Hey Guys, couple questions for you, first off what are most of your guys 400's running for temp cruising around? I have a 68 400 4 Spd and cruising around down the road around 60 its always between 195-205 depending on outside temp, 205 is the hottest it will get moving at speed, if its real hot outside and I'm idling or barely moving through town it will slowly climb up to 210 maybe 215, but in those instances if I park and shut it off the temp gauge will climb and climb which I know is normal to an extent because the engine is hot and nothing is moving, but sometimes it will go up to like 230 maybe even 240 and push a bit of coolant out before it starts going down, start it up and get it circulating and it will go back under 220-215 rather quickly, but shut it down and will climb right up for a period of time, just curious as to this being normal, and if that's hot enough to cause damage? What could a guy do to help it?

Been reading up on the water pump mod that I've seen on several forums, does that apply to the 8 bolt pumps? Not that it will help after engine is shut off, but if it will help keep it a hair cooler while running I'd like to give it a shot.

Thanks in advance!

What thermostat do you have in there? Factory or aftermarket gauge?

Your running temperature is normal so I don't think make water pump changes will help you. At idle it may be getting a little hot. May check the thermostat that it is opening at the correct temperature and you have a good 16lb radiator cap. Keep your fluid 2in from the top so it has room to expand. You can verify your timing and air/fuel mixture is good. They can cause over heating but since running is good, they are probably fine.

I use the flow kooler water pump. It has been good.

I believe there is a 160-165 thermostat in there, and the gauge is a new Auto Meter. It stays right around that 200 mark driving around even on the hottest days, so it seems as though everything is working as should, but turn that key off and it really climbs. Maybe that’s normal, 230-240 seems hot, but maybe not?

Seems to me that if the temp is consistently that much higher than the thermostat is rated, your cooling system is working at its full capacity. (Doing all that it can.) What is its condition? How old is the rad? How old is the thermo? An old rad might look ok but have lost much of its cooling capacity from minerals and crud stuck inside. I run the 11 bolt water pump and have seen in the past that corrosion on the center steel plates/seals can reduce circulation.
Also, where is your temp sending unit? Stock location? Is the fan shroud intact, mounted correctly? What fan do you run?
Drove all my Ponchos in Phx heat for many years and these are some of the things that come to mind.
Best of luck,
Ron

!

It’s a brand new rad out of Classic Industries, stock size and what not, with original fan shroud I believe? Is there supposed to be 1” gaps between the shroud and rad on sides? Had the stock 19” flex fan with stock 2 1/2 spacer, talked to Flex a lite and ended up ordering a 6 blade 18 3/8” Nylon Fan from them, haven’t been able to try it yet, said the blades won’t flex and it moves a lot of air.
Sending unit is right in front/top of performer intake!

That 1" space you mentioned between shroud and radiator could allow air to be pulled past the radiator instead of though it. How did it fit on the old rad?

It's all about flow. Flow of the water; capture the heat from the engine thru to the rad. Flow of the air; reject the heat from the rad.

If your water pump is not pumping properly, then you cannot reject the heat from the engine fast enough to keep the engine cool.
If your fan does not suck the air thru the rad, then you cannot reject the heat from the engine fast enough to keep the engine cool.

Flex fans and clutch fans are designed to maximize heat rejection from the rad when car is low rpms (car stopped). Once car is moving you don't need the fan to draw out the heat, the incoming air will do that. Therefore, these fans can be more provide better performance.

Have a look at this thread in regards to flex fans https://firstgenfirebird.org/forums...gus68+%2Bflex&Search=true#Post269319. I would go with a flex fan for your car. I put one in and it was amazing how cool it kept my engine. My engine use to overheat and I would have trouble restarting it. Make sure you have a fan shroud and installed properly.

Thermostats are installed on your car for heating. Cold winters...then get a high temp t-stat. Warm winters and summers then get a lower temp t-stat. Basically what it does is opens the valve to the rad from the engine in order to cool the engine. When engine running hot in summer you want it to open at lower temperature so it has more time to cool the system before she gets to hot. In winter you want it to stay closed longer so the heat can build up in the engine to transfer heat to heater core (warm the car).

The only thing bad about a thermostat is you don't want it to get stuck closed or partially open. That will lead to your engine overheating.

In a predominately warm environment you can consider leaving the thermostat out of the engine. You don't need it in summer.

