Z/28 302 camshaft selection

[markjohnson]

I've always heard that the #140 Off-Road Camshaft was just what it's name implies and that the stock Street Z/28 (#178) was much better for a street car. Chevrolet's 60's era musclecar camshafts were notorious for lots of duration, especially that #140 Off-Road Cam. As it's name implies, it's geared towards lightened Trans Am-style race cars that spend ALL of their time at high RPM zipping through corners and blasting down straightaways. Those small cubic inch 302's aren't known for having loads of torque anyway. If you've ever driven a four speed street car with a massive duration camshaft, it's really not a lot of fun and at least 4.11's in the rear axle is an absolute must to try to compensate for it. My vote is for the stock #178 Z/28 camshaft.

[SSRSBOB]

Mark,

We have the 178 cam in the engine that I sent to CHP. Car was a turd with it. 3.73 gear and M21. We will change that. From what I was told by CHP and others who know the 302 better than anyone is that this engine needs gearing for it to perform like a performance car. Camshafts will not give this engine more torque.

One of my best buddies bought a brand new 68 Z8. 3.73 and M21. He sold it less than a year later because he was very disappointed in the performance. Back then, D. Harrell told him that these engines need gearing too. Doing that awakes a sleeping giant.

Bob

[BUIZILLA]

the 140 cam must have 4.56 or better gears, most likely a 4.88/5/13 works the best..
302/3.73/M21 is a dog.... 4.10's and M20 is MUCH happier street driving, 4.56/M21 for drags

[SSRSBOB]

Mac Neish has a local Camaro Z28 customer with 4.10, M20 and 140 cam that runs in the low 13's at 108 on street tires and closed exhaust. That is our goal. I am going to call this customer and ask him directly too.

Bob

[markjohnson]

A wide-ratio Muncie with the 2.5 First Gear is an immense help towards getting those 302's rolling from a dead stop. What they lack in low-RPM torque needs to be compensated for by gear-multiplication.

[drdave69]

I concur with the opinion on gearing and the right transmission. My old Z/28 had the stock replacement cam with M20 and original 4:10 rear. It performed pretty well (except on the freeway).

[Hotrodpaul]

I wonder what the little 302 with a street friendly solid roller cam, modern tremec 5 speed with low first gear, and some 4.10's out back would be like? A similar situation exists with the Mustang Cobra's 4.6L 4 valve engine that has little bottom end but loves to rev. I had a 98 model with T45 trans and 4.10's and the car was a blast! That low first gear (3.37 I believe) with the 4.10's gave great torque multiplication with the overdrive (.67) dropping the cruising revs on the freeway. This would be a great tranny for a swap into a non concours first gen Camaro.

Paul

[Lynn]

Thanks for the offer Dave. I went ahead and ordered two of the comp cams.

I have run a 140 cam with a single four barrel, and it absolutely screamed from 6000 to 8000. I didn't find the idle that objectionable. Kept it set at about 1,000 warm.

[Salvatore]

Most people work on the wrong end of the car when talking about a sb Chevy, especially the 300 inch motors. I like the 4.56 and the M20 for the Z/28's. Keep the hood closed and jack the rear up.