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AMunro327 Offline
#1 Posted : Sunday, 9 December 2012 8:25:37 PM(UTC)
AMunro327

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Having some problems keeping my HK 307 cool. It's not too bad when travelling, but quickly gets hot as soon as the car stops. I've tried most of the usual things to cure overheating, but to no avail so far. Don't really want to go down the thermo fan road, but now willing to try anything.
I've heard that the AU Falcon thermo fan assay fits neatly on a HK V8 radiator and does the job of keeping the engine cool.
Just wondering if anyone has had first hand experience with the AU fan set up.
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#2 Posted : Sunday, 9 December 2012 9:14:56 PM(UTC)
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Sounds like there must be a problem somewhere. If its a standard engine and your cooling systems in good order it should not have overheating issues. I would be looking a bit deeper for the cause before going down the thermo fan path. Somethings to check. Is engine running too lean, is the timing correct, it should have the original fan shroud to help draw air, try putting in new thermostat, does radiator and engine need a flush, Is fan belt loose, is water pump buggered, does it have original correct fan, does it have correct pressure radiator cap.

Edited by user Sunday, 9 December 2012 9:32:26 PM(UTC)  | Reason: Not specified

j.williams
AMunro327 Offline
#3 Posted : Sunday, 9 December 2012 9:53:03 PM(UTC)
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I agree, shouldn't have to go to thermo's, but need to do something. Situation is.......
* Reco'd 307 + 40 thou, Edelbrock alloy heads. about 9:1 compression.
* Thermostat removed until this problem is sorted.
* Timing is 12 degree at idle (a little advanced but it doesn't ping), mixture is OK.
* Pumped 140 lb into each cylinder, no leaks into coolant.
* Camera inserted down thermostat hole to ensure head to manifold openings are OK
* New 3 core Adrad radiator.
* Added a capillary temp guage to check against original electric.
* New water pump. Remove top hose from radiator (thermostat removed) and get a good gush of water when engine started.
* Added a Davies Craig electric pump in bottom hose as bandaid solution.
* Extended the shroud and fitted an 18" 7 blade fan on viscous hub.
* Only other thing I haven't done is to remove the air con condenser and try it, but there are millions of cars running condensers, so can't see how this can be the cause.

Edited by user Sunday, 9 December 2012 10:04:31 PM(UTC)  | Reason: Not specified

Dr Terry Offline
#4 Posted : Sunday, 9 December 2012 9:58:37 PM(UTC)
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HGV8 is correct, unless something is wrong, it shouldn't overheat.

My guess is that the radiator shroud is missing or the radiator itself needs a good clean out.

On the tuning side, if you have a non-standard camshaft fitted you will need an increase in radiator size, to make up for the loss in engine efficiency at low RPM.

Other things to check are the base ignition timing & also to make sure that the vacuum advance is functioning properly.

If in doubt. see a pro who has good experience with stock 'old school' engines. Don't just cover the problem up with extra fans etc. These put extra load on the electrics meaning a larger alternator is required @ extra $$$.

Dr Terry
If at first you don't succeed, just call it Version 1.0
Dr Terry Offline
#5 Posted : Sunday, 9 December 2012 10:02:02 PM(UTC)
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Your second post came thru as I was writing a reply to your first one.

You now mention air cond. If your car has (or had) factory air cond it would have a viscous fan clutch. This device is now almost 45 years old & most likely won't be anywhere near 100% effective. Get it checked out.

Dr Terry
If at first you don't succeed, just call it Version 1.0
AMunro327 Offline
#6 Posted : Sunday, 9 December 2012 10:17:11 PM(UTC)
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Hi Dr Terry. I stuffed up my last post and had to edit it. It's now been redone. Everything on the car (ute actually) is new. Just in case the radiator had a problem, I had top & bottom tanks removed, they reported no blockages. Viscous hub is new. Air Con is aftermarket and, of course, new. Condenser sits about 25mm from radiator.
Dr Terry Offline
#7 Posted : Monday, 10 December 2012 5:19:25 AM(UTC)
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quote:
Originally posted by AMunro327
Hi Dr Terry. I stuffed up my last post and had to edit it. It's now been redone. Everything on the car (ute actually) is new. Just in case the radiator had a problem, I had top & bottom tanks removed, they reported no blockages. Viscous hub is new. Air Con is aftermarket and, of course, new. Condenser sits about 25mm from radiator.

