Suggestions; 69Z 302 Engine Rebuild

[1966L72]

I was adjusting my valves yesterday and noticed an intake stud starting to pull out of the head. Instead of just having the head redone I decided its time to go through the motor and freshen it up. Any suggestions to improve the low end performance to have a little more fun on the street ? I want to keep the original 4053 carb, 480 distributor and original valve covers in place... thanks

[Stefano]

A 350ci type stoker kit, will substantially increase your torque and fun factor on the street.

[VintageMusclecar]

Does the car have factory exhaust manifolds or headers?

Eric

[1966L72]

Eric - - I'm running stock manifolds, non functional aAIR pump, power steering

[47Hammer]

If you were to slap a set of headers on that 302 it would make a surprising difference and be much more drivable on the street. In addition it's gonna sound incredible too! http://www.yenko.net/ubbthreads/images/graemlins/headbang.gif

[waynemiller]

Give Jerry MacNeish a call, he rebuilds tons of DZ's and they make ton of power and look and act stock!

He is at Camaro High Performance.

Wayne

[VintageMusclecar]

Bart is right, headers (and a free-flowing exhaust system aft) will open the door for significant power improvement, esp. since they allow you to step away from the OE cam should you be so inclined. If you plan on staying with the factory manifolds, stick with the GM cam as it's been proven time and time again to work best with them. Quality machine work during the rebuild can also make a noteable difference. A little port work on the heads can pay off quite nicely if you're not against the idea.

Aside from that, stick with the tuning basics re: jetting, timing, lash, etc.

Eric

[1966L72]

I want to stick the original exhaust manifolds & non function smog setup, the car also has SS chambered exhaust. I think porting the heads is definite, for cam selection both Crane & Comp Cam regrind the original, is there a difference based on others experience ? ... .thanks !

[ChuckDX77]

I just did a full DZ spec re-do on my 69. I stayed stock. You will get lot's of opinions, but I can tell what actually happened on mine, as other will also. If you are interested, in a nutshell, here's what I did. Stock dated -618 block, 4 bolt main, .060 over, I used Classic Industries hyper-eutectic pistons as they have the correct dome. Do not under-estimate this fact. #1178 crank, NEW steel rods, pressed pins,I used the original -186 heads with the correct Crane recommended springs and retainers, new stainless valves, the Crane "Blueprint" 30-30 cam, original intake and exhaust manifolds, revised advance can, Echiln #VC-1810, manifold vacuum, not ported vacuum, 72/72 jets, and it runs great, nice idle, with some lope. To address the low end issue, any changes you make away from the stock cam will move the low rpm horesepower down some. This engine runs great in stock form. You will have a devil of a time trying to improve both ends of the power spectrum at the same time. It's a trade off. On the other hand, if you want a stock look only, and want gobs of torque, a mild 383 will do wonders and no one will ever know...."yeah...it's a 302"...for my car, since it is an original Z, I could only put another 302 back in. It's your car, so only you can decide...however, if you plan on a 302 rebuild and want more power, you lose it big time on the bottom. Others may chime in and give you their experiences and now, well, you have mine. I wish you the best and hope it all turns out great...let us know!

[GREEN4SPDSS]

Hello 1966L72 I have a 1969 Z/28 With a DZ 302 I'm running a Comp Cam CS 282S-10 282 duration 495 lift With 110 lobe Separation. I really like the Drivability with this cam. I have a 3:73 gear. Driving on the highway it really pulls nice. I'm running exhaust manifolds and factory style Exhaust system.

[1966L72]

thank you all for the responses

[Salvatore]

John, If you freshen up the motor to the right specs and so forth you will be in good shape. Most people work on the wrong end of a Z/28. You can keep the hood closed if you are happy with your rebuild and jack the back of the car up. That is where you have to work on the little 302. Minimum of 4:10's and if you have a chance to put an M20 trans in the car better yet. The key to that motor is the gearing. Even 4:56's would be OK on the street! Good luck! Sam http://www.yenko.net/ubbthreads/images/graemlins/3gears.gif

[1966L72]

Sam thinking about it I agree, my last 69Z had 4:11 gears with M20 tranny and it was alot stronger through the gears. The trans in my current car is the original M21 with 3:73 gears so with a fresh engine build and upgrade to 4;11 or 4:56 gears the car hopefully will go a long way... thanks

[Salvatore]

Now your talkin! http://www.yenko.net/ubbthreads/images/graemlins/biggthumpup.gif http://www.yenko.net/ubbthreads/images/graemlins/3gears.gif

[47Hammer]

I still like the headers...
http://i14.photobucket.com/albums/a321/megavin/th_DSCN2734.jpg (http://s14.photobucket.com/albums/a321/megavin/?action=view&current=DSCN2734.flv)

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[drdave69]

I agree with the gear change. My first Z/28 had the 4:10 factory gears behind the original M20. After a stock rebuild and jetting the carb according to Jerry M's advise, the car ran very strong.