[Custom10]

Fella I know has ended up with a 283 in his 69 RS with a very lumpy cam making next to nothing for vacuum. He says he thinks it is a special factory order cam that was available for the 69 302 and that the lift is over .500 on the intake and less than .500 on the exh? The idle characteristics of this cam/motor are hell bent, yes the smaller cubes don't help, he has had this car sitting for over 12 years, now he just got it back from body and paint and is focusing on the mill, he himself is not sure exactly what he has inside the little beast. The piston/head combo is good for at least 11.5 or 12:1 SCR or so he was told years ago. Was wondering what this cam is all about or if there is such an animal?

[ericnova72]

We would need more info, there were 2 over the counter "off-road" cams offered. First Design and Second Design designations.

[Custom10]

thanks eric, we are not sure what is in there, he has not opened it up yet but when he told me what he thought it was I wanted to start with finding out if there was such a cam at all, he said he was told the cam had higher lift on the intake than exh, this is what first got my so called mind wondering as well as the mystique of a special grind, just fishing for some info, any as always is appreciated. what are the specs/info on the two you mention?

[DoubleVision]

If it`s been sitting that long without being ran if he didn`t cycle the engine as if the cam were new on start up by doing a 20 minute break in cycle he`ll soon be referring to the cam in the past tense. Also it`s possible there is many different cams in there that would create the same effect. Most times when dealing with older vehicles the seller will say anything that has to do with "special high performance" or "factory special high performance" just to up the resale value. That`s where we came up with the terms from other legendary sayings such as "350 rocket" "3/4 cam" "pop up pistons" "police interceptor" and the classic "it`s a vette engine"
If the engine has that high compression ratio and on pump gas, detonation will be audible rather easily. Not to say the engine hasn`t had done to it what`s been claimed, I`m only saying can`t believe everything your told as the former owner may have dug up a bone stock 283 and stuffed a big cam in it, however, the cam wouldn`t have to be that big to knock the wind out of a 283 due to it`s small cubic inches. You should be able to look up the performance grinds GM has to offer for the small block and see if you find anything that comes close to what you discribe. To be honest with you, I can`t ever remember any GM cam having less lift and duration on the exhaust side than the intake side. GM always stuck to more on the exhaust side than the intake even so it wasn`t needed on performance engines.
Here`s a list I found maybe it`ll help you.
http://www.nastyz28.com/sbchevy/sbccams.php

[OneMoreTime]

Cou;d be one of the old 327/365hp cams as they were lumpy and had poor vacuum but they did go like stink..

Sam

[johnnya]

3849346 Mech. 254/254 .485"/.485" 11.0:1 114 327/365HP & Z-28 302
This is the famous "30-30" cam
3927140 Mech. 257/269 .493"/.512" 12.0:1 112 Off-road
This what most people mean if they refer to a "Z-28 off road" cam..I had one of these in a 66 Nova 350HP 327 while I was in the Air Force in the late 60's. It was too much for me for daily driving, and I went back to the 350HP hyd cam.
3965724 Mech. 262/273 .488"/.509" 12.5:1 112 2nd design, short track, road race
I never knew of anybody that had one of these, but I knew they existed.
JA

[Custom10]

DV yes you are correct it could be that he was miss informed, I did not think that there was a GM cam with greater lift on intake then exh so that part is smells of BS. He has ran this motor from time to time, maybe not enough but time will tell. All I know is that having listened to it run just the other day it sounded absolutely rank. It is surely high compression as well, the 12:1 would not be out of the question but he will not know until he gets in there and takes it down. It is way too much for the street what ever it is. The tranny is a TH400 with 3000 stall and it has 4:88's, we are going to take it out before the snow flys and have been getting great weather for Oct up here, should be fun, the body/paint is outstanding and the interior is nearly mint.

Thanks for the links and info guys, we know it is a mech cam and if it is truly a GM cam then its one of the four, if its the first/second design cam it could be a very rare part indeed.