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

Mon Oct 6 14:48:12 EDT 2008

Undoubtedly above the crank centerline as the oil pan rail is level with crank center.

Tomas

----- Original Message ----- 
From: "Larry - Ohio Time Corp" <larry at ohiotimecorp.com>
To: "'Tomas Gunnarsson'" <guson at home.se>; "'DetomasoList'" <detomaso at realbig.com>
Sent: Monday, October 06, 2008 8:33 PM
Subject: RE: [DeTomaso] Venting crankcase to valve cover (was Oilpangasketrecommendation?)

> 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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