30-30 Cam and the 409?

[George J.]

Duke, et al,
In reading the book Fast Chevy's I came across a reference to the 30-30 cam profile being designed by a Denny Davis for the 409 engine. It states that it was not used for this engine, but was later redesigned by Denny McKellar for use in the small block. Is this common knowledge?
I have attached the portion of the book. Look at the second column, second paragraph from the bottom.

George

[Duke W.]

Re: 30-30 Cam and the 409?

First time I ever read that. I never knew who "designed" the 30-30 cam other than it was not Duntov, but he likely had input/oversight into the design.

As far as adapting a lobe design from one engine architecture to another, that was the case with the LT-1 cam. The inlet lobe has identical eccentricity to the L-72 lobe, but the base circle had to be reduced so the sum of base circle and peak lobe lift was less than bearing bore diameter.

The LT-1 cam exhaust lobe is the same as the 30-30 (which used the same lobe on both sides), but it is phased four degrees earlier - 122 deg. BTDC vs. 118.

It's clear from the detailed lobe eccentricity data that a somewhat different philosophy was used in the two designs. Though both lobes are asymmetric, the L-72 lobe has a higher degree of asymmetry, which represents another couple of years of valvetrain research and the fact that the L-72 lobe was originally designed for a heavier valvetrain, so softer dynamics were necessary.

Back in that era GM was making net after tax profit margin of about 10 cents on every sales dollar, and these huge profits allowed big engineering development budgets, so the engineers were having a ball designing and building all kinds of exotic stuff, but that came to an abrupt end in the late sixties when engineering had to refocus on upcoming emissions and safety regulations.

Circa 1963/1964 Hot Rod Magazine had a cover with Pontiac's engine guy McKeller surrounded by all the exotic Pontiac experimental engines - OHC etc. When I went to work for Pontiac in 1968 I inquired about them, and one of the veteran engineers led me down to the basement of the engineering building where we found them in a heap in the corner - covered with dust and long forgotten.

Duke

[Dick W.]

Re: 30-30 Cam and the 409?

Denny made a presentation on the design and evolution of the small block at the NCRS National Convention in 1985. Supposed to have been about 1 1/2 hours long, we all were still in the room close to midnight. He had interviewed a lot of the early engineers that were on the design and development team, and had those interviews on video.

[George J.]

Re: 30-30 Cam and the 409?

Duke,
I thought you would be the first to reply. This was a fascinating discovery, to me. I thought you might put this cam profile in your simulator with a 409 engine and see how it fares. I wonder why it didn't get used.
If you have not read this book, it has some great, in-depth, interviews.

George

[Clem Z.]

Re: 30-30 Cam and the 409?

the chevy stamped steel rockers arms came from the pontiac side of GM so no reason not to believe that cams did also

[George J.]

Re: 30-30 Cam and the 409?

Denny made a presentation on the design and evolution of the small block at the NCRS National Convention in 1985. Supposed to have been about 1 1/2 hours long, we all were still in the room close to midnight. He had interviewed a lot of the early engineers that were on the design and development team, and had those interviews on video.

Dick,
those videos would be worth tracking down.
Dick Keinath and his wife showed up to Elphi's memorial service and I had the opportunity to sit with them at lunch. I wish it had gone on for a lot longer than it did.

George

[Duke W.]

Re: 30-30 Cam and the 409?

Duke,
I thought you would be the first to reply. This was a fascinating discovery, to me. I thought you might put this cam profile in your simulator with a 409 engine and see how it fares. I wonder why it didn't get used.
If you have not read this book, it has some great, in-depth, interviews.

George

I've never simulated the W-block engines. I don't have enough data on the details (like head flow) to do accurate simulations, and that particular engine never interested me being as how is was pretty much obsolete by 1965.

It's an interesting design, but a big, heavy lump of cast iron. I don't think it could ever have been shoehorned into the Corvette without major surgery. The 396 was certainly tight, but just needed a notch in the front cross member to clear the front damper. The W-block was a lot wider. It was originally designed as a truck engine, but was souped up and added to passenger cars as the horsepower wars escalated. The Mark IV was a huge improvement.

The 30-30 cam would provide better useable torque bandwidth in a long stroke, large displacement engine than the short stroke, small displacement 327, and the dynamics are mild enough for a heavier valvetrain with a bit more spring force.

There's not a huge differnce between the 30-30 and L-72 lobes. The L-72 lobe has about 8 degrees less effective duration and slightly milder dynamics. With the excellent head flow (particularly on the inlet side) of the Mark IV a big cam was not required. High flow efficiency and moderate duration is the best way to achieve broad, useable torque bandwidth in a high performance road engine.

Using the L-79 lobe as a baseline the L-72 lobe has 11 degrees more effective .050" duration and the 30-30 lobe is a whopping 19 degrees longer. So the respective .050" lifter rise durations are 220, 231, and 239. In order to compare hydraulic lifter and mechanical lifter .050" lifter rise durations/timing points, you have to add the height of the clearance ramp to the mechanical lifter rise, so the L-72 lobe much be compared at .062" lifter rise and .067" for the 30-30 lobe. Otherwise it's apples and oranges because with a mechanical lifter cam the valve does not move until the clearance is taken up. On a hydraulic lifter cam, essentially all of the lifter rise above the base circle is converted to valve opening since there is zero running clearance.

Big cams can be used to some degree to overcome head flow deficiencies in the search for greater peak power, but the price paid in low-end torque is huge. It's a case of ever-diminishing marginal returns. For every incremental increase in duration and overlap you get ever smaller top end power gains and ever larger losses of low end torque.

