Re: Tbi swap build thread
 

I thought I was the only one that hated the down side of headers? I have had nothing with problems with them leaking at the head and the collector. How much horse does a decent set give you? Is it worth the problems? I know you can buy high dollar aluminum gaskets and retainers studs that don't back out.....but I'm a tight wad.

Re: Tbi swap build thread
 

It all depends upon how restrictive the stock manifolds are to the engine and if the tube size of the headers actually fits the way the engine is built.

If the tubes are too big or too small they won't work as well.

I have seen numbers as small as 5 hp for some smog motors and 50+ on high hp 60's muscle cars where they designed it with the intention of the owner putting on headers so the factory strapped the most restrictive passenger car manifolds on it they could find.

Our trucks probably only see 5 to 10 hp for headers without other engine mods to take advantage of them like a better cam, intake, carb, exhaust system, air cleaner, etc... Not really worth it in a fairly stock application for the headaches they typically cause.

Re: Tbi swap build thread
 

Well, headers alone will not add significant performance gains. As 68 TT mentioned about 5-10 HP on a stock engine. From my experience you have to look at a complete engine in combination with drivetrain. Engine is nothing more than air pump which has finite volumetric efficiency. This discussion can go on forever, but a total package should be considered vs. individual pieces. Some parts work better than others when combined in engine package.

//RF

Re: Tbi swap build thread
 

Well I got my motor fired up last night, and let it run for 30 seconds (I had to many wires laying around to much heat).

Now I'm still trying to finish up some wiring on 700r
My comp and wiring came from 89 truck and my motor and trans came from a 89 caprice. My harness does not have a c7 wire -- Can I re-pin c7 and it will work as the high gear wire, or will the comp need to flashed? Also what does TCC stand for torque converter control?
Thanks guys for all the help!!!!

Re: Tbi swap build thread
 

Wow I thought I was the only one to have bad luck with header leaks. My collectors would leak badly (too much frame flex) after every off road trip. I cut the collecter off and welded them straight to the exhuast pipe. No more leaks there but still had plenty at the heads. My block huggers are top of the line ceramic coated inside and out. I have used the same headers in a toyota v-8 swap with no leaks after two years. I just hope they will not cause the o2 sensor to read wrong.

250cows was your donor truck auto w/ overdrive? If not you may have to do more than pin c7 in, but I am no expert. I bet rf can tell you, he seems to be quite knowledgable about these systems. Torque converter control sounds right for TCC. It tells the converter to lock and unlock.

Have a good Friday the 13th everyone! :lol:

Re: Tbi swap build thread
 

I'm assuming my comp donor was manual, because I dont have a wire in c7.

Re: Tbi swap build thread
 

250cows

Can you post your ECM part number and broadcast code (BCC)??? Trucks equipped with THM400 did not use 4th gear indicator. You donor truck may have had either manual or THM 400 transmission. This explain absence of C7 wire - which addressed by inserting wire and pin into C7.

//RF

Re: Tbi swap build thread
 

Here are the #
86asdx k391991245
16139481
If it is a for a 400 or manual, can I still have the tcc lock up option?

Re: Tbi swap build thread
 

Can anyone answer the question above?

Re: Tbi swap build thread
 

I have no idea....

Re: Tbi swap build thread
 

Not to severly deviate the topic, but since all of this good info is here in one thread I thought I'd add this for those of us following along that are in 72 and older trucks.

The below article (see link) has some info on how what the magazine guys did a 5.3 swap in a 68-72 C-10. Specifically what sparked my interest is what they did for the return line. I plan to take it a step further and make a line that attaches to the pipe thread fitting they welded in and dumps at the bottom of the tank and pointed away from the pickup.

I hope this helps someone.
Thanks to the OP and knowledgeable posters for adding thier info. I have yet to start collecting parts, but the TBI Swap is in my top 3 of my short list of things to do this thread will be invaluable when the time comes to start installing parts.


http://www.classictrucks.com/tech/09...all/index.html

Re: Tbi swap build thread
 

Is that the number off the chip itself or the ECM housing label? They are two different numbers.

Re: Tbi swap build thread
 

On the housing label

Re: Tbi swap build thread
 

Sorry - dropped the ball on this one.
From the limited information that I could find ASDX was used on 350 trucks (1227747 ECM) with manual transmission. For 350/700R4 (TBI) look BBC ASDZ calibration which was used in 1/2 - 3/4 ton C/K and G1 G2 (Vans) V1 R1 (old body style 1/2 ton truck). You can swap a chip or burn your own with a copy of ASDZ.

If you chose to burn your own Bin files visit

http://www.moates.net/

- for all the necessary tools, adapters and bin file images.

You'll need to add TCC enable output and 4th gear input to your harness - see schematic posted earlier in this thread.

