1986 TBI engine upgrade questions

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Dr Evil

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Tennessee
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Russ
Truck Year
1974
Truck Model
C10
Engine Size
350
I have the opportunity to pick up an 86 G10 4wd long bed. It needs a couple things, nothing I can't handle after what I just went through on my 74 build.
I want something suitable for daily driver use but would likely only be used for weekends hauling the boat or normal truck duties.
The truck currently has a 305/700 combo. I like the overdrive.
I like the TBI system
I dislike the 305.
How hard is it to upgrade the TBI to support a mild 350 build?
I'd build another engine very similar to what I built for my 74.
350 roller motor
.030 over
Mild cam... Probably in the 204int 212ex mid .450 lift range on a 116
Possibly set of small chamber 305ho heads.
Headers.
This combo works really well for good driveability in a truck. Combined with over drive it would make a very nice driver.
Is this doable while retaining the TBI?
I assume I will need to swap injectors and proms. Anything else?
 

Vbb199

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Engine Size
350, 502
Prom, injectors, ecm

I have a recommendation for a prom chip burner guy as well.
 

Vbb199

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Engine Size
350, 502
Maybe the actual tbi itself? Idk what the cfm is for a 305 tbi.

The 350 tbi is advertised at 500cfm.
 

Dr Evil

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C10
Engine Size
350
So it's not a huge under taking? Those parts are pretty easy to find. Even better if a custom prom can be easily burned.
Is there a difference between the ECMs though? I figured it was a prom issue, not necessarily the ECM.
Any issues to worry about with a different ECM running the other functions like TC lock up?
 

Vbb199

B-rate Hillbilly Customs
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Location
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Truck Model
89 Suburban R1500, 79 C10
Engine Size
350, 502
So it's not a huge under taking? Those parts are pretty easy to find. Even better if a custom prom can be easily burned.
Is there a difference between the ECMs though? I figured it was a prom issue, not necessarily the ECM.
Any issues to worry about with a different ECM running the other functions like TC lock up?


Prom does fueling, afr, timing curves, and **** with TPS and some other variables.

Thinking on it, youre correct.
That prom is whats needed.

You also need a
350 specific knock sensor
350 ESC module
 

Vbb199

B-rate Hillbilly Customs
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Vince
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89 Suburban R1500, 79 C10
Engine Size
350, 502
From what ive understood , the tbi system only does a max of 400hp.

My motor makes 330hp, 385 ft lbs (engine alone, no mods)
On my 89 tbi ive got a performance prom, EGR delete and blockoff, aftermarket 30k coil and ignition box, nee HP distributor, and regapped plugs appropriately for the C/r.

After all that, the poor flow of the 500cfm unit has been exposed. In conjunction with vortec heads. Its sucking for air at WOT

Even in that state, for a 89 r1500 burb.... it fuggin MOVES with a 3.42 and 31" tire (undergeared)

Ive machined myself a 46mm bore tbi to go on my truck, and will also need another prom for it.

Just a thought for you if you are heading the route of a high performance motor and using tbi.
 

Dr Evil

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Joined
Dec 2, 2018
Posts
26
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Location
Tennessee
First Name
Russ
Truck Year
1974
Truck Model
C10
Engine Size
350
No high performance goals here but improved driveability and everyday power would be great.
300hp 350trq would be fine.
 

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