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How to: 305 To 350 swap....everything you need to know

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How to: 305 To 350 swap....everything you need to know

Old 08-25-2007, 01:55 AM
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Re: How to: 305 To 350 swap....everything you need to know

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Old 08-25-2007, 02:04 AM
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Re: How to: 305 To 350 swap....everything you need to know

ok because im getting a prom programed and the guy that is doing it said:

"The motor needs to have the 350 injectors 5235206 truck injectors from
www.injectors4u.com and it needs the 350 ESC module and 350 knock sensor.
The 305 parts are too sensitive for use with a 350."

so should i just tell him everything is there or not because i have the injectors and esc from my old 305 and they seem to work fine.
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Old 11-15-2007, 01:19 PM
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Re: How to: 305 To 350 swap....everything you need to know

hey dwillis i would like to know how your swap went...i am embarking on a very similar project this very weekend and any advice would be greatly appreciated... 1988 camaro 305 tbi to a stock 350 tbi out of '88 blazer adding a set of heddman headers and y pipe. the donor is complete with injectors, knock sensor, ecm and even wiring harness although i plan on using my exsisting harness. concerns about the t-5 transmission and the ecm... can i swap the prom form the 350 ecm to the camaro ecm or just change the entire ecm? anyone with helpful hints would be appreciated. sorry if i am not going about this the correct way but i just joined today...
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Old 12-01-2007, 07:47 PM
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Re: How to: 305 To 350 swap....everything you need to know

there has been alot of talk on this thread about fuel injectors, what about the fuel pump? i dont think the stock L03 pump is enough to feed a 350 tbi. where is the best place to buy the right pump and how much should it cost? i assume im going to have to drop my fuel tank to replace it.
do you buy a fuel pump for a caprice or truck equipped with a 350? i don't know if that will work because the tank shape or depth is probably not the same.
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Old 12-03-2007, 06:46 PM
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Re: How to: 305 To 350 swap....everything you need to know

Originally Posted by ad356 View Post
i dont think the stock L03 pump is enough to feed a 350 tbi.
The L03 (305) and L05 (350) pumps are the same, so if your 350 is mostly stock, the original pump should be ok if its in good shape. Keep in mind that the wiring and connectors on these pumps can get funky over time and improved replacement wiring harnesses are available from Carter and some other companies.

I looked at using the best stock replacement pump I could find for my L03, and it looks like the pump Carter sells is the same one they use for several 454 truck TBI applications, while AC Delco lists 2 different pumps for those 2 apps, so the Carter pump may have higher volume output. However I can't find any specifications to verify that.

There have also been several posters on these forums that stated that their stock pumps were fine with modified 350's, at least running the stock 11 to 13 psi pressure.

However, a lot of people with pumped up TBI engines move up to the Walbro 190 pump, which is good for up to 400 horsepower or so. This pump will apparently work ok with the stock wiring, while the next bigger Walbro pump won't. The Walbro 190 costs about the same as a stock replacement pump, but you may have to modify or replace your fuel pressure regulator to handle the higher pressure output of this pump. There are a couple of suppliers that sell this Walbro pump with all the required addtional parts for TBI or TPI cars, if you search "Walbro 190" in these forums I'm sure you'll hit them.

Paul T.
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Old 12-29-2007, 11:47 AM
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Re: How to: 305 To 350 swap....everything you need to know

I had a 350 built for me, bored out 30 over, Vortec heads, and with the stock or hot chip for my car it didnt work. I had to special order one from Motovation, programed to the specs of my motor,cam too.I guess I still need the 350 injectors, right? Its still a hell of alot faster then before. I have no traction, the tires just want to spin till I bought these new tires now they dont spin as bad.
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Old 01-01-2008, 10:44 AM
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Re: How to: 305 To 350 swap....everything you need to know

I dont know why they ever put the anemic 305 in these cars, they could have at least made my horsepower.
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Old 01-03-2008, 04:26 PM
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Re: How to: 305 To 350 swap....everything you need to know

Fast car, you are way past what the stock programing can deal with. Anything much more than full exhaust requires custom tuning. With that said, custom tuning is NOT a mail order chip. It is impossible to make up a chip based on a list of mods, you can get the injector size right but everything else needs tailored for your paticular engine with lots and lots of testing.

