I am doing a complete rebuild on my original DZ302. Externally the engine has to be completely stock. My question is should I go stock internally (11:1 pistons, 30/30 cam, etc.) or utilize updated technology and go roller cam and roller rockers, etc., etc. I think technolgy may result in a more drivable engine (run better in cruises, traffic, etc.) and more horsepower!? Any one have experience with this?

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1969 RS-Z/28: DZ302, M20, 3.73, Tuxedo Black, Deluxe Black Interior, Factory Tach, Clock and Console Gauges, Rear Defrost, Spoilers, ZL2 Hood.

The old engine parameters made the Z28 302 one of the greatest enginepackages ever built. What a neat deal. But, as you already know, low speed driveability and fules tolerance were definately on the outs here.

There are a lot of people who do leave the engines alone and resolve to live with a great engine, and others who make the compression more fuels tolerant and tame the cam to match, for better fun in a truely historic vehicle.

It all comes down to the cam and compression ratio. The initial cam has a very gradual ramp grind on it, and this bleeds a lot of compression pressure off at low engine speed, and that's what makes the earlier performance packages get away with not very much pinging on today's pump fuels.

Today's cams have altered ramps, opening and closing the valves is much more aggressive, allowing lower compression ratios to make better overall power, without much sacrifice from the earlier design cams, giving better fuel mileage, better low and mid range driveability and more tolerance against detonation.

Not an easy chioce to make with a 302 engine, I really don't think the newer tech will help the really short stroke engine as well as it does to a bigger one. Keep it historically correct or make it more user friendly. I myself, really like the solid cam sound, and the historic engine, but I'm a purist as far as factory musclecars is concerned.

My opinion, if it doesn't go back dead stock and full on resto, then go hog nuts with it and make it a real fun deal.

I know this didn't help much.

BS Dave, it was right on the money. DW, you want to do exactly what I did with my L88. Cut the compression ( I went to 10.8 with aluminum heads ). Where to is a question for a real pro, but I'd stay at 10:1 with iron heads.

Secondly, use a modern profile cam, not a 30/30. Definitely SOLID, and if you choose the added expense of a solid roller, you might get all your HP loss from cutting compression back. I run the smallest Crane solid flat tappet. In a 302 I would run their smallest solid flat tappet, or their 2nd or 3rd smallest roller.

I use roller rockers ( hopefully they have longevity) to gain back some of the HP I lost. And I also use a very free flowing exhaust with an X-pipe and tails. Again, trying to gain back what I can and make this thing worthy of the L88 moniker.

Now let me tell ya. Everyone says that an L88 is not "streetable", the square port heads are too big, yadda yadda.

Not to gloat but the "modern" L88 runs on 93 ( pref 94 thats how close the CR is the cusp)gas, and downright hauls ***. 502 are maybe a good race and Mustangs, unless heaviliy modified, are nolo contendre.

No matter what, your 302 will need more gear. The rat can do all her magic with an M20 and 3.55 on 26" tires. You'll need more 1st,2nd than that for sure.

But I think with a little planning you can run an engine just as strong as the original DZ302 on today's crap gas.

To sum, I'd cut the CR to 10 ( an easy fluycutting of pistons and then rebalancing )and install the smallest Crane solid here:
www.cranecams.com/master/apps/chevy21.htm (http://www.cranecams.com/master/apps/chevy21.htm) .

If you scroll down to the blueprint series, you can see your DZ302 cam.

To keep similar characteristics, I wouldn;t go with the smallest roller, but the 2nd or 3rd one up on the list. Here:

www.cranecams.com/master/apps/chevy27.htm (http://www.cranecams.com/master/apps/chevy27.htm)

Yes, I would go a bit modern on your rebuild, but keep the general charateristics of the mill intact. Solid cam/high revver/ relatively large carb/high compression ( 10-10.5 TOPS!)

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G.Chaas
67 SS396/427L88 A body


[This message has been edited by 427TRI (edited 08-15-2000).]

My 2 cents is this. I think you shoud save your precious number matching motor in the garage and build a modern driver clone 302. Why risk putting a rod through your one and only original motor. I think I'm going to do the same with my non original 302. Stay with 302 inches but update it to run and still have that 302 revablity and feel.

That's my dilema too. Since I'm going to run a crossram and I already have some ported angle plug heads from TRACO on the car, do I rebuild the original block and risk breaking something or buy a 350 block for $50? Seems like a no brainer, but it does take away from the "it's matching #'s" claim. ?????? Don't foget, you can always put a 350 crank in it and it will look like a 302. The extra cubes = extra torque and better driveability.

