brocluno

I just bought a standard original bore 283 SBC to build for my family truck (1970 Chevy Longbed). Right now the truck has a .040 over 454 driving through a TH400 to a Dana 60 with 3.73 gears. LOTs of fun on the street, but you can't afford to go anywhere due to the 7 MPG mileage. So, enter the 283.

I've had them before and they are happy little motors. I'll be putting 305 Vortec heads on this one for four reasons: 1.) to get modern chamber profiles, and 2.) for smaller chambers for a CR bump, and 3.) I have them, and 4.) I can get modern accessory bracket bolt points.

It'll be exhausting through the Vortec iron manifolds into a 2 1/4" dual system with H pipe (that's serving the 454 nicely). Intake is a dual plane medium riser manifold and initially it will be topped with my Holley 600. As more funds are available, I'll move to an after market TBI setup with O2 feedback.

Targets are 225 HP at something like 4500 and 15~20 MPG with light throttle at 55 mph. Now the questions, how to build and what parks to use? I'm already leaning strongly in the direction of roller rockers as I use them on other motors to reduce friction. How about a roller cam? Total sealed rings? Certainly roller timing chain. HEI with custom vacuum curve?

Any help with this and other ideas greatly appreciated by me and the planet

desrtrat

for parts, i would go with a good stock rebuild. you need to see if your cylinders are good then decide what pistons you are going to use. all the fancy crap you want to use is just that, crap for what you want. 225 hp on a good stock rebuilt 283 is easy to do. all you need i a little more of a cam. if the motor is already running, then do your head/cam, a new stock distribution, manifold, carb swap and call it a day..

good luck

brocluno

Motor not running. 0.040" over 454 is in truck now. Am building small mouse motor out of what I have and with gas headed back to $4/gal soon - I'll look for small but meaningful improvements. Roller rockers are good for 7~11 HP at 5 grand, but that means they are good for 2~5 at highway speeds. Zero Gap rings are good for 12 HP at 5 grand, but they make a couple at highway speeds and keep the oil cleaner longer so that's nice. How long it takes to pay these back - years maybe, but as gas prices go up, it gets to be faster payback all the time

I'm still working out the details and all suggestions are welcome and helpful. Thanks for the ideas. Stock OEM rebuild is the easiest, but may not be the most fuel efficient for this application? With 3.73 gears, this engine will live a bit higher in the RPM range than some, so higher pumping speeds with higher vacuum levels need to be considered

therewolf

Power VS Economy- you can't have it both ways.

Seems you want to avoid gas guzzling, so it would probably make sense to go for a strong build versus extra horsepower.

Avoid intakes and cams, but a double roller timing chain and gears, and roller lifters, sodium valves, while not increasing horsepower, would all help your engine handle higher revs when you do put your sipper to more severe service, for instance.

Headers would sponge heat away from your block, as opposed to cast iron exhaust manifolds which would lock heat in.

There's a lot of parts which will make your engine run more efficiently, and cooler, without increasing horsepower, and costing you MPG.

.

brocluno

Yeah, been thinking JetHot coated shorty headers. I have the iron manifolds, but headers are pretty reasonable so that's a good possibility. The 305 exhaust manifolds are pitiful. I guess with the motor all choked up with CATs, it does not matter. But the rams horns look like they will flow at least 25% better that the OEM 305 manifolds

Great valve job is another. It's something that the factory does not spend time doing because of cost. Just like bowl blending. They can't afford it, but I can do my own. No hog outs, just smooth and clean with a little extra work on the short side exhaust to help. I've seen 15 CFM gain at .400 lift on these heads on both sides - intake and exhaust. That means they can use a bit more cam.

No, the combo won't beat a 350 (all things equal), but a 350 won't beat a 400, etc. Where do you want to draw the line at cubic inches? Using an Olds Rocket block it's not that hard to build a 426 small block, but that does not do much for the guy with a 283, 305 or 307 bolted in place and just looking for a bit of gain? Besides, it is fun to build a cheap mouse motor. For my project it might not be so cheap as 283 parts are getting a bit more expensive. But a friend at the local auto parts store is going to give me another 283 as of today. I'm curious to see if it has a steel crank? My manifolds were all free. the HEI was free, the carbs were free - all I need to do is get the internals right

Think I'll build one for the truck and one for a play car Anyone got a nice used Monza chassis sitting around?

brocluno

The initial carb (2CG) that will be used for start-up and break-in is off the Carb Shop in SoCal for a rebuild. TBI to come later.

The 601 heads are in the hot tank. Turns out they are 53cc, so the CR will be like 9.4 and that should make things interesting.

Still trying for pistons. KB have installed height of 1.805", the Silv-O-Lites are 1.779" and the Federal/Mogul rebuilders are 1.654" (yuck - way down the block ).

Depending on how the compression calcs all come out with the final work on the heads will determine the choice of pistons and head gaskets. Shooting for squish area clearance of .040" plus a bit

May add Somender's grooves (slot) to the head to aid in turbulence. Have to talk to another machinist about that? It's coming into focus one bit at a time

Going to run the 929 cam grind with 1.6 rockers. The intake is a dual plane Edelbrock 2 barrel unit with small runners so it will make good bottom end torque and vacuum. It came off a Jeep with a small block that spent days idling around and ran super well. The vacuum advance HEI will help once I get it recurved. Any ideas on where to get that done in the SF Bay Area?

OBTW - the numbers say we'll make 230HP and 310 Lbs Ft of Torque from about 2400 till it runs out of air. Should be crisp with that compression and strong enough to get down the road