[twobirds]

guys be careful when you are thinking about installing a highflow waterpump with an original heater core.think about it,now you are pushing a great deal of water,faster and with more pressure through that old heater core, and guess whats going to happen,yep,a pile of antifreeze on your pass. feet.when you install a highflow pump,theres a couple of things you can do to protect it a little,get yourself a piece of round stock about an inch long and drill a 1/4 inch hole in it and install the[3/4 and 5/8] into the hoses,this will let it still circulate through. if by some chance you have already blew out your heater core and you dont want to replace it,here is a little trick that will work for a long time,take both hoses off at the engine,timing cover and intake, go to your local auto parts place and go to the help section,there you will find CORRECT rubber nipples 5/8 and 3/4 and these are for plugging off the heater core. slip those on the outlets of the intake and timing cover and put a little grease of vasaline on the inside of the hoses and trust me, you are going to grunt a little,but they do slip on the hoses.clamp them down and wala.! cant even tell that there is any problem with anything,especially you guys with show cars.

[Pepi]

Good tips and tricks

[Pontirag]

radiator cap determines pressure.
but your warning is a good one.

several years ago i found a NAPA part number for a pontiac heater nipple. it was not located in the catolog where you would normally find cooling/heater system stuff. I had an old school parts counter person who hada fiebird so he knew a bit. he searched for about 20 minutes before he found it. It was pretty pricey at 19 bucks each. I bought 2 and used one and misplaced the other.

what was interesting about it is that it had a bi matellic coil spring that was flat inside it.. it opened when hot enough and when a surge or slug of water came through the heater hose the uncoiled bi matellic spring would be pushed shut to prevent the damge you speak of.

nobody will take the time to look and find it now. too bad. it was an excellent idea.

[hgerhardt]

The original outlet nipple in the RH head had a restrictor built into it, but I suspect most of them are rusted away by now. Also, the heater core inlet nipple was pinched down to restrict the flow somewhat. You can do that yourself if it isn't done already.