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Some questions about tbi swaps

88trailblazer

88trailblazer

1/2 ton status
Joined
Apr 11, 2004
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Location
Miami, Florida
I'm currently running a 350 that was rebuilt last year .40 over with an aluminum intake, torquer cam, aluminum roller rockers, arp rod bolts and a new 600 Edlelbrock. I was running a 750 Holley, but downgraded for gas mileage and reliabilty. It also has Headman long tube headers with true dual flowmasters. Also running a built th350 and np208 if it matters.

Now the questions:

1. Would this engine combo work with a tbi setup?
2. Would i need to change out the cam and/or heads?
3. Would i have any issues running the th350 instead of the 700r4?
4. Should i expect to loose or gain any power?

I know the easiest thing would be to swap a whole motor, but i have too much money into this engine already. Any help would be appreciated.
 
The cam is typically what screws with the TBI, since it uses a MAP sensor. This can be tuned around. I suspect if you can get away with a 600CFM carb you will probably be fine with stock injectors/throttle body.

Sounds like grinding the intake will allow the later manifolds to fit the earlier heads, so no problem there.

Transmission shouldn't matter, as long as it wasn't the 4L80E. A 700R4 ECM MIGHT throw a code without the 700, but I don't know for sure.

You'll probably gain low end power, upper end fuel injection advantages start to fall off. Driveability is 100 times better though, so in that regard alone it's worth it.
 
As Dorian said you will need a custom chip tuned for your cam, heads,and intake.. Getting a custom chip will be cheaper than new heads/Cam.
I think with proper tune and bored throttle body your power will be the same or better because FI is more efficient.
You can get a bored to 46 MM TB. That will give 580 CFM. Stock is around 480 CFM. Then use an adjustable fuel pressure regulator to fine tune it.
If you do this swap. You should DL winALDL its a free program and it reads the data on the ECM
You can run a data log and send it to a chip tuner and it really helps them get it right.
Or
If you want to get into it. You can get the equipment/programs to burn your own chips. For just a little more $ as much as a custom chip will cost
 
Where is the best place to download winALDL? My brother also wants it for his '88. Also what grinding needs to be done to the intake? I don't mind swapping intakes if needed, but i'm not sure if the tbi intake would work with my current heads.
 
The 4 center bolt holes on the TBI intake need to be redrilled. To match bolt angle of old style heads. You must also make angle washers so bolt has flat seating on intake. In short you redrill center holes to match the rest of the holes on the intake.
 
There are a few sites out there for winALDL, it's free.

You might want to try tunerpro RT, I like the interface a bit better.
 
88trailblazer said:
Where is the best place to download winALDL? My brother also wants it for his '88. Also what grinding needs to be done to the intake? I don't mind swapping intakes if needed, but i'm not sure if the tbi intake would work with my current heads.
Click to expand...

Just use the manifold you have now. All you have to do is get a TBI adapter plate and bolt it on your manifold. Easy bolt on it if you keep the TH350. If you dont have EGR on your manifold. You will have to have the EGR function deleted when you have a chip programed.

I am assuming you have a square bore manifold.You can get the adapter here:http://marine-performance-parts.com/gmtbitosquarebore4bblintake.aspx
They also have performance TBI stuff like bored TBs, Spacers, Injectors,ECT

Go here for Winaldl and other info and to get a chip burned:http://www.tbichips.com/WINALDL.htm
Also Read the page "Good TBI mods" From the list on the left.
 
I was just about to ask wether you could use the existing intake. I have no egr hookup so i guess i would ned a custom chip. Is anyone running a carb to tbi adapter?
 
I ran the adapter for awhile. With no egr hooked up it will throw a code. "mine does" only way to fix is have custom chip made. I've had no problems with it giving code still runs fine after I get code and goes away next restart.
 
Thanks for the info everyone. I'm gonna start looking out for a complete donor truck. Maybe i'll get lucky and find a 3/4 ton tbi truck.
 
Well, i might have a line on someone that wants to trade their TBI setup for my Carb setup. I believe that all he'll need from me is the intake and carb, but what do i need from him? If i do this, i'll also buy his built 700r4/np208 to go with it.

Here is what i have so far:

TBI
Intake
ECM
Harness
Knock Sensor
O2 Sensor
Map Sensor...


Do i really need to trade the distributor? What about the heads? What am i forgeting? I want this truck to be reliable and able to handle long road trips without killing my wallet. BTW this will be going with a set 4.88's, front OX and rear Detroit.
 
Tbi

I hope you don't think I'm high jacking this. I thought I would ask a question or two.
It seems to me there is alot of modifications to the chip and tbi to get where you need to with the stock GM tbi . I was hoping that someone could express there feeling about the Howell tbi? I was thinking about going in this direction. Any help along this?
Thanks
 
Damn it man, here come the hijacks,... just kidding.:D

I also looked into the Howell system, but it's way out of my budget. If this trade goes through it would only cost me a few misc parts and i would have all of the parts needed to set it up.

The only reason i can think of for me needing a custom chip is because i have a non-tbi cam. I may be wrong though.

I'm not even sure if the tbi intake would bolt up to my heads.
 
You will have to redrill the holes to get it to bolt up. I would just run the spacer, thats what I plan on doing and get a custom chip burned eventually.
If you end up with any extra parts PM me cuz I am looking for TBI stuff :D

Good luck with the swap and keep us posted.
 
Okay, now if i keep the intake manifold and just buy the tbi to carb adaptor, do i still need the distributor? Also, what would happen if i run the stock chip for now with no EGR and the cam that i have?

Would i be looking at poor fuel economy or an undrivable truck?
 
If i remember correctly the distributor gear is smaller on the tbi models so you would need the tbi dist. Not sure on that one though but I am sure someone will answer that.
 
You need the distributor. You need *everything* that is connected to the ECM/TBI system, you'll want fuel lines, tank, fuel pump, etc.

Really depends on the donor truck of course, if it's identical, the lines and what not will work, otherwise, try to make those fit, or make new.

'78 is going to throw some issues at you, since the fuse panel is still glass, correct?

IMO you're better off re-wiring the whole thing with the newer fuse panel, but that's me.
 
Damn, this is getting more and more complicated each time. The fuse box on my truck uses blade fuses, but i could have been changed by the previous owner since the body is off a 2wd truck.
 
If it's blade, it will be easier. You'll just need to run the power wires for the various injection components from the empty "accessory" terminals on it.
 
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