That's okay in a racing engine where you are only concerned about average power in the top 25-30 percent of the rev range (or 10 percent in the case of F1 engines), but in a road engine you want to get pushed back into the seat when you punch it at 1500 revs.

Duke

[Dick W.]

Re: 30-30 Cam and the 409?

Circa 1963/1964 Hot Rod Magazine had a cover with Pontiac's engine guy McKeller surrounded by all the exotic Pontiac experimental engines - OHC etc. When I went to work for Pontiac in 1968 I inquired about them, and one of the veteran engineers led me down to the basement of the engineering building where we found them in a heap in the corner - covered with dust and long forgotten.

Duke

When I was at Ray Nichels shop in Highland IN, there was one of the Pontiac Indy engines setting on a stand in a back corner. Magnesium oil pan, valve covers, front cover, some sort of fuel injection, Hilborn maybe. Often wondered what happend to that engine.

[Duke W.]

Re: 30-30 Cam and the 409?

I don't recall that engine. Was it a "stock block" pushrod engine of the era, like the one that Smokey Yunick developed from the SBC? IIRC in that era "stock block" pushrod engines were allowed 256 CID. This Pontiac engine may have been developed independently without direct factory support. I think that was the case with Yunick's engine.

The McKeller/engine Hot Rod Cover photo may have been later than '64 because I recall in included the new OHC six along various Pontiac big inch V-8s with overhead cam heads and exotic induction systems.

Duke

[Dick W.]

Re: 30-30 Cam and the 409?

Duke, that engine, or one like it was featured in Hot Rod Magazine sometime in the late '50's or early '60's. Best I remember it was a push rod version. Probably would have been in a car driven by Paul Goldsmith, as Nichels and Goldsmith were partners in several ventures.

Nichels, until he became the Dodge racing parts source, was the "go to" for Pontiac racing parts. I figure this is how he had the engine.

[Clem Z.]

Re: 30-30 Cam and the 409?

I've never simulated the W-block engines. I don't have enough data on the details (like head flow) to do accurate simulations, and that particular engine never interested me being as how is was pretty much obsolete by 1965.

It's an interesting design, but a big, heavy lump of cast iron. I don't think it could ever have been shoehorned into the Corvette without major surgery. The 396 was certainly tight, but just needed a notch in the front cross member to clear the front damper. The W-block was a lot wider. It was originally designed as a truck engine, but was souped up and added to passenger cars as the horsepower wars escalated. The Mark IV was a huge improvement.

The 30-30 cam would provide better useable torque bandwidth in a long stroke, large displacement engine than the short stroke, small displacement 327, and the dynamics are mild enough for a heavier valvetrain with a bit more spring force.

There's not a huge differnce between the 30-30 and L-72 lobes. The L-72 lobe has about 8 degrees less effective duration and slightly milder dynamics. With the excellent head flow (particularly on the inlet side) of the Mark IV a big cam was not required. High flow efficiency and moderate duration is the best way to achieve broad, useable torque bandwidth in a high performance road engine.

Using the L-79 lobe as a baseline the L-72 lobe has 11 degrees more effective .050" duration and the 30-30 lobe is a whopping 19 degrees longer. So the respective .050" lifter rise durations are 220, 231, and 239. In order to compare hydraulic lifter and mechanical lifter .050" lifter rise durations/timing points, you have to add the height of the clearance ramp to the mechanical lifter rise, so the L-72 lobe much be compared at .062" lifter rise and .067" for the 30-30 lobe. Otherwise it's apples and oranges because with a mechanical lifter cam the valve does not move until the clearance is taken up. On a hydraulic lifter cam, essentially all of the lifter rise above the base circle is converted to valve opening since there is zero running clearance.

Big cams can be used to some degree to overcome head flow deficiencies in the search for greater peak power, but the price paid in low-end torque is huge. It's a case of ever-diminishing marginal returns. For every incremental increase in duration and overlap you get ever smaller top end power gains and ever larger losses of low end torque.

That's okay in a racing engine where you are only concerned about average power in the top 25-30 percent of the rev range (or 10 percent in the case of F1 engines), but in a road engine you want to get pushed back into the seat when you punch it at 1500 revs.

Duke

a friend had a 409/425 HP engine in a 57 vette. the carbs stuck thru the hood BUT boy would that sucker go in a straight line.

[Dick W.]

Re: 30-30 Cam and the 409?

Found what I was looking for on the Pontiac engine. Nichels built a '59 Kurtis Champ car powered by a Pontiac. I cannot find any reference, so far, that it ever raced at Indianapolis. When I get time, I will dig out my old Hot Rod Magazines.

[Jake D.]

Re: 30-30 Cam and the 409?

Back in the day (1964) we put a McKeller #11 cam in Richie's 389 Pontiac Catalina. Boy! did that cam wake up that Pontiac!!

[Craig B.]

Re: 30-30 Cam and the 409?

I believe the Kurtis champ car that Dick Whittington is refering to was used to break the 180 MPH barrier at Daytona in 1959 or 60 with Art Malone driving. The first person to break 180 MPH received $10,000 at which Art was successful. However, I don't believe the CAR was owned by Nichels at the time the record was broken. Another driver died trying to break that record prior to Arts attempt. Stockblocks were only allowed 255 ci in 1959 and 60 at Indy.

[George J.]

Re: 30-30 Cam and the 409?

Duke,
did you live in the Detroit area, at some time in the past?

George