1985 fuel injector knowledge needed
Thread Starter
Instructor
Joined: Jul 2023
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Before buying I spoke several times with FIC. They were the ones that convinced me to switch to 22lbs. I was told that you can get a fuel pressure regulator for an 1985 and the switch to 22lb. infevtor and run a 43lb regulator just like the factory for 1986. If I could get a regulator I would try the at home clean up of the factory injectors. Can you still get 1985 (36lbs) fuel regulator anywhere?
I spoke to a friends mechanic who said he got some off ebay that worked and saw savings. I should have run he numbers when I first got them. I'm returning them Monday.
I spoke to a friends mechanic who said he got some off ebay that worked and saw savings. I should have run he numbers when I first got them. I'm returning them Monday.
Thread Starter
Instructor
Joined: Jul 2023
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my 2-cent opinion, FWIW -- first, "hands-on" experience with 85's and bosch injectors. originals were first generation bosch - definitely a good injector. i cleaned mine several times before going to 24 pound gen-3 bosch injectors from FIC. i agree, a smaller 22 pound injector, at the same or higher pressure maybe a better combo and may spray and atomize better - i once read 19 pounders are even better yet. GM went to 22 pound injector on the L98's in 86 when they switch from bosch to multec. not sure of the correlation, but they must of had a reason (besides saving a buck 
, must of had something to do with aluminum heads, fuel economy and/or EPA regs - my money's on the EPA ). early multec injectors were problematic due to the ethanol gas screwing with the injectors internals. multec's manufactured after 1994 don't seem to have that issue. first generation bosch injectors have a single port spray nozzle whereas gen 3 and 4 have multi-port spray nozzles. by design, they will spray and atomize better. my advice - unless you have an adjustable fuel pressure regulator, stick with the 24 pounders, upgrade to gen 3's from FIC. and don't try to out-think the factory. if purchased from FIC, they come as a matched set - flow rate, spray pattern, coil resistance, etc.. unless you have some 100 point show car or museum piece, i wouldn't sweat the originally stuff. i've been running bosch 3's in my 85 for years - no problems or issues. again, my opinion....
, must of had something to do with aluminum heads, fuel economy and/or EPA regs - my money's on the EPA ). early multec injectors were problematic due to the ethanol gas screwing with the injectors internals. multec's manufactured after 1994 don't seem to have that issue. first generation bosch injectors have a single port spray nozzle whereas gen 3 and 4 have multi-port spray nozzles. by design, they will spray and atomize better. my advice - unless you have an adjustable fuel pressure regulator, stick with the 24 pounders, upgrade to gen 3's from FIC. and don't try to out-think the factory. if purchased from FIC, they come as a matched set - flow rate, spray pattern, coil resistance, etc.. unless you have some 100 point show car or museum piece, i wouldn't sweat the originally stuff. i've been running bosch 3's in my 85 for years - no problems or issues. again, my opinion....I guess this weekends a bust for getting running again. Plan to get the manifold off, cleaned and set back on.
Melting Slicks
Joined: Aug 2011
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I'll be calling FIC and getting injectors from them. If they tell me Bosch IIIs, what other questions do I need to ask? Did you get clips with yours when you switched? Is it a different style injector clip? I looked at some pics of Bosch IIIs and didnt even see a slot in the top injector body for a clip. Any input definitely appreciated.
I guess this weekends a bust for getting running again. Plan to get the manifold off, cleaned and set back on.
I guess this weekends a bust for getting running again. Plan to get the manifold off, cleaned and set back on.
Southbay has nice pressed on extensions to make up for length Instead of double o-rings like fic uses.
Race Director
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D3s from fic or sb for that matter don’t use a clips. Voltage offsets are slightly different than bosch so not a real plug and play but might be your only choice other than Accel 24s
Southbay has nice pressed on extensions to make up for length Instead of double o-rings like fic uses.
Southbay has nice pressed on extensions to make up for length Instead of double o-rings like fic uses.