If you "chip" was programmed for the stock 305 injectors then slapping in 350 injectors will only make you rich. You are giving up major HP with that chip, you need to look at my "free tune" sticky and see about learning to do it yourself.

Burnouts,

When GM engineered these cars they had several goals in mind, mainly pass emmisions, fuel mileage, and "pep". Tire shredding torque was not on their list. They made a base model engine that got mid to high 20 mpg, passed emmisions with ease and was quicker than 80% of other cars on the road at the time. They did OK, but we can do much better today.
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Old 01-03-2008, 10:37 PM
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Re: How to: 305 To 350 swap....everything you need to know

well the the chip was programed from motivation for my motor specs not injector size.
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Old 01-11-2008, 09:43 PM
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Re: How to: 305 To 350 swap....everything you need to know

Is everything mentioned at the top of this thread relevant to swaping 305 to 350 in a crossfire engine? I'd immagine that I'd need a computer out of a Vette, but as far as changing the knock sensor and injectors and such, this would be a simalar swap wouldn't it?
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Old 01-11-2008, 09:47 PM
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Re: How to: 305 To 350 swap....everything you need to know

Originally Posted by Fastcar92 View Post
well the the chip was programed from motivation for my motor specs not injector size.
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Old 01-11-2008, 10:09 PM
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Re: How to: 305 To 350 swap....everything you need to know

I think what Fast355 was trying to say is that you totally missed the point of my post. It is NOT possible to make a chip from a list of mods. The grand tuning meister himself can't do it. There are litterally thousands of parametes that can be changed, the ONLY way to get a proper tune is with testing, which you can't do if you have never even seen the car.

The chip you have is a crutch at best and most likely a rip off for the money you spend on it.
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Old 02-20-2008, 12:29 PM
  #113  
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Re: How to: 305 To 350 swap....everything you need to know

i just swapped the 305tbi in my 92 camaro for a 350tbi from a 90 silverado. i have changed the knock sensor, esc module, 350 injectors, and have put in a hypertech street runner chip for a caprice with a 350tbi engine. my problem is that i can get the car to start but it has a very bad loping idle and seems to be running way rich. i have removed the smog pump. i have tried everything i can think of. i'm stumped because the engine was pretty much exactly the same as far as all the plugs and sensors. everything plugged in like the engine came in the car. if anyone has any suggestions that might help me out, i would greatly appreciate it.
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Old 02-20-2008, 01:14 PM
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Re: How to: 305 To 350 swap....everything you need to know

Looney, are you saying you have a Camaro ECM and you put in a chip from a Caprice?

If so that's most likely your problem, the Camaro and Caprice ECM's are different and I don't believe you can swap chips between them like that, the engine is probably running in emergency "limp home" mode and that's why its so rich.

You'll need to get a chip that will work with a 350 in your current Camaro ECM, if you ask around here someone will probably point to to one.

Good luck-

Paul T.
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Old 02-20-2008, 05:09 PM
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Re: How to: 305 To 350 swap....everything you need to know

i've heard otherwise on the ECM thing. don't the camaro and the caprice both use the 746 ecm. i believe they do.
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Old 02-20-2008, 05:22 PM
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Re: How to: 305 To 350 swap....everything you need to know

yes, i am right. all you have to do is go to any parts store online and you can see that the 92 camaro/305tbi and the 92 caprice/350tbi use the exact same ecm. any other suggestions would be greatly appreciated. thanks ayways paul t

