"Old School" Stocker Cams

[SSDiv6]

Originally Posted by GTX JOHN

We run the old Isky Square Cams that are the same ones
as we ran in the 80s. They were designed Al Etter ( Ken's
Dad RIP) and Don Studley ( Shane's Dad RIP).

We have spent Thousands on Stocker Cams but always
go slower!

These Old School Cams are BRUTAL on the Valvetrain
and we do not recommend them to most people!.

Those old school cams are still used by many. I believe that when Don closed GK, John at Bullet Cams purchased some of the tooling. Cam Dynamics was also ahead of their game with dwell lobes too. Do not know what happened to Cam Dynamics tooling after they were split and acquired by other companies. Glen Steyer's was the man at Crane Cams for Stock Eliminator cams. Glen now has his own camshaft business and still makes some great cams.

With the advent of the spring rule allowing higher spring pressures, it allowed racers to take full advantage of the dwell lobes, called by many, square lobes. As a result, rocker arms and lifters subsequently became the next weakest valvetrain component to fail and as a result, the rule change to allow solid lifters and aftermarket rocker arms.

Those that have access to and pay for Spintron testing, will find and discover they can make more power with less aggressive lobes and less spring pressure.

Reducing reversion before TDC is the key. Earlier intake valve openings allow for higher pressure exhaust gases. The less reversion, the earlier airflow starts after TDC. When camshafts have an optimized area at mid-lift and higher lift, it allows the valve to have more time to fill the cylinder with an air/fuel mixture with higher inertia.

[Stan Weiss]

Originally Posted by SSDiv6

Those old school cams are still used by many. I believe that when Don closed GK, John at Bullet Cams purchased some of the tooling. Cam Dynamics was also ahead of their game with dwell lobes too. Do not know what happened to Cam Dynamics tooling after they were split and acquired by other companies. Glen Steyer's was the man at Crane Cams for Stock Eliminator cams. Glen now has his own camshaft business and still makes some great cams.

With the advent of the spring rule allowing higher spring pressures, it allowed racers to take full advantage of the dwell lobes, called by many, square lobes. As a result, rocker arms and lifters subsequently became the next weakest valvetrain component to fail and as a result, the rule change to allow solid lifters and aftermarket rocker arms.

Those that have access to and pay for Spintron testing, will find and discover they can make more power with less aggressive lobes and less spring pressure.

Reducing reversion before TDC is the key. Earlier intake valve openings allow for higher pressure exhaust gases. The less reversion, the earlier airflow starts after TDC. When camshafts have an optimized area at mid-lift and higher lift, it allows the valve to have more time to fill the cylinder with an air/fuel mixture with higher inertia.

Can you please explain how that works?

Thanks,
Stan

[SSDiv6]

Originally Posted by Stan Weiss

Can you please explain how that works?

Thanks,
Stan

In many of the Stock, Super Stock and Comp Eliminator engines I have been involved, one of the typical issues that were common with some of the profiles issue with exhaust reversion. Clues of exhaust reversion were sooty intake manifold plenums and exhaust ports.

It has been a known fact and proven that any valve opening event or lift that takes place prior to TDC will effect the performance of an normally aspirated engine.

The intake event during overlap at BTDC, can expose and contaminate the intake charge with exhaust gas all the way to the TDC event when the piston reverses direction and starts down on the intake stroke. The reduction of reversion improves port velocity and improves cylinder filling.

Many years ago, friend asked for help with his new Comp engine that supposedly made enough power in the dyno to make him top of the class. It did not happened and when the engine was put in a different dyno, it did not make the power claimed by the builder. The problem was reversion. Based on his cylinder head and intake flow data and other details, I had a new camshaft ground with different timing events. The result of both the camshaft change and intake plenum volume change was 89 HP. Moreover, the engine required less timing, and although the cam had more duration, the engine had more PTV clearance with the new cam. After the camshaft change, the intake plenum volume was also reduced and the engine picked up 89 HP with both changes.

[Greg Reimer 7376]

Back in the scary days of the early '70's, I worked at a Chevy dealer beginning in 1975 up till about mid 1980. The cars they made between those years were not exactly exciting as to drivability and gas mileage. Beginning in 1971, the typical 4 barrel 350 that you got in most cars, came with 9.0 to 1 compression by using a piston with a small dish and a large CC combustion chamber in the heads. The '71 engine had the same camshaft as the 67-70 engines, .390" intake lift, .410" exhaust lift. Those cars still ran pretty well. It seemed that NOX emissions were a real concern, and excessive heat or combustion produced it, so the quick fix was to drop the compression down to 8.5 or so to 1, pull ignition timing out of it, and they ground a different cam with more lift,.398I,.430E, as per the NHRA engine specs in the guide. The problem was that the exhaust valve opened early and closed late. Also, the exhaust system in the car was quite restrictive. The sleeve on the right side exhaust manifold where the exhaust do-nut went had a noticeable restricted opening. This was an attempt to cause back pressure in order to trap a portion of the exhaust in the combustion chamber as a precursor to the EGR systems that came out in '73. Also, the presence of an inert gas in the mix combined with the retarded timing (4-6 degrees initial ) was designed to get the NOX emissions low enough to pass some federal standard. This resulted in a car that just didn't have it compared to its predecessors. This also was the start of a rash of 350 Chevy motors that used to get flat camshafts in about 20-30,000 miles. The factory replacement cam was the earlier cam, so when the line mechanics at the local dealer got one of these cars,'72-80 for a camshaft and lifter replacement, the earlier cam went in, and the customer got his car back with a noticeable improvement in drivability. We always set the timing to the factory specs and marked it so that the state smog gestapos wouldn't come visit the dealership and fine us for "tampering". In 1970-72, we had no idea the horrors awaiting the auto industry regarding upcoming emission control constraints! Now, if you have a Stock Eliminator car, all attention is being paid to making all the cylinder pressure and thermal efficiency you can for maximum power at the wheels when the car needs it most. The whole science of camshafts and their effect on engine performance is a huge field, and sometimes understanding what it takes to make an engine work better is to review why some engines didn't work right in the first place.

