Ok. If the following has errors, someone correct me:
267 has 3.1 inch crankshaft stroke and 3.5 inch bore.
283 has 3 inch crankshaft stroke and 3.875 (3 7/8) inch bore.
302 has 3 inch crankshaft stroke and 4 inch bore.
305 has 3.48 inch crankshaft stroke and 3.736??? bore.
307 has 3.25 inch crankshaft stroke and 3.875 bore
327 has 3.25 inch crankshaft stroke and 4 inch bore
350 has 3.48 inch crankshaft stroke and 4 inch bore.
Lets consider 4000 feet per minute as the practical limit of piston speed.
First look at the 283 and 302 with the 3 inch stroke. Every revolution of
the piston will be 6 inches. So at 8000 rpm, the pistons are traveling
8000*0.5 ft per minute which is 4000 feet per minute. Now consider the 305
and 350 with approximately 3.5" stroke will reach 4000 feet per minute at
6897 rpm. The 327 will reach 4000 fpm at 7385 rpm.
Incidentally, the ford 302 in mustang has 4 inch bore and 3 inch stroke just
like the 302 chevy had.
What I am pointing out is that the engines with the shorter stroke are
designed to rev higher. With 3.90:1 gears and no overdrive, one of the
engines with short stroke will be more appropriate and under less strain.
However, they will also have less torque at low rpm. The knock against the
3.875" bore engines is that there is insufficient room around the valves
for proper breathing. Consequently, no one uses 2.02 " intake valve on
small bore engines. However, the 1.90 x 1.5 valve heads work fine with the
small bores, but have less potential for mega horsepower.
Personally I am planning to rebuild a 283 for my '57. It will use
compression about 9.5:1, 461 or 462 casting heads, and a roller camshaft
from crane or compcams. Goal is 350 ft-lbs torque and 300 horsepower. The
1961 283 rpo 354 achieve less torque but made 315 horsepower. With the
camshaft advances made with roller cam grinds, I think my goals are
reasonable.
Back to your question regarding performance potential for the 283, 305 and
307? This is just my 2cents, but I'd say the rpm potential of the 283 and
307 are greater because of the shorter stroke than the 305. However, if you
plan on mild, low-rpm usage, the 305 might be best.
There was a very interesting article in a recent Chevy High Performance on a
327 buildup that made 408 horsepower at 5700 rpm using 9.1:1 compression and
a comp cams roller camshaft. I can scan it and forward if you are
interested. Also, the "Chevelle" edition of Chevy High Performance recently
started an article on 283 in a chevelle wagon. I think the next issue is
going to go into more detail about the 283.
Finally, parts are going to be cheapest for the 305. Next cheapest might be
307 because 350 pistons are same bore size. 283 parts are probably most
expensive. Of course, the only parts that are unique are the pistons,
rings, crankshafts. Most other stuff is same regardless of the engine size.
--- Original Message -----
From: "Spencer" <wits_end@worldnet.att.net>
To: <oletrucks@autox.team.net>
Sent: Thursday, February 13, 2003 7:44 PM
Subject: [oletrucks] Smaller of the small blocks
> Hi, All. I recently picked up a 305 for my '55 1st Series Chevy, then
began
> wondering if it was the engine I really wanted. I'm planning on running a
> 700R4 tranny and the stock 3:90 rear end and definitely don't want a 350
or
> larger engine.
>
> My question is a litttle off topic. What are the performance differences
> between the 283, 305, and 307 small blocks? And wasn't there a 302?
>
> I'm mostly wondering what makes one engine or another better for a mild
> buildup. I'm planning on a new cam, higher compression pistons, manifold,
> headers, etc. Nothing too high dollar.
>
> Thanks in advance, and thanks for all the other info I've learned from
this
> list.
>
> Harry
> 1955 1st Series Chevy
> Reno
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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