//RF

Re: Tbi swap build thread
 

Welcome to the board and the TBI swap thread.

Firstly, I would advise you not to weld-in return line bung at the bottom of tank! The reason for this is that a stock TBI system is a relatively low fuel pressure system (stock TBI is content with 13 PSI give or take). TBI uses a spring loaded fuel pressure regulator (FPR) on top of the TB. For FPR to function correctly (i.e. steady 13 PSI) there should be minimum back pressure in the return line. By installing return at the bottom of the gas tank the return fuel must overcome the weight of fuel present in the tank. Soooo with that in mind install return line at the top of the gas tank as shown in the classic trucks article. In addition, I would also add a vapor line from the tank a charcoal canister. IFRC, early trucks did not have charcoal purge canisters, but it makes good sense and it does not cost any performance.

//RF

Re: Tbi swap build thread
 

Would this be the best way for me to get torque converter lockup?
http://700r4.com/tech/tcc/relay_install/index.shtml

Re: Tbi swap build thread
 

Without TBI yes you would need that kit to have functional converter lock up, with a TBI conversion installing and wiring in the correct dual purpose brake switch and making the connections to the ECM are all you would need. The ECM will take care of the rest.

Re: Tbi swap build thread
 

But will my manual shift ecm work -- can I just install a c7 wire and hook it to my tan/blk wire from trans.?

Re: Tbi swap build thread
 

The ECM & added pin wiring no problem. You will need a chip from an auto trans version with the 700R4 to work though. There are T-400 versions out there too that will be different programming so it needs to be a 700R4/4L60 version to work right and have TCC functional. Look for a half ton truck or Suburban and any Blazer as a donor.

Re: Tbi swap build thread
 

Thanks for the help.

Re: Tbi swap build thread
 

I wasn't planning on returning it in the tank at the bottom. I was going to attach a tube to the part that gets welded into the top of the tank. This way the return line is submerged, but it will still enter the tank at the top.

Re: Tbi swap build thread
 

C3 ECM (1227747 - you have a later service replacement p/n ECM) was designed to handle all drive train combination's. There are no ECM hardware differences between 'manual' and 'auto' ECMs. What sets them apart is the 32k EPROM chip which provides configuration tables and instructions to a microprocessor in the ECM how to handle different engine - trany combination. Different configurations stored in EPROM's are identified with GM lingo - aka broadcast code - BCC.

Before tying TCC line from transmission into ECM it is a good idea to verify the actual TCC lockup and release operation by manually enabling and disabling (i.e. pulling this line to ground). In some applications 700R4 were configured with positive logic vs. common negative logic - ECM pulls C7 low to enable TCC. For the life of me I do not know why GM did this, but it was done. As 68 TT mentioned you'll have to get a dual poll brake switch - GM 25524845. One set of contacts is normally closed (NC) this will be used with TCC wiring to provide +12 volts to the trany. When you step on the brake paddle NC switch contacts open and de-energize TCC circuit thus kicking out TC lockup. The normally open (NO) set of contacts will be used with brake light circuit in a normal fashion.

If you need a schematic - ask.



//RF

Re: Tbi swap build thread
 

I'm a slow learner on elec. stuff.
A schematic would be great.
My wires coming from trans are purple, blue, tan/blk.
When you say pull c7 to ground to check, is this normally a ground or a voltage wire?
Also you're saying my ecm and chip will be fine.

Re: Tbi swap build thread
 

OK, here it is - the in CAB TBI conversion wiring. This schematic covers the following circuits talked about elsewhere in the thread: TCC with brake pedal disengagement switch (GM 25524845), VSS circuit using a standalone 2000 ppm inline VSS pulse generator from JTR (or equivalent), minimum ALDL connector wiring, SES light, P/N switch wiring using a relay and an isolation diode, and power for injectors. ECM power circuit is not shown.


http://i226.photobucket.com/albums/d...g20091201a.jpg

Schematic was not closely reviewed - please check against references for typos. As always please perform a sanity check.

//RF

Re: Tbi swap build thread
 

I haven't messed with the stock early TBI mechanical speedo dashes that have the optical sensor on them before. All my other EFI conversions were port injected so they used different setups entirely.

How would that three wire module coming off the back of the speedo interface with the ECM? I know one wire is a ground and one is ignition on power so I'm assuming the one remaining wire goes into the ECM at A10 like the JTR module. How does this interface with the DRAC and how is it wired in?

