Just not sure if I needed "H" pipe or not. I recently got the car running . Started right up. I could not of done it without this board! Now to decide what color to paint it...

LS1RS89

You only need a tee if you have a heater control valve. The valve will shut off the coolant flow through the heater core when the air is on. These are very common pieces in older chevy's even up into the 90's. On the LS1 the t-stat will not get coolant flow over it without heater core flow so a small tee can be used in the heater hoses to allow the coolant to circulate over the stat. I would just not use a heater control valve unless you are running hot with the air on, then the valve ann help a little.

Andy

Andy1

This subject was brought up once before, and I questioned whether the heater valve was a bypass type (keeps coolant flowing back to the water pump when in the closed position). Someone anwered by saying "look at the heater valve." Well, I don't have a late model (98-02) heater valve to see if it is a bypass type. Anyone?

I know the stock thermostat has 4 holes in the diverter to presumably keep some coolant flowing in order for the thermostat to see when the water gets hot. The diverter also is on a spring to presumably bypass incidental high pressure water under higher RPM's when the thermostat is still closed.

Andy1

mjls1

iTrader: (1)

It has the heater control valve and shuts the coolant off to the heater core. I talked to the manufacturer a while back and they said they had no known issues with this problem. But I have read that some are having touble with running hot as soon as shutting the valve. The heater hoses are 5/8". My next question is if I use a "H" pipe, what diameter pipe should be used for the center (cross over) pipe? Smaller like 1/2" or same size 5/8"? Thanks

LS1RS89

I don't have a heater valve so this is second hand information, but from what i have found a 3/8 crossover is all thats needed to keep the coolant flowing. Some have tried larger but had problems with the heater not producing good heat. If it were me I would either eliminate the heater valve all together and run the hoses right from the pump to the core, or use a small 3'8 crossover pipe. Good luck and let me know your results

Andy