CFI TB project
#1
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CFI TB project
Finally finished my 56mm TB project for my motor. These are a pair of badass TBs for CFI I have been working on for a while. They also have needle roller bearings vs bronze bushings on the throttle shafts...oh soo smooth. Hopefully I will install these soon and maybe get to blast the car down the track and see how the motor likes them. I even cut balancing ports into these for easy balancing to make easier for me. A tune tweak will have to happen I'm sure and I need to find time for all this along with other projects that I'm working on. I'm also going to raise my fuel pressure up to 33psi, which should make things a little interesting. The way I see it, this is nothing but, CFI ZOOOOM!
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#2
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Car: 1983 G20 Chevy
Engine: 305 TPI
Transmission: 4L60
Axle/Gears: 14 bolt with 3.07 gears
Re: CFI TB project
Are they going on a Renegade intake on a decently powerful engine? A twin 50mm GM throttle body 454 large IAC footprint style marine TBI with 61# high pressure injectors that flow ~104 lb/hr @ 30 psi was not a limitation on a Victor Jr 2bbl manifold at the 450 hp level for me. Even at ~6,500 rpm the TB had more than adequate flow. I will say the 454 TBI on that Victor Jr 2bbl liked the Holley Projection heated TBI to 2bbl adapter though with divided bores. Might be worth fabing up a couple of TBI spacers at some point and testing them. 1" tall spacers might see some torque gains, if you have room under the hood for them. I have never had a TBI engine that did not run better with a TBI spacer.
Last edited by Fast355; 03-18-2024 at 01:22 PM.
#3
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Re: CFI TB project
Are they going on a Renegade intake on a decently powerful engine? A twin 50mm GM throttle body 454 large IAC footprint style marine TBI with 61# high pressure injectors that flow ~104 lb/hr @ 30 psi was not a limitation on a Victor Jr 2bbl manifold at the 450 hp level for me. Even at ~6,500 rpm the TB had more than adequate flow. I will say the 454 TBI on that Victor Jr 2bbl liked the Holley Projection heated TBI to 2bbl adapter though with divided bores. Might be worth fabing up a couple of TBI spacers at some point and testing them. 1" tall spacers might see some torque gains, if you have room under the hood for them. I have never had a TBI engine that did not run better with a TBI spacer.
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Car: 89 Firebird
Engine: 355 TBI
Transmission: 700R4
Axle/Gears: 10 Bolt.Posi-3.73s
Re: CFI TB project
I broke 2 7.5 in 10 bolts. One on a car running 13.4s and one running 13.7s. Replaced with a 9bolt and if iirc got down to 13.2s and never broke that one.
#5
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Car: 1983 G20 Chevy
Engine: 305 TPI
Transmission: 4L60
Axle/Gears: 14 bolt with 3.07 gears
Re: CFI TB project
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dmccain (03-19-2024)
#6
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Car: '92 Corvette, '89 1/2-a-'Vette
Engine: LT1, L98
Transmission: ZF6, ZF6
Axle/Gears: 3.45, 3.31
Re: CFI TB project
Hey Tom, Can you radius that transition from the bore to the mouth a little? I'd think that abrupt angle there might negate some of the benefit your looking for, with those beautifully done TB's. Gorgeous work.
Rooting for your 11.99.
Rooting for your 11.99.
#7
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Re: CFI TB project
Yeah, I've been thinking about that for a little. I was wondering if that would really hurt the flow that bad. These were a PITA to do and get right for sure. I LOVE the needle roller bearings, they work so nice now. I'm going to take another look at this and see if there is an easy way to round/taper that edge a little.
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#8
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Car: '92 Corvette, '89 1/2-a-'Vette
Engine: LT1, L98
Transmission: ZF6, ZF6
Axle/Gears: 3.45, 3.31
Re: CFI TB project
This may seem "hack", but could you use a 3-stone brake cyl hone to just put a little radius there? That would not cut too fast, and it would look nice/finished when you're done, I think
I BET the bearings are sweet! Those'll be the nicest CFI TB's ever made! I dig 'em.
I BET the bearings are sweet! Those'll be the nicest CFI TB's ever made! I dig 'em.
#9
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Re: CFI TB project
Well, I decided to get another chamfer bit and redo that edge more and see how that works out. I have too many projects going on and may take me longer than I want to do this. The manifold project is taking more of a priority right now.
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