ghostrider20

I was talking to a fellow today and he mentioned the "stage II camaro cam" that was a solid lifter cam. Is this the "30-30" cam? I know they ran the
"30-30" in the late 60's camaro's.

Mark

SWCDuke

Sounds like the guy has his head in a dark place.

Beyond this Chevrolet developed two racing cams in the late sixties that were used by Penske in his Traco-engined Trans Am cars. The "first racing design" - 3927140 is a bit milder than the "second racing design" - 3965754, but both have extreme duration and overlap and are only suitable on a racing engine with tuned headers and open exhaust. They would be stones on the street, but will give great rumpity-rump idle for guys who are more concerned with achieving a "big cam idle" than good street performance.

There is also a "third design racing cam" that uses mushroom lifters. All these cams are listed in the old Chevy Power Manuals from the seventies and eighties, but they were never referred to as "stage...whatever".

The 30-30 cam was OEM in the production 302 CID Z-28s from 67-69, but the '70 Camaro used the same LT-1 engine with the 3972178 "LT-1" cam as the '70 LT-1 Corvette. The '70 Z-28 LT-1 engine was essentially identical to the Corvette LT-1 engine, the only significant difference being different exhaust manifolds, which may account for the fact that the Z-28 carried a rating of 360 gross HP versus the Corvette's 370.

Duke

Kid_Again

..duke, what's a mushroom lifter?

66427-450

As I understood it..... mushroom lifters had to be installed from the bottom, they had a "large dia portion" or foot, that rode against the cam lobe........ intended for cams with steep ramps I guess (makes since if you think about it, but I don't know how effective the design actually was)
:seeya

DZAUTO

That is correct, mushroom lifters (upsidedown T shaped) are installed from the underside (which MUST be done before the cam is installed). But first, the bottom side of the lifter hole must be machined flat. The third design offroad cam required the mushroom lifters. A later solution to this was to oversize the lifter bores and use a larger diameter lifter (seems like it was brand Fxxx).

Mark,
As I'm sure you know, the 30-30 was the cam used in the 64-5 365hp (Holley) and the 375hp (FI) 327s, and then as mentioned, in the original 302 Z/28 (67-9) engines. I have absolutely no clue where someone would get the term for the "Stage II" for the 30-30 cam. Back in 68, when the 140 cam was first introduced as an over the counter "field installed" cam, it was SPECIFICALLY intended for the 302 engine for road racing. In the circle of my friends/acquaintences during that time, the 140 cam was referred to as the optional Z/28 cam. This was BEFORE the second or third offroad cams were introduced, thus it was NOT known as a "first" design offroad cam.
It may be possible that your friend is referring to this 140 cam as the Stage II cam. Who knows?





[Modified by DZAUTO, 12:33 PM 1/22/2003]

joe58

He may be thinking of the solid lifter cam known as the Z/28 "off road" cam that is in the old Chevy Power catolog.

SWCDuke

In order to achieve more lift with the third design racing cam, they had to reduce the radius of the base circle in order to get the cam lobes through the bearings. As the base circle gets smaller you need a larger diameter lifter base, which is why they designed the "mushroom" lifters for this cam.

Net valve lift with the third design cam - 366293 - at 1.5:1 true rocker ratio is .560"/.575". The six digit part number would indicate an early mid seventies release as in this era GM uncovered some old unused six digit part numbers and began using them. Many of the EFI parts in my Cosworth Vega carry six digit numbers

Duke

SWCDuke

The "Z-28 offroad cam" refers to the first design racing cam - 3927140. It is also known as the "140 cam". As I stated above, this cam would be very unsuitable for street operation with mufflers because of the very high overlap - much more than even the 30-30, which has too much. Like all other Chevrolet racing cams it was designed specifically for a racing engine that has headers and open exhaust.

Duke

63FI

Hi Mark,
I had the 140 cam in an '67 Camaro with a 327. The car screamed! Did 11.5 in the quarter. It was my quickest car so far. I used it every day and loved it. Did'nt drive it in the winter months, so I had to just look forward to spring once December came around. Unless you are really into tinkering, as I am, listen to what everyone else has said about it. Just wanted to let you know, put together with the right components, you would have fun with it.
Lou

ghostrider20

Great info guys. The fellow that mentioned this to me is one of the A/C mechanics at the airport. He mentioned that he had a 66 chevelle and in
68-69 he poped the motor and GM warrantied it. At that time he had them install a "stage II" solid lifting cam. He said it was very radical and the car idled around 1800 RPM and was a real thumper. I was sceptic but had no reason to dispute his claim. He was not sure of the actual cam, only the "stage II" name. I was wondering if he happened to order a "30-30" cam. The 30-30 will idle well below 1800 rpm although one guys idea of radical is differant then the next. So I offered this to the experts for clarification. ;)

Mark