Last edited by looneybug26; 02-20-2008 at 05:37 PM.
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Old 02-20-2008, 05:58 PM
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Re: How to: 305 To 350 swap....everything you need to know

i put a hypertech chip in and was wondering if i needed to maybe have the chip programmed for my engine, and if so can it be done with the chip in the car.
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Old 02-20-2008, 08:13 PM
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Re: How to: 305 To 350 swap....everything you need to know

Was there anything done to the motor like ,cam size, bored? Try Motivation thats where I got my custom chip from, they program your cam size, bore and headers,intake Manifold,ect..
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Old 02-20-2008, 08:55 PM
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Re: How to: 305 To 350 swap....everything you need to know

no, everything is pretty much stock. no headers, cam, intake, or anything that i know of.
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Old 02-21-2008, 11:40 AM
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Re: How to: 305 To 350 swap....everything you need to know

>yes, i am right. all you have to do is go to any parts store online and you
>can see that the 92 camaro/305tbi and the 92 caprice/350tbi use the exact
>same ecm. any other suggestions would be greatly appreciated.

I think the parts store is giving you bad info. My '91 Caprice uses a 16136965 ECM, which is on all the 91 and later TBI Caprices, both 305 and 350's. Your ECM is most likely a 1228746. Generally you can't swap chips between different ECM numbers.

Paul T.
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Old 02-21-2008, 12:13 PM
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Re: How to: 305 To 350 swap....everything you need to know

hey paul, go to autozone.com and search the ecm on a 92 caprice and a 92 camaro. they are both the exact same part numbers. generally autozone does not give the wrong part numbers when you tell them the car and engine size.
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Old 02-21-2008, 03:54 PM
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Re: How to: 305 To 350 swap....everything you need to know

hey paul, you're right. autozone was giving bad info. they only used the 746 ecm in the 89-90 caprice. and th bad part is that the chip i bought can't be returned after the box is opened so i'm just out 120 dollars on that one
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Old 02-21-2008, 04:09 PM
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Re: How to: 305 To 350 swap....everything you need to know

does anyone know a good place to get a chip for the 1228746 ecm for a 89-90 caprice 5.7LTBI. most i've found run from 120-200 dollars. something a little more inexpensive would be nice.
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Old 02-21-2008, 05:04 PM
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Re: How to: 305 To 350 swap....everything you need to know

Looney, I'd push hard both on the store and on Jet to let you at least swap that chip for one that will work for you. Afterall, it was their bad info that led you to that wrong chip in the first place.

Try to get at least credit from the store, and if that doesn't work, call Jet and try to get them to make it right. That chip only costs them about 5 bucks to manufacture, so it wouldn't cost them much to make it right for you.

Paul T.
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Old 02-26-2008, 11:05 AM
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Re: How to: 305 To 350 swap....everything you need to know

yo Paul T. i pushed and pushed on autozone, threatining with lawyers and slander until the manager finally caved and said he would give me the credit for my other chip even though he was not supposed to. lets hope this new one does the trick. thanks Paul.
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Old 02-26-2008, 11:53 AM
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Re: How to: 305 To 350 swap....everything you need to know

Way to stick to your guns looney, they were stupid for fighting with you on this, like I said earlier those chips cost them about $5. to make. Jet probably would have set you straight on it if Autozone hadn't caved in.

Paul T.
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Old 02-26-2008, 01:46 PM
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Re: How to: 305 To 350 swap....everything you need to know

just can't seem to get it right. i'm still running rich and i don't know what it could be. i have the right chip now as well as the knock sensor, esc module, and the 350 injectors. i've checked the timing over and over again. anything else that you guys can think of. i'm about ready to light this thing on fire and let it burn to the ground. lmao
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Old 02-26-2008, 09:12 PM
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Re: How to: 305 To 350 swap....everything you need to know

oh yeah, any reason why i would have a faint gas odor in my oil or is that because it's running so rich. could i possibly have a leaking head gasket.
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Old 02-26-2008, 09:25 PM
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Re: How to: 305 To 350 swap....everything you need to know

Looney, I think at this point you need to get your hands on a laptop, one of these adapter cables -

http://www.moates.net/product_info.p...roducts_id=127

and a copy of TunerPro RT with the correct .xdf and .ads files for your ECM. This will allow you to scan the ECM in real time and will tell you what's going on and allow you to verify the performance of the ECM and all the various sensors.