[SSDiv6]

Originally Posted by Greg Reimer 7376

Back in the scary days of the early '70's, I worked at a Chevy dealer beginning in 1975 up till about mid 1980. The cars they made between those years were not exactly exciting as to drivability and gas mileage. Beginning in 1971, the typical 4 barrel 350 that you got in most cars, came with 9.0 to 1 compression by using a piston with a small dish and a large CC combustion chamber in the heads. The '71 engine had the same camshaft as the 67-70 engines, .390" intake lift, .410" exhaust lift. Those cars still ran pretty well. It seemed that NOX emissions were a real concern, and excessive heat or combustion produced it, so the quick fix was to drop the compression down to 8.5 or so to 1, pull ignition timing out of it, and they ground a different cam with more lift,.398I,.430E, as per the NHRA engine specs in the guide. The problem was that the exhaust valve opened early and closed late. Also, the exhaust system in the car was quite restrictive. The sleeve on the right side exhaust manifold where the exhaust do-nut went had a noticeable restricted opening. This was an attempt to cause back pressure in order to trap a portion of the exhaust in the combustion chamber as a precursor to the EGR systems that came out in '73. Also, the presence of an inert gas in the mix combined with the retarded timing (4-6 degrees initial ) was designed to get the NOX emissions low enough to pass some federal standard. This resulted in a car that just didn't have it compared to its predecessors. This also was the start of a rash of 350 Chevy motors that used to get flat camshafts in about 20-30,000 miles. The factory replacement cam was the earlier cam, so when the line mechanics at the local dealer got one of these cars,'72-80 for a camshaft and lifter replacement, the earlier cam went in, and the customer got his car back with a noticeable improvement in drivability. We always set the timing to the factory specs and marked it so that the state smog gestapos wouldn't come visit the dealership and fine us for "tampering". In 1970-72, we had no idea the horrors awaiting the auto industry regarding upcoming emission control constraints! Now, if you have a Stock Eliminator car, all attention is being paid to making all the cylinder pressure and thermal efficiency you can for maximum power at the wheels when the car needs it most. The whole science of camshafts and their effect on engine performance is a huge field, and sometimes understanding what it takes to make an engine work better is to review why some engines didn't work right in the first place.

You are correct. There are many variables from one engine manufacturer and year to the other. One limiting factor, especially in Stock Eliminator is the lifter diameter. The lifter diameter on GM engines limits the lobe and ramp when compared to Ford, Chrysler and AMC that uses a larger diameter lifter, hence, allowing more aggressive lobes.

[Greg Reimer 7376]

Maybe, that could explain why so many small block Chevy cams went flat all through the '70s and 80's. It's also a possibility that a cam vendor had problems with quality control that caused a lot of problems. Seems to me that some Ford engines in the late '50's and early '60's had a bunch of issues like that, too. I think it was with the onset of the FE engine and the MEL engine, 352,390,430's, etc.

[Ralph A Powell]

Originally Posted by Greg Reimer 7376

Maybe, that could explain why so many small block Chevy cams went flat all through the '70s and 80's. It's also a possibility that a cam vendor had problems with quality control that caused a lot of problems. Seems to me that some Ford engines in the late '50's and early '60's had a bunch of issues like that, too.

It was the Ford Y-Block (272 292 312s) they had a nail head (mushroom) style solid lifter.

[Dave Gantz]

Originally Posted by Greg Reimer 7376

Maybe, that could explain why so many small block Chevy cams went flat all through the '70s and 80's. It's also a possibility that a cam vendor had problems with quality control that caused a lot of problems. Seems to me that some Ford engines in the late '50's and early '60's had a bunch of issues like that, too.

It wouldn't surprise me if Chevy tried to save a penny or two by changing the "recipe" of the steel or iron that the cams were made from. The vendors only adhered to the provided spec. Short term quality problems were more likely a vendor issue.
I say this from my experience working at a vendor that provided tooling and stampings for the big three. We would order steel that was to the customers spec ("recipe"), and it was checked by QC. It would then rust through in a few years until Japanese competition magically made UAW stuff better (late 80's,early 90's). If there was a vendor QC issue, we worked to get it back to the customer's standard, whatever that may have been.

[Bunkster]

Ford 292 lifter:

[Greg Reimer 7376]

Seems that many an engine assembler putting together a 292 or a 312 would get his bare block on the stand, stick in the cam, the crank, the front cover and balancer, then put in the pistons and the rods, button things up, install the pan, pickup and the pump, then turn the engine over and start to install the lifters and then discover one of Ford's better ideas. It was the FE engine that went with a conventional lifter which Ford stayed with ever since. The lifters went into the block on the Y block first, then the cam slid in, then the rest of the bottom half went together. Lots of Ford line mechanics had a set of spring clothespins in their toolbox to hold those lifters up so they could replace a camshaft in the car if need be.