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planning to do some work to the 350 tbi

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planning to do some work to the 350 tbi

Old 05-09-2010, 12:34 AM
  #1  
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Join Date: May 2006
Location: east aurora, ny
Posts: 367
Car: 1989 camaro rs
Engine: 305 tbi
Transmission: 700r4
Axle/Gears: 3.23 lsd swap
planning to do some work to the 350 tbi

first off let me start out by saying that i have a 350 tbi swapped into a 89 camaro RS 305. i have edelbrock TES headers, 3" catco cat, and a 3" catback system. i also have a 10 bolt limited slip rear from an iroc installed and 16" iroc wheels with cooper zeon ZPT tires. the engine has an edlebrock performer plus camshaft and i also have a 255L fuel pump.

my plan is to swap heads. right now i have the crappy 193 heads and i have a nice set of 083's on my bench im going to install. im fairly happy with this engine but i know it has more to give.

my question is should i change my intake and tbi unit over to the holley 670 cfm projection style. what is the stock tbi unit capable of? how much am i going to gain just by doing the heads and leaving the stock intake and tbi alone with possible plans of swapping that out in the future. i could afford the better intake/tbi unit but don't really know if its worth it if i would be happy with just the better set of heads. im a homeowner now so plunking down 700 bucks in cash is allot of money for me right now.

comments or suggestions would be helpful
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Old 05-09-2010, 04:56 AM
  #2  
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Join Date: Jan 2002
Location: Moorestown, NJ
Posts: 9,962
Car: 88 Camaro SC
Engine: SFI'd 350
Transmission: TKO 500
Axle/Gears: 9-bolt w/ 3.23's
Re: planning to do some work to the 350 tbi

Swapping out the intake and TBI will help a lot. The stock TBI will be fairly restrictive, even with a single plane. The 670 will help a lot (I sent you a PM, BTW). The stock TBI is limited to around 500 CFM in 4 bbl carb terms. I recall pulling quite a bit of vacuum with the stock unit on my 350.

As for intakes, you have some options. The stock intake obviously will need to go. You can go with a carb intake with adaper, or an aftermarket TBI intake. The carb intakes will offer more performance, but typically have no provisions for temperature control. The stock manifold is fully jacketed. This is important with TBI. If the manifold is not heated, it can cause drivability issues. I believe there where 2" TBI manifolds made for SBCs used in marine applications. You might want to look into getting one of those. I dont recall if they used the standard or vortec ports, but if you can find one, it would be the best bet from an ease of use standpoint. It would also be a good match for the performer plus cam, which likes smaller dual plane manifolds from my experience.

Also, its STRONGLY recommended that you get into prom burning. You WILL need to tune it, or the car will run terrible.
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Old 05-09-2010, 10:42 AM
  #3  
Member
Thread Starter
 
Join Date: May 2006
Location: east aurora, ny
Posts: 367
Car: 1989 camaro rs
Engine: 305 tbi
Transmission: 700r4
Axle/Gears: 3.23 lsd swap
Re: planning to do some work to the 350 tbi

also how much more can i do to my car before i have to install subframe connectors? i dont want to twist the snot out of it. how much more can i do before the 10 GM becomes to weak to support additional power?

i guess the real question im after is that would heads alone make a difference with a stock intake and tbi or is it a waste of time unless i change all 3 items?

Last edited by ad356; 05-09-2010 at 10:45 AM.
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Old 05-09-2010, 06:11 PM
  #4  
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Join Date: Jan 2002
Location: Moorestown, NJ
Posts: 9,962
Car: 88 Camaro SC
Engine: SFI'd 350
Transmission: TKO 500
Axle/Gears: 9-bolt w/ 3.23's
Re: planning to do some work to the 350 tbi

You'd get the most by doing all three. At the least, you will need better fuel inectors if you currently still have your stock ones. The stock TBI and intake will become a restriction above ~4k. That cam can make power out to around 4500 RPM or so. 5k if you have a good set of heads.

As for the heads. You might also want to do a little porting to get the most out of them. You dont need to hog out the I/E ports, but some cleanup and minor reworking can really help flow and top end power. While their better than your current heads, they still did not flow a whole lot.

If your car has t-tops, get SFCs sooner rather than later.
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