Thread: 283 with small journal 327 crank

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Hello all,
First time poster long time reader here. Thought i might pick your brain about building a 283 with a 327 crank. i have a 1964 283 and would like to increase the cubic inches. I believe this will make a 307. the engine would be going in a 69 chevy half ton truck with a turbo 400 and 373 gears. the truck is used primarily as a daily driver so gas mileage is the primary concern. I am currently running a stock 454 and getting around 6.5 mpg in town and 10 on the highway. I seldom tow or haul much that is very heavy. I welcome any ideas or suggestions.

Dumb Butt has edited this post becuase "HE" I mean "ME" didn't realize what he was posting above his pay grade!!!!!

Roland

I thought the DZ 302 was the 327 block with the 4" bore and the 283 crank with 3"stroke?????? Not a chebbie guy, but I believe the 327 crank is 3.250" stroke....

The SB Chevy 283 Block is standard 3.875" bore same size bore as a 307 L/J Block . The stock 283 uses the 3.000" Stroke crankshaft . By using the 3.250" Stroke Crankshaft and different pin height pistons Chevy made the 307 . How about your 283 bored 60+ over with 60 over 307 pistons and that 3.250" Crankshaft = 316ci Build . Not bad ? Or on some early 283's if they are check . They can be Punched out to a 4" bore and you could use standard 327 Pistons now you will have a S/J 327 Build .

Roland I believe you are thinking of the a 283 crank in a 327 block which yields the "302"

The other way around..... a standard bore 283 with a 327 crank yields 306.624 (307).

Although I have never done this stroker build I have run a few slightly modified 307s, they produce torque but do not wind up.

Personally I would not expect a huge mileage gain with the 307 maybe 3 or 4 MPG.

I would take a guess and say that your current gas mileage is affected by 2 areas.... wind resistance (trucks have aerodynamics of a brick) and RPM. While you can't do much about the shape of the truck a gear change or addition of an overdrive would likely give you as good or better mileage than the small block swap.

I’m sure what the interstate speeds are there but at 75 MPH and assuming a 31 inch tall tire what ever engine you run would be at 3032 RPM (plus a little bit for converter slippage).

Changing to a 3.08 would drop the RPM to 2500, and leaving the 3.73 gears and installing a 700R4 would drop the RPM to around 2100 RPM.

Unless you already have other plans for the 454 the 700R4 swap would be the way I would go. I believe it would give the biggest mileage gain and still be cheaper and easier than an engine build and swap.

Guys, Well what could I have been thinking !!! DUUUUUH That was one of those embarassing senior moments. DAMN

Of course ----And I stand corrected----- I was referring to the 327 4" Block and the 3" 283 Crank........

Roland

Hey, no biggie Roland!!!! Old age and CRS is a common condition around here!!!!

You can probably pick up a 305 or 307 cheaper than trying to upgrade the 283 and be ahead in many ways,you will have a large journal crank and rods which are stronger and a crank with a bolt on Harmonic balancer, a lot of 283's were pressed on.A 305 HO from a Camaro would be your best buy,there should be a fair amount out there for a good price since guys will swap for 350's and sell them cheap.

just curious; I heard gm did not build many 307 engines..If true, why
did they not build many? I have owned, 283, 305, 327,350, &454, but
never a 307...rdobbs

Cuz they were a pooch!!!!

Thanks for the input guys. Me thinks i'll look for a set of 3.08 cogs and keep my current combo. Just gots to do something with that little 283 though. Hmmmm.

take the 283 bore it .060 get it up to 10:5 or 11:1 use a 270h or a 280h cam performer rpm air gap, 600 holley 373;s 391's have some fun, i love them little 283's this spring we are eyeballing 11.70's on the motor

It's tough to find affordable pistons that will yield 11.0:1 in a 292 with decent heads. Here's what I came up with just foolin' around on the DynoSim.
283 bored 0.060"
Keith Black hypers, KB166-060
L31 Vortec heads, cut 0.040" for 58cc chambers. Stock 1.94/1.50 valves, springs and retainers matched to lift. Makes static compression ratio of 10.5:1. Heads are bone-stock except for springs and retainers and the 0.040" cut. You can rescue 'em out of a boneyard. Casting number 12558062 in a '96-'98 Chevy truck with 5700 Vortec motor. Look for a saw-tooth design on the front of the heads. Get the rail rockers and center bolt valve covers at the same time you're gettin' the heads.
CompCams solid flat tappet cam. 12-221-5, grind 280B-8, 280/285, 242/250, 507/532, 108.
Large tube stepped race headers
Edelbrock RPM Vortec intake w/750 carb
RPM HP TQ
3000 201 252
3500 253 380
4000 312 410
4500 372 434
5000 424 446
5500 457 436
6000 489 428
6500 502 406
7000 507 380
7500 505 354
8000 495 325
136 mph top speed @8000 w/4.88 gear, 28" tire. Use 3000+ stall converter with auto. Would be way more fun with a 4-spd/5-spd. I realize the original poster asked for a way to enlarge his 283 to pull a truck. This is not the motor to do that. This is a play-toy built the way Scooter might do it. I just wanted to dyno it and see what it looked like. Who says you can't make 500 hp out of a budget 283??? A guy might have to massage the domes a little to fit the chambers, but you'd still make 500 hp even if you dropped the SCR a couple of tenths. Disable the centrifugal and vacuum advance and lock it up at 34-36 degrees. Install a switch through a relay to disable the ignition while cranking, then flip the switch to ignition-on while the motor's spinnin'.

and people say im dumb for using something smaller!!!!!out of 35 runs on this motor, its only lost head to head against a car 4 times, but if you count the breakout and reldight

Originally Posted by tango

The SB Chevy 283 Block is standard 3.875" bore same size bore as a 307 L/J Block . The stock 283 uses the 3.000" Stroke crankshaft . By using the 3.250" Stroke Crankshaft and different pin height pistons Chevy made the 307 . How about your 283 bored 60+ over with 60 over 307 pistons and that 3.250" Crankshaft = 316ci Build . Not bad ? Or on some early 283's if they are check . They can be Punched out to a 4" bore and you could use standard 327 Pistons now you will have a S/J 327 Build .

3.25 is a 327 crank and it does make a 307 ..307 & 283 have the same bore