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S.B 350 need help


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smitty911
Novice

Sep 15, 2007, 2:44 PM

Post #1 of 4 (1681 views)
S.B 350 need help Sign In

i have a 1984 gmc c15 pickup. its got the 5.7 liter 350 its bored 10 over has headers edlebrock 600 carb dynomax exhaust with cutouts. the problem im having is that it doesnt seem like its getting full power. i put new plugs new wires and reset the timing. its better than it was before but it still doesnt seem right. i cant do a burnout unless i turn and cant do a brake torque to save my life. its kind of embarrasing when some yells smoke em and you cant. i want to be able to do a brake torque but it wont. please if anyone can help please do. thank you.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 15, 2007, 5:55 PM

Post #2 of 4 (1677 views)
Re: S.B 350 need help Sign In

The small block chevy has been a mainstay of dependable power for decades on end. Long before 1984. The 70s and 80s were troublesome years with meeting emmissions standards and they were detuned by design. You have been working mostly on the exhaust side for more power and that is just a small percent of what you do to an engine for power. The carb may look nice but probaby isn't worth any more power than oem quadrajet.

What will gain horsepower the most is the heads, camshaft, then intake items like intake manifold, carb etc., for more yet in the era you went for higher compression and exacting the timing.

Things that feel like more power are higher gear ratios in the rear end, and high stall speed torque converters in automatics. Now the same size engine that pollutes little and gets tons more fuel economy with just 87 octane fuel will blow your doors off with more accurate technology. One from the 60s could burn rubber without doing a brake stand in like mommas station wagon right from the factory.

Also note that trucks by nature expect loads in the back and more braking pressure is routed to the back in trucks thru the combination perportioning valve. Some folks used to cut out rear brakes for easier brake stand which is what I called them back then,

T



smitty911
Novice

Sep 16, 2007, 4:12 PM

Post #3 of 4 (1673 views)
Re: S.B 350 need help Sign In

i dont really want to tear apart the engine just yet. i probably will start on it in the winter but for now i just want to be able to do a good burnout. i have a couple things that i think might be wrong. maybe the carb is out of adjustment? and i also here a little air leak. i thought it was the header gaskets but i changed those and it went away a little but i still can hear something else. could the intake gasket or the carb gasket be leaking? i asked a couple people and they seem to think that the carb is out of adjustment.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 17, 2007, 7:13 AM

Post #4 of 4 (1669 views)
Re: S.B 350 need help Sign In

If you have gasket leaks that are vacuum leaks it will make for a lousy idle. You can check for those with plain carb cleaner spray at the suspect spots and the idle shouldn't change. Of course go easy as the carb cleaner can flash.

The fuel to air ratio probably is adjusted. If you simply richen the mix it won't help performance as it still has to atomize the mix before it's compressed. Raw gas is just lamp oil and makes no useful power for you.

You have attacked the exhaust side as far as will really help. You are limited to atmospheric pressure to push the mixture into the engine. That's why turbo charged and ram air are used. They are increasing the force of intake which still must be atomized or it's useless. Compressing the vapor and sparking it makes the formidable force and horse power/torque. Smooth long intake manifolds help - buzz words like "high rise" are used. The intake valve can be enlarged to take more in until you bore it into the water jackets and have a junk head. The camshaft lobes determine the duration of the intake valve staying open and the CFM that can pass thru. That's where the power comes from. To make an engine runs nice and smoothly and be more fuel efficient while polluting less the camshaft is changed as for regular use most folks would be ticked at an engine that could barely idle like the dragsters and funny cars where you hear them constantly revving them up not to stall before take off.

If your whole objective is to burn out from low speed or a stop change the gear ratio at the differential. Get a high stall torque converter, and easiest is to rig a windshield washer pump to spray water or better yet bleach on the tires which will make them slip like on ice and you could make an electric golf cart do a burn out with that trick.

Also look at your tires. Most are made not to slip. The tire when slipping has no useful grip for moving or stopping the vehicle,

T







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