Can you use 21lb injectors in 1990 5.7 ?
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Joined: Jan 2010
Posts: 164
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Car: 1990 Iroc Z
Engine: L98
Transmission: 700r4
Axle/Gears: 9 bolt
Can you use 21lb injectors in 1990 5.7 ?
I recently installed 21lb injectors and adjustable fuel pressure regulator in my stock 5.7 1990 IROC. Are there any problems associated with using this size injector and how do you determine where the fuel pressure should be set at for optimum performance.
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Joined: Apr 2011
Posts: 113
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From: Dinwiddie VA
Car: 1986 Camaro Z28
Engine: 5.0 305 TPI
Transmission: 700R4
Axle/Gears: posi 3.73
Re: Can you use 21lb injectors in 1990 5.7 ?
I have a friend on here that owns a 1990 IROC with the 5.7 and he uses the 21lb injectors with absolutely no problems!!!!!
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Member
Joined: Jan 2010
Posts: 164
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Car: 1990 Iroc Z
Engine: L98
Transmission: 700r4
Axle/Gears: 9 bolt
Re: Can you use 21lb injectors in 1990 5.7 ?
Thanks for the input. I've put a couple hundred miles on them and they seem to be working out pretty good. I see a lot of people on here talking about 22lb injectors and I don't really know what the rating means, what the difference is, or what the car came with stock and how it would affect performance. I do not know if the injectors I replaced were original. I believe the injectors I replaced and the fuel rail had the name Rochester on them.
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Joined: Mar 2011
Posts: 2,893
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From: Central Texas
Car: GTA
Engine: 350 TPI
Transmission: 700R4
Axle/Gears: Aussie 9-bolt/3.27 posi
Re: Can you use 21lb injectors in 1990 5.7 ?
iirc, 21 is the stock size for 5.7s (19 for the 305).
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Joined: Nov 2008
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From: Rockville Centre, NY
Re: Can you use 21lb injectors in 1990 5.7 ?
Thanks for the input. I've put a couple hundred miles on them and they seem to be working out pretty good. I see a lot of people on here talking about 22lb injectors and I don't really know what the rating means, what the difference is, or what the car came with stock and how it would affect performance. I do not know if the injectors I replaced were original. I believe the injectors I replaced and the fuel rail had the name Rochester on them.
21lb/22lb.....engine will never know the difference.
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Joined: Sep 2009
Posts: 95
Likes: 3
From: Virginia
Car: 1990 Iroc, 1984 Buick Regal
Engine: 5.7, ZZ4 crate w/FIRST injection
Transmission: 700r4, 700r4
Axle/Gears: 3.73, 4.11
Re: Can you use 21lb injectors in 1990 5.7 ?
I run 24lb injectors and they are great, the factory size was 22lb... You should be fine...
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