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Old 02-28-2007, 02:15 PM
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350 performance upgrades

Hello,
I installed a new sb350 in my 85 chev pu a few years ago, upgrading from a 305. When I did the swap I kept everything stock to comply wih local IM but now I am not using as a everyday driver and I want to wake it up! I was wondering if anyone had any advice on carbs, intake, and exhaust systems. I am not looking for a race truck but I would like to have good clean relibile power, I have had this truck for 15 years and it has allways been way under powered! Any advice would be great.

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Old 02-28-2007, 06:52 PM
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Heads are really where you make your power, what is the casting number? For a mild street engine you cant go wrong with a set of vortec heads you will need a vortec intake and valve covers. If you don't want to change the cam and heads you might look into 1.6 rocker arms.

An edelbrock preformer intake manifold. I think their still the best for a mild street engine. Holley or Edelbrock / Carter 600 or smaller carb. I like the Edelbrock, their easy to set up and hold the tune well. Long tube headers, with 2 1/4" dual exhaust, and free flowing mufflers, theirs a bunch to choose from.

An RV cam or one of the more modern cams, like the Voodoo cams. If you do use stock vortec heads don't use a big cam or high lift rocker arms. Stock vortec heads should be able to accept cams up to .420-.430 some people say more.

Jordon

Last edited by xxllmm4; 02-28-2007 at 08:48 PM.
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Old 02-28-2007, 10:34 PM
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Or buy the bare heads and assemble 'em yourself with the Crane Cams high-lift kit, part number 10309-1. Includes retainers and springs, no machining for 0.550" valve lift with stock seals. In addition to the specific intake manifold, you'll have to run Vortec-specific rail rockers to maintain rocker/stem alignment. It sounds like a lot of trouble, but the heads are worth it in my opinion.
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Old 03-01-2007, 07:39 AM
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Quote:
Originally Posted by mcbride
I have had this truck for 15 years and it has allways been way under powered! Any advice would be great.
The cheapest way to get real "seat of the pants" improvement would be to change the rear end ratio to a lower (higher numerical) ratio. Look for around 3.70-1 up to 4.11-1 for street use. Fuel consumption will go up.

Another cheap (almost FREE) improvement is a good tune up and increasing the timing from the factory settings. Look for 10-12 degrees initial and 32-34 degrees Total mechanical for the STOCK engine. Use Full manifold vacuum source for the vacuum advance.

A good set of headers would be my next choice.

Next I'd consider a mild cam upgrade (not too expensive) followed by a better set of heads (getting up there in costs).

I'd skip the Edelbrock Performer intake (it's not much different than the stock GM intake) and opt for the Edelebrock RPM (high rise) intake.

Top that with either an Edelbrock 600cfm carb or a Holley carb. I've used both and prefer the Holley for performance although I think the Edelbrock is easier for initial adjustments.
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Old 03-01-2007, 02:02 PM
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Here is what I have done so far on a budget.

Ceramic coated headers dual exhaust
Edlebrock Performer EPS manifold
Edlebrock 600 cfm carb
1" alum carb spacer
MSD ignition
New wires
1.52 Comp Cams roller tip rockers (not driven this mod yet)
Raptor mufflers
Shift kit in the 350 tranny
Timing set at 14 initial about 36 total plus vacuum (I tried both ported an manifold, manifold got hard to start with all the advance.)

This is all on a stock 72 350. Not all produced a noticeable difference. I was surprised how much the spacer seemed to increase my get up and go. $10 on ebay.

I have plenty of power and decent fuel economy. My attempt in all these mods was not horsepower but engine efficiency to try to gain better fuel economy. I bought a lot of stuff on ebay to keep costs down.
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