Hey guys, I've been reading the boards for some time now, not an F-body owner anymore, but still find the threads interesting.
I wanted to applaude you guys for the groundwork you have laid for us less talented EFI guys. !!!!!
I read Fast355's "BUDGET TBI BUILDUP" thread, and am amazed at how much everyone has accomplished over the past few years. Which leads to a project I am planning, and I wanted opinions from those who have "been there and done that".
On the 24th of this month I will be purchasing a 1990 K1500 Extended Cab pickup, with a factory 350 TBI/700R4 setup.
I already have a stock 350 Vortec engine on hand, already installed and running in my older pickup, with an Edelbrock Performer intake and 600 cfm carb. Bought it from a local salvage yard a few years back with 20K miles on it, so the engine is solid.
Also have two 400 SBC's, both bored .030 over, all machine work done, just waiting to be assembled, along with a spare set of Vortec heads machined for larger valve springs and the valve guides machined to handle lift up to .530 lift.
This may be kinda long winded, so please bear with me.
The truck engine has 220K miles on it, but the guy who owns it has pretty much replaced or rebuilt everything BUT the engine, so I am thinking the only weak link will be that engine, and that leads to my project questions.
From Fast355's thread, I got the impression that you need to calculate what HP you expect your engine to produce, then calculate your fuel injectors needs to feed that engine. If I got that right, then I have the option of using either the Vortec 350 (which I really dont wanna have to pull out of a running vehicle to install in this truck) OR one of the small block 400's. I am looking for low end and mid range torque, not too concerned about horsepower, so none of the engines will be built up too extravagantly.
I have access to a PCM from a 1994 1/2 ton pickup with a 350TBI and 4L60E, along with the complete wiring harness(es).
My plan is to swap in one of the above engines, pick up the old 4L60E tranny for use as a core, take the tranny to a tranny shop and have the thing rebuilt but have the output shaft from the existing 700R4 4x4 tranny installed so I can have electronic control over the tranny.
Does this sound like a swap worth doing?
Also, if I go with the PCM, I wanna use a MAF like Fast 355 did, but I dont know what vehicle to look for in the salvage yard to get one from. Any tips on what I need to look for?

Thanks in advance, and for all you've done and posted here to help the rest of us.

PS--I looked in my garage and took inventory, and I still have the TBI to 4 barrel adapter I used several years ago for another vehicle, along with most of the parts I will need. Forgot to add that when I posted this.

 

The only problem I see is that the MAF setup takes place of the VSS input that runs the 4L60E. At this point in time, you can have one or the other, not both.

 

Okay....I can live with the 700R4 then, as it only has 10K miles on it since being rebuilt.
Your opinion, please: Which would you install were the vehicle yours, the 350 or one of the 400's? I know some have had bad luck with them, but I have had nothing but great results with them myself. I know what tricks to do to keep them from overheating and other problems. I kinda like the idea of the extra low end torque from that long stroke.
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I've done some mods to one of the 400's to allow me to utilize a factory hydraulic roller cam, so I did think about using an LT4 cam.......I think a 400 with a ZZ4 cam like your Vortec 350 would be pushing the limits of the TBI injectors and be harder to tune. Your opinion?

 

I honestly don't think that a 400 with a ZZ4 cam will push the TBI injectors too far. It will be slightly harder to tune, but still easier than my 350 Combo.

My 350 isn't even a Vortec. It has ported TPI 305 heads on it. I am thinking of putting ported Vortecs and a Whipple on it soon though. I have the unported vortecs and the whipple as we speak. Lack the GMPP intake and the time to do it in.

Given the choice, I would do a 400 without a doubt.

Dimented24x7 has setup the MAF code to work with a VAFPR. 454 injectors will work well into the 30 PSI range. With a vacuum referenced regulator and a ZZ4 cam in a 400, you can have the dynamic range to run just about anything you want to run. With the 400 you will probably be looking at 18 in/hg of vacuum or so with the ZZ4 cam. Choose your regulator correctly and that can easily be high teens in fuel pressure at idle and mid-high 20s @ WOT. 25 PSI with 90# big-block injectors will feed somewhere around 500 HP, up to about 6,000 rpm. With the vacuum referenced fuel pressure regulator it will idle down around 17 psi or so. Roughly 1 psi for every 2 in/hg of vacuum. So you set it at 26 PSI for WOT, no vacuum and with 18 in/hg of vacuum, it drops 9 psi to 17 psi for a nice clean smooth idle.

Edit- Considering how tame my ZZ4 cam is at idle in my 350, I would not hesitate to the least degree to recomeend it for a 400. With the right compression and head flow, it will pull pretty good.

http://www.youtube.com/watch?v=3Byd1ejQknU

A TBI 400 buildup

https://www.thirdgen.org/forums/tbi/...spot-help.html

 

by your post i take it you have more than 1 harness for a 4L60E. if you do & you want to have electronic shift control, setup a second ECM for the trans only. you just need to splice into the engine harness for the needed inputs into the trans controller. the inputs i know you would need are TPS, VSS, & RPM, there may be one or two others. zero out all the engine stuff in the trans controller & you should be good to go. there was a write up on doing this, i think it was over in DYI PROM some time back, im pretty sure Fast355 made some posts in the thread.

 

Tossing around $$$'s and I am still torn between running a simple hydraulic cam setup, or going ahead with the retrofit setup I did on my 400.
Fast355, since I am going to be getting the PCM out of the 94 pickup, would it be worth it to harvest the complete underhood wiring harness from that truck while I am at it?
I looked at the EBL and dont really like what I see, still thinking I should go with the TBI PCM and MAF....have been digging through reference materials to figure out what repinning I might need to do on the project truck when I get it in my possession.
The more I look at this, the more I salivate.....lol! The idea of the stump pulling torque these 400's produce makes me smile just thinking about it.
One thing I have never liked about the 90 model trucks is the instrument panel....why Chevy never offered a factory tach til late 1992-early 1993 has always baffled me. Oh well, I guess I could fabricate an insert and install an electric speedo and tach setup.............

 

I too cant see any issues with the 400 and TBI. You probably wont even need a VAFPR as itll have a fairly narrow powerband so the WOT and idle fueling will be closer.

I think that the MAF and 4L60-E can be made to work together, but its going to take some more research. I still have to figure out all the e-trans code and see if the TIS input will work for the trans output speed. Ive gotten through alot of the e-trans code, but still have alot left. It also appears to be written in a high level language originally, which makes it all that much harder to figure out as its kinda sloppy and repetitive in places.

 

Oy

 

Vey

 

All in all, how much does the swap to MAF run on average? I see I need a MAF, the PCM, and a "proper" intake bonnet. Are there any other parts needed? And, having never tuned an ecm/pcm, how hard is it to tune?