This is my expierence with converting my 91 Camaro 305 tbi to a speed density tpi. Many others have made this conversion and have posted here on TGO. I would like to extend my appreciation to them for helping me with this project. This is for reference and to assist others with the decision or completion of such a conversion. This conversion was not all about performance, appearence, mpg, or hp. It was what I wanted to have and enjoy doing.
I am still in process and will update as I gain progress.


This is the donor car for this project. I only hope it was parted out for other restoration projects.




This is where the sd tpi will find its new home.


1991 Chevrolet Camaro RS
305 tbi
t-5 5 speed
a/c delete
hedman headers
emissions delete

After I get done, I will be listing the tbi, harness, and all other unneeded compnents for sale here in TGO.

 

I received from the donor car: $300.00
tpi intake assembly
complete wire harness
ecm and chip
distributor
misc. connections and hoses

I will not be doing a tbi harness pin out. I suggest a search for that thread if that is how you choose to go.

I reused the following:
distributor
coil
vacuum lines


I did go and purchase:
k&n air filter $35
complete tpi gasket set (jegs) $30
tpi throttle cable (ebay) $20
fuel filter $5
fuel pump $75
coolant $10
heater hose (3ft) $5
oil and filter $20


Plan to take your time and do this right. If this is a daily driver for you, prepare for a weekend to get this done. I am doing this on my weekends off and Im in no rush.

Inspect your parts. Check your harness, look for damage, and TAKE PICTURES before any disassembly or cleaning!!!! This is the best time to clean up, in and out your tpi. Polish it, paint it, or leave it natural.

Mauro here did a tech article on this conversion. I recommend you read it, print it out, save it. I would also recommend you have a computer handy and the following:


Lay out your plan and stick to it.

 

1. disconnect and remove your battery.
2. Pull your spark plug wires and cap.
3. Disconnect the connectors at the:
tbi
distributor
starter
power steering
brake booster
all sensors
a/c
alternator

4. drop your lower radiator hose and let the motor drain.
5. disconnect your heater hoses.
6. release fuel pressure and remove the fuel lines at the hoses behind your alternator.
7. mark and remove distributor.
I removed my hoses and fuel lines but left the tbi on. push the harness out of the way and unbolt the tbi intake. I didnt need to take off valve covers but i did move the alternator around to get the fuel lines out .



Carefully remove the intake and set aside. There may still be water in it and gunk on top. Afterwards, you can prepare to remove the harness.

 

To remove the harness:
1. disconnect the ground behind each vavle cover.
2. unbolt (1/4 nut driver) the black connector to the right of the brake booster. the nut is in the middle of the two blocks.

3. wiggle the harness from the driver side to the passenger side carefully.
4. remove the ecm and disconnect wire harness under passenger side dash board.
5. remove clip and push harness through hole behind the passenger kick panel.


6. turn wheels to the driver side and pull open your passenger inner wheel well liner. you can see the harness and pull it through. also easy to push the new harness in.



7. pull the harness up through the hole next to the a/c heater blower, inside fender area, and set it aside.

 

Using your references for installation such as haynes, childers, or what ever, lets start installation.
1. gaskets set, drop down your intake manifold, and set it according to specifacations.
INTAKE MANIFOLD TIGHTENING SEQUENCE TPI:

2. cover the distributor hole and any other valve cover hole with tape to prevent debris.
3. lay out your harness and get familiar with what goes where. An idea here would be to tape and identify each connector.
4. set in in the engine bay and push the harness through the hole in the fenderwell. Go through the opening in the wheel well liner and push the connector side through the hole into the passenger kick panel.
5. lay out the harness across the engine bay and bolt it in next to the brake booster.
6. connect the grounds and bolt them back in behind the valve covers. (there were two on each side, plus the ground strap on the passenger side.)
7. go ahead and install fuel rail, runners and plenum, making sure you connect all vacuum lines and attachments.
8. drop in distributor as marked prior to removal.
9. I removed and reused my thermostat from my tbi. throw that in there or replace with a new one. As for the upper radiator hose I measured, cut and reused my tbi hose.





more to come.