Re: Tbi swap build thread
 

I am no expert in DRAC interfacing - all my swaps were done using standalone inline VSS modules (non electronic dashes). DRAC - aka digital ratio adapter controller was used as a 'glue' module to get various early electronic controls working in some resemblance of a harmony. The following are good read on VSS /DRAC /ECM interfacing:

http://www.fullsizechevy.com/forums/...1-post279.html
http://www.jagsthatrun.com/V8-chapte...ed-Sensors.pdf
http://www.tbichips.com/drac/
http://www.syty.org/gallery2/main.ph...&g2_itemId=203
http://www.thirdgen.org/techboard/di...ico-trans.html


DRAC I/O
C15 2000PPM
C14 2000PPM
C13 40PPR (1:1)
C12 Signal in??? not sure
C11 2000ppm
C10 128000 PPM
C9 12V
C8 GRND
C7 VSS input
C1
C2
C3
C4 VSS cruise control

//RF

Re: Tbi swap build thread
 

Thanks for the links and info. I will do a bit of reading and see if I can get a handle on it.

I haven't found a wiring diagram that shows the DRAC, speedo sensor module and ECM connections under the dash. Anybody have one?

Re: Tbi swap build thread
 

Found another good thread on DRAC VSS.

http://www.coloradok5.com/forums/sho...d.php?t=124012

This one covers a bunch but does address the two-pulse optical buffer on the back of the speedo in some cases that I have and want to use.

http://chevythunder.com/fuel%20injec....%20pg%20B.htm

From what I have read I believe those with the 2-pulse optical buffer coming off the back of the speedo do not need a DRAC since the speedometer gears in the trans do the job of the DRAC in converting driveshaft speed into the proper 1000 rotation per mile output to the speedo. The optical buffer speedo has two trigger points the optical sensor sees so it outputs the 2000 ppm signal the ECM wants.

This type of optical buffer was also used on the early TPI cars and can be used with the later speed density TPI ECM if you do a little work in the program to change which input it is looking for and to convert the 2000 ppm DC signal from the optical buffer to the 2000 ppm AC signal the 730 ECM wants to see. Nice to know as I will eventually get my old TPI system installed into my Malibu and it has a newer dash with the optical buffer coming off the speedo.

Re: Tbi swap build thread
 

I just ran the numbers for calibrating a DRAC to my combination out of curiosity and I would have to install 33" tall tires just to make my setup come close to the highest pin setting calibration a DRAC can be configured for.

Re: Tbi swap build thread
 

Hello again,

I finially had the time to re-install my old intake and put the TBI onto it using an adapter plate.

I got the truck started but it is ideling very high about 1900rpm and has a VERY loud whistling sound to it. I let it run for 5 min or so and it did not stop whistling. It is almost unbearable. If you remember from my other posts I eleminated the EGR. Does this have something to do with it?

I thought the whistling was coming from the IAC so I replaced it. no change.

The truck will also act like the idle is going to come down but then back fires through the TBI.

The truck starts fine but won't idle below 1800rpm unless I turn the dizzy to adjust the timing but then it backfires and dies. I can not get the idle low enough to use a timing light but I rechecked the rotor position in relation to TDC of #1 and I am close to "0" degrees timing.

I did not have this idle or LOUD whistling issue with the OEM manifold and EGR valve, but the truck would not idle correctly and would backfire out the exauet with it on. That is why I put my old intake "Edelbrock 2101" back on.

I did install a fuel pressure gauge and ran 3/8 allumminium? tubbing from the tank. The fuel pressure is only at ~ 6psi by the TBI. could this be the problem? The TBI is spraying a nice steady mist when the truck is running.

I found a post by RF on IAC adjustment....do I need to do this?

The truck did not have these issues with old OEM intake and EGR, I know I installed the new intake correctly and do not beleive that I have a massive vacume leak causing the LOUD whistling. I am at a dead end and any help would be greatly appreciated...Thank again, Pancake:metal:

Re: Tbi swap build thread
 

You my friend have a vacuum leak some where. Be sure to check everything you touched on the intake swap. Go back over all your vac. hoses and check all you bolts.

Re: Tbi swap build thread
 

Hmmm. My got feel tells me that you have several problems conspiring against you.

Idle at 1900 is not a good thing - you have a vacuum leak. Check TB to intake manifold gasket - there are different gaskets out there. Some seal better that others. Make sure that throttle plates are fully closed. I have seen post where throttle cable is too short and keeps throttle plates partially open!

YOU MUST RESET IAC - no if buts or whatever. This must be done as ECM has no idea where IAC is positioned, but if it was set to a known position it can make adjustments to adjust idle.

