[DeTomaso] Venting crankcase to valve cover (was Oil pan gasket recommendation?)

adin at frontier.net adin at frontier.net
Fri Oct 3 16:33:28 EDT 2008


some folks "today" run a vacuum pump on the crankcase . . .

Those long pulls at 9000rpm can be trouble!



Quoting Ken Green <kenn_green at yahoo.com>:

> I recall that back in the mid 70s people did things to keep oil out   
> of the heads, things like restricting the flow of oil through the   
> pushrods.  I think the belief was that under prolonged high RPM   
> running (which might be 5,000 RPM with a stock Cleveland) the oil   
> did not drain back into the pan fast enough, resulting in oil   
> starvation.
>
> Ken
>
> --- On Fri, 10/3/08, Tomas Gunnarsson <guson at home.se> wrote:
>
> From: Tomas Gunnarsson <guson at home.se>
> Subject: [DeTomaso] Venting crankcase to valve cover (was Oil pan   
> gasket recommendation?)
> To: "DetomasoList" <detomaso at realbig.com>
> Date: Friday, October 3, 2008, 12:01 PM
>
> 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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