TBI to vortec engine, ECM compatible?

[crossy]

Has anyone here ever bolted a stock TBI set up on top of STOCK vortec engine. I originally had plans of modifying a rebuilt 350 TBI, flat tappet bottom end with some 350 vortec heads I bought, but I recently ran across a a 350 vortec with only 2000 miles on it. I know how to do the adapting for the intake and TBI, but more so havea question of how well the stock TBI computer relates to the vortec roller cam and high flow heads. (custom chipped???). I have no issue with a stock, good running TBI engine and even have a Crane Compucam I was going to install, but man my 100% stock 97 vortec ran it’s butt off. I’m sure I could upgrade the TBI unit eventually from turbocity, but just wondering if stock TBI ECM to stock vortec engine is compatible.
I also forget if the vortec exhaust ports are compatible to my TBI engine headers.? Thanx , crossy

[79blazer]

As far as I know TBI should run any 350 up to a max horsepower at 4000 RPM, where the engine is limited by the air flow of the stock TBI. It shouldn't matter that you are using roller cam, It will probably run lean. Quick fix would be to bump up fuel pressure, and/or injector size, but PROM chip burning would be the real solution. Even stock motors can befit from tuning.

I put a stock TBI, on a edel intake, on a new 350 crate motor rated around 250 hp, stock exhaust. It ran awsome, except for intake backfire off idle. It blew my Cadillac intake in two pieces. I was thinking it was running lean, so I used a tiny 6x2 air cleaner, and it ran fine. That's limp mode until i get the stuff needed to make my own chips.

[rfmaster]

In short TBI ECM (1227747) is more than capable of controlling L31 type engine (350 with vortec heads) provided that spark advance and VE tables are modified.

Vortec heads are highly efficient and have very good flow ratings and with mild exhaust porting can make serious top end power which truck application does not need. Stock vortec heads can not handle more than 0.450 of valve lift. This can be remedied, but for stock applications like yours it is more than adequate - truck needs low end torque!

Vortec heads share the same chamber design as the famed corvette LT1 (looks like heart) which does not require a lot of timing to run. Also volumetric efficiency will be different. Which leads to a custom chip or you can do it yourself if you are willing to learn tuning...

Knock sensor will be different since roller engine tends to produce noise due to a roller cam.

If you are swapping a complete L31 - you may have to invest into GM VORTEC TBI INTAKE MANIFOLD P/N 12496821 which will bolt to your vortec heads in factory like manner. Vortec heads do not have exhaust passage so if you have to have operational EGR the exhaust gasses must be plumbed from the exhaust manifold into the intake manifold. Many exhaust manifolds (or headers) have drilled and tapped holes that can be used to for this. You may have fabricate an exhaust gas tube (soft steel tube can be used). In the 1996 and later pickup truck with L31 350 engine uses exhaust manifold 12557828, EGR pipe 10220275, and fitting 12552329. That combination will fit this manifold. Vacuum controlled EGR valve 17113457 and gasket 12337972 can be used in some applications. You may want to spend a bit more time and look at these finer details before starting your swap.

Alternative to GM intake is to use L31 carburetor specific intake manifold (Holley, Edelbrock with carb to TBI adapter plate on top.

//RF

[Beavis502]

Check this link out http://www.tbichips.com/blackmagic.htm

Brian at TBIChips is a good guy and can help you out with that swap.

[KD95TAHOE]

i did this swap a few years ago. i used the gmpp intake in between the vortec heads and the tbi, and set up an egr line as described by rfmaster. i ended up plumbing it from the screw in port on the drivers side to the no. 1 cyl header tube. all in all the install wasnt bad, the problem i had was the stock tune of my ecm. it wasnt set up for this motor. we tried to adjust the timing but just couldnt get it right. it ended up at around 2-3 degs. adv. for a stable idle. the motor runs ok but i'm not getting its full potential and it eats alot of gas. bottom line, dont do this swap unless you or someone you know has the equipment and the knowhow to tune a gm obd1 ecm/prom which from the research ive done is not something you can learn in one day. as far as buying chips goes you will need one which matches your stock bin file and mask id and is specifically tuned to use a tbi/88-95 distributor to feed a vortec engine with its different breathing capacities and internal configuration, notably its cam and heads. also i tried 2 chips from brian above and they both werent even close in performance to my stock prom. actually they seemed wrong for the set up.