6 PSI is too low - it maybe enough for idle, but ECM VE calibration tables are setup for two injectors (62 lb/h) operating at 13 PSI. Injector delivery rate changes non-linearly with fuel pressure. Popping though TB is an indication that engine is running lean (or timing is way to advanced)! You need 3/8" supply line - soft steel or aluminum with a fuel pump rated at least 20 PSI and capable of moving 40GPH (aka GSL393, Carter P5001, others). Do you have carb rated pump by any chance??? 6 PSI is a carburetor rated working fuel pressure. Cheap fuel pressure gauges are also known to give false readings. (I had good luck with Summit SUM-800130 as it tracks within 2 PSI window of Auto Meter 2239). What is is the supply voltage at fuel pump - it better be around 12volts!

EGR - re verify that you do not have vacuum leak under block off plate!!

Take couple hi res photos (if you can) of your engine bay around TB and lets see if we can spot the obvious.

//RF

Re: Tbi swap build thread
 

The guys on the DIY EFI GM ECM list have had several different aftermarket TBI adapters leak at bolt points. Some went so far as to fill the bolt head areas with epoxy so the TB wouldn't leak.

Did you make your adapter or is it an aftermarket one?

Re: Tbi swap build thread
 

My 90 Z71 with the 5.7 TBI made a pretty loud whistle / sucking sound at idle when the air cleaner was off and only slightly muffled when the lid was flipped. With the air cleaner assembled like from the factory it all but disappeared.

If you have more than about 4 degrees advance and less than about 30 it should only pop or backfire if the plug wires are grounding out or connected wrong. Check the routing and condition of your plug wires after seeing what amount of initial advance you have. Your engine might like more advance too. My Camaro will start to pop & miss with less than 8 degrees advance due to the cam profile and compression.

Re: Tbi swap build thread
 

Hello again,

Well you guys were right....it was/is a vacuum leak!!

When I installed the trans-dapt 2206 adapter plate, two of the bolts that hold the TBI in place are positioned directly over the edge of the spreadbore on the intake!! when I tightened these bolts down they crushed the intake where it sealed to the adapter plate!! I did not think I was applying that much torque, the bolts went in really easy..but did a lot of damage to the soft intake.:waah:

Well, I ordered another intake after finding the problem. I think this will "fix" my leaks.

As for the fuel pump...I do have a summit feul pressure gauge, 3/8 aluminum line to and from the tank, and a TBI fuel pump mounted inside the tank. I will check the voltage going to the pump and will also try moving the fuel pressure gauge closer to the tank to see if I have a kink or restriction in the line somewhere.

Is there a way to remove the intake so that no coolant gets into the oil? I am tired on buying 5 quarts of oil every time I pull the intake off. I do drain the raditor before removing but there is always some coolant left in the intake.

Thanks again for all your help and Happy Holidays.:metal:

Pancake

Re: Tbi swap build thread
 

Pulling the bottom bolt on the passenger side of the water pump should let the coolant in the top end drain out so there won't be any high enough to dump out of the heads into the intake valley. You can then pull the thermostat and use the shop vac to suck out all the coolant left in the crossover passage of the intake.

Re: Tbi swap build thread
 

Great tip 68 TT

Any update on fuel pressure??? Another all too common reason for low fuel pressure is a bursted fuel hose between fuel pump output port and gas tank feed through (inside gas tank). Remember, that small piece of hose must be have fuel submersion rating - SAE 30R10! Anything less than that will result in a slow leak over time!

Happy holidays!


//RF

Re: Tbi swap build thread
 

A little cold here (Colorado) so I have not worked on the truck too much latley....so no update on the fuel pressure. I did replace all the fuel line with 3/8 aluminum with 3/8 high pressure rubber fuel line attaching it to the tank and the TBI. I also replaced the fittings on the tbi so I could put -6an to 3/8 barbed of the TBI. I might be a weak fuel pump? I will have to see when it gets warmer. I did receive the intake and gasket kit so I will also be replacing them when it warms up a little:metal:

Happy Holidays....Pancake

Re: Tbi swap build thread
 

Just started wiring up my CJ/buggy.Does anyone have a diagram of what sensor is where on a 1988 7.4L bigblock?I think I know what is what but not sure.Thanks.

Re: Tbi swap build thread
 

Welcome to the thread and happy new year.

Regarding BBC EFI wiring - it is nearly identical to SBC wiring commonly found on light and heavy duty trucks (use 1227747 as a guide). The two things to look for are:

1) IAC is different and unique to BBC application. It has been reported by some that two wires in one pair have to be swapped - I have not had a chance to verify this. I'll get to this once I get going on my 383 TBI project.

2) Some HD BBC applications did not use KS. Consequently timing tables are very conservative. This can be easily fixed by reprogramming EPROM to suit your engine needs. HD BBC applications used 1228747 ECM with various BCC EPROM's although there are others (7747, etc) can be found out there.

3) BBC TB is prized by some for its large bore size (2" vs 1-11/16) and higher flow injectors. Note that late model injectors (94+) operated at 30 PSI vs. 13 PSI for 87-93.

//RF