[Half-Inch Stud]

OK, I bit, so here's my response for STREET/Strip.

First, Are you getting the performance, responsivness, and ping-free operation that you expected? Then determine if your overheat occurs during steady-State Highway cruise, Thermal rise at a stoplight [Idle], or both. If both, you could have anything odd going on from notes threaded above to poor cam timing, or wiped rod bearings.

My problem was a thermal rise at stoplight.
Thus, insufficient airflow.

I researched using 2 electric fans..no good. Clutch fans...no good.
Back to the 5 or 7-Blade GM Flex.
Get the Aluminum Water Pump & Watch the impeller design!
Use fresh donut tubes within the Timing cover.

MEDICINE [see this at the GRove on Sunday]:
1. No more Tranny heat to Radiator cold-side. Parked a finned aluminum Tranny cooler at the passenger inner fender port at the Radiator support.

2. Radiator Shroud [duh], but installed smartly, Spaced the fan blade to be mostly-inside/kinda outside of the shroud and the mech fan blades fill the Shroud hole with minimal clearance [I forget - about 1"?].
Moreso, close-off upper area in front of Radiator from hot engine air recirculating forward [Back-to-Front flow]. Easy to do on GTO's not so easy with Firebirds. I used black headliner material and with nip and tuck got a decent air barrier.

3. Block the Exhaust crossovers. The better you do this [pour molten metal vs steel shim plates] the better the results.

4. Two heads of water meet at the Thermostat housing. One head flows while the other stagnates. That's one hot bank of cylinders. My favorite: Removed the water crossover and replaced it using a Y-connect to upper hose.

[MoJo]

vaccaraj,
A flex fan was the only way I cooled my 72 400 down in my bird. I fought all of the above options to no avail (except the alum radiator). I know it's not correcting the root cause but it keeps it on the road in this Texas heat. I run the stock fan setup in cooler weather.

[vaccaraj]

tonight i installed a water outlet nipple on the back of the left hand cylinder head just like the one thats on the right hand side head(used for the heater core). i then took a piece of 5/8" heater hose and connected the 2 nipples. i refilled the system with pure water. the car ran for about an hour in stop and go traffic and some steady speed driving. the temp. hovered at 185 degrees. i'm pretty satisfied with this. my next step is to take it around town for 2 or 3 hours. if the temp stays at 185, then i'm basically finished with the cooling system.
i'm still considering putting a pusher fan on connected to the brake pedal switch if the temp climbs to the 200 degree range.
thanks for all of your comments guys.
tony
i also put a bottle of water wetter in the system. hopefully it has a corrosion factor to it, because i didnt notice a temperature reduction at all.

[This message has been edited by vaccaraj (edited 08-15-2000).]

[Colorado Bill]

Vaccaraj:
Did you just connect the heads at the back, or did you "T" them into the heater core or the front of the intake? How has the temp been since your last post?

[vaccaraj]

i connected them together. but i'm going to change that. i'm going to run a hose out of each nipple to the front of the intake manifold and tee into one of the ports at the water crossover. there are two ports on my manifold, i use one of them for the temperature gauge. old man taylor, who also writes on these forums, sent me a picture of how he did it on his car. but, he has a victor intake, and he was able to run all of the hoses under his intake. if you get his e-mail address, he probably will send you the picture so you can see how its done.
tony
the temp will still crawl up to 200-210 in hot, stopped traffic. but because of the modifications i've made, the temp comes right down as soon as the car starts moving.
it will run at 185-190. i have a couple of more things that i'm going to do to try and make the cooling system work a little better.

[This message has been edited by vaccaraj (edited 11-07-2000).]

[JSchmitz]

I have to question how much flow you will get by running the lines to the front cross-over. You get flow through the heater core because it goes to the intake side of the pump (ie., pressure differential). I would think the pressure across the block would be pretty even. There is a pressure drop across the thermostat however. I am thinking a "T" in the upper hose, or a bung on the radiator would work. Then have a heater control valve or thermostat to control the flow. Otherwise, you would be bypassing the thermostat when cold. My cooling system is working pretty good. I just need the "icing on the cake". I may try this myself. I will have to wait for hot weather to see if it works.

