Stock Cam Profile

[donald w. miller]

I am wondering if anyone in the group has details regarding the stock 455
camshaft?

Is the stock cam a special grind for the GMC or a standard Tornado issue ?

Stock timing duration and lobe separation numbers?

Stock rocker arm ratio ?

Anyone tried advancing their stock cam ?

Also like to hear of results from those using after market cams in their
GMC, especially roller cams and roller rockers.

Someone mentioned ceramic coating stock exhaust manifolds. Sounds like a
good idea for those who don't want to go the header route. A neat way to
cure the manifold warping problem and also reduce engine compartment
temperatures.

Don Miller

 

[thomas g. warner]

The GMC used a special RV cam that is different from the toronado. It works
fine for low end torque. the real problem with this engine is heat, heat,
and more heat. It is just to hot under the hood and this heat leads to
problems.

You need to decide whether you are shooting for performance or reliability.
For reliability the stock coach block is very rugged and needs nothing. In
IMO it could use new cylinder heads that breathe better(the J smog heads are
the worse that GM made), and when you are at it seal off of the exhaust
crossovers on the cylinder heads to reduce heat in the engine compartment,
a set of Thorley headers(and install fender vents), 3 inch exhaust,
recalibrated carb for modern gas, little hotter HEI ignition (Dick Paterson
has nice ones for about $160) and finally change the Thermostat from 195 to
180 degrees. These changes will add at least 60 HP to the stock engine and
increase its reliablility also. These mods are what I am doing to my engine.

IMO going to roller cams and rockers only increases the expense and
decreases the reliability. The stock lifters, rockers and studs are very
rugged and have proved themselves in many millions of miles. I did replace
the rockers on both cylinder heads as they were slightly worn (cost $16)

Aren't opinions wonderful?

>I am wondering if anyone in the group has details regarding the stock 455
>camshaft?
>
>Is the stock cam a special grind for the GMC or a standard Tornado issue ?
>
>Stock timing duration and lobe separation numbers?
>
>Stock rocker arm ratio ?
>
>Anyone tried advancing their stock cam ?
>
>Also like to hear of results from those using after market cams in their
>GMC, especially roller cams and roller rockers.
>
>
>Someone mentioned ceramic coating stock exhaust manifolds. Sounds like a
>good idea for those who don't want to go the header route. A neat way to
>cure the manifold warping problem and also reduce engine compartment
>temperatures.
>
>Don Miller
>
>
>
>

 

[zachary zehnacker]

Don,
We have been pretty pleased with an Edelbrock Performer cam we installed
in our 455. It along with an Edelbrock Performer intake (requires a raised
section in the engine cover) and Holley carb really picked up the power and
mileage of our 455. The stock cam and intake on these engines are
terrible. The intake sits down in the engine inviting fuel to puddle. The
cam was designed right when the EPA was going nuts and the easiest way the
manufacturers had to make them happy was to turn down the power with the
compression ratio, cam, and heads.

You will find that there is not much out there in the form of roller
rockers and cams for the Olds engine. Harland Sharp makes a set of roller
rockers, but I don't know if they are really designed for street use. They
also say the require a modified head (not sure what gets modified though).
We did go with a set of Comp Cams Magnum Rockers on our recent rebuild.
These offer the roller tip but are not roller rockers. Both of these
options are available from Jeg's mail order. You are pretty much stuck
with Mondello's high prices if you want any other options in roller rockers
or cams. I would agree with the person who already posted his concerns
with reliability of these roller setups. Most of the stuff for the Olds
motors are race only parts that are being put into street motors because
that is all that is available. These are probably not going to last like
the rollers you see going 100,000 miles in the new cars or those designed
for the street for the more popular SBC and BBC engines. It wasn't that
long ago that even the rollers for the SBC weren't very reliable.

Hope this helps,
Zachary Zehnacker
Seemann Bros. Racing

>I am wondering if anyone in the group has details regarding the stock 455
>camshaft?
>
>Is the stock cam a special grind for the GMC or a standard Tornado issue ?
>
>Stock timing duration and lobe separation numbers?
>
>Stock rocker arm ratio ?
>
>Anyone tried advancing their stock cam ?
>
>Also like to hear of results from those using after market cams in their
>GMC, especially roller cams and roller rockers.
>
>
>Someone mentioned ceramic coating stock exhaust manifolds. Sounds like a
>good idea for those who don't want to go the header route. A neat way to
>cure the manifold warping problem and also reduce engine compartment
>temperatures.
>
>Don Miller
>
>
>