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350 HO tpi swap

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Old 11-05-2023, 05:30 PM
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Car: 88 IROC-Z
Engine: 350 H.O.
Transmission: 700r4
Axle/Gears: 3.73
350 HO tpi swap

I recently purchased an 88 iroc with an LB9, I have to replace it because it has a knock. The motor going in is a 350 HO crate motor. Specs are as follows

Intake manifold: Edelbrock lower base, SLP runners, stock fuel pressure regulator, “280 150 785“ Bosch injectors (supposedly 30#hr? @ 57psi or 24#hr @ 43 psi)

Engine: 217 heads (same as 083), GMPP 212/222 cam .435/460 112.5 LSA, 9.1:1 CR

what would have to be done to run this setup correctly? Or can I run it the way it is due to the larger injectors?

Last edited by leakyz28; 11-07-2023 at 12:55 AM.
Old 11-05-2023, 09:05 PM
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Car: 1989 IROC-Z
Engine: L98 350 TPI
Transmission: 700R4
Axle/Gears: BW 9 Bolt / 2.77 Posi
Re: 350 HO tpi swap

It will need a tune, otherwise sounds good.
Old 11-06-2023, 07:49 AM
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Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: 350 HO tpi swap

It'll run on the stock tune but it'll be much better with a correct tune.
30lbs probably a bit much inj for stock tune. The stock 19s with a fuel psi bump would work best

Last edited by TTOP350; 11-12-2023 at 05:42 AM.
Old 11-09-2023, 10:08 PM
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Car: 88 IROC-Z
Engine: 350 H.O.
Transmission: 700r4
Axle/Gears: 3.73
Re: 350 HO tpi swap

I have an Edelbrock EPS intake kit with a Holley 670 avenger ready to go worst case scenario, the car is gonna get Holley EFI on that EPS intake eventually so I'm debating whether or not its even worth bothering with the tuned port setup since it's gonna need a good amount of work to run correctly. The EPS intake and carb I can just throw on with a regulator and call it a day. I don't wanna risk running it too lean and burning out my new motor or washing the cylinders and diluting the oil due to it running pig rich 24/7. I get that I could get a PROM chip and tune the ECM but that'll cost a decent amount of money for something I'm not gonna use in the long run. I think the EPS intake and carb route is the best route lmk what you guys think
Old 11-09-2023, 10:30 PM
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Car: 1989 IROC-Z
Engine: L98 350 TPI
Transmission: 700R4
Axle/Gears: BW 9 Bolt / 2.77 Posi
Re: 350 HO tpi swap

Put the induction system you want to put on the engine to begin with and don't cheap out. The custom TPI needs a tune, the other two need different fuel pumps, it's all going to cost double what you've budgeted and the only thing more expensive is doing it twice.
Old 11-10-2023, 04:03 PM
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Axle/Gears: 3.45, 3.31
Re: 350 HO tpi swap

Originally Posted by leakyz28
lmk what you guys think
I think: I agree with TTop350 that you CAN run it the way it is, mess with fuel pressure and base timing to make it "good enough" to run well, and neither "wash cylinders", nor, "run lean". I once did this and ran a SBC 400 with a 224/234 cam, ported intake, headers etc ...on a 305 ECM...and it ran great, for years.

What I REALLY think? You'll do what you really WANT to do. I made the 400 combo work, b/c I ws highly motivated to do it. It seems like you're motivated to do the EPS intake.....that's probably what you should pursue. That's what I think.
Old 11-14-2023, 03:02 PM
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Car: 88 IROC-Z
Engine: 350 H.O.
Transmission: 700r4
Axle/Gears: 3.73
Re: 350 HO tpi swap

Originally Posted by Tom 400 CFI
I think: I agree with TTop350 that you CAN run it the way it is, mess with fuel pressure and base timing to make it "good enough" to run well, and neither "wash cylinders", nor, "run lean". I once did this and ran a SBC 400 with a 224/234 cam, ported intake, headers etc ...on a 305 ECM...and it ran great, for years.

What I REALLY think? You'll do what you really WANT to do. I made the 400 combo work, b/c I ws highly motivated to do it. It seems like you're motivated to do the EPS intake.....that's probably what you should pursue. That's what I think.
Yeah you’re 100% right, TPI is a great system and I’m sure it’ll run amazing with a little bit of work. I guess I just like the classic look of a carburetor better, that’s not to say the TPI doesn’t look awesome, I think they look amazing, just not really my thing. I want the carb look with the fuel injection ideally


Last edited by leakyz28; 11-16-2023 at 09:37 PM.
Old 11-16-2023, 09:33 PM
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Car: 88 IROC-Z
Engine: 350 H.O.
Transmission: 700r4
Axle/Gears: 3.73
Re: 350 HO tpi swap

TPI has been growing on me, I think I'm gonna run the carburetor for now and in the meantime over the winter I'll port out my runners, plenum and lower intake and really clean it up in the meantime to make it flow as much as possible. FiTech sells a harness that modernizes the ECU and harness, if it can match or make more power than what the EPS/Carb combo is capable of then I'll do that and retain the cool factor of the TPI. My biggest worry is that I'll go through all that effort to make the TPI flow well and the EPS/Carb combo will still make more power, if both combos are identical with the operating range this engine is gonna see then I'll totally go TPI, its that 4500-5400 range I'm worried about.


Last edited by leakyz28; 11-16-2023 at 10:27 PM. Reason: more info
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