[buwalda]

ELK67,
Thought I would offer my thoughts on your coolant temps. Even though you appear to have done everything to optimise your cooling system, outside factors that can get overlooked could be adding to coolant temps. Things like binding brakes, holes in head gaskets blocked with sludge, scale in the water jackets, too much anti freeze [ poor heat conductor ] & INSUFFICIENT initial ignition timing. Not enough initial timing hurts idle cooling. I see you have a RAIII car. That has a reasonable size cam in it, & I think you said you run about 12 -14 initial. If you are not using vacuum advance hooked to manifold vacuum, try advancing the initial to around 26-28 degrees. reset the idle speed & let it idle for awhile. I'll bet it runs cooler & that means you should have vacuum advance hooked up for best idle cooling [ and other benefits ]. Good luck.

[bobbyj1]

I did the divider plate and cast impeller mod as well and gained maybe 10 degrees. All other cooling components are stock. I have the same problem you described with your 67. Temps creep up when stuck in any kind of traffic. I have a Rodney on order as well. I also purchased a pair of cast iron HO exhaust manifolds. I am wondering of the aluminun headers are causing some excess heat in the engine compartment. Once I get the Rodney I will report my results.

Thanks for everyones help

[mc67gtoconv]

Geoff,
Thanks for the tips,but Brakes are not binding,cooling system is clean,I am running a 50/50 mix of glycol prestone and distilled H2O.
As far as the head gasket I don't see any evidence of problems,and I change oil like a baby gets their dipes changed (no sludge).
I am a little hesitant to advance the timing that much,won't that cause pinging and detonation,and I will definately have a hard time starting when engine is hot.
I am going to buy an advance timing light soon and then I will do some tinkering with the total timing.
Yesterday I drove in 80 degree heat and it was humid and I was runnig 215-225,still a little too hot for me.
B.T.W my car is not a ram air 3 but I do have a ram air 3 cm in it.
Vacuume advance is hooked up to the carb and is working good.I may try to go with manifold vacuume,but I want overall temps down that is why I also am waiting on a rodney red aluminum radiator.

[mc67gtoconv]

Bob,
Hi,I will be posting my progress as well when I get the radiator,but I want to give credit to the divider plate mod Idea.
It did help my 67 run cooler by about 5-10 degrees but I need more of a safety margin.

[mc67gtoconv]

Geoff,
Do you have your initial set to 26-28 and do you have trouble starting once your car gets hot?
How about detonation,I don't want to get too far off topic tho (cast impellor).

[PMDRACER]

Sounds like you have two options to try.
1. Hook vacuum advance to manifold vacuum. This will give you advance at idle. Doesn't always work, but something to try.
2. Advance your initial timing. If you need (want) to keep your total (initial + mechanical) timing where it is, you can install a limiter bushing, lighter weights, or you can run heavier springs that will still give the higher total timing, but will delay the curve.

[PMDRACER]

One thing that seems to be overlooked is that just because you don't hear the ping, doesn't mean your engine is not detonating. If the fuel is pre-igniting in the cylinders, not only is this hard on parts, but the engine will run hot.

My suggestion is before anyone goes and does any major changes, such as electric fans and aluminum radiators to at least swap the pump and divider plates as we've been discussing, but to also retard the timing at cruise 2 to 4 degrees and see if it solves the overheating at cruise and highway speeds. An easy way to test is put the heaviest springs on your advance weights you have. Granted you will be down on power during this test, but we're testing for temps, not 1/4 mile E.T.'s.

Yes, it flies in the face of what I and everyone else has been saying - that advancing the timing can bring down temps - but there is still what's called too much of a good thing.

It solved the overheating problem in my wife's '69.

Just my 2 cents.

[mc67gtoconv]

PMDRACER,
I tend to want to keep my initial timing between 8-12 degrees but I am thinking about trying just about anything to get the temp down.
I currently still have my initial at around 12-14 and it does run cooler at idle,but I am concerned about possible unheard detonation so when I get my rodney it may give me the leeway to change my initial.
I have already done the internal housing and divider plate mod on a high vane pump with some success.
Thanks George K.

[mc67gtoconv]

Remember I have a Ram Air 3 cam so my car really wants more timing.
Gotta kinda keep the whole picture in mind,it is a tricky balacing act,but that is the challenge right?

[PMDRACER]

ELK67GTO -

That's what I mean. Use the heaviest springs you have to hold the centrifugal timing as far as possible. Hopefully this will pull back 2-4 degrees of timing at cruise speeds. This way you can leave the initial and vacuum advance alone.
A limiter bushing would do the same thing, but can be a PITA for quick installs for 'testing'.

[aerosmyth]

Hello, newbie aerosmyth here with a cookin 230deg
389 WS motor. Did the home brew '0' clearance
volute (aka Flowkooler) 8 bolt and its still as hot as the days before total professional rebuild. I sketched up a trouble shooting flow chart, which included every item this forum has discussed and it comes down to heat generation must be well below ability of cooling system to reject it at high ambient temps. A lot of factors
of which a few are likely the culprit (wondering
about insulative scale in cooling jackets).

I'll return to recurving timing, richer jetting,
checking the 4 core Harrison coolant tubes (take the top tank off and rodding it out), hi-flow TS
and recheck the diameter match on my home brew
pump. Posiibly restore the original impellor to
plate design at least clearnace.

'Gots ta solve this before drive to MI in July.