I still think the ECM may be running in emergency limp home mode, which would explain the rich condition.

Paul T.
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Old 02-26-2008, 11:21 PM
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Re: How to: 305 To 350 swap....everything you need to know

one ? paul. would it be worth a try to clear the trouble codes from the ECM by unplugging the ECM power harness connector that's located by the battery.
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Old 02-28-2008, 02:15 PM
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Re: How to: 305 To 350 swap....everything you need to know

ooook, that didn't work. will this cable you are talking about paul get my ECM out of the Emergency Limp Home Mode.
----------
i do know that when i use a jumper on the A & B terminals of the diagnostic connector that i am not getting any trouble codes. i don't know if that means anything but just thought i'd throw that out there for some of you experts.

Last edited by looneybug26; 02-28-2008 at 02:19 PM. Reason: Automerged Doublepost
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Old 02-28-2008, 03:00 PM
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Re: How to: 305 To 350 swap....everything you need to know

what about the knock sensors. i think the original 5.0L that came in my camaro came with two knock sensors, and this 5.7L only has one. i just checked under the car and have found what seems to be an extra knock sensor connector. would this affect the ECM in any way. seems like it would. if so, what can be done to address this problem?
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Old 03-14-2008, 12:51 PM
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Re: How to: 305 To 350 swap....everything you need to know

[QUOTE=OS3Fleming;3312786]Got a quick question. I am doing a 350 swap in my 3rd gen z28. It is carbed what will have to be changed will I need to flash the ECM?
[QUOTE]

NM...moved question to carbed forum...

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Old 03-20-2008, 04:32 PM
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Re: How to: 305 To 350 swap....everything you need to know

I just got a 350 (L05 roller) from a friend and I have a few questions.
Fuel injectors- Is there any place to buy them new? I've looked at the regular sites (summit, etc.) and only can find injector sets of 8, which I assume are for TPI engines.
Computer- Since I'm going with EBL, do I still need to swap ECMs? I would assume no, but I've been wrong before.
Intake- With the right injectors, fuel pump and regulator, can the stock throttle body support 350 HP, or will a 454 or bored TB be needed?
Thanks for the help, I'll probably come back for more.
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Old 03-20-2008, 04:57 PM
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Re: How to: 305 To 350 swap....everything you need to know

If you google search using "TBI Injectors" you'll hit a bunch of places that sell "Rochester" TBI injectors. You can also get them off Ebay, but that can be a little hit or miss. Fortunately TBI injectors are pretty robust, so as long as they haven't been sitting outside in the rain and got corroded in my experience they are usually ok. You can have them cleaned and tested for $17. each by www.witchhunter.com . The 62's (stock 350) or 68's (cop car) injectors will be ok for your engine if you can bump your fuel pressure up (note- with 62 injectors, running a fuel pressure of 33 to 34 psi will give you 350 HP capability).

A stock 305/350 TBI unit flows around 490 cfm, and is good up to 280 HP or so. By having that unit bored to 46mm (www.rvmorsemachine.com , turbocity.com or xtremefi on ebay) you can make up to 320 to 340 HP, depending on who's numbers you want to believe, but somewhere in that range is probably about right. Going this route lets you keep your stock throttle linkage and kick down linkage. Next step up is to a BB 50mm unit which should be good for 400 HP (some claim more), but will typically require reworking the throttle linkage and opening up your intake manifold for the bigger bores. I don't think you'll make that with a L05 shortblock, so the bored stock unit is probably the best way to go.

On www.dynamicefi.com he has a list of the ECM numbers that the EBL system is directly compatible with.

Good luck-

Paul T.

