Well, I am back again. Since my last post, I have installed a new 4 core radiator, removed the thermostat, installed a high flow water pump, and I am still running at 200 degrees going down the highway at 65ph.

Does anyone know if the Head 6272292 will work on the 1971 402 block that I have in my 1967 Chevelle SS?? Don't know if the cooling ports on this head will match up with the block or not. I am starting to grasp at straws here. How about a leak in the head gasket or something like that. I have not ran a pressure test on the radiator, need to go buy a tester for that. Not sure if that would cause the temp to be so high or not.

It also seems to not idle very well when it gets up to the 200 degree mark. I really need to bring it somewhere to get the carb checked out. I set the idle mixture screws as someone had instructed on this forum a while back.

Any insight that you may have would be useful. I will include my previous post below for more background information.

Thanks to all.

Kevan

(Old Post from a week ago)

I have a 1967 SS that I recently purchased. It has rebuilt 402 in it that is mildy rebuilt over stock. This car has vintage air in it and also a transmission cooler inbetween the Radiator and the condenser.

I was driving the car last weekend and it was about 82 degrees out. The car at a cruising speed of 65mph gets to around 215 degrees(with the air off). This seems hot to me, more than it should be. It has a 180 degree thermostat in it(stock style) and also has a 4 core radiator(25" by 22",original era I think). I have added a overflow tank and a 16lb radiator cap. It has twin electric fans mounted on radiator that seem to move a lot of air. The car is timed to 16 degrees BTDC initial and a final of 34 BTDC. The sending unit is located in on the front of the intake manifold as well.

This car has a TH 400 with 2:73 rear end gears(Next thing to change), so the RPM at 65mph is quite low.

I have ordered a new 4 core radiator, I have a new GMB high performance water pump on order as well, and I put in a high performance Mr. Gasket 180 degree thermostat. I also plan on removing the Trans cooler and hooking it up to the bottom of the new radiator. I hope this helps as well.

I was wondering if anyone out there knows what temp should this car run at if it is cooling properly?? Also, will the changes drop the temp??

I appreciate any info and help.

Thanks

Kevan

34 degrees total? seems a bit low for a big block unless have some high Zoot modern combustion chambers.
Out of curiosity have you advanced the timing a bit more?
38 or a bit more might help.
Also are you running factory ratio pulleys?

If you had a 180 stat, it should run at 180. I was running into the same problems as you, check and make sure that all the air is going through the radiator and not over. Also if you can put a mechanical fan on. I had 1 3/4" between my water pump pulley and the radiator. I was able to squeeze a stock style 7 blade flex fan, and I never get above my 160 thermostat

I have not tried more advance on the timing, but I can try that to see if it makes a difference. I have no idea on the pulleys, if they are stock of not. There is a 3 groove on the harmonic balancer, a 3 groove on the water pump, and a 2 goove on the power steering pump. All belts are tight and in line.

The heads I just looked up are a oval port 113cc heads from 1971, at least the casting numbers were referred to on a couple of web sites.

Thanks for the help.

Kevan

Do you also have a fan shroud on yours?? I will measure how much room I have. I don't Think it is as much as you do. My pully is about 1/2 inch away from the electric fam that is on there now.

Thanks

Kevan

Kevan,
Have you actually checked to see if the temperature gauge is correct ? Either borrow and infrared heat gun and point it at the sender and see what it says, or buy a cheap mechanical gauge and put it in temporarily as a test. You can check the mechanical gauge by putting it in a pot of boiling water, should read pretty close to 212.

Until you actually verify the gauge reading, you may just be wasting a lot of time and money :(

Do you also have a fan shroud on yours?? I will measure how much room I have. I don't Think it is as much as you do. My pully is about 1/2 inch away from the electric fam that is on there now.

Thanks

Kevan

nope no shroud, these are some of the best mechanical fans I have ever seen, it will suck a shop rag to the grill! I left my electric fan on the other side of the radiator thinking if and when I overheat I'll just kick it on and be cool. I haven't had to use it yet. I've purposely got caught in stop and go traffic and never overheat. I'm soooooo excited that I don't overheat

I have not checked the gauge. It sure seems like it is getting that hot in the engine compartment.

Kevan

When you fill the rad, make sure that you get all the air bubbles out of the cooling system. Jack the front of the car up, so that the radiator fill is the highest point and fill. You might have an air bubble in the system,

IMHO, the car is not driving you nuts, you're driving yourself nuts. 200 is a perfectly acceptable temp, you're chasing your tail on this.

