Finally got my 84 Z28 back on the road after a year.The owner that owned it before me blew up the stock 305 and swapped in a 350, but I don't know from what kind of vehicle. Problem is that it doesn't have any pull above 4000 rpm and I cant get it past 120 mph. I thought I read that these cars went 134mph with the 305 HO. Could the motor be from a truck and the truck cam is what is killing my top end or should look at timing/tuning? I think it's a 1975 to 1979 motor and I have a 3.23 rear end and a T-5.

 

A bone stock mid 70's truck motor would be rated at 165-175ish HP. The '84 L69 305 was rated at 190HP, and is indeed faster. So yea, you could be going slower with more cubes, if the guy used a box stock 350, and if it had a HO motor stock.
Valve springs and cam will be whats holding you below 4000RPM. And yes, definately look into tuning, check the timing first thing.

 

175 horsepower. With 45 more cubes... That would explain some things. My Camaro can pull a house down but dont ask it to run fast. Anyways, I was asking about a new intake, cam and some mid/late 80's 305 heads in another thread, would those three parts, properly matched to each other solve the problem and give me more top end? I'm certain it will but I want to make sure.

 

Oh yea, big time. See my combo in sig.

 

Try a Performer EPS and the .420/.442 cam and the valve springs that match. See what that does for ya.

 

I already have a Performer RPM manifold waiting to be installed, just need to grab some 305 heads and try my inexperienced hand at porting them. Already have headers so the next thing is finding a cam to tie it all together. Moneys a little short for the present though so what can I do to speed it up before I install the intake? Would advancing the cam a couple degrees do anything to add horsepower at the expense of some low end torque?

 

No, don't even bother messing with the stock cam, you'd just be asking for trouble.
Just wait, save up. Port the heads, give it some decent exhaust, and
a decent cam and you're laughing. A summit cam and lifter set is a paltry $70 or so, the 214/224 would work great for ya. It's not a fantastic cam by any means, i'd rather see you get a comp cam, but $70 vs $200 (cam and lifters), it's a good cam to try for the short term.

 

Sonix you beat me to it lol. Yeah the summit cams are inexpencive.

 

The cam you suggested, would that be to use with the stock motor or with all the other parts I mentioned?

 

yes