i have the chance to swap out my stock cam ( that i've heard was fairly soft in my year) for a polished one out of a zz4 crate with less than 100 miles on it. should i do it?

 

what motor do you have? and is it a roller motor? the ZZ4 cam is a very nice streetable cam that can easily make 350hp with the right setup, but its a roller cam so you might want to make sure your block has the roller provisions. Also you might want to make sure your heads can handle .530 lift or so. Good Luck.

 

my motor is a stock 350 in my 80. sorry, how can i tell if it has roller provisions? im going to replace my lifter and put in some gm performance roller rockers at the same time. still have stock heads. can it work. thanks agian

 

87 is when Gm came out with the roller block. Anything before that and you will need a retro-fit roller cam. I have seen records of people drilling a pre-roller block for factory provisions. However, if you want a roller cam, I would go to a retro-fit design. It is a far simpler design than using the middle spider and all that stuff.

 

from nastyz28.com on the LM-1 cam
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The camshaft is very unconventional. In addition to having a higher lift on both intake and exhaust,than the standard 350, the timing is about 180 degrees off, compared to any other cam that I have seen. I have compared this cam to an aftermarket RV cam and it looks like the lobes are shifted by one position. When I asked Crane Cams Tech support for about this configuration, they said it would never work. It seems to be derived from the old mechanical lifter Z28 cam that was used in the original Z28 302 engine. (PN 3972178) The specifications that I have for the LM1 cam are:

Lift Intake .2600 Factory Service Manual
Lift Exhaust .2733 Factory Service Manual

These angles were measured from the cam from my LM1.
Lobe Separation 94.64 Deg.
.050 Duration 165.6 Deg. (Crank)
.050 Duration 154.4 Deg. (Crank)


I believe that this cam was designed to raise the dynamic compression ratio because this engine had a very low static compression ratio. (8.2)

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zz4 cam
.474" I, .510" E
duration @ .050: .208deg I, 221deg E.


should i even mess with it

 

No.

LM-1 = "Lame, mild-one".

 

oh yeah on the topic of my heads
1.94/1.5 valves w/75.47cc will i hurt em with any performance cam?

p.s. i dont like my LM-1 but it beats my friends 84 z28 5.0 HO (stock)

 

thats not fair, haha, you beat me when i only had 7 cylinders firing, we need to re-race, youll still win though..haha