over heating issues

[rwcstang 201]

so lately my car has been over heating at idle, during high speeds the car will cool down and stay at the half way mark but the moment im at a stand still it will steadily climb slowly. 

 

I have it set at 14 degrees (when car is hot) at idle when vacuum advanced port is plugged, the vacuum line is actually connected to the port on my holley.  

 

 

this is what I am currently running (cooling wise)

 

180 t-stat

aluminum radiator 3 row

fan shroud

flex a lite mech fan

high vol water pump 

march pulleys

 

motor 

 

392w 195 avenger heads (vic jr head copy cats from FPS solutions)

custom cam (no specs, build sheet is long gone) 

bored .30

hedman long tubes

c4 auto with 2500 stall

 

 

is there something i missed when tuning?in the morning while warming up I can see the temp needle go back in forth but the moment the car is hot it doesnt want to go down. i've looked at the other threads on here but doesn't seem to make a difference.

 

should I be adjusting timing through a manifold vacuum instead or ported vacuum (carb)? is my fan at fault? can i run a stock fan with a clutch?

 

help me obi-wan ur my only hope! lol 

[barnett468 418]

what engine is it?

 

do you have the distributor vacuum port plugged?

 

what is your timing at idle?

 

how long has it been doing this?

 

do you have a radiator shrud

 

if so is your fan around 1.2 way in the shroud.

 

is it more than 1" smaller than the shroud?

[rwcstang 201]

what engine is it? 351w stroked to a 392

 

do you have the distributor vacuum port plugged? yes, I have it plugged when I set timing

 

what is your timing at idle? at idle i have set at 14 degrees, started with 10, idle speed is around 850rpm i have adjusted it to 850-1200rpm but no change, keeps heating up.

 

how long has it been doing this? well when I got this motor built at first the valve seals kept coming off and smoking, I couldnt really drive it to fully test out the car, when I got the valve seals replaced, the car was accidentally hit and had to go to the body shop, until now Im recently working out the bugs. 

 

do you have a radiator shroud? yes I do 20"

 

if so is your fan around 1.2 way in the shroud. I need to check this in the morning its 8:22pm here so i measure that 

 

is it more than 1" smaller than the shroud? will check tomorrow morning and report back to u

I took pics though i doubt it will help u but it should give u an idea of my setup, i measure the fan looks to be a 16 6 blade fan.

 

 

[barnett468 418]

ok,

 

why does it look like the fan belt only touches the top of the water pump pulley?

 

plug your vacuum advance and leave it plugged until further notice

 

reduce the idle as low as possible

 

check the timing

 

advance the timing 4 degrees and see if the rpm increases and if it still runs smooth.

 

if it does, take it for a drove in second gear at 15 mph then floor it fast until 30 mph and see if it hesitates or pings.

 

post results.

 

 

your rad fan is pretty much useless . get one that is 1" to 2" smaller than the shroud opening.

 

you can move your fan to around 3/4" away from the rad until you get another one if you want.

 

if your thermostat is not a high flow one, get a high flow one.

 

if you live where it is doesn't freeze. you can reduce your coolant to 25% coolant and the rest distilled water and add a bottle of water wetter.

[1969_Mach1 333]

The symptoms are indicative of lack of air flow through the radiator at idle and low speeds.  At least from the pictures, and like barnett468 mentioned,  the fan looks fairly small.  Regarding flex fans, my preference is Derale brand over Flex-A-Lite brand.  I've used both.  The Derale seems better made and with no sharp edges.  Plus, on the Derale flex fans the blades are a little thicker material and not razor sharp.  I don't know how true it is, I've read clutch fans will move more air at lower speeds than a flex fan.

 

Like barnett468 mentioned, use a high flow thermostat.  They all look similar, but I've had best luck with Stewart brand high flow thermostats.

[ray1970 88]

At the risk of saying the same thing.

Your fan and shroud combo looks almost useless... 

More fan or less shroud....I would go with the more fan....

[DocWok 30]

As others have mentioned your fan is too small for the shroud you are using.

 

In your first post you mentioned your engine tended to overheat at idle, I know others will disagree but it's a fact that your motor will run cooler at idle if the vacuum advance is connected to a full vacuum advance port.

 

Limit your total vacuum advance to 6 or 8  degrees and try it for yourself first regardless of others who say it won't work.

 

For your combination it may improve things, if not you can always drop back to ported advance.