 

Ah finally someone show this with pictures! Well done! So you arent swapping to the TPI heads?

 

no im not switching heads. however...years ago the original motor was replaced by another 305. the new motor that was put in was a replacement for the 305 tpi from advance auto parts.

there will be many more pictures to add, as i get them downloaded and finish this conversion. diagrams help, but pictures do more.

im figuring out the vacuum lines and hoses. im going forward with the throttle body bypass and egr lines. there is no emissions concerns so the heater valve diverter is gone and egr may be next. i dont think im going to hook up a canister either. im guessing that i can remove the a/c connectors and the two emissions connectors in the same area of the harness as the a/c connectors are.

the connector for the power steering was also not part of the 92 harness i installed. anyone have an idea about that?

 

Nice. You never see these swaps with pictures. Subbed

 

I would like to know is when you are totally done how much difference do you notice from the tbi to tpi performance wise?

 

Just a comment on your cannister. If you remove it and block off the vent line, you will build a lot of pressure in the tank. I had gas puking out the filler pipe, and a lot of pressure blowing out through the filler. I recommend that you keep the cannister- it won't affect performance at all- it just collects gas fumes and allows them to be burned.

 

I will be done in the next week or two at the latest. I definetly will post about the diffrence between tbi and tpi.

I am keeping the egr and vapor canister. After some thought I see no reason to exclude them. After its running I would feel better knowing everthing was properly connected if I was to have to chase vacuum leaks, or any other problems.

At this point I need to complete the following:
1. heater core coolant lines (tb line delete)

2. install throttle cable
3. battery connections
4. dual fan set up. (currently i have a single fan but the harness came with a dual fan connection. im looking to purchase a dual fan set up.
5. fuel pump change out. (drop the tank and switch.)
6. knock sensor
7. canister and passenger side ccv connections
8. Plug wires:





After you have everything in and ready to start, go back and double check all connections and bolts. Turn on the ignition but do not start the car. Look under the car and around the engine bay. Check for fuel leaks and inspect the wires. IF all looks good, start it up.
I had to crank the car few times to get it to start. I also had to move the distributor a little. After a few attempts it started. Now get ready to set the timing.
Disconnect the connector near your a/c or passneger firewall, get your timing light and set the timing. Once you have it, tighten the distributor bolt, reconnect the wire and pull the negative cable from the battery to reset the computer and codes.
Restart the car and let it run so it can adjust itself. Check the coolant level, your gauges and watch fpr the service engine light. If the light comes on, turn it off and check for trouble codes with yur trusty paper clip.
Whn you get a code, repair,adjust or replace to clear the code.
by next weekend i should be done.

 

SUBSCRIBED - Looking to do this to my 88, and my wagon

 

can't wait to see it done! found a guy selling a complete tpi setup on craigslist for $250. manifold, sensors, and the pcm. Ill probably wait til spring though because I'm looking to swap the cam, lifters, and springs and its my DD

 

Your ECM should not see any issues with the TV cable disconnected because the trans is not electronic. From what I've been taught, it controls line pressure and the trans does not use computer controlled solenoids.

 

ok great. thanks for the info.

Ill have more updates and pics this coming week. They will be added or edited in this post.

 

good luck with the build doing the same thing with mine

got my tpi unit from a 87 camaro


91 tpi heads

all throwing it in my 92 firebird!

i also have a build thread mine is just taking alot longer due to the lack of parts and somewhat knowledge
by any chance can u reuse ure intake bolts from ure tbi to tpi (probbly stupid question)

there was one major problem that happened in my build leaf fell in my block . . . .

check mine out is should be on top of the board
but everyone says it is hard to follow ehhhhh w/e

good luck!

wondering the motor stock???
cause i saw u have a 4.10 gear
so i thoughT mAYBE more than just headerS???

