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How big of a difference will it be

Z

Z3PR

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Okay, most of y'all know I have a 78 El Camino with a factory original 305. When I can afford it I plan on a 350cid 290hp GM crate engine. How big of a difference will that be ?? I have no idea what the factory HP and torque rateing is for the factory 78 305. I also have no idea what the factory rear end gearing is, but I also plan on a posi rear with 3.73 gears, and a 700r4 transmission. I think that combo would be a great match. So anyone have any advice or comments ??
 
motor, gears, everything, I think you will be very happy with it. My 305 to 350 swap was a good jump in power in my K5. That was mostly torque gain though and with 2.73 rears it still sucked. With gears that would have been awesome. Will you see a HUGE jump, I don't think so, but all put together it should be a little rocket.
 
those g bodys flex big time and need some extra stiffeners added to help body twist . my friend runs them and his 87 monte ss was big time flex off the line and we put in 6 point cage and wow big improvment. he also runs air shocks rear with at least 50-60 psi for traction help. this is all at the track 1/8 and 1/4 miles
 
I'm guessing your 305 was rated at no morre than 180 horses. You will notice a vast improvement in acceleration, with probably the same mpg.
 
RingMaster4x4 said:
what size tires are you going to run? I plan on 3.55 with 275/60 tires with my 700R4 in my chevelle. just a thought.
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I want too go with 16" rims because I plan on upgrading the breaks. I'm not sure on tire size. I do want the same size tire on all 4 corners. I'd like the widest tires that will fit without any rubbing. Front will be lowered 1.5" to 2", and rear will be lower 1".
 
I'm getting phyced about that crate motor.
The HP 290/350 is GM Performance Parts' value leading crate engine, with 290 horsepower @ 5100 RPM, and 326 lb-ft of torque @ 3750 RPM on 87 octane fuel. The HP 290 horsepower will provide great long term durability with its 4-bolt mains, PM steel rods, strong cast aluminum pistons. The camshaft has .450'' intake and .460'' exhaust lift with hydraulic flat tappets. The cast iron cylinder heads have 1.94'' intake and 1.50'' exhaust valves with 76 cc combustion chamber. The heads have the conventional 12 bolt intake manifold attaching design used from 1955 through late 1980. This 350 engine is not intended for marine use, and should be used in 1979 or earlier pre-emissions street vehicles or any off road usage.
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After the warranty runs out, think a pair of Dart Pro-1 heads, and a Comp Cams 270-H magnum camshaft. What do you think that would bring it up to ??
 
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