[barnett468 418]

PORTED VS MANIFOLD VACUUM

 

It is NOT a fact that using manifold vacuum instead of ported vacuum will magically make your engine run cooler, plus t can cause your idle to be eratic . I just finished helping my friend fix his $20,000.00 engine after his stupid engine builder built it improperly and his engine idles best with 22 degrees of mechanical advance AND it instantly starts when he turns the key when it is ice cold even without a choke . You can see and hear it start when it is ice cold in the video below.

 

I tried 24 degrees and it barely idles, and I tried 26 and it won't idle at all, so in his case as with many others I have seen in my 40 years of doing this, if he had a vacuum can and we connected it to manifold vacuum and it only added a few degrees of advance instead of the 10 degrees or more that these cans often add, it would idle like crap or not idle at all . Using ported vac to "over advance" the timing at idle can also cause the idle to be eratic.

 

It is also unscientific to simply plug the distributor into full manifold vacuum without knowing how much timing it adds because it could add anywhere from maybe 2 degrees to 20 degrees of additional advance which is a massively huge range, so how do you determine how much additional vacuum at idle is optimal and will NOT cause some type of problem.

 

Yes, using more timing at idle thru the vacuum can than you can run with the mechanical portion of the distributor can in some cases cause an engine to run cooler and idle BETTER, however some ways to do test this are better than others, and all of them ideally should be done with a timing lite . I have found that the cases that benefit the most from using manifold vacuum are ones where an engine has a radical cam that causes low vacuum at idle, however, the better way to deal with this type of situation is to run the amount of timing at idle that the engine likes the best and f it causes it to turn over too slowly when it reaches operating temp, install a timing retard box that retards the timing during starting.

 

Here's the deal . The more CORRECT thing to do instead of just willy nilly plugging your distributor vac int manifold vac is to set your idle timing AND entire timing curve so it is optimal for your particular engine, and I can tell you exactly how to do this in a way that it will not in any way cause a problem . Once this is done, you can use an ADJUSTABLE vacuum can, SMP part number VC31 or BWD part number V311 and adjust it so it adds around 4 to 6 degrees of additional timing . To do that you use an allen key thru the port and screw the screw in clockwise until it stops then turn it out 5 turns . Out = less advance and In = more advance . You will need to recheck your idle timing with the hose disconnected every time you move the screw . Any more than that can cause problems you don't want, besides, you do not even need the vacuum can . It adds ZERO performance . All it does is "over advance" the timing when the engine is under light load so you can get maybe .3% better mileage, big deal.

 

I have used the method above for around 40 years and it has always served me very well, and as far as I know, I am the only person that has posted this particular info on any site which I have done several times trying to keep people from reducing performance or possibly harming their engine by simply moving the vacuum line from ported to manifold vacuum.

 

Also, if your idle rpm increase noticeably and the engine still runs smoothly and it still turns over easily when it is at operating temp when you increase the timing by 4 degrees as I suggested, the additional 4 degrees of advance will in fact reduce the engines cooling requirements and increase its performance.

 

Now someone may post the highly vaunted and highly inaccurate Chevy paper regarding this issue and say that in the pre smog era, all cars used manifold vacuum.

 

 

FAN CLUTCH

 

Strangely enough, a fan clutch does not fully lock up and spin at the same RPM the water pump pulley does, therefore, a fixed fan will in fact move a little more air than a clutch fan if both setups used the same type blade.

 

 

 

 

.

[rwcstang 201]

sorry for the late response, but i haven't gotten around to diagnosing this, but i did notice when in the morning when its cold, the temps would not rise even after warming up, it would rise slightly but then go back to normal, but when it go hot outside, the temps would rise and not fall. 

 

Currently bought a new thermostat so I will installing that this weekend and will burp the system before I run the Barnetts tests. 

 

also for the shroud, its currently not centered due to the line fittings and lower rad hose so I can't adjust it, maybe its due to the aftermarket radiator? the fan blade is an inch and half away from the lower portion of the shroud and the upper portion is roughly 2" inches, so most likely i have to toss the shroud and go with a bigger fan. also, my water pump reverse rotation not sure if that answers your 1st question barnett. 

[Brian Conway 264]

Sounds like the water pump.

[bosephus 10]

Did you get a reverse rotation fan(to keep it pulling the air rather than pushing) to go with the reverse rotation pump on your serpentine setup?

[rwcstang 201]

so good news!!! 

 

I replaced the thermostat (went with the 180 high performance model), changed temp sensor and burped the system with a kit I bought from amazon, after that the car temp gauge has been in the middle and hasn't moved up as much, it would slightly climb to the middle then go down, I think i still will need to go with a bigger fan and toss the shroud but for now, looks like the issue has been resolved.