Where do guys get this deal that the car needs to run 180 or 160 or whatever? This like that stuff where guys think they have to have 60lbs oil pressure at hot idle. What for?

What do you think you're going to gain by having it run 180 or whatever? That's hardly hot enough to drive off the water and condensation in the crankcase.

We're not in the 60's anymore, y'know?

What really matters is that the temp is stable, doesn't keep getting hotter as you drive until it's up to 250 and you have to shut it off. Modern cars don't even turn the electric fans on till 230, that's a normal operating temp.

Tom, thanks for your feedback.

The reason I am concerned is for when I want to take the car out on a 90 degree plus day. I am sure it would get up to that 230 range.. I just want to make sure that with the Air on, on a hot summer day, I will not have any problems. Any car that I have had in the past ran at a cooler temperature than this one.

Thanks all for the feedback.

Kevan

Do you also have a fan shroud on yours??

If you don't see if you can match one up, they can make a huge difference!

Have you tried running without a thermostat to see what it does?

Ripping out the thermostat is NOT the cure.

Chevrolet--and every other manufacturer--built approximately eleventy-billion autos that had 195 thermostats. They sold 'em to little old ladies who couldn't see over the steering wheel and never drove faster than 5-under the residential speed limit; and left the thing idling at the grocery store while they shopped. They sold 'em to folks who punched an 80-mile-per-hour hole in the wind while towing a thousand pounds--or more--of trailer. A properly-functioning thermostat is NOT the cause of overheating. REMOVING a properly-functioning thermostat is NOT a proper repair for overheating.

I know that but the thought was just to test, maybe he needs a Hiflow therm.
OhOh here we go again water going too fast won't give it enough time to cool.:Dl:)

Oopps!! I see he already did that.:o

I read this when first posted and wanted to see what the responces are, pretty close to what I expected;
1: Is this just parania? Over 200 is not a problem
2: I don't trust those elec fans. My 454 with 9 blade 19" I think it is at a 700 RPM idle there is so much wind I have to wear safty goggles to use the timing light, "suck a rag to the radiator" is woosy! Forget "flex fan" unless you want 1/2 the wind and tripple the noise of a stock setup. Go get the correct big block fan & clutch and shroud.
3: Advance the ignition until it pings, then put a timing light on it, see where it is & back up a couple degrees. Check when the vac is doing what and where the centrificle is doing its thing, goal 1 should be centrificle does nothing until 1000RPM then is full in by 2800. Vac should pull timing back at 2" of vec below idle level. Total all in should be no less than 38 but the number that works is very dependant on your cam & compression. I was shocked by how much mine will take but it has Edelbrock heads and a Hyd roller, is very happy at 60 degree total but if yours is a stock cam it will not go there.

Mine is a 350 conversion so does not have the big radiator, has a 180 thermostat and has not seen 200F but that fan will almost pull the car down the road! Maybe I should put a 195 in it and get better mileage?

I installed a 6 blade flex fan today and removed the electric fan. It is 81 degrees out and while driving in town with the Air conditioning on, it went as high as 200 degrees. On the road at 70 mph, it went down to 190. I may look at putting a factory Big Block fan and clutch in the future.

I think I have it fixed now. Thanks to all of you for your help and advice.

Kevan

Kevan,if you go with a gm bbc clutch fan #772 that has 7 blades or a fan like it use this fan clutch thats correct for your ac application from Napa pt# 271303 - H/D or Haydens -2747 H/d.

BTW,it didnt surprise me at all that the elec fans were part of the heating up problems with your setup.

The elec fans do have their place/use like with big perf motors with maybe 489/496/500cid & more running lrg AL rads to keep them cool . But for stock to mild street perf the stock gm setups will work very well "when setup correctly" with proper ign timing when running a perf cam/run a vac adv/use high quality h/d fan clutch /gm's 772 7 blade clutch fan/stock fan shroud/hi flow w-pump & hi flow 180 deg stat/proper fuel calibration that's not too lean/ & good 3-4 core stock type rad "which are the key items to get right".


Scott

Scott,

Thanks for the advice and the part numbers. I will stop by Napa on Monday and order what you recomended. I will also put in the Mr Gasket 180 degree thermostat that I took out earlier in this operation. I will have to order the fan shroud from either year one or SS396, I doubt that Napa will have that.

At least it is all new now, the Radiator, High flow water pump, Thermostat. ($600.00 later) Wish I would have tried this before I went thru all the headaches.