A 25mm gap is the norm, but you didn't mention the camshaft.

I'm not sure that an electric water pump in the lower hose in addition to the factory water pump is a good thing, it may be more of a restriction.

If your happy that the cooling system is all good, check my points about vacuum advance & ignition timing. Vac advance at idle (i.e. not ported) will also help, that's how factory 307 Powerglides are set up.

Dr Terry
If at first you don't succeed, just call it Version 1.0
Holdenute Offline
#8 Posted : Tuesday, 11 December 2012 10:56:14 PM(UTC)
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Sometimes not running a thermostat does more harm than good. What some used do was just remove the center from the therostat and leave the flange in place. Too much flow can be a bad thing.

This is right isn't it Terry?
Never late in a V8
AMunro327 Offline
#9 Posted : Wednesday, 12 December 2012 12:53:24 AM(UTC)
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Thanks for your replies.

The thermostat has only been removed as a temporary measure until I get this issue sorted.

To answer Dr Terry's last post ...... The camshaft is a modest 218 degree (50 thou figures)
The Davies Craig web site lists running their electric pump in addition to a mechanical pump as one of the accepted setup methods, particularly if there is an overheating problem. Vacuum is currently ported, but it's at 12 degree initial so shouldn't be a problem. Not sure what the overall advance is, but you can see the centrifugal advance come in when the engine starts to rev.
Dr Terry Offline
#10 Posted : Wednesday, 12 December 2012 12:55:29 AM(UTC)
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Removing thermostat causing overheating ?? I'm not sure if it's myth or fact.

I've never personally experienced it, but I've spoken to a few who have.

I can understand the theory, but all problems I've had with overheating have involved restrictions or coolant loss, never too much flow.

Dr Terry
If at first you don't succeed, just call it Version 1.0
Dr Terry Offline
#11 Posted : Wednesday, 12 December 2012 1:01:23 AM(UTC)
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quote:
Originally posted by AMunro327
The camshaft is a modest 218 degree (50 thou figures)

A 218 @ 50 thou cam is going to need help at low RPM.

Try manifold vacuum advance firstly without altering anything else (although you may need to drop the idle speed a bit).

If that makes a difference (which it should) get your dissy re-graphed to suit that cam & run full manifold vac at idle.

Dr Terry
If at first you don't succeed, just call it Version 1.0
git Offline
#12 Posted : Wednesday, 12 December 2012 2:55:27 AM(UTC)
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quote:
Originally posted by AMunro327
I agree, shouldn't have to go to thermo's, but need to do something. Situation is.......
* Reco'd 307 + 40 thou, Edelbrock alloy heads. about 9:1 compression.
* Thermostat removed until this problem is sorted.
* Timing is 12 degree at idle (a little advanced but it doesn't ping), mixture is OK.
* Pumped 140 lb into each cylinder, no leaks into coolant.
* Camera inserted down thermostat hole to ensure head to manifold openings are OK
* New 3 core Adrad radiator.
* Added a capillary temp guage to check against original electric.
* New water pump. Remove top hose from radiator (thermostat removed) and get a good gush of water when engine started.
* Added a Davies Craig electric pump in bottom hose as bandaid solution.
* Extended the shroud and fitted an 18" 7 blade fan on viscous hub.
* Only other thing I haven't done is to remove the air con condenser and try it, but there are millions of cars running condensers, so can't see how this can be the cause.


Greetings, The problem lies with the radiator and its ability to exchange the heat to the atmosphere. The factory fine core 307 radiator will be much better than some three core Adrad. Count the number of fins per inch and the tubes of a 307 unit and it will be higher than the Adrad. Not enough surface area here and its overheat whilst stationary and idling big time. The 307 unit also has less restriction to the airflow passing through it than the three core Adrad.
look out, the guru is coming through...
AMunro327 Offline
#13 Posted : Wednesday, 12 December 2012 7:26:05 PM(UTC)
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Dr Terry, thanks for the tip about switching to manifold vacuum, I hadn't thought of that. Changed it this morning and took the car for a bit of a run. It seems to be a hell of a lot better now. It's a bit cool today, I'll try again when the weather warms up a bit.
Last time I had a dizzy graphed it was with a place in Kogarah. Forget their name but I believe they're long gone now. It's probably a dying art these days. Who does distributor graphing in Sydney now?
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