Melting Slicks
Joined: Aug 2011
Posts: 2,844
Likes: 176
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 764
I'll be calling FIC and getting injectors from them. If they tell me Bosch IIIs, what other questions do I need to ask? Did you get clips with yours when you switched? Is it a different style injector clip? I looked at some pics of Bosch IIIs and didnt even see a slot in the top injector body for a clip. Any input definitely appreciated.
I guess this weekends a bust for getting running again. Plan to get the manifold off, cleaned and set back on.
I guess this weekends a bust for getting running again. Plan to get the manifold off, cleaned and set back on.
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 764
Last edited by Joe C; Aug 26, 2023 at 12:30 PM.
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Melting Slicks
Joined: Aug 2011
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now we're throwing camaros in the mix. if i'm not mistaken, 305 camaros originally came with 19 pounders. not trying to argue the point, but this sounds like we're mixing apples and oranges and trying to make a fruit salad. this is what i'm talking about - don't try to out think the factory. it's one less thing you'll need to think about and worry about. the OP needs to get the correct injector as defined by GM for his particular year - no muss, no fuss. been doing this 85 corvette-bosch injector thing for 28 years now. 170K miles, factory spec'd 24 pound injectors (as well as everything else), and running like a top.
Race Director
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just look at the data see a huge difference in how low pw as well as voltage pw is different. Will it run “yes” is it plug and play “no” can it be improved on by looking at fuel trims “yes” injectors just because they flow at 3 bar doesn’t make them equivalent to factory. The 1226970 is a slow baud rate ecm . It will learn alittle but would benefit from tuning. My friends 85 with accel 24s ran great no tuning. Then he swapped to vortec heads this really leaned it out. Voltage offsets added fuel in all maf tables and recurved sa to correct int/Blm . Not bringing in the f bodies just observe the data difference .
Melting Slicks
Joined: Jul 2005
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When you change injectors, you really need to get the datasheet for them so you can input the correct voltage offsets. On Bosch-III's in particular, you also typically want to zero out the low puleswidth injector offset table. The Bosch-III's don't need any "help" to flow properly at low pulsewidths, like the older Multecs must have.
If you swap injectors and the car runs "ok" to you (without having done any scanning of the ECM data), what's probably happening is your BLM fuel trims are probably up into the 150 range, but not maxed out at 160, so the ECM is able to still adjust your fueling for decent operation during normal driving. But it's certainly not ideal. GM's power enrichment is also typically biased pretty rich, so you're also probably not at risk of going dangerously lean. In addition, some people run into cold start issues, and some don't.
That said, there's probably some performance being left on the table by not getting the calibration adjusted to properly account for injector performance characteristics.
An exception to this from what I've heard are Delphi's. While a bit pricier than Bosch-III's, from what I understand people have verified that they don't need tuning to maintain factory fuel trims.
If you swap injectors and the car runs "ok" to you (without having done any scanning of the ECM data), what's probably happening is your BLM fuel trims are probably up into the 150 range, but not maxed out at 160, so the ECM is able to still adjust your fueling for decent operation during normal driving. But it's certainly not ideal. GM's power enrichment is also typically biased pretty rich, so you're also probably not at risk of going dangerously lean. In addition, some people run into cold start issues, and some don't.
That said, there's probably some performance being left on the table by not getting the calibration adjusted to properly account for injector performance characteristics.
An exception to this from what I've heard are Delphi's. While a bit pricier than Bosch-III's, from what I understand people have verified that they don't need tuning to maintain factory fuel trims.
Thread Starter
Instructor
Joined: Jul 2023
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No problem using 24lb. If I can get a 1985 fuel pressure regulator, which I have been able to find. I found a Boosh data chart that said the the 0 280 150 223 injectors used on my car flow 21.36lb with a 36lb regulator (2.47 bar). With that said several were not tight and it seemed to have 2 different plugs in it. Can you still get a 36lb regulator??
Thread Starter
Instructor
Joined: Jul 2023
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