 

there are no dumb questions. the next person to do this conversion may need these answers. i am going to follow your thread as well,

i did reused my intake bolts. i cleaned up the threads and heads on them to remove corrosion and paint.

its a regular 305 engine with headers, smog and a/c delete, msd ignition, and the tpi.
i came across the rear end when searching for a disc brake rear. it was rebuilt prior to me getting it under a car i bought. id would rather have more of a stock gear back there. i may consider a trade out if someone was local.

 

thanks this means i can put her on tommorrow i took my map sensor of and need help where to put it some wher on the passenger side to connect to the fpr

im going to get a 3.42

she gonna have some mods! listed in my thread

ported n polished top end (intake/heads)

lt1 cam
hooker headers to full exhaust

and did u torque ure intake bolts guys at autozone told me just to torque the head bolts and not worry about nothing else. . . .
and i will follow ures as well!!

just need to get gasket adhesive!

im really worried about that leaf in my block now though. . . .,

cause i left the distributor hole open the whole build like a dumb ***

 

i looked up the torque and sequence in the manual. i dont recall exactly what they were, but they were odd compared to the tbi manifold. ill look it up and post a pic of it tomorrow.
map sensor i have bolted to the passenger side of the plenum. an alternative is to mount it like the tbi, against the rear firewall. look up in the pics and youll see both.

 

i have the book i hope its the same from a 87 to 92 dont see why not thanks man i was thinking to get some bosch threes maybe.. . .

also it has in the manaul for the intake two torque specs


one in inch pounds

the othe in foot pounds

i believe like 89 inch pound

then it says

35 foot pounds

do u know if u do inches then the pounds to torque or is it giving u a option confused with it

and wat about headers?? did u trq these ?

 

is there really any difference between the tbi and tpi heads? just picked up my manifold, com, and wiring today

 

Tony, PM sent. THANKS Jim

 

I am done!!!!
Last Tuesday I dropped the gas tank and switch out the pump. That was not the first time I had done that and from start to finish, it was about 4 hours. While I was at it i cleaned the electrical connections, and replaced the fuel filter.
Today I finished up the connections to the sensors and after several hours could not figure out why I had no power. Thanks again to TGO member "pocket" for assitance with that. It turned out that I had not had all connections to the starter. This is why I said "check everthing twice".
It started up and ran a little rough. Im going to set the timing and all in the next day or two. The only codes sent after a little tuning was 42 and 43. I have not switched out the knock sensor, and of course I have timing to get perfected. Otherwise so far so good.
Ill have performance and opinion results sometime this week. so far im excited about the conversion and look forward to tpi driving and customizing.

All TBI pieces will be listed for sale.

I will be editing and adding info and pics to the previous posts.

 

congratz!!!man im stalling today and work on it tomorrow before work
weather permitting
what kind of feul pump did you use?

and had to buy new intake bolts

 

What was the part number for the K&N you bought? Nice write up

 

[quote=dabird07;5105973]congratz!!!man im stalling today and work on it tomorrow before work
weather permitting
what kind of feul pump did you use?

i got a walboro pump. you get it from a vendors on the forum.

"What was the part number for the K&N you bought?"

it was from summitracing.com im pretty sure it was r-5000.

 

i also got me a walbro gotta wait for some summit parts and i can install the rest of the intake

 

A 90-92 TBI to TPI conversion is 99% plug and play using a 90-92 TPI harness

Move one wire at the C207 and bypass the buffer box. Use a paper clip to pop the speedo wire out of C207 pin D (GRY) and move it to pin K. Then find the buffer box and unplug it. Bend a short length of wire into a U with a spade terminal on each end. Insert into pins C and F

Thats it

 

"A 90-92 TBI to TPI conversion is 99% plug and play using a 90-92 TPI harness

Move one wire at the C207 and bypass the buffer box. Use a paper clip to pop the speedo wire out of C207 pin D (GRY) and move it to pin K. Then find the buffer box and unplug it. Bend a short length of wire into a U with a spade terminal on each end. Insert into pins C and F"

thanks for the information. what exactly is this for and what will it do or not do?