Last edited by titchener; 03-20-2008 at 05:47 PM.
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Old 04-15-2008, 11:04 PM
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Re: How to: 305 To 350 swap....everything you need to know

Okay..i have a 305 computer...(746)...and a 350 computer (747). Will the 350 EPROM operate right with the 305 computer?

when we put the 305 PROM in the 350 ECM it had a constantly flashing SES light.

is there a site where I can get the pinouts of these computers? ive already figured out the pinouts for the 305 computer...i need the pinouts for the 350 computer.

the 350 computer came out of a 1994 K1500
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Old 04-16-2008, 12:05 AM
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Re: How to: 305 To 350 swap....everything you need to know

Would you plug an AMD processor into an Intel motherboard?

They won't work together at all. You just need to use a 350 calibration on a chip in the 8746 ECM you have. That's your best bet, but if it's a modified 350 at all it may not run very well on any stock PROM's tune.
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Old 04-16-2008, 12:33 AM
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Re: How to: 305 To 350 swap....everything you need to know

thankyou that is what I was looking for
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Old 04-16-2008, 12:51 AM
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Re: How to: 305 To 350 swap....everything you need to know

btw that question is for me, we are trying to figure this out... What do you mean by

"They won't work together at all. You just need to use a 350 calibration on a chip in the 8746 ECM you have. That's your best bet, but if it's a modified 350 at all it may not run very well on any stock PROM's tune.

I understand the 8746 ECM is my 305 computer, but what do you mean by using a 350 calibration with my 305 ECM? My motor is all stock, the only thing I added was headers, no cat, and flowmaster, so it shouldnt have a problem if its tuned right?
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Old 04-16-2008, 12:55 AM
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Re: How to: 305 To 350 swap....everything you need to know

Originally Posted by BronYrAur View Post
Would you plug an AMD processor into an Intel motherboard?

They won't work together at all. You just need to use a 350 calibration on a chip in the 8746 ECM you have. That's your best bet, but if it's a modified 350 at all it may not run very well on any stock PROM's tune.
okay....so if the Pinouts on the 305 (1228746) computer are the same to work with a 1993 350 Engine with 350 knock sensor and 350 injectors...why would the car still be running rich?

We have the 350 (1227747) ECM with the 350 PROM in the car right now....the Pinouts are NOT the same on the 350 computer as the 8746 305 Computer (I have verified this). The car has no cat..full exhause+headers. we changed the O2 sensor becasue the one that was on there was bad..car is still running rich.

Is it just the PROM that needs a tune? Should we tune a PROM (for 350 specs) and put it in the 305 1228746 computer?
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Old 04-16-2008, 03:13 PM
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Re: How to: 305 To 350 swap....everything you need to know

Let me try........the 8746 that came in our RS's with 305 TBI's are basically the same comp that came in the Caprice's with 350's even with the so called "cop" car calibrations which I have a bin for if any one wants. 1990 model. They are nothing special.

To all the above who are seeking the "holy grail of all chips" ........it does not exist. As others above have tried to explain GM made generic chips for cars which would all be built the same and were exposed to a very wide range of operating conditions. Now modify one of those cars beyond much more than a larger air cleaner assy. and headers and free flowing exhaust and explain how it would run the same without being tuned for the way it was modified.
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Old 04-16-2008, 04:52 PM
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Re: How to: 305 To 350 swap....everything you need to know

what is the password?
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Old 04-16-2008, 08:44 PM
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Re: How to: 305 To 350 swap....everything you need to know

Thanks for clarifying my stuff DM ha. When I said a 350 calibration I meant the 350 calibration for the 8746 ECM (ie caprice) as DM stated.

Originally Posted by BrOdBaNd View Post
btw that question is for me, we are trying to figure this out... What do you mean by

"They won't work together at all. You just need to use a 350 calibration on a chip in the 8746 ECM you have. That's your best bet, but if it's a modified 350 at all it may not run very well on any stock PROM's tune.

