Flat tappet cam; what oil?

In reply to BrokenYugo :

Very good point about modern camshafts and their ramp speeds.

 

Going back to taking things in historical context, why did all the American pushrod engines go to more expensive/complex roller cam setups in the late 80s-early 90s? This was well back into the time when oil supposedly had superior EP wear characteristics. Did they see oil being ruined coming and alter engine designs they knew would be out of production and out of warranty by the time that happened just for the hell of it? Or did they do it because they had too, because the lifter load from snappier cam profiles (and I think the stiffer springs that go with them?) for improved performance and emissions were just too sketchy no matter the lubrication provided? 

They did it for friction reduction and fuel economy. OEM cam profiles and spring rates have never been milder and lighter, also for friction reduction and increased fuel economy.

I've ground a lot of cams over the years and in every application I've only recommended currently available synthetic 5 or 10W30. 15W40 Rotella is an excellent budget choice and $13/gal last time I was across the border.

I have never had a warranty claim for a worn lobe.

In reply to BrokenYugo :

A few things are still changing. Modern diesels have catalytic converters on them which zinc will kill.  Not saying that all oil with zinc is gone but it is getting harder to find.  In a lot of cases what is available isn’t the same as what worked so well a decade or more ago.  

I love synthetic’s and use them whenever I can.  Yet some cars, notably the British cars up into the late 80’s and early 90’s used seals that do a lousy job of keeping oil in.  You almost don’t bother tightening the oil plug because the reverse scrolls used to keep oil in do such a lousy job keeping oil in the pan.  (Just like old Harley Davidsons!  

In reply to BrokenYugo :

Nope!  They did it because the old oils were plugging up catalytic converters.  Well and they wanted better fuel mileage to advertise.  

Brad Penn or Joe Gibbs.

I am not a fan of adding ZDDP additives (don't call it "zinc", it's the phosphate that does the work) to modern oils, as this can actually have a negative effect.

Does anyone have an article link to said "negative effect?"

Amsoil has an oil for flat tappets.

BrokenYugo said:

In reply to BrokenYugo :

Very good point about modern camshafts and their ramp speeds.

 

Going back to taking things in historical context, why did all the American pushrod engines go to more expensive/complex roller cam setups in the late 80s-early 90s? This was well back into the time when oil supposedly had superior EP wear characteristics. Did they see oil being ruined coming and alter engine designs they knew would be out of production and out of warranty by the time that happened just for the hell of it? Or did they do it because they had too, because the lifter load from snappier cam profiles (and I think the stiffer springs that go with them?) for improved performance and emissions were just too sketchy no matter the lubrication provided? 

You pretty much nailed it.  A typical roller cam ramp is much faster because of the approach angle being handled by a roller instead of a domed flat face.  The result is across-the-board benefits in many cases.  They are often heavier which sometimes limits float RPMs, but in nearly all street/production vehicles it is a non-issue.

In general, a roller profile can get the same area "under the curve" with less duration, meaning it pays off in net output with less penalty to emissions.  Roller lifters are a means of advancing technology that we have learned about valve timing events to get closer to ideal valve motion which is the main reason for their use.

In reply to SkinnyG :

The Camaro was previously a Schnieder Street Lighting Pro cam with a 440/465 lift. I replaced it (twice, loss the first one) with a Summit 465/488 lift cam. I have Dart S/S heads with springs OK to 510 lift.

I do not use any additives with the Rotella.

I also have used Rotella in a mild 350, and a stock 69 430 Buick (although stock was 360hp/470tq). 

I have used the synthetic Rotella 5w40 for a long time in my 290K 99 GMC Sierra 4.8.

Standard Rotella you can find in 10w30, 15w40, and 20w50. Some Walmarts only have the 15w40. Tractor Supply often has larger 2.5 gallon containers.