[Zimtok]

It seems to me that if you are cooling down when the car is moving then it would be one of two things.
1. not enough air is flowing across the radiator when sitting still. Make sure that you have good flow of air across the radiator.

2. The water pump is not circulating enough volumn at a slower speed. Make sure the pump is in good condition and the passage ways are open. if the aluminum casting is coroded and allowing the water to leak back into the pump cavity the pump will not push the volumn of water it needs to cool it down.

These are the two things that change in the cooling system when you start moving down the road.



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A.S.D.Zimtok

[Old Man Taylor]

JSchmitz - I don't understand your point. Tapping into the heater core flow simply recycles hot water. Going through the thermostat cannot be too much of a restriction because that is where all of the return water flows. That is the whole point of the thermostat, to control the flow. I do not see a limitation by plumbing into the manifold water cross over. It returns the hot water the same as the rest of the water from the engine (except the heater). My connection is through a 1/2" pipe fitting. Am I missing your point?

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Jim

[JSchmitz]

I assume that, by running the heater outlets to the front of the engine, you are trying to route this water through the radiator instead of recycling it via the heater core. I was trying to figure out how much coolant would actually flow to the front through those lines. The thermostat provides a restriction that helps pressurize the block. If the pressure at the heater outlets is the same as the pressure at the cross-over (I don't know if it is), there shouldn't be much flow through a line that connects the two. I would like to see your setup. I also may be missing the point. :~) My whole thinking here is, it makes sense to connect both heads and go through the heater core. That way both heads are recirculating, not just one. I started thinking after reading this post that it would be better if that water went through the radiator. I hope this helps my point.

P.S. If you don't mind E-Mail me a picture of your set-up.

[This message has been edited by JSchmitz (edited 11-09-2000).]

[vaccaraj]

you have an even pressure in the cooling system. mine is 15 psi. water goes into the water pump, then pressurizes the block, heads and manifold. and the water will travel the path of least resistance. in the stock set-up, the water goes up in the right head and part of it flows to the intake coss-over. the rest of the water goes out of the nipple to the heater core, then back to the timing cover. the left head, blocked at the rear with a soft plug, has water coming up through it and only flows to the front of the head to the cross-over. obviously at a slower rate than the right head. the hot water stays in the left head longer than the right head because it has only one route in which to leave the head. it seems to me that the left head would run a little hotter than the right head. by putting the extra nipple at the back of the left head and connecting both nipples together provided another path for the water to go. i believe its only a slight circulation, but the water is not staying in the left head any longer than the right now. its better than the old set-up. but after some consideration, i believe running both nipples to the water cross-over would be much better because you're routing the hot water to the t-stat housing and right into the radiator, to be cooled. think of it this way, you have constant flowing water going in the right direction- to the radiator.
if you run from the head to the heater and then to the timing cover, you're recirculating hot water right back into the engine. i dont run my heater because i run the car two maybe three months in the summer.
also, you're right about an air-flow problem. but according to alot of people i've talked to, nunzi romano being the most prominent, say that the early gto's, tempests etc.. have an air flow problem because of the way the front sheet metal is designed. it does restrict air-flow. thats why pontiac ran a rubber air deflector under the car behind the front bumper to direct as much air through the radiator as possible. also, putting anything in front of the radiator (electric fan) could hinder air-flow and make the problem worse.
its also been said that pontiac had a ton of downflow radiators left in 1967, so they continued to install them in the gto's, etc.. the big pontiacs that year got the cross-flow radiator, and some of problems were eliminated.
my water pump is a brand new gm unit with new divider plates. i'm also running a 7" diameter water pump pulley instead of the stock 8" for 1967. water flows real well. i was even thinking about experimenting with an even smaller pulley just to see if it would help.
whatever you guys agree or disagree with, i now have a handle on my cooling system and i'm not afraid of building in more horsepower.
this is long, but i tried answering any quetions from from the last few postings.
tony

[This message has been edited by vaccaraj (edited 11-10-2000).]

[Old Man Taylor]

JSchmitz - What Tony said. I will dig up some pictures and mail them to you.

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Jim