When you engine is at operating temp, put your hand on the top rad hose. If it's hot the thermostat is working and is open. Otherwise, it's restricting the flow to the rad.

Not really sure, the car was in pieces when purchased, radiator looked real rough, so just ordered one through Classic that was supposed to be the same as original. Shroud bolted right on and looks to fit well with fan and everything, just there is a 1” gap on sides, top and bottom are tight. Have the original 19” flex fan with original 2 1/2” spacer and looks to fit real nice in shroud, approx 1” around blade tips and shroud and sits about half way in.

That is not the original shroud mounting set up. It looks like if you removed the 2 "fabricated" brackets on the top and replaced them with the factory one, the shroud would slide forward to fit tight against the rradiator. Can't quite see what's going on at the bottom in the photos. I use a stock solid (HO/non AC) fan and have found that the stock fan and shroud (mounted correctly) move an amazing amount of air through the radiator.
Will make a huge difference, I'd start there.

Wouldn't happen to have pics of what the original shroud mounts look like?

My 69 is still in paint shop so it may be a day or two before I can get a picture. Look at the two holes on the top center of the shroud and the two holes on the top center of the core support (engine side) that's where it mounts. There is only one mount at the top of the radiator.

Here is a couple.

By the way, none of the numbers you mention are too hot.

Should be no gap between shroud and radiator core.
Pick also shows fan to far into shroud. That will cause air to spin around inside instead of though.
Remove the upper spacers and any on bottom. Remount shroud like pic above.
I use a 19.75 inch flex fan with 175 & 185 stats depending on summer heat. Runs quicker times and gets better fuel milage when temp is at 190*-200* Haven't had any problems at 550hp @ 6200 rpm.
One thing worked best on mine is to have blades 1/3rd outside of the shroud on install. They will flex back straight up into the opening while engine is running.
That should take care of problem.

Thanks for the pics guys, appreciate it. I see Ames sells the bracket on top center that mine is missing, and they also sell some for the bottom, anyone happen to have pics of what that’s suppose to look like? Probably a tough spot to get pics though. Mine is mounted the same way on bottom as it is on top.

My 400/468, 500+hp engine runs cooler with a 185* thermostat. I only run above 200* if I'm stuck in traffic. When I had the 165* thermostat installed, it ran hotter. I think the 185* 'stat keeps the coolant in the rad a little longer...

Ordering the front upper shroud bracket from Ames to get my Shroud closer to the radiator like its supposed to be. I see they also have these two pieces, anyone have pics or diagram of how they go? Cant really tell by crawling under car.
https://secure.amesperf.com/qilan/Detail_Web?part_num=FP315K&order_number_e=NDU5MDExMA%3D%3D%0A&web_access=Y

https://secure.amesperf.com/qilan/Detail_Web?part_num=FP315N&order_number_e=NDU5MDExMA%3D%3D%0A&web_access=Y

Our's run consistently 185-200 w/stock 5 blade flex and stock radiator shroud. We've also done the water pump mod.

However, we get vapor lock if driven 10 miles or 100 miles if it sits after parking.

Lived with cracking the hood a few inches when we park to let heat sink escape.

Attributing it to different fuel than these were intended for 50 years ago.

Yup
The fuel absolutely is garbage
It boils and vaporized in my fuel lines and carb to the point that it would take a full minute of cranking for it to start after parking it when it's above 90 degrees here.

Forget about the car ... 90 degrees outside ... I start melting at that temp! My operating range is -40F to +80F lol

I'm having the same problem when it's over 80 or more, I started another thread, along with the fuel I'm thinking it's also the engine design with the exhaust cross over, it's pretty open and I'm thinking Pontiac V8 intakes get much hotter than others, great for cold weather driving but.....tossing around cool can or electric fuel pump, crossover blocking gaskets, ???

I put in race gas not for the higher octane rating but it's ethanol free. No hot start problems anymore

Ordered the top center bracket from Ames and removed the brackets that were on the radiator. Anyone know how/where these clips all go and what the correct bolts look like?

Snap the nuts /w clips unto the steel mounting plate. Be sure to have the nuts on the correct side (see pics).

Thanks Gus, that’s kinda how I thought they should go, but they didn’t slide up all the way, I’ll just have to grind a bit off the bracket to get them slid up and matched with holes.

The clips can be found locally (NAPA). Take the piece over there and see if there is a better nut clip that will fit better.