what would it take to get my 283 to about 300-350hp with the setup below. i'm thinking about a new cam but i don't know what cam to get. i should have about $1000 to spend on it after i sell a 78 malibu i have.

 

I'm running a 60-over 283 myself, and although it isn't impossible to make 300 or 350 horsepower with one be prepared to rev the thing to insane speeds to make it! The low-speed driveability will suffer too.

That gets expensive because you need top-notch valvetrain components to get into 7000+ RPM reliably.

Keep your eyes open for a cheap & solid 350 shortblock and swap all your goodies onto it.

 

it has a cc q-jet that the MCS isn't working in so its running REAL rich. how much hp do you think that it robbing? if i put on an edelbrock intake and carb, put the headers on and got a new cam how much do you think i could make?

I'm thinking about a comp 268 or 270h cam, would that be good?

 

The non-functional MCS won't affect full-throttle power, so it won't be robbing horsepower there. It will be killing your fuel economy and part-throttle response for sure.

The short stroke of the 283 makes it pretty sensitive to valve events, I would stay conservative there. I'm running the Comp 268H and I wouldn't go any hotter than that, in fact I might choose the 260H if I were to do it again. Mine will rev past 7 grand, but it suffers in the low-end department and fuel economy because of the relatively 'hot cam'.

I think you should be able to get 250 or more horsepower with a streetable 283. Plugging in the quarter mile trap speeds into a horsepower calculator indicates about 270 crank HP from my combo, but I wouldn't recommend my combo! The torque peaks somewhere around 4500 to 5000 and the HP probably over 6500.

I suggest you call Comp Cam's free tech line and see what they have to say, I would bet they recommend the 260H or something milder.

You would very likely lose some low-end response going with the Edelbrock Performer as it is designed around (what else?) a 350 inch motor, but gain some horsepower.

I'm a real David Vizard fan, and he claims that a manifold that shows gains from 3000 RPM up on a 350 may not show gains on a 300 inch motor until 4500 RPM or so, and the low-end loss will be that much greater on the 300 inch engine than a 350.

Likewise, a camshaft like the Comp 268H works from 1500-5500 on a 350 but perhaps 2200-7000 on a 283.

I know I'm having a hard time doing it, but especially with the 283 you gotta think small.

How about finding a non-CC Quadrajet to work with your factory aluminum intake? They're both good pieces.

 

Oh yeah - I was going to mention that you should spend your money on good headers and exhaust, you will definitely feel the difference there. I would think there is 40 horsepower to be gained with a decent exhaust system.

 

rusty, what heads and compression ratio do you have on yours?

whats the difference between open and closed chamber heads?

my cam right now is just a little less than the 260h on the intake side, its got 2.02 intake valves and it has more off idle torque than a 305 malibu i have even with the carb prob. i could deal with less low end right now but i'l have to see what the headers do. do you think the headers will take away much low end?

some time down the road i was thinking about a getting domed pistons to get it to about 10-10.5:1 comp and porting the heads. how much of an efect will this have?

 

Rusty's recomendations are the way to go for a street 283.


But just for reference you can build up your 283 to make that kind of power. You have alot of the basic parts.

You would have to shave the heads and block deck to get the
measured compression ratio to 10:1 minimum. may have to angle mill.
You would use a Comp Cams Magnum solid mechanical 282S-10
or 294S-10 cam. You would use Comp's recommened springs.
You need to max port those 041 heads but the 1.94x1.50 valves are fine.
get a Performer RPM intake.
This engine will make peak hp (About 350/3365) at close to 7000 rpm, maybe more.
A 4/5 speed and 4.56:1++ gears are nessessary.
A 4500/ 5000 stall converter is needed for best performance on an auto trans car. The converter must be designed for a 283
not a 350. Not very street friendly...

A 350 short block will make the same power at a lower rpm
with this (ora milder) top end package. Won't need near as much gear or converter. Will cost a lot less and be better on gas.

 

my bigest problem is that i have a stock 2 bolt bottom end that shouldn't be reved past 6000, 6500 max. i'm going to get a 350 or 400 if i can find one when i get the money and time to put it in.

 

are 400 blocks reliable? i hear there not from some ppl and that they are from other ppl as long as you have a good radiator and drill steam holes in the heads.

 

400 blocks are very reliable.

People that own 400 blocks are not so reliable.
they won't change the oil, watch a temp guage or idiot light.
They won't flush out a radiator or top up the level.
They won't use the right octane gas for the motor either.
or get their foot out of the gas if they get engine knock either.
This is the main source of the 400 sbc's undeserved reputation.

 

I'm running Edelbrock Performer RPMs (2.02/1.60) with 170cc intake runners and a 64 cc combustion chamber. The large chamber combined with a thick composition head gasket and crummy deck clearance makes for a whopping 8.0:1 compression.

The difference between open and closed chamber heads is the shape of the combustion chamber. A true open chamber is larger and covers most of the cylinder. A closed chamber is usually somewhat D-shaped and closes off a portion of the cylinder.

 

i have about 9:1-9.5:1 on mine. the heads have been milled and the deck clearance is pretty good. the headers should bring it up to about 250-260. its got a flowmaster 3" catback. how much would it bring it up if i raised the compression to 10.5:1 and ported the heads?

 

From what I understand the compression increase would be worth a handful of horsepwer and possibly a noticeable increase in throttle response.

The head porting is hard to say, good porting would help across the torque curve but by how much I couldn't say. You stand to lose some low-end by increasing the runner volume and reducing velocity. I'd be really careful there.

Exhaust, man! That's where I would be concentrating if I were you. I saw a website where they were reprinting tests on an LG4 and simply swapping out the stock exhaust system and putting on headers and a pair of flowmasters brought the power up to just under 200 HP from 145. Of course F-bodies don't lend themselves to duals easily, but there are many good single systems that are a major improvement over the factory setup.

Your combination probably stands to gain even more power than the smogger 305 example.