ok....... im haveing a bit of a problem with my heater core.... the hose im useing is way too big for the fitting on the left. yet if i use a smaller one i wont be able to connect it to the radiator. the hose im useing barely stretches over the radiator fitting anyways. i tryed useing teflon tape to make the fitting on the heater core bigger and it worked for a few weeks. but the teflon tape is so slipery i can pull the hose off with little effort. this causes little watter dropplets to squeeze through and get into the interior. this is how my coolant system is set up......

radiator -> intakemanifold/thermostat houseing -> back to radiator through bottom of water pump. that part works fine. then its; intake manifold -> oil cooler(in right tube, out left tube) -> heater core (in right hole, out left hole) -> radiator. originaly this was a tuned port injection engine, but ive converted it to carb and i had to re-route some of the coolant hoses. the hose never used to go straight from the heater core to the radiator though. is there a special conversion peice i can buy that will connect a 1/2 inch hose to a 1/4 hose? or do i have to go back to home depot and create my own useing their plumbing section peices? surely im not the only one whos had this problem am i? how else would this work? do 87 and earlyer f-bodys have smaller rad->heater core fittings or something?

 

ok, ive just discovered something... there is this little canister thing with a round top and a tube comeing down from it with 3 ports sticking out. one is big and 2 are small. one small is pointing in the same direction as the big one and the other small is pointing at a 90 degree angle from the other 2. at the top of the thing, there is a little vacume port. i have a vacume line that goes no where, and comes out of the dash(i think). could this be what controlls my vents? cause i havent figured out how to change from defrost to anything else. its stuck. i rerember hearing a vacume noise when i changed it before. is it possible this thing uses the flow of coolant to create a vacume for the controls? please say yes, this would make so much sense and i would be able to kill 2 birds with one stone here. because its got the perfect fittings. ill still need to go to home depot to buy more hose and clamps. this little device could convert the hose size for me. i just thought it was part of the emmision controls so i took it out. ill try and post a pic of it later. i dont want to "asume" anything here, if any of you guys know for sure what this thing does, please tell me.

 

ok heres the pic

 

that's the hot water valve. it controls when the heater core is on/off. read this thread, i explained all this last week with pictures explaining the theory of how it operates too...

https://www.thirdgen.org/techbb2/sho...hreadid=158114

 

btw, the vacuum comes off a check valve on the back passenger side of the plenum, and it's an air vacuum. there's a pic of the valve too in that thread

 

ok, is it at all possible this vaccume controls the vent setting? because there are several vacume hoses comeing off the heater controls in the dash. do i mabey need this resistance to make a vaccume so i can change it? in theory i understand how it works, but im running a carb now so i dont have something comein out of the uper plenum

 

look at the picture of the check valve in that thread. the check valve is in the engine compartment, (about 4" from the intake plenum on a TPI car, to the right of the "Trans Fill" dipstick. little black cone/cylinder) it goes to the hot water valve and its other output feeds the vacuum controls.

if you don't have it, it's a $4 part at the dealer.

 

here's the one i thought i posted on the other thread...

 

ok, can someone tell me what i need to do to make the vents change, from defrost, to mid section, to feet and whatever else there is..... all i know is on the back of the controlls there are several vacume hoses. and i recall hearing a vacume noise every time i changed it before the conversion. man, sometimes i feel like im the only guy whos ever converted from tpi to carb.....

 

got your PM, but just wanted to answer here in case anyone plans to look at theirs as well. i don't think it's really critical whether you use 1/2" ot 5/8" hoses/fittings. just use whatever's on the valves and radiator.

if the core has a 1/2" and 5/8", then that'll determine which size you T off. just make sure that when the valve is in the off position, the T is before the core, and when it's in the on position, the flow must go through the core. if i remember, the check sends vacuum to HVAC control so vacuum can be applied to the right devices when the control lever on the dash is moved. i have only had the TPI cars, but to check whether the vacuum is on or off with the heater on, put the check valve in, turn the heat control on, and just feel the end of the vac hose going to the HW vavle. then turn the heat lever off, and make sure the opposite happens. (or just stick the HW vavle in and make sure it moves when the lever is moved).

if you have a 1/2" inlet on your radiator, then you can use all the 5/8" hoses you want, but they won't flow any more coolant than 1/2"s, since that last leg of the trip is the limiting factor. if your radiator is a 5/8", then try to use 5/8" when possible, since you'll need slightly less pressure to push the same volume through, which would cause a minimal reduction in strain to your water pump (though nothing to worry about)

anyway, here's a schematic that explains the engine layout. refer to the other thread for the better water flow diagrams and close-up pictures.

 

also, if it wasn't obvious, unless the fittings are different on the core, there's no reason the hoses have to crisscross, i just built it to work with leftovers in the shop (on a friday afternoon) that was flushing my system and didn't realize i'd need the T, so i just went with what we could get. just because i have a 5/8" hose doesn't mean its supposed to be there from the factory, but it will work.

 

If your vents are stuck on one setting, most likely the defroster setting, then vacuum isn't getting to the vacuum motors inside the car. Those motors move some doors to direct airflow depending on what the setting is. I had a problem with mine where I only got airflow from the defroster vents. I bypassed the factory vacuum line and made my own line from the check valve to a valve inside the car that's placed before the motors and controls. It worked.

