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81chevyk5
08-22-2007, 01:06 AM
any one know what is involed in switching from carb to tpi? any pros or cons to it? if i keep the blazer i will do the swap, ive been lookin around and can get a full used set up for around 400 bucks including wire harness and computer.
151FAB
08-22-2007, 06:15 AM
I think Painless and others have a harness that is used for swaps, hotrods and such. It would be worth the money ( the ford one is about 350-400 bucks) to use that one if your looking for a clean easy install. The factory harness has a ton of extra wires for all kinds of things you'll never use and doesn't come with a manual;). The aftrermarket harnesses are labeled, and come with enough directions that most gear-heads could easily handle it.
81chevyk5
08-22-2007, 10:32 AM
would i still be able to use a stock harness though? or am i adding myself alot more work? i really dont want to get a new harness as it will make it harder for me to do the swap

thanks for the info though
Blanco
08-22-2007, 10:46 AM
Why are you considering this swap?

Just run what cha brung.. :cool:

what are you gonna do with the blazer?
for genral desert play a Carbs fine.

Now if your gonna be getting into all sorts of angles & such then, I could see wanting a FI.

Oh & my Carb guy ( Chris at Warrenty Carburetor in Burbank Ca. ) said when he say my girlfriends TBI that he liked those & that they're really good.
But I asked him what about compared to TPI & he said well the TBI is really good but maybe not as nice as the TPI.

I'm not sore but I'm thinking the TBI just bolt on to any Carb intake manifold? :confused:
& if so, I can see some interesting combos to mix & match..
fj40
08-22-2007, 01:44 PM
would i still be able to use a stock harness though? or am i adding myself alot more work? i really dont want to get a new harness as it will make it harder for me to do the swap

thanks for the info though

Yes, you can use a stock harness and yes there will be some extra work involved, like cleaning the the donor harness and identification of wires you are going to use (using wiring diagrams you can download), you can find many swap treads in the web in this particular engine/vehicle. Read a few to see the different directions each took, decide which one you like and stick to it.

I did the TBI swap on the narrow spaces of my land cruiserīs 305 Chevy engine this way but skipped some steps that haunted me in the end......

The end result?? I really like the way it works, no more cold-start problems or fuel delivering whoops on any angle and many more thing to list.

I did the swap on a budget, or else i would had gone whit the TPI.

If you decide to do this i can help you whit some pointers and diagrams.
81chevyk5
08-23-2007, 01:24 AM
the reason for the possible swap is for better fuel economy, better running truck and more performance.....i hope! im still kinda tossing around the whole idea of selling it, i figure since im not driving it i might as well do some of the things ive always wanted to do to that motor and truck. if i can get better gas milage out of it in the process then ill keep it and slowly build it. from what ive seen it about the same work to swap in tbi as it is for tbi you still need to change the manifold add a ecu and wire harness mess to deal with.


fj40, if i go through with the swap i will defenitly hit you up for info and advise. what kind of problems did you have when you swapped in your tbi? and can you post some pics of it in your ride?
fj40
08-23-2007, 09:30 AM
Will do. and mark in blue the parts where I goof.... had some trouble.
Ok, here are some things you will need to consider before you pull out the first connector or unscrew the first bolt.....
The most important is fuel delivery (i later learn), are you going to use an external fuel pump, is your tank in good condition (any little rust will be pick up by the extra pulling pressure of the pump), if it is, you will need to Build a return line and a breather in your tank (after many head banging sessions i got my hands on a racing fuel cell and haven't look back at this problem).
http://i193.photobucket.com/albums/z249/tioernesto_2007/PICT0013.jpg
You can barely see the gas cap above the spare and the first experimental cell breather line to the right (this one didnīt work as it kept sucking the plastic bladder.... back to the drawing board)

My guess is that it could be cheaper to swap a complete fuel tank from a newer blazer, this will include both fuel pumps and save you half the pain (just send a couple of cables bacl for the connector).
The new system will be using more power that the old alternator can handle (65 - 75 amps), you will need the to upgrade to the serpentine pulley two cables type (105 - 110 amps). This extra power is great, now i can run a two speed electric fan to keep the SBC cooler it the tight space of the Land Cruiser engine comparment.....

