<VV> Removing lower Shrouds

[Bruce Schug]

On May 23, 2004, at 9:50 PM, Larry Forman wrote:

> Hi Russ,
> My thoughts are to do whatever you can to lower temps and still retain 
> them and THEN, after knowing your temps, do that as one of the the 
> last approaches to lower temps.
>
> There are a LOT of things you can do to lower temps.  Some of them are:
> 1. Deflash your heads really well.  This is the first place to start 
> lowering temps.  Once you do a set of heads and compare the difference 
> you will be sold.

That one should be in caps!

> 2. Run with synthetic oil and lower oil temps by about 20 degrees.
> 3. Run with a 12 plate oil cooler WITH side plates as used on A/C cars.
> 4. Run with the new style fan, even though there might be arguments 
> for another heavier style.
> 5. I like to paint the outer half of the pushrods with white VHT, even 
> though some people say it does nothing.
> 6. Braze a washer in the outer end of the exhaust pushrod tubes, 
> making very sure the inner hole in that washer does not contact the 
> pushrod under any cam position.

I guess this is to keep the oil out of the push rod tubes, huh? Good 
idea.

> 7. Make sure your thermostat doors are operating properly and adjusted 
> right.
> 8. Run with a deep oil pan and lowered oil pickup.

How will this lower oil temps? I think you mean to use more oil in the 
deep pan. More oil won't lower oil temps either. It'll just take longer 
to warm the oil up to its highest point, I think.

> 9. Maybe have radiused and improved the oil cooling flow path when 
> rebuilding the engine and had the crank straightened during the 
> rebuild to reduce crank bearing friction.
>
> I am sure there are more and some people might disagree with this 
> list, but it is a starting place.  Then start measuring your temps, 
> either oil or CHT, and opinions differ for that also.  But, KNOW where 
> your temps are for your typical driving style, weather, etc.  Then 
> when you consider removing the lower shrouds, you will have the 
> knowledge that you did it for the right reason and it really did 
> something for your temps and you know how much that was.
>
> The downside of removing the lower shrouds is that the engine does not 
> warm up properly, as when the shrouds and damper doors are where they 
> belong.  GM did not add this expense and engineering process for no 
> reason.  This can create excessive engine wear during the startup 
> period.  I understand that running with these removed in the AZ area 
> is pretty common in summer.
>
> HTH,
>
> Larry Forman

Larry,

I agree; you can do all of this... or you can simply remove the shrouds.

Removing the shrouds will lower the oil temps a great deal. (I have 
quantified this, but don't have the numbers in my head.) Whether you 
should remove them or not depends on several factors. The engine WILL 
warm up slower. If you only drive short distances it will NEVER warm 
up. In that instance leave the shrouds on.

I agree that all of these things should be done if it is practical to 
do so. If you're not taking the engine apart, some can't be done.

I have run with my shrouds off in the summer for years. Extra wear? 
Perhaps. But most owners don't drive that many miles. They'll never 
wear their engines out.

Oh, and the 10th item you forgot is a good remote oil cooler like my 
Mazda cooler tucked up in the plenum. That, plus most of the 
modifications you suggest keeps my oil temps under control on the 
hottest days with my air-conditioned +.060 140.

Bruce

Bruce W, Schug
CORSA South Carolina
Greenville, SC
bwschug@charter.net

CORSA member since 1981

'67 Monza. "67AC140"