'91 RS ECM and TBI 350 PROM?
#1
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'91 RS ECM and TBI 350 PROM?
I have a simple question that I have been searching for the answer to for a few days and am running out of time so I was hoping for a quick answer. I have heard that in order to do the 305 tbi to 350 tbi swap I will need several items, one of them being a PROM from a 350 tbi car. I have seen them on ebay for cheap but I wanted to make sure that it is directly swappable on my ECM out of my '91 RS before I buy one.
Any info is appreciated.
Any info is appreciated.
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Car: 92 Camaro RS, 25th Anniversary
Engine: 305 cid, 5.0L V8, TBI
Transmission: 700R4, 4 Spd Automatic Transmission
Axle/Gears: 2.73
Re: '91 RS ECM and TBI 350 PROM?
I have a 92 RS TBI and that fuel injection does no do any better with TBIs and it won't do any better with a 350. If you have a 350, you have to run it with either with a 4 barrel carburetor or With a TPI.
#3
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Re: '91 RS ECM and TBI 350 PROM?
I just have a question with the computer aspect of it.
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Car: 92 Camaro RS, 25th Anniversary
Engine: 305 cid, 5.0L V8, TBI
Transmission: 700R4, 4 Spd Automatic Transmission
Axle/Gears: 2.73
Re: '91 RS ECM and TBI 350 PROM?
No problem, remember TBIs are designed only to give higher mileage. Most high performance parts you add to your engine will only give higher mileage but little performance. My Camaro showed that. Go to summit racing and buy a TBI spacer for trucks and goes between the TBI and the intake manifold. Is called Trans-Dapt Performance TBI Spacer. I recommend the swirl torque TBI spacer part number TRD-2533. It cost less than $50.00.
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Re: '91 RS ECM and TBI 350 PROM?
I have a simple question that I have been searching for the answer to for a few days and am running out of time so I was hoping for a quick answer. I have heard that in order to do the 305 tbi to 350 tbi swap I will need several items, one of them being a PROM from a 350 tbi car. I have seen them on ebay for cheap but I wanted to make sure that it is directly swappable on my ECM out of my '91 RS before I buy one.
Any info is appreciated.
Any info is appreciated.
As long as you use the 350 injectors the stock RS 305 PROM can be used.
Check the TBI board here for a sticky on a 305 to 350 swap. It will also mention the knock sensor and filter. But again you can get away with using the 305 filter with the 350 sensor. I say it that way as I am assuming a knock sensor will be in the 350 as delivered.
Otherwise just use the 305 sensor for now. Although, being in the water jacket, it can be better to put the correct sensor in right away.
RBob.
#6
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Re: '91 RS ECM and TBI 350 PROM?
The Caprice's that used the '8746 ECMs have PROMs that will swap right in. Just check that it is a 350 under the hood.
As long as you use the 350 injectors the stock RS 305 PROM can be used.
Check the TBI board here for a sticky on a 305 to 350 swap. It will also mention the knock sensor and filter. But again you can get away with using the 305 filter with the 350 sensor. I say it that way as I am assuming a knock sensor will be in the 350 as delivered.
Otherwise just use the 305 sensor for now. Although, being in the water jacket, it can be better to put the correct sensor in right away.
RBob.
As long as you use the 350 injectors the stock RS 305 PROM can be used.
Check the TBI board here for a sticky on a 305 to 350 swap. It will also mention the knock sensor and filter. But again you can get away with using the 305 filter with the 350 sensor. I say it that way as I am assuming a knock sensor will be in the 350 as delivered.
Otherwise just use the 305 sensor for now. Although, being in the water jacket, it can be better to put the correct sensor in right away.
RBob.
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Re: '91 RS ECM and TBI 350 PROM?
Okay, I read somewhere that the 305 PROM would make it run rich if I was using the stock 350 injectors.. However, that prompts a different question. Can I use a stock prom at all if I am going to run a mild cam etc? I know that is getting a bit off track but I want to ask while I have your attention!
Although some of the later 5.7l TBIs did get larger injectors.
55#/hr and a 305 = 5.54:1 ratio
61#/hr and a 350 = 5.73:1 ratio
A 3.3% difference.
The other side of this is that a Caprice is a heavier vehicle. So a 5.7l Caprice PROM isn't always the best answer either.
As for a mild cam, once you start any mod's, best to get into tuning.
RBob.
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#8
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Re: '91 RS ECM and TBI 350 PROM?
