SamW

I was trying to find some info about the Chevrolet 302, but couldn't seem to find much. So any help would be appreciated. My questions are: What was the redline on these engines? How wild was the stock cam? Were they anything more than a 327 block with a 283 crank? Thanks, I'm sure I'll think of more questions soon.

ZONES89RS

iTrader: (25)

They are a 4 inch bore block with a 3 inch stroke, they revved to 8 grand if i have heard correct.

kenSS

iTrader: (1)

the stock cam in these motors had .485 lift and .254 duration at .050. on a 114 lobe sep. this cam had a range from 4500-7200. hope this helps

SamW

Thanks, can anyone shed some info on a good set up to run with a motor like this?

ZONES89RS

iTrader: (25)

Well, you need heads that flow good and a excellent valve train.

SamW

I saw a dyno vid on a website earlier and it rev'd to about 9500 iirc. I'd like to have a motor that could rev that high. Would forged rods and pistons be good enough? I also read some where that all 283 cranks were forged. If this is true, is that good enough for that rpm? If the compression was kept to around 10-10.5, would 93 octane be enough? Would 4.10's be good for this setup, or would 4.30's be more optimal? I figured it would be neat to use a t-56 out of a LT1 so I could use a little more gear and still be friendly on the highway. Would a 327 or a 350 block be better to use?(i.e. which is stronger?) Thanks

cnorton

iTrader: (1)

1968 and 1969 Z-28 (302) engines had four-bolt mains and large journal crankshafts, both of which are a plus in a high-revving motor. The bore/stroke combination correspond to the nominal 327 bore (4.00) x 283 stroke (3.00). NHRA specs indicate a slight overbore (.002) and overstroke (.005) which, I suspect was done to increase the displacement to 302 cubic inches. "Back in the day" we referred to the 327 x 283 combination as a 301 inch motor.

I would hesitate to use a 283 crankshaft since it was counterweighted for lighter pistons and rods. You could end up with a hefty bill for heavy metal to achieve a balanced assembly.

There's no way I would build a big RPM small block without some very strong rods (my personal preference is Manley) and at least a forged piston. The factory Z28 motor had a TRW-type forged piston and specially selected rods.

A 327 piston is set up for a 3.25 stroke so the wrist pin height would not work.

The biggest advantage to the Z28 was the breathing of the heads. With bigger valves and the solid lifter cam, it far outperformed the other small blocks of that time. But, by comparison, a good, stock LT1 or LS1 F-body would cover a street-driven and tuned '69 Z28 by a good margin.

I can think of no reason to put a lot of money into a 302 unless you wanted to have RPM bragging rights. If you spend the money, you can make an LT1 run and live at 8000+. Not much else to say for the 302 other than to recognize it as a very special piece in its day.

SamW

Where do you find aftermarket crankshafts that coudl be used in a 302 at?

MrOverkill

iTrader: (1)

Tons available on Racingjunk.com and eBay from circle track race teams, you can buy used billet short stroke crankshafts for dirt cheap......

SamW

Ok, thanks. Who should I consult about a cam for this project?

firehawk238

iTrader: (1)

i have a 1966 chevy truck that has a 283 in it, and when i rebuilt the engine i learned that my forging number is the same as the cranks used in a 67' 302. it is indeed a forged steel crank. not all 283 cranks are forged though. there were some that got cast cranks, though they are few and far between, and im sure most have been used and destroyed through the years. only the stronger steel cranks would have survived. if you really wanted to duplicate the 302, id go for some very high cfm heads from someone like afr, or dart and use nothing but forged lowers. also the cam that was used in the 302 was a solid lift cam, but if it were me id go to a hydraulic roller for the effeciency of it. would also use 1.6rr. holley makes an aluminum intake that is an exact match to the old 302 4bbl with one difference, it has a 1" taller rise than the GM piece. then just get a good carb and perhaps some MSD ignition. then id follow it up with a real good set of long tube headers, and some very high flowing exhaust such as the SLP bullet resonators. if using a T56 id use a 4.10 geared rear if going to street drive a lot, and if not, id go with a 4.56 just for the extra pull on the bottem end of the rpm range. just me though.

karl

SamW

Can you give me a link to that intake? I searched but I don't think I found that one.

CNC BLOCKS N/E

I have a brand new small journal 3 inch stroke crank and new 11:01 trw pistons with rings and a set of 327 rods.

You can actually use the 350 block with a set of MS 1110-H main bearings.


If interest PM me.

firehawk238

iTrader: (1)

the intake manifold is a holley street dominator part # 300-36. i also run a lunati blue print cam for a 350hp 327ci chevy. its a pretty good street combo for an old truck.

NightTrain66

iTrader: (7)

big bore, short stroke. Worked well back then for classes based on cubic inch since the motors ran so well. Also allowedthe heads available at the time to feed tan engine to a high RPM wher as the same heads on a 350, 383 or 400 would make peak HP way sooner and run slower at the track in a car set up for racing (light car, lots of gear, 4 speed, LOTS of top end, not much low end or mid range power.etc).

before they had the DZ 302, people would take a 283 and bore them .125 over to get a 302 (actually 301.xxx). Very thin cylinder walls and would run warm but make power.

Now days you can chose MUCH better heads and feed a 350, 383 or 406 to a higher RPM and make more low and mid range TQ while doing it.

Only reason to build on is if you have a factory DZ302 car and matching block. If not, save your $$$ and build a 350, 383 or 406 and make more HP, more TQ and you will be happier with the way the car runs.

firehawk238

iTrader: (1)

as much as i hate to say it, he is right. however im a fan of doing things different than everyone else, so i still run a 283 in my old truck. cammed and everything else. its still fun to drive and has enough power for me. and its not a 350 so i love it. just like being different is all.

karl

NightTrain66

iTrader: (7)

I understand about being a lil different, it is just the extra FREE HP and TQ from a 350 woul be nice. I would just build the 350 and buy some "283" stickers for valve covers or air cleaner, lol.

Lloyd

s/c'd cav

iTrader: (10)

the 302 heads were no different from the rest of the heads of that era , other than the 2.02 and 1.60 valves , unless you managed to get 1 with the angle plug heads

whats funny is both chevy and fords 302 both had 4.0" bore and 3" stroke , and the chevy reved higher , and made more usable power

factory rating was 290hp , and was closer to 340 , and even closer to 400 with the headers and dual quad cross ram

cduke1780

iTrader: (2)

Not defending the ford 302, but the chevy did have larger port cylinder heads, a solid flat tappet cam and a rod/stroke ratio higher than the ford 302, so not exactly apples to apples. The chevy was designed to rev and meet TransAm cu/in requirements while the ford 302 was just a regular run of mill workhorse engine.
Caleb

s/c'd cav

iTrader: (10)

not entirely true , ford competed against the Z28 with a BOSS 302 which wasnt a regular run of the mill 302 , and the BOSS heads were larger than chevy's heads

so ford probably had 1 year of running against the Z28 with the small port heads