 

the thing is, none of what im doing has any trace of stock left. its all custom. but im "trying" to rebuild the coolant circuit that was there before. that check valve i thought was emmision related, the hw valve i also thought it was emmision related. do i need both of them hooked up so i will have my controlls back? cause i do have 2 small plastic vacume lines comein out of the dash, but i cant see how these would have a vacume of their own. it probly used a vacume source off the upper plenum right? i USED to have TPI, but it was so long ago that i cant rerember how it was set up and i dont have any pics. i want a set up like you got, but i just dont understand how you can make a 5/8 hose hook up to a 1/2 inch rad fitting. before, i had a 1/2 hose going from the heater core to the rad and it just didnt work, it was too loose. the heater core needs a 5/8. i was thinking there had to be some "right" configuration to make everything fit up like before. thanks for the drawings though, im gona print them out and try to set it up like that with the check valve, hw valve and T-thing. i can probly hook up one of those to the full vacume port comeing off the front of my carb (i think?) hope it doesnt screw up my nice smooth idle though....

 

ok, look, if the core has two 5/8" fittings, than it gets 2 5/8" hoses. if the HW valve has 2 5/8" fittings to the output side, it gets 2 5/8" hoses. if the radiator has a 1/2" fitting, it gets a 1/2" hose. that means you need a T that is a 5/8" straight with a 1/2" side outlet, or a 5/8" T and a fitting to reduce 5/8" to 1/2" to go to the radiator.

i wasn't saying to put the 5/8" hose onto the 1/2" fitting at the radiator, it's just that you have to use whatever hoses fit, and choose the T's and routing to compensate for changes you need to make.

as for the vacuum check valve and HW valve, they both need to be there to control when you want heat or not.

the check valve shoule be able to pull from any vacuum source.

 

ok, besides that, i see on your drawing you have the vac line going from the hw valve to the check valve..... i know 100% my vac line went from the hw valve to the dash, and another one comes out of the dash and went to the check valve. is yours seriously set up like that? i have 2 hard plastic tubes stickin out of my firewall. also, the hoses sound simple, but honestly they dont seem to have the proper fittings i need in any store around here. all i need to do is convert a 5/8 to a 3/4 and no store caries anything i need. i found a plastic 3/4 fitting but some how it wont plug into the hose. both the hose and the fitting say 3/4 on them....... somethins ****ed there...... but yeah... about that vac line....

 

that's probably fine. if you have a long one from the dash to the engine compartment, that should be for the HW valve.

 

ok, i rigged mine up EXACTLY like yours, with the long tube going into the top of the water valve. with this set up i now have no heat at all. i checked the long tube and theres no suction comeing from it or the water valve. im guessing i have to hook up my full vacume port on my carb to the second tube that goes no where? i seriously dont think i even need that check valve. if i do, please tell me why, cuz i cant think of a reason. mabey the other tube needs suction to distribute it to the rest of the controls includeing the water valve tube. what do you think? i can deal with freezing my *** off to work everymorning, but im not sure if ill be able to see out my window. also i noticed another...."relic" sitting on my shelf from the tpi. its this little modual with a plug on the side for some electrical source, and two long small hard plastic tubes comeing out of it. i think the EGR valve had one hose connected to that and the other to the check valve. i dont have an EGR valve port on this manifold so i just left it on the old one. could this modual have something to do with the vacume control? or was that pure emmision related? thats why i think mabey i dont need the check valve. mabey it was just some way of distributeing the vacume to other sources? correct me if im wrong..... its the only way ill learn

 

uh well, i hooked up the full vacume port to the 2nd plastic tube and my heater controls kicked in. but still no hot air. im gona try and either split the vacume 3 ways to open up the valve, bypass it completely or just remove the valve. im starting to wonder if theres any point in haveing it. my car never had problems warming up without that valve, and if it wasnt for that one hose size problem i never would have put the valve in. ill see if i can get some pics of what i have done so far. the only real good thing about all this is that i figured out how to make my vent settings change. i mean seriously... the purpose of this valve seems so minor thats its not even worth the space it takes up in the engine compartment. basicaly ive traded heat for vent control......

 

the short vac hose that "goes nowhere" into the firewall is the feed for the lever controls (a rotary vacuum switch). when that switch is ON, it pulls a vacuum from the long tube (the lever "output"). that will raise the plunger in the HW valve, and circulate coolant through the core, assuming your coolant hoses are set up for a flow.

even without the HW valve hooked up, you should feel a vacuum from the long hose when you have the heater control on and a vacuum on the short hose.

if the control works and you have vacuum to the HW valve, and still no heat, you must have the coolant hoses backwards (T'd in the wrong place)

 

uhh... yeah i think they are in the wrong position. because when i remove the vacume from the water valve my heat kicks in.... man that is a kick in the groin. but it is set up exactly like yours in the pic and on the drawing. exept for one thing, insted of haveing mine go from the middle of the t straight to the radiator, it goes to the oil cooler then to the radiator. that seems pretty efficent if the hot water from the block gets slightly cooled by the heater core, then to the oil cooler where it gets hot again, then to the rad.

 

well, then something about yours must operate differently, either the vacuum is default-on vs default-off, or whatever. anyway, if you move the T to the other hose attached to the core, that should solve it. but check the flow diagrams, or figure out one for your setup.