On the 5.0L and 5.7L TBI engines GM based the injector flow rate on the displacement. It was a ratio between the two. So the fueling is similar as the ratios are close.
Although some of the later 5.7l TBIs did get larger injectors.
55#/hr and a 305 = 5.54:1 ratio
61#/hr and a 350 = 5.73:1 ratio
A 3.3% difference.
The other side of this is that a Caprice is a heavier vehicle. So a 5.7l Caprice PROM isn't always the best answer either.
As for a mild cam, once you start any mod's, best to get into tuning.
RBob.
Although some of the later 5.7l TBIs did get larger injectors.
55#/hr and a 305 = 5.54:1 ratio
61#/hr and a 350 = 5.73:1 ratio
A 3.3% difference.
The other side of this is that a Caprice is a heavier vehicle. So a 5.7l Caprice PROM isn't always the best answer either.
As for a mild cam, once you start any mod's, best to get into tuning.
RBob.
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Re: '91 RS ECM and TBI 350 PROM?
RBob.
#10
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Re: '91 RS ECM and TBI 350 PROM?
Not exactly sure what it is but its an older block we had sitting around already. Can't tell ya much other than its a 350 2 bolt main. And I have read the swap thread a couple times but there is a bit of contradiction between posts and it gets difficult to get straight answers.
Side question, how different are the older 350 heads and the 305 ones? The 350 heads I have don't have the right accessory mounting holes so I was gonna slap on the 305 heads for now.
Side question, how different are the older 350 heads and the 305 ones? The 350 heads I have don't have the right accessory mounting holes so I was gonna slap on the 305 heads for now.
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Re: '91 RS ECM and TBI 350 PROM?
Not exactly sure what it is but its an older block we had sitting around already. Can't tell ya much other than its a 350 2 bolt main. And I have read the swap thread a couple times but there is a bit of contradiction between posts and it gets difficult to get straight answers.
Side question, how different are the older 350 heads and the 305 ones? The 350 heads I have don't have the right accessory mounting holes so I was gonna slap on the 305 heads for now.
Side question, how different are the older 350 heads and the 305 ones? The 350 heads I have don't have the right accessory mounting holes so I was gonna slap on the 305 heads for now.
Well, then it is a mix & match. Most likely a two-piece RMS, if so need a different flex-plate.
The old school heads are non-swirl port. So the SA calibration won't be correct with those heads. And putting the 305 heads on is likely going to raise the compression ratio. How much I'm not sure. Get the casting numbers from both the 305 & 350 heads and do a 'net search for chamber volume.
It may end up that the stock 350 compression ratio is so low that the 305 heads will work. Also depends upon which pistons are in it.
RBob.
#12
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Re: '91 RS ECM and TBI 350 PROM?
Yea, I just reviewed the first page of that thread. Once past the first post a lot of misinformation in it.
Well, then it is a mix & match. Most likely a two-piece RMS, if so need a different flex-plate.
The old school heads are non-swirl port. So the SA calibration won't be correct with those heads. And putting the 305 heads on is likely going to raise the compression ratio. How much I'm not sure. Get the casting numbers from both the 305 & 350 heads and do a 'net search for chamber volume.
It may end up that the stock 350 compression ratio is so low that the 305 heads will work. Also depends upon which pistons are in it.
RBob.
Well, then it is a mix & match. Most likely a two-piece RMS, if so need a different flex-plate.
The old school heads are non-swirl port. So the SA calibration won't be correct with those heads. And putting the 305 heads on is likely going to raise the compression ratio. How much I'm not sure. Get the casting numbers from both the 305 & 350 heads and do a 'net search for chamber volume.
It may end up that the stock 350 compression ratio is so low that the 305 heads will work. Also depends upon which pistons are in it.
RBob.
#15
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Re: '91 RS ECM and TBI 350 PROM?
Alright I confirmed it is a 2p piece. I am usually the exact opposite but this time i'm in a hurry. Is there a part number or description of what i'm looking for as a new item?
#17
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Re: '91 RS ECM and TBI 350 PROM?
Rbob, is this the right part? According to rockauto this is the OEM replacement for the '85 lg4 flexplate. *DORMAN Part # 04326*
Please let me know as soon as you can as I need to order it today if possible.
Please let me know as soon as you can as I need to order it today if possible.
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Re: '91 RS ECM and TBI 350 PROM?
RBob.
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Re: '91 RS ECM and TBI 350 PROM?
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