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Is it time for 30lb injectors?

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Old 05-13-2018, 01:26 PM
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Car: 1987 IROC Z
Engine: 350 TPI L98 block
Transmission: 700R4
Is it time for 30lb injectors?

I have an 87 iroc-z with a 350 TPI, and I'm in the process of swapping out my fuel injectors. I believe one of them is leaking as my car started to bog heavily just in idle and I was getting a lot of smoke. I also can smell gas in my oil. I am also deleting the cold start injector as I want to eliminate that as a source of failure.
The car had some Ford blue tip injectors from a cobra that flow 24 lb added by the previous owner. I'm wondering if I should get higher flowing injectors now. I've done some mild upgrades to the car listed below.
- Holley high flow 255 liter per hour fuel pump
- afpr set to 40lb
- MSD 6AL
- ACCEL Coil
- headers
- larger Lingenfelter cam
- roller rockers
- flowmaster cat back exhaust
- lingenfelter larger flowing runnners to the plenum
- CAI - SLP
- exhaust cutouts, that dump shortly after the headers, typically closed
- B&m high stall torque converter
- block was bored over .5 after
-chip was programmed into accept the 24-pound injectors
- appropriate horsepower stickers.. at least 30 horsepower out of those :-p

I've already ordered some 30lb accel injectors and a 52 mm throttle body, and I'm wondering if I've got enough to justify the 30lb injectors. Haven't installed them yet and contemplating switching them back to new 24 lb injectors.

This will probably be the last set of major upgrades done to this vehicle. I just want to be able to run it comfortably. I'm not putting the money in for a stroker kit or forced induction. Once I've got it running stably again, I'm done with upgrades to this motor.

Your thoughts gents?
Old 05-13-2018, 02:38 PM
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Re: Is it time for 30lb injectors?

You will need to get a new chip for your ECU to run anything other than the stock 22 lb injectors. I dont think you need 30 lb injectors yet. We would need to know more about the cam, heads, and intake you are running.
Old 05-13-2018, 03:39 PM
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Car: 1987 IROC Z
Engine: 350 TPI L98 block
Transmission: 700R4
Re: Is it time for 30lb injectors?

I'm running stock heads with roller rockers and the Lingenfelter/accel 74211 cam (specs shown in image) . .Cam
Old 05-13-2018, 04:11 PM
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Re: Is it time for 30lb injectors?

I also have an Edelbrock manifold as well. I'm realizing that there's not too much more I can do for bolt ons before I start messing with internals. Maybe a head upgrade would be in order?
Old 05-13-2018, 04:23 PM
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Re: Is it time for 30lb injectors?

No 30s for you.
Old 05-13-2018, 04:46 PM
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Re: Is it time for 30lb injectors?

The way to know if you have the correct size injectors is by the air fuel ratio and duty cycle of the injectors and there is no way of knowing that without datalogging. We can only guess what size injectors work best. The best way to guess is to look at what size injectors a certain engine comes from the factory with. Some times you have to convert for fuel pressure differences but it usually works well. So if you have a 300 wheel hp engine you can look and see what GM put in the LT1 fourthgen. 350 look at the LS6, 400 then look at, well, you get.
Old 05-15-2018, 10:45 AM
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Re: Is it time for 30lb injectors?

Your 24lb injectors are fine.
Old 05-28-2018, 09:29 PM
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Re: Is it time for 30lb injectors?

Originally Posted by 91RS5speed
You will need to get a new chip for your ECU to run anything other than the stock 22 lb injectors. I dont think you need 30 lb injectors yet. We would need to know more about the cam, heads, and intake you are running.
i have 36 psi injectors with no tune factory comp and prom and i adjust my fuel pressure to get it where it wants to run and i did this 25 years ago still runs strong
Old 02-17-2023, 01:52 PM
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Re: Is it time for 30lb injectors?

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