 

After i did a little tuning im throwing a code 42. at the same time it seems like theres a high idle. i checked all vacum lines. also have the filter inline to the brake booster and it seems the breaks are weak? any ideas?
otherwise there does feel like a diffrence in power. more to come...

 

Check for vacuum leaks around the runners. I've had mystery leaks there before.

 

i got the timing set but still seems like a high idle. i checked for leaks but havent found any. when i push the throttle back towards the screw stop it seems to idle down. so im wondering if its the iac or adjustment to the tps.

 

Was your donar car a 5 speed also? I am trying to do a similar swap on my 89 RS but i am having trouble finding a 89 tpi 305 tpi 5 speed harness that is complete. I am wondering if the automatic and 5 speed harnesses are the same.

 

The only real difference is the reverse light plug for the side of the trans.

 

WOW i have wasted lots time and have passed up some decent 89 camaro tpi harnesses lol how do i adapt my backup switch to the auto harness? I have a computer and prom chip from a 89 iroc 305 tpi 5 speed but the harness has been the biggest challenge so far.

 

You'll have to tap into the autos neutral safety wires. Two are for the reverse lights and the other two are for the nss. Extend the wires into the trans tunnel and to the clutch safety switch. I don't remember the colors but theyre easy enough. Twist them together and the lights should go on.

 

I also heard that the tbi harness is part of the headlight harness, is this true? I want to be able to do this swap with the most ammount of knoledge possible

 

The headlight harness is separate from the engine harness. They go through the firewall on the drivers side near the brake booster. The smaller one is for the lights.

 

Thankyou for your help!!!

 

When I put the harness in, both plugs on the transmission plugged in. I havent had any issues with the lights or transmission, and I didnt have to convert any conectors or splice wires for either.

The headlight harness is not part of the tpi harness. In the camaro, there are connectors to the power steering and charcoal cannister. These are near the connectors to the headlight hanress and may cause confusion. On the TPI harness there was no connector to the power steering. There hasnt been any issue with it either. Maybe someone can shed some light on that one.

 

so u have her dynoed yet? rough estamite on power increasE? im curios on wat to expect from mine i love how these tpi units look!

 

I havent dynoed the car, only just drove it around the block a few times. im stil doing some tuning and working on little issues. it does feel like thier is a little more response and feels stronger shifting through the gears. acceleration feels quicker and it sounds a little beefier.

 

How about carb to Tpi? What are your thoughts on swap for that? (I'm thinking about doing it)

 

on the carb u would need all the sensors and tpi unit and change ure mechanical feul pump into eletrical and of course get a ecm and wire harness

great yeah that tune will show alot more also im got alot of upgrades on mine well just ported n polished heads and intake and a lt1 cam with a custom cai and a 3.42 gear with posi should see alot of difference bad thing mine is a auto .. . . . . good luck

 

Niiiice Tony....soooo those fans you are asking for gonna be part of this built?

 

What are the comparison between having a carb vs tpi Daily Driven? Pros and cons?

 

i cant tell u one pre better fuel mileage
and one con
tuning lots of it

it all depends wat ure into

ive only had fuel i njected my dad has a carbed vortech 350 cheyenne and it sucks gas quick!

but maybe some one else with carbs could pitch in!

 

Based on my conversion,Pros- Better gas mileage ( 2-3 MPG), good cold start performance, better low end torque, lower idle, WOW factor when hood is open. Cons- Money and time spent doing the conversion.
Lots of files, spreadsheets, etc on my website if you want more info. https://sites.google.com/site/darbyselky/home

 

Thanks alot, really answers alot of questions. I couldn't open the first 3 files and the last one on TPI Conversion page. Money wise on thirdgen ranch sell a tpi set for $375 which isn't much, and time to spend on conversion for the pro is worth it

 

The first three files are for tuning, and require Tunerpro ( free software download). The last file is a file of Bookmarks I saved. You can import these into your browser. The $375 is just the start. Go over the costs in my spreadsheet to see other things I needed. Total cost was well over $1500. You can get by cheaper, if things like sensors, injectors, Fuel Regulator, etc are known good.