I understand the 8746 ECM is my 305 computer, but what do you mean by using a 350 calibration with my 305 ECM? My motor is all stock, the only thing I added was headers, no cat, and flowmaster, so it shouldnt have a problem if its tuned right?
So if your motor is all stock with just that stuff why would you want a 350 ECM? Am I reading that wrong? Is it an all stock 350 w/ the headers, etc.? If it's a 305 with just that stuff you listed, certainly do not change the ECM, it would run much worse with a different calibration unless you personally tuned the chip.

Read some of the stickies about tuning the ECMs
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Old 04-16-2008, 09:00 PM
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Re: How to: 305 To 350 swap....everything you need to know

NO, this is my setup. 350 tbi, headers, no cat, flowmaster, KNN air filter. I am using the 350 computer and prom. I heard all I need to use is my 305 computer with the caprice "cop car" prom
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Old 04-16-2008, 09:07 PM
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Re: How to: 305 To 350 swap....everything you need to know

Correct (kind of) The caprice cop car prom in your 8746 ECM with the 65lb injectors that came stock on teh caprice would work...kind of ok. I see you have a T56 also, manual cars are much more difficult to tune the transients. Meaning, changes in throttle are now going to cause you very lean or rich conditions.

The best way for you to get your car running well is to stick with stock ECM and chip and learn to tune it yourself (the info to do so is all over this site) Or you can buy the EBL and learn to tune with that and have an easier time. (www.dynamicefi.com) Believe me, that car will never run right until you tune the computer yourself.
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Old 04-17-2008, 11:21 AM
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Re: How to: 305 To 350 swap....everything you need to know

well its about damn time someone made a system like that lol
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Old 04-17-2008, 11:32 AM
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Re: How to: 305 To 350 swap....everything you need to know

will this board work on TPI engines?
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Old 04-22-2008, 07:44 PM
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Re: How to: 305 To 350 swap....everything you need to know

ok now that my head hurts from all the info i still seem to be at a loss. maybe im just reading wrong. i am being offered a 350 block from a guy out of an 88 i-rock z. now what i have now is an 89 305 TPI. now from what i picked up in a previouse post i asked about doing a swap and switching everything from the 305 to the 350 as far as bolt on's like the heads and intake everthing that i not in the block except for the cam i would use the same cam if can at least for now. till i can get the money for it (i have stricked budget). now i was told from a responce to this post that i would be able to use the same ecu and even the same chip since i would be using the same injectors and everything. but this post implies other wise. now id be using the same injectors at first because this is my daily driver. and would change those when i get the money. now from what i read here i would need the following:
350 injectors, ecu, prom, and knock sensor. so could use the same wiring harness and other sensors then too. nothing else would have to be changed? like i said this is my DD so i would want everything there that is need because this will be one of those done in a few days projects. which wouldnt be hard since i work at a dealership and i can use there lifts and equipment.

Last edited by bob8703; 04-22-2008 at 07:48 PM.
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Old 04-24-2008, 09:13 PM
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Re: How to: 305 To 350 swap....everything you need to know

k guys again a possible nother swapee i am looking at a 350 tbi from a blazer or s10 i think can i just take the engine and ecm all the censors will be on the engine as it is complete and running if i grab the ecm what should i look for for numbers on it to just plug and play or grab the chip sry forgot mine is an 88 camro the donor is an 87
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Old 05-06-2008, 11:10 PM
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Re: How to: 305 To 350 swap....everything you need to know

This is a great thread, but it didn't help my problem. I just purchased a 91 RS with the 305 to 350 conv. done already. Alot of times when i take off easy it wants to "studder" and a couple of times it backfired slightly then it takes off normally. When it's idling the rpms drop(almost stall) then idles back up and sometimes it idles normal. So far i've changed the fuel filter and the temp sensor(due to A.Z. selling me the wrong part). The M.A.T. sensor is not in the air cleaner. Will that cause it? I don't know if the conversion was done right like you guys have it listed to do. How do i tell if it has the right ECM or throttle body on it? I want to make sure the conversion was done right and fix the problem. Help will be much appreciated!
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