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Jeff H - 93 Indy 500 Pace Car(supercharged), Hugger Orange 69 Z28 with JL8 brakes & crossram

Thanks to all of you who have responded! This is quite humorous as all these opinions so far have been exactly what has been going thru my mind.... stock is great as it is a stock restored #'s car and a great engine design...... modern is great for crudy gas, cruises, driveabilty in general, etc.....and I have already considered putting #'s engine on stand and building a 350 with stock externals but that does leave you wondering what to say at all those car shows when EVERYBODY ask's "is it matching numbers?"

Keep the advice coming.... would really love to hear from someone who has built a 302 recently stock or otherwise!

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1969 RS-Z/28: DZ302, M20, 3.73, Tuxedo Black, Deluxe Black Interior, Factory Tach, Clock and Console Gauges, Rear Defrost, Spoilers, ZL2 Hood.

When people ask if it is a number matched rig I always tell them no but it's a heck of a lot faster than a "stocker". I say build a monster in disguise (383+ painted aluminum heads, full roller etc.) But I could be biased about big motors. If you need an engine builder try Bob Hubler in Cascadia. He helped me out with my Chevelle and it rocks! Kinda strange a ford guy could build such a BBC http://www.camaros.net/forum/biggrin.gif. Good Luck

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Jeff
69 SSRS 396(roller 427 http://www.camaros.net/forum/biggrin.gif )
My Chevs (http://www.tcg158.homestead.com)

[This message has been edited by ace841 (edited 08-16-2000).]

DWCamaro69, I am restoring my numbers matching ’68 MO 302. I went the stock route while utilizing the benefits of new technology where beneficial. I had to bore the block (0.040”) to clean up some old ring damage and replaced the pistons with J&E. They are the superstock replacements but are much lighter and stronger. When I had the assembly balanced, the machinist did not need to touch any of the pistons. My car was an early build (2-bolt mains with large journals) and had pressed pins so I converted them to floating with double Spirolox retainers. Used the Crane blueprinted 30/30 cam, magnum roller rockers, and Crane matching lifters. Complete head re-build with new guides and Ferrea valves – sooo much lighter than stock. Minor head clean-up and ARP fasteners. It will utilize the original intake, distributor and Holley. Right now, I am planning on going with Hooker super comp headers.

I know it will be finicky down low in the rev. range, always was, but I wasn’t willing to give up the top end and true characteristic of the engine. This way it looks stock and keeps with the general intent of the 302’s design. I kinda though of it as what GM would have done if making money wasn’t their first concern!

I should have hastened to add that I am not running the orignal block either, just a '73 2 bolt 454. The original has 1 build left on it. And this isn't even a numbers matching deal. Mothball the numbers matching block for sure.

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Gene Chaas
67 Chevelle SS 427/L88 (http://www.chevelles.com/showroom/chaas00.jpg)

I go to shows and talk to owners of "real" Z/28's with 350's or strokers. My car is the opposite, it's a Z clone but with a "real" DZ 302 motor. It's amazing how many people never heard of the 302.
Austin

The Chevy 302 is very much a secret outside of the Camaro enthusiast world, isn't it. Just about every time I go to the auto parts and tell the guy a Camaro with 302 the response is "Are you sure, the 302 was a Ford engine." The last time this happened the guy went into the back room and later came out very apologetically saying he just found out Chevy made a 302 for three years.
Mark

I understand what you are going thru with your project. I have a 1969 SS 396/375 car
and the original block was damaged. I found
another 396/375 and began to build it. I went
back and forth many times on original or modified. I kind of decided both. Motor looks
somewhat stock with updates. I installed the
GM Performane Parts aluminum heads, moderate
Crane hydraulic cam and headers. I think it is the best of both worlds.....

DWCamaro69,

Have you thought about this combination;
A 400 .060" over block
A 3.25" 327 big jounal crank
Flat top pistons of about 9.5 or 10.0 to 1 C.R. with a 64 CC big valve modern after market heads
The longest rods you can afford that will fit
A 230 to 240 duration at .050" solid cam
Carb, intake and headers of your choice

You should get somewhere around 357 cubic inches with this combo and have the same type "git" that your 302 has but a lot more of it, plus be able to do it easier on "pump gas" and have better low speed driveability.

If you do decide to rebuild your DZ engine then please drive it like the General meant it to be run. If not build one to romp and stomp on. pdq67

pdq, I've been building the short stroke 327 crank/400 block 350 combo for over 20 years before the magazine article about them came out and said it was the way to go in a 350. I already knew it was. It just makes me laugh when I hear how good the 3.480 stroke 350 is the greatest engine ever made, by some nutball magazine dweeb writer or "expert" who just doesn't have a clue.

I've not noticed a loss of anything from the short stroke 350s, in fact, I have always found they run harder than any stock stroke 350.

There are only 5 engine sizes I would build for the small block, 283, 302, 327, short stroke 350, 400. Everything else is just a real letdown for me.