86' 4 eye 306 carb. Built. Overheating

Oct 29, 2018
23
1
13
38
Stafford, Va
Ok, I bought me a 86 mustang with a 306 carb engine. Holley 4 bbl, edelbrock performer air gap intake, gt40 heads with comp cam alumi saver roller rockers 1.6, edelbrock long tube 4 to 1 headers into single chamber flows. That being said I purchased the car with an overheating problem. The radiator, water pump, thermostat have been changed. Also replaced junk heads for gt40's with nice rocker set up thinking heads where just warped. Still overheating, Could it be a air pocket? Could it be a bad radiator? Or most likely is it the block at this point? And if it's the block what's the best bet for a new short block for my set up? Mostly to drive and enjoy but some street/track stuff.
 
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HotFox

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Just a quick thought since the water pump sounds like it was changed...they made a right and left rotating water pump.
 

95BlueStallion

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Do you have a fan shroud on the radiator? I ran dual electric fans on a nice three core radiator and still had overheating issues at stop lights. Installed one large fan with the correct shroud, and boom, fixed.
 

CarMichael Angelo

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Do you have a fan shroud on the radiator? I ran dual electric fans on a nice three core radiator and still had overheating issues at stop lights. Installed one large fan with the correct shroud, and boom, fixed.
You're about a fan shroud suggesting individual aren't you?

I think its best if you post pics of the existing install. One things for sure.....Its not the block:O_o:
 
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KZGUNS

I can swing up to 11”
Jul 23, 2018
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Could be air pocket. Have you tried to burp it? Jack up the front. Could also be pump rotation incorrect. What is your timing at? Does it begin to over heat really quick? As mentioned a fan shroud. My 66 tbird would get really hot until I spent the money for a shroud and for that thing it wasn’t cheap but I can sit in 90° traffic with no issues. Oh if you’re running stock fan/clutch make sure it’s good as well
 
Oct 29, 2018
23
1
13
38
Stafford, Va
Do you have a fan shroud on the radiator? I ran dual electric fans on a nice three core radiator and still had overheating issues at stop lights. Installed one large fan with the correct shroud, and boom, fixed.
It's a large single electric fan no shroud but don't really see room for a fan. Unless I can find a flush shroud
 
Oct 29, 2018
23
1
13
38
Stafford, Va
Could be air pocket. Have you tried to burp it? Jack up the front. Could also be pump rotation incorrect. What is your timing at? Does it begin to over heat really quick? As mentioned a fan shroud. My 66 tbird would get really hot until I spent the money for a shroud and for that thing it wasn’t cheap but I can sit in 90° traffic with no issues. Oh if you’re running stock fan/clutch make sure it’s good as well
Takes about 10 mins to overheat. The pump spins clockwise and showed a mechanic and said correct pump is in the car. Timing is @12degrees
 

90sickfox

I didn't really have an issue with the stink...
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Get a set of ford contour fans. Cheapest best upgrade. Found mine in a JY and it keeps my turbo 331 cool. A lot of aftermarket fans don't pull enough cfm for our cars.
 
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CarMichael Angelo

Nobody appreciates me..I'm gonna cut my ear off
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Takes about 10 mins to overheat. The pump spins clockwise and showed a mechanic and said correct pump is in the car. Timing is @12degrees
if it's just overheating after 10 minutes of running, then I think you aren't moving any water through the engine.
 

96pushrod

Advanced Member
May 15, 2018
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Does then radiator hose get hot, like there’s hot coolant circulating through it? Most water pumps I’ve seen for 5.0s are reverse rotation. Does yours have a ribbed or smooth pulley?

My cheap $200 sve radiator and stock sn95 electric fan keep my 347 plenty cool in 90 degree heat.

As others have said make sure the thermostat is in correctly. I’ve had good luck with the mr gasket high performance 180* tstat.

Burping 5.0s is pretty easy, just take off the radiator cap, squeeze the hose a couple times once the tstat opens and it usually does the trick.

Was the head gasket put on with the correct orientation?
 

General karthief

wonder how much it would cost to ship you a pair
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Post #4 stated the upper and lower radiator tubes where cold, figure your talking about the hoses, that is a sure indication of no flow.
#1 check/replace thermostat
#2 check rotation of water pump. This will likely require removal.
#3 possible head gasket on backwards. It is possible to install both gaskets on backwards and cause a no flow issue.
it also would be possible that the radiator is plugged, that is easy to verify.
 
Oct 29, 2018
23
1
13
38
Stafford, Va
Does then radiator hose get hot, like there’s hot coolant circulating through it? Most water pumps I’ve seen for 5.0s are reverse rotation. Does yours have a ribbed or smooth pulley?

My cheap $200 sve radiator and stock sn95 electric fan keep my 347 plenty cool in 90 degree heat.

As others have said make sure the thermostat is in correctly. I’ve had good luck with the mr gasket high performance 180* tstat.

Burping 5.0s is pretty easy, just take off the radiator cap, squeeze the hose a couple times once the tstat opens and it usually does the trick.

Was the head gasket put on with the correct orientation?
It's a ribbed pulley moving clockwise facing the engine. I showed the water pump to my mechanic friend and mechanic at my body shop. Both agreed it's correct pump moving in the right direction and looked to be in perfect shape. Unfortunately. When I put the heads on paid very close attention to the correct placement of the gasket knowing that it's common that they are out on covering up the wrong holes. Made sure the thermostat was in correctly too. But that being said the hoses are almost cold to the touch especially near the radiator once gets to temp on the upper and lower hose.
Post #4 stated the upper and lower radiator tubes where cold, figure your talking about the hoses, that is a sure indication of no flow.
#1 check/replace thermostat
#2 check rotation of water pump. This will likely require removal.
#3 possible head gasket on backwards. It is possible to install both gaskets on backwards and cause a no flow issue.
it also would be possible that the radiator is plugged, that is easy to verify.
Yea I'm gonna check radiator for flow and get a better thermostat. And burn the system. My guy at the shop has a vac that will do it more efficiently so will be utilizing that this weekend.
 

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