[DeTomaso] Head Gasket Holes

Asa Jay Laughton asajay at asajay.com
Wed Jun 16 23:13:57 EDT 2010


Tony,

You do realize that head gaskets for the 351C are unidirectional.  That 
is to say they are only properly installed one way.  Installed the other 
way and they will give you cooling problems.

Also to note.  Several years ago I finished an engine and put a brand 
new temp sender in.  The gauge in my car was not graduated with actual 
numbers.  It showed running hot all the time.  I checked it with a 
thermocouple.  It was running just fine, except reading high on my dash 
gauge.  Checking with several other owners in my Mustang club at the 
time, I found everyone who had replaced a temp sending unit in the past 
few years, suddenly had higher than normal temp readings on their dash 
gauge without having done anything else.

So two possible causes there:
- head gaskets installed backwards
- temp sending unit out of spec.

Asa Jay

Asa Jay Laughton, MSgt, USAFR, Retired
&  Shelley Marie
Spokane, WA
******************************
http://www.racingagainstautism.com
http://www.teampanteraracing.com


On 6/16/2010 18:38, Tony DiGiovanna wrote:
> Here is why I raise the question, and here is what I think:
> I have an engine that runs 230 deg F in my Pantera, when all of my previous
> engines ran 190.
> It ran hotter before I removed the perfectly functional thermostat.  It ran
> hotter before I had the radiator cleaned.  It ran hotter before I flushed
> the block out backwards.  This engine just runs hotter.  Everything else
> checks out OK.  If there is an issue, it is not an easy one to find/correct.
> I'd like to bring the temp down.
>
> Water always flows by pressure differential, so I think all the holes flow
> some from the block into the head.  I think the holes are sized to be the
> controlling orifice of the system; 1) to ensure positive delta-P along the
> entire head (like a pull-up resister for you EEs) so flow is ensured in one
> direction.  2) to ensure some fresh flow along the middle and front of the
> head.  Otherwise, the rear cylinders would always be colder and the front
> hotter.
>
> However, I think the sizing is based on factory engineering or experience
> with the stock 260HP engine and component.  I think the old additional
> "steam hole" revision was actually just an increase in water flow.  Not sure
> what steam has to do with it.  The system isn't in steam phase unless it's
> already boiling - too late.
>
> I'm thinking the flow thru entire engine could be increased by increasing
> all the holes by a fixed percentage of area and result in a decrease in my
> water temperature, maybe.
>
> I'm probably going to try it.  I'll post results.
>
> -----Original Message-----
> From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
> Behalf Of wkooiman at earthlink.net
> Sent: Tuesday, June 15, 2010 9:13 PM
> To: Tomas Gunnarsson; detomaso at realbig.com
> Subject: Re: [DeTomaso] Head Gasket Holes
>
> Don't make the tiny holes bigger.  They are steam holes.
>
> The water enters both sides of the block by the water pump.  It travels to
> the back, and enters the heads.  It flows through the heads and back to the
> front.  It re-enters the block, then to the thermostat in the block, and to
> the water bottles.
>
> If you make the steam holes larger, too much water will flow from the middle
> of the block to the heads.  I don't know if it would happen, but I'd bet it
> would cause the head to run hot near the rear of the block.
>
> If you make the large hole near the front of the block larger, it should
> make the water flow faster - assuming the hole is a restriction.  My guess
> is the restriction is the thermostat housing, though, so if you make the the
> large holes larger, it shouldn't do anything.
>
> I wouldn't mess with any of the holes in the head gasket.  They are a
> specific size for a reason.
>
> -----Original Message-----
>    
>> From: Tomas Gunnarsson<guson at home.se>
>> Sent: Jun 15, 2010 3:32 PM
>> To: detomaso at realbig.com
>> Subject: Re: [DeTomaso] Head Gasket Holes
>>
>> Which holes are you talking about? All or only selected holes?
>>
>> Tomas
>>
>> -----Original Message-----
>> From: detomaso-bounces at realbig.com
>> [mailto:detomaso-bounces at realbig.com]On Behalf Of Tony DiGiovanna
>> Sent: den 14 juni 2010 23:59
>> To: detomaso at realbig.com
>> Subject: [DeTomaso] Head Gasket Holes
>>
>>
>> So..what happens if you make the water passage holes in the head gaskets
>> bigger?
>>
>>
>>
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