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Old 09-10-2011, 07:17 PM
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1969 Firebird Engine Cooling Questions

I have a 95% stock 1969 Firebird. Its a 350 2bbl, no AC. Initial timing is set to 9 degrees. C.R. is 9.2 to 1. I run 91 Octane. I switched out the stock 4 blade for flex fan. I live in SoCal, avg temp outside is 75 degrees everyday.
Back in Oregon, I had a leaky rad, but it wasn't a big deal, just a drip drip drip, check it once a week and top it off. I began to have problems about 2 months ago when I moved down to California. Temps in traffic went up to about 230. Replaced the old rad with a summit aluminium rad, but I was still having higher than normal temps. Discussed it with my friend. He thought my water pump was dieing because it stayed at 190 at 65mph but soared to 215 at idle. I investigated the water pump and it turned out that the weep hole was weeping. I replaced my water pump with a refurbished one from Carquest. In the process I also replaced the thermostat with a new 180 degree one. My temp gauge happened to go out yesterday and so I got a new one today. My temps today are not as low when I got the car about 2 years ago. It used to be that the FB never went over 200 except when I crossed over Mt. Hood and that was with the 4 blade fan. Today the Firebird idles at 200-205, 40 mph stop light to stop light is 190-200, and cruising speed is 188-192. Are these temps within range for 105,000 mile 69? What is the procedure to make sure that my head gaskets are intact? What effect does the ratio of coolant to water have on water temp? Thanks for reading all this.

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Old 09-10-2011, 08:50 PM
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Your temps are not too high, but you do have room for improvement.

Coolant mix should be 50/50. If you have more coolant than water, it will lower the boiling point of the mix. At 50/50 and 15lb radiator cap, boil point will be 260*-265*

Do you have a fan shround in place. If not, get one.

Your fan blade is not pulling enough air thru the radiator. Get a 6 or 7 blade type factory fan, install so that it is as close to the radiator as possible if you dont have a shroud.
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Old 09-10-2011, 10:44 PM
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Pontiacs have some issues to check when dealing with cooling....I'm assuming your 69 has the 11 bolt pump?

1. check the waterpump being used has the correct cast iron style impellor - the pressed metal impellors found on some replacement parts are not particularly efficient.

2. ensure the divider plate has been checked for the clearance between the back of the impellor and the hole in the divider plate - .025-.040" should be the range of clearance with a gasket between the divider plate and the pump.

3. ensure the transfer tubes in the timing cover are intact and not corroded and leaking water internally within the timing cover - ie, pressure to suction side.

4. run a 160-180 thermostat in summer.

5. ensure the lower radiator hose has a spring inside it to stop the hose collapsing from suction.

6. run a radiator shroud - I'm not impressed by flex fans, if you don't want to convert to a quality shroud mounted electric fan and controller (Derale is good) then I'd run a 5 blade factory fan with a new clutch hub.

Hope these ideas help out....been playing with Pontiac V8s for some years in my Trans Ams and Firebirds.
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Old 09-11-2011, 09:08 AM
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I've got a fan shroud.
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Old 09-11-2011, 09:10 AM
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replace your timing chain and gears. with that many miles on it, they are wore out. nothing will keep that motor timed right.
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