Do you know how much room will be needed for the Fan and the fan clutch you recomended?? I have about 2 3/4 inches of clearence between the fron of the pulley on the water pump to the Radiator.

Thanks again for the help Scott.

Kevan

I also have a 71 402 in my 67. My engine has only been running for 2 days, but seems to max out at around 190 deg. I have a short water pump and 7 blade fan. No shroud installed, but I do have one. Currently my thermostat is removed, because it was defective, but will probably be installed tomorrow. Running headers with Pypes 'X' exhaust.

Have you considered that maybe the temp gauge is out of calibration? Not sure if it even can happen, but just a thought. Maybe borrow another and hook it up just to be sure

I installed a 6 blade flex fan today and removed the electric fan. It is 81 degrees out and while driving in town with the Air conditioning on, it went as high as 200 degrees. On the road at 70 mph, it went down to 190. I may look at putting a factory Big Block fan and clutch in the future.

I think I have it fixed now. Thanks to all of you for your help and advice.

Kevan
this tells me it's an airflow problem. you need more airflow from your fans, and a good shroud to make sure it only pulls air thru the core.
and as someone already said, make sure that all the air that goes thru the grille at speed gets rammed thru the radiator and doesn't flow around it. if necessary, add a chin spoiler like can be found on every G body built from 78-88. it simply bolts to the bottom of the radiator support and keeps air from going under the car- which create a low pressure area under the hood that causes more of the high pressure air being pushed in front of the car to go thru the rad core and taking away heat.
also, adding more ignition lead is a good idea, as well as hooking the vacuum advance to full manifold vacuum.

Dont forget to test that 180deg stat in a pot of hot water to see if its opening at 180 deg becasue lately the mr gasket stats have had some issues .

If you find its not working well try a robert shaw stat from sunmmit.

Lastly,if your running the long w/pump in your 67 it can be an issue,you need to get a short pump and the correct slightly shorter hd/ac fan clutch too.

The fan clutch pt#'s i gave you were for the 71 motor your running that comes with a long pump so it my or may not clear . But with a short pump the long fan clutch pt#'s i gave may clear but with a long pump the long pump fan clutch PT#'s i gave you will likely not clear so keep this i mind when ordering a fan clutch frm napa.

But whatever you do spend the few additonal $ to get the hd/ac type fan clutch that will cool better esp in traffic.

And yes he did have an airflow issue,the dual elec fans were blocking some airflow and the mechanical flex fan also pulled more air thur rad. so with more airflow avail with the dual elec fans removed along with the flex fan installed its no wonder the temps dropped some. The dual elec fans were blocking some airflow and were not doing a good enough job of moving air when they were turned on which can happen at times with elec fans on some setups,they dont always work well in all cases,period.

scott

1) 200 degrees is not that hot...if it never goes higher than 200, don't worry
2) Always run a thermostat
3) If you're using a belt-driven fan, a stock fan & clutch set up is the only way to go

>> "I installed a 6 blade flex fan today...."

those flex fans are not recommended, they have long-standing and well-known issues with pitching blades. I personally was almost beheaded by one. There's also issues with the blades flattening out at RPM, like have a round piece of plywood for a fan. Checking the thread, I'm glad the guys here didn't give that advice.

All,

I am persuing trying to find the pulleys and brackets for my engine to mount a short water pump, alternator, pwr steering pump, and air conditioning pump up with a short water pump. I am having difficulties finding all the pieces at a reasonable cost, but hopefully I will find all that I need and then I will install the H/D clutch with a standard 7 blade 772 fan.

If anyone knows where to get these parts, I would appreciate that info.

Thanks for all the help. You guys are great!!!

Kevan

i always like to read about these kinda problems and how alot of folks over compensate on the cooling systems because there are problems elsewhere.

not once was it mentioned about timing at cruise and fuel.

retarded timing and lean conditions are the most over looked areas in the cooling system and if your having problems keeping a car cool at 70 mph it sure is not lack of air flow thru the radiator unless you have it blocked off with cardboard.

engines getting hot at these speed you should be looking at the engine having enough ignition lead time and enough fuel at cruise.

you run retarded timing and a lean motor it will get nothing but hotter.

and what do most folks do? start reaching for the high end radiators, high flow water pumps, electric fans and so on.

i have been running several bbc thru the years on the street with stock style 3 row radiators and stock 17 dollar water pumps and stock fans and shrouds and my stuff sits and idles for long periods of time not getting over 180 and can be driven anywhere with no fear of over heating.

:yes:

Stewart Stage One high-flow pump....... :D .........works for me.