[DeTomaso] Venting crankcase to valve cover (was Oilpangasketrecommendation?)

Mon Oct 6 16:47:16 EDT 2008

Note, I don't have a bare block at the moment.

It would appear to me, the oil enters the top block surface just to  
the lower left and right of the top two corner head bolts holes.  See  
this shot:
http://www.351c.info/gallery2/v/asajay/351C_Build_2001/bareblk2.jpg.html

On the left, we start with the large square hold for coolant.
next down is a hole for a head bolt.
The next one down just to the left is the oil drainback (I think)
Then we have an elongated coolant hole and the lower corner head bolt hole.

On the right of the photo, same story except no square coolant hole at  
the top.

Now, from here, does it drain to the valley or drip into the pan?
 From this photo here:
http://www.351c.info/gallery2/v/asajay/351C_Build_2001/spider1.jpg.html
You can pretty much see the lifters are in the way of allowing a hole  
to the head area illustrated in the block photo above.  So my guess  
here is that the hole in the top face of the block where it meets the  
head, drains down a passage next to the cylinder wall into the pan.

Again, I like to be wrong about a lot of stuff and I don't have an  
engine apart at the moment to look for certain.

Asa Jay

Quoting Larry - Ohio Time Corp <larry at ohiotimecorp.com>:

> How / where is the oil exiting into lower engine? Is it above or below the
> center line of the crank? It would be best to get it into the pan with out
> it getting mixed up in the turmoil of the crank spinning around.
>
> Larry - Cleveland
>
>
>
> -----Original Message-----
> From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
> Behalf Of Tomas Gunnarsson
> Sent: Monday, October 06, 2008 2:18 PM
> To: DetomasoList
> Subject: Re: [DeTomaso] Venting crankcase to valve cover (was
> Oilpangasketrecommendation?)
>
>
> ----- Original Message -----
> From: "Doug Braun" <doug at silicondesigns.com>
> To: "Tomas Gunnarsson" <guson at home.se>; "DetomasoList"
> <detomaso at realbig.com>
> Sent: Monday, October 06, 2008 6:51 PM
> Subject: Re: [DeTomaso] Venting crankcase to valve cover (was Oil
> pangasketrecommendation?)
>
>
>> Thomas,
>>
>> Yes there is an issue.  The valve cover openings are the ONLY crankcase
>> vents to the atmosphere in a 351C (as long as the engine doesn't leak
> oil).
>
>>> I'm with you here.
>
>> Vent-wise, the lifter valley lies between the crankcase and the valve
> covers
>> so oil from the heads drains into the lifter valley and then to the
>> crankcase.
>
>>> I have looked at pics I've taken and ones found in the Tom Monroe rebuild
> handbook. To me it seems like the head drains don't exit into the lifter
> valley. The oil drainback holes are actually outboard of the outermost
> headbolts.
>
>  Crankcase venting gasses and head oil drain back are both
>> fighting for passage (in opposite directions) through the heads' two each,
>> 3/8" diameter or so, drain passages.
>
>>> I see this differently. Oil primarily runs down the drains. Crankcase
> gases can pass up those drains too unless they're filled with oil. Should
> they be filled with oil, gasses can pass up into the lifter valley past the
> camshaft through the four 1/2" or so holes above the camshaft. I understand
> that there's also a certain amount of oil flow from the lifters going down
> these holes at the same time. From the lifter valley there are eight pushrod
> holes (~1/2") to each valve cover that are only partially filled with
> pushrods.
>
>   Any blowby that the lowly PCV can't
>> handle gets shoved into the air cleaner assuming the stock type emissions
>> hose is present between the oil filler cap and the air cleaner.
>
>>> This is the way it's supposed to be as far as I can tell. The hose
> connected to the intake could never handle much gas flow.
>
> Tomas
>
>
>> -----Original Message-----
>> From: detomaso-bounces at realbig.com
>> [mailto:detomaso-bounces at realbig.com]On Behalf Of Tomas Gunnarsson
>> Sent: Friday, October 03, 2008 12:02 PM
>> To: DetomasoList
>> Subject: [DeTomaso] Venting crankcase to valve cover (was Oil pan
>> gasketrecommendation?)
>>
>>
>> Is there really an issue with venting the lower part of the engine to the
>> valve covers? I'd have thought that even with the head drains completely
>> filled with oil returning to the crankcase there'd be enough combined
>> passage area through the lifter area floor and pushrod holes to vent
>> whatever blowby there is.
>>
>> Tomas
>>
>> ----- Original Message -----
>> From: "Barry Seib" <oldwheel at mts.net>
>> To: "Drew, Mike" <MikeLDrew at aol.com>; "DetomasoList"
> <detomaso at realbig.com>
>> Sent: Wednesday, October 01, 2008 11:01 PM
>> Subject: [DeTomaso] Oil pan gasket recommendation?
>>
>>
>>> Mike
>>> I think Larry may be right on with his suggestion. If there is no leak
>>> except at high RPM, that's a very strong indication that no matter where
>> the
>>> leak is, excess crankcase pressure is likely causing it. I suspect the
>>> factory PCV system is totally inadequate for sutained very high revs. You
>>> might try the same run with extra NASCAR or circle track type breathers
> to
>>> see if the problem is solved.The other issue is making sure that the
>>> crankcase can breathe to the valve covers (if that's where the extra
>>> breathers are). If the heads and drainbacks are all flooded with oil so
>> that
>>> can't take place, you will have to remedy it first - or put a breather
>>> directly to the crankcase by some other route to stop the leak. MD must
>> have
>>> dealt with this issue a long time ago.
>>>
>>> Dawg? What say you?
>>>
>>> Barry
>>>
>>>
>>>
>>> [DeTomaso] Oil pan gasket recommendation?
>>> Larry - Ohio Time Corp larry at ohiotimecorp.com
>>> Wed Oct 1 12:54:55 CDT 2008
>>>
>>>
>>>
>>> Hi Mike,
>>>
>>> You may want to check you venting / PCV system. At high RPM the blow-by
> is
>>> at its highest. I have seen crank cases pressurized and blow oil out a
>>> normally good seal. If your heads are full of oil the venting system may
>> not
>>> be working to well.
>>>
>>> Larry (no, tarter sause) - Cleveland
>>>
>>>
>>>
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