[COLCantwell]

Originally Posted by KD95TAHOE

i did this swap a few years ago. i used the gmpp intake in between the vortec heads and the tbi, and set up an egr line as described by rfmaster. i ended up plumbing it from the screw in port on the drivers side to the no. 1 cyl header tube. all in all the install wasnt bad, the problem i had was the stock tune of my ecm. it wasnt set up for this motor. we tried to adjust the timing but just couldnt get it right. it ended up at around 2-3 degs. adv. for a stable idle. the motor runs ok but i'm not getting its full potential and it eats alot of gas. bottom line, dont do this swap unless you or someone you know has the equipment and the knowhow to tune a gm obd1 ecm/prom which from the research ive done is not something you can learn in one day. as far as buying chips goes you will need one which matches your stock bin file and mask id and is specifically tuned to use a tbi/88-95 distributor to feed a vortec engine with its different breathing capacities and internal configuration, notably its cam and heads. also i tried 2 chips from brian above and they both werent even close in performance to my stock prom. actually they seemed wrong for the set up.

- Did you ever find a .bin file or did TBICHIPS finally get it right? I am going to do this swap on my 87 K5 soon. I was thinking about getting a Dynamic EFI system and just dyno tuning it at a local shop, but chip would be easier. Did you install a different fuel pump and fuel pressure sping?

[KD95TAHOE]

yes i did get the bin file. i dont think it will help though. from my experience with this setup i dont think it can be tuned properly using the tbi/ecm scenario. i cant seem to get the setup to not give me fluctuating MAP/vacuum readings. the best options are either carb or LS in my opinion if your using an electronically controlled tranny (4l60e or 4l80e). some aftermarket setups look promising such as the holley avenger with its self tuning capabilities. bear in mind its all really a gamble that costs alot of money to take a chance on. im still driving with the vortec/tbi setup and its still running the same, but it does pass state inspections. in your situation with an 87 blazer i would most likely go with a new intake and maybe a 650 cfm carb. that way you wont have any tranny problems assuming you have either a th400 or non electronic 700r4(you may need to try a different vacuum modulator possibly), also an HEI coil in cap distributor. thats probably you're least expensive and best bet for compatibility. you can also change cams, heads etc. without having to deal with ecm issues. let me say if you decide to go the FI/ecm route you will need to do a ton of research to understand how they are programmed and also buy some equipment to burn chips including a laptop, ALDL cable, software, and the actual chip burning hardware. any questions you have i'll be happy to reply to, as ive given this topic alot of thought and research. let me know what you eventually decide. good luck

[COLCantwell]

Originally Posted by KD95TAHOE

yes i did get the bin file. i dont think it will help though. from my experience with this setup i dont think it can be tuned properly using the tbi/ecm scenario. i cant seem to get the setup to not give me fluctuating MAP/vacuum readings. the best options are either carb or LS in my opinion if your using an electronically controlled tranny (4l60e or 4l80e). some aftermarket setups look promising such as the holley avenger with its self tuning capabilities. bear in mind its all really a gamble that costs alot of money to take a chance on. im still driving with the vortec/tbi setup and its still running the same, but it does pass state inspections. in your situation with an 87 blazer i would most likely go with a new intake and maybe a 650 cfm carb. that way you wont have any tranny problems assuming you have either a th400 or non electronic 700r4(you may need to try a different vacuum modulator possibly), also an HEI coil in cap distributor. thats probably you're least expensive and best bet for compatibility. you can also change cams, heads etc. without having to deal with ecm issues. let me say if you decide to go the FI/ecm route you will need to do a ton of research to understand how they are programmed and also buy some equipment to burn chips including a laptop, ALDL cable, software, and the actual chip burning hardware. any questions you have i'll be happy to reply to, as ive given this topic alot of thought and research. let me know what you eventually decide. good luck

I think I'm going to just drop in a Ram Jet 350. It seems like the best option at this point. Many people have told me that hte L31 would be fine with a fuel pump upgrade and stock TBI tuning; I knew that probably wasn't the case. Thanks for your response.