[DeTomaso] Head Gasket Holes

Charles Engles cengles at cox.net
Wed Jun 16 22:38:30 EDT 2010


Dear Tony,


       One other place to look for a hidden restriction is the front engine
plate.   I have a collection of, umm, six or seven plates.    Four or five
are loose in the parts warehouse.  Someone smarter and more observant than
me told me that there were *two* versions of the engine plate.   I looked at
mine and he was right.  One of the plates had openings for the water pump
that were bigger than the other plates.  Apparently, there were two
stampings.  One stamping has a terrible mismatch for the size of the plate
opening with the engine block and with the pump.  The other stamping has
much more modest restrictions.  I was shown that if you then take a FelPro
water pump gasket and add it's fitment to the block,plate and pump opening
mismatches, then it can add further impedance to flow.  

      Consequently, as you are trying to rationally sort out your hot engine
and you're not finding any obvious source, then you might consider the
"heart" of the cooling system: the triad of the front of the block, the
front engine plate and pump (and the gasket).  I would think that coolant
flow is impeded in an average 351C and could be optimized with attention to
these physical mismatches.  In particularly bad cases where everything is
especially mismatched with others, then flow might be bad enough for a hot
engine with no easy answer in the usual places.  I don't know that, but I
think it is possible.

       I will attach secret photos visible only to you (as the list strips
attachments).  See what you think.


             Your fellow engine builder,  Chuck Engles





-----Original Message-----
From: Tony DiGiovanna [mailto:tonydigi at optonline.net] 
Sent: Wednesday, June 16, 2010 8:38 PM
To: wkooiman at earthlink.net; 'Tomas Gunnarsson'; detomaso at realbig.com;
'Charles Engles'
Subject: RE: [DeTomaso] Head Gasket Holes

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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