Thanks for all the good posts and details.....
staying tuned, aerosmyth

[george kujanski]

Touched on this B4, but one thing I would like to say is when taking data and making measurements, it's important to know if the instrumentation being used is correct; i.e., observing temperature readings and not knowing if the gauge is accurate will lead to chasing ghosts and problems that may not be there.

Not intending to criticize anyone; just bringing the idea to the top. I've been bitten by this B4..got into the habit of verifying a strange reading with a second meter or gauge.

Welcome to the forums aerosmyth, looking forward to your results. Seems like recently several members have reached an impass same as you. Be nice to see if you come up with any new approaches, Summer's here!

George

[grandville455]

I think on some of these applications i am hearing about There is more than just water pump problems,Like timing,pistons in the hole to far ,passages blocked etc.....My grandville had the stamped steel pump before i changed it out with a 1/4 clearance!! never ran hot! Has only a 3 core stock radiator,with a flex steel 19 inch flex fan...Now it has a cast impeller with a 180 super stat and even
days like today when it was over 95 degrees it never went past 190!Idling ,driving etc.JMO

[Malky]

Hey, aerosmyth, it is not enough to just rivet or screw on a front shroud to the impeller. You also need to minimize the clearance between the new front shroud and the pump housing so water cannot short circuit from the pump discharge back outside of the shroud to the pump suction. I am not sure from your post if you did this. And by minimize, typically that means 0.010' to 0.020" gap in the normal pump world. Although in the Pontiac pump world, anywhere from 0.050" to 0.25" seems to work for some people and not others.

[mc67gtoconv]

Grandville,
Now thats what I am shooting for 190,but I would be happy with a range of 190-205 degrees under all driving conditions.

[mc67gtoconv]

areosmyth,
I had a flowcooler,before buying the Napa 58-299 high vane pump that others have had success with after doing the mod to decrease the gap between the vanes and the internal housing.
Now the flowcooler cooled better than another 1/2 high vane 8 bolt that I had installed,but my 3/4 inch high vane pump runs slightly cooler than the flowcooler now that I have done the impellor mod.
Just my experience.
Although I did not try the mod on my flowcooler that I had installed previously I don't see why it would not work.
I just felt the 3/4 inch high vane pump was the way to go. Now if the high vane had a plate welded onto it in addition to the clearance mod maybe it would work even better.
Anyone with the expertise opinions please?

[aerosmyth]

Malky, I could get long winded, but suffice to say that the clearance to the back divider
plate is the head height of the button head
screws (~.065 for a 4-40) + .010 to .020. I formed a zinc metal bead around the two divider
plates, creating a tight seal to the interior
timing cover and effectively tilting the top
back out to become a uniform clearance to the
water wheel. Does it help..not really

I do not know if this actually helps so Im back to square 1 per my earlier post to go through
the equation of generate less heat and improve
cooling through as many techniques as possible.

Any chance Ross dished pistons (11 cc), zero
decked block (035 head gasket) with 093 (closed)
heads creates this extreme heat inneficiency at
calculated 9.8 CR. She runs great..just cooks.

Have I missed a post where an actual Pontiac
combustion and or thermal management engineer
has stated the problem we face and how to solve?

I am going to solve this!! And will post results.

aerosmyth, Eau Claire, WI

[buwalda]

ELK67GTO,
To answer your questions, I have 36 degrees initial advance, & no, my car is not hard to start. That is because the initial static timing is 12 degrees & once the engine fires, the vacuum advance which is connected to full manifold vacuum, adds the remaing 24 degrees. The starter only sees 12 degrees initial. The amount of total initial depends on a few things, but the cam duration plays a major part & I have a fair size cam. When I had a smaller cam, I only ran 28 initial.
The original suggestion I made to you to try 26-28 initial, was to let the engine sit in your driveway & idle & watch what the temp does. My bet is it will run ALOT cooler than it has been. If you find that helps, then it shows your engine could use additional timing at idle, & the method to have that extra timing & NOT have difficult starting is to use manifold connected vacuum advance.
My engine has been running like this for 3 years & only gets stronger.
I recently modified a Pontiac dist to fit a friend's 440 Chrysler, because Crane has stopped making the adjustable vacuum advance for B/B Chryslers, & he saw how much improvement the vac adv made on my engine & wanted the same. Since fitting the Delco dist to his Dodge, his engine idles smoother with more vacuum, runs cooler, has better throttle rsponse & better mileage. His engine runs with 32 initial [ 12 static initial + 20 from vac adv ].

[buwalda]

ELK67GTO,
I should have added to the prievious post that my GTO [1966 ] came STOCK with manifold connected vacuum advance, which provided 20 crank degrees [ 6 initial ]. So at idle, it had 26 degrees from the factory! And that was with a mild 067 cam that has around 200 @ 050 duration, 10.75:1 comp ratio & closed chamber heads. Later engines had lower comp ratio & open chamber heads, both of which require more timing. The only reason Pontiac dropped manifold vacuum & went to ported vacuum advance later in the 60's was that ported was better for emissions [ but nothing else ].

[mc67gtoconv]

Geoff,
Thank you for explaining exactly what you meant,I have a mallory unilite distributor with the vacuum advance and I will have to look into if it is adjustable. I know I have 24* of mechanical advance.
I am also seriously considering changing to manifold vac for the vacuum advance and I may play around with the springs,I have never had to alter anything but the static timing before so this is a little new to me.
It is going to be close to 90 today so I am willing to try some different things.
Emissions are not a problem here in IL, so I am open to suggestions.
http://www.centuryperformance.com/default.asp
The above site has some good information on timing.