http://i193.photobucket.com/albums/z249/tioernesto_2007/Land2.jpg

I kept the stock manual tranny, at first the engine worked fine and then idle erratically and run ruff..... I skipped the part that addressed the VSS and parking switch wires need of being grounded sow the computer ignored their signals (at least when its running, as it will show in the scanner that the vehicle is parked)
fj40
08-23-2007, 05:35 PM
OK, first some pics:
http://i193.photobucket.com/albums/z249/tioernesto_2007/PICT0019.jpg
This is the intake where the TBI and most of the sensors are located (at least the ones i needed for this swap)
fj40
08-23-2007, 05:53 PM
This is from the other side whit the air filter on
http://i193.photobucket.com/albums/z249/tioernesto_2007/PICT0016.jpg
the knock sensor seats just beneath the "Y" in the harness.

http://i193.photobucket.com/albums/z249/tioernesto_2007/PICT0018.jpg
The O2 sensor just ahead of the headers collector.

http://i193.photobucket.com/albums/z249/tioernesto_2007/PICT0017.jpg
Spark Control Module and fuel pump relay mounted on the firewall.

http://i193.photobucket.com/albums/z249/tioernesto_2007/PICT0015.jpg
Computer mounted beneath the dashboard as well as the test connector and the fuse cluster.

http://i193.photobucket.com/albums/z249/tioernesto_2007/PICT0014.jpg
check engine indicator, fan on and low oil pressure LEDs.
151FAB
08-24-2007, 09:25 AM
Really cool special-opps stlye FJ.
peteh
08-28-2007, 11:15 AM
i swapped in tpi. it took a while for me to gather all the parts(i was doing everything cheap). i did my first engine swap at that time too.(well only engine swap as of now) and while the engine was out i decided to go tpi. it ran really really well(now its in the garage getting suspension stuff done)..it was pretty cheap, id say just about a grand for all tpi related items and my bargain motor(originally had holly carb and stuff). i don' see getting any cheaper then that though.

the internet has so much info and theres a couple books flying around.. check some camaro sites and stuff.

if i could do it over i'd just save more money and just do an ls motor.
Chasespeed
08-28-2007, 11:22 AM
TPI is actually a pretty good set-up in its own right, pretty much tuned for torque, and great midrange...

THAT being said. only bolt in issues I possible see, which year camaro did that lower manifold come off of?

you will need an 85-86 manifold, (that who setup is better, mass air, etc)

The 87 and up, use different heads, than your older carbed chevy...

The bolts that hold the manifold are canted...the older ones arent...

It can be made to work, but, it will take some patience...

Check out,
http://www.tpis.com

They are who I got most of my stuff through, when I built my last L98 motor...

Hope that helps

Chase
fj40
08-28-2007, 04:20 PM
The bolts that hold the manifold are canted...the older ones arent...

It can be made to work, but, it will take some patience...

a good air drill and some grinding bits...... and more patience.

I dont remember what year it was, i just checked the inyectors where the ones used for the 305 engine, when it was finished, fabricated a bonnet to raise th air filter.
Chasespeed
08-28-2007, 05:44 PM
BUT, the TBI manifold, was only used on the Centerbolt heads..

The TPI was used on both...

Chase
81chevyk5
08-30-2007, 02:40 AM
thanks for all the info guys you all are awesome!!!!:cool: the pics were a big help fj40 i wasnt expecting that much pics :) im gonna leave the carb on it for now because of "empty wallet syndrome" but tpi is the way im gonna go ima slowly gather all the right parts and then go from there once again thanks for all the advise guys
fj40
08-30-2007, 11:15 AM
Great, glad to be of some help.
peteh
08-30-2007, 03:57 PM
chase has mentioned good points.
i had the manifold bolt to head issue. but just did what everyone else said to do, it was easy.

i chose speed density..i figured all that dirt would be bad for the mass air flow. and i think its cheaper.
Chasespeed
08-30-2007, 05:13 PM
chase has mentioned good points.
i had the manifold bolt to head issue. but just did what everyone else said to do, it was easy.

i chose speed density..i figured all that dirt would be bad for the mass air flow. and i think its cheaper.


The MAIN reason for suggesting the MAF versions, it will compensate for Power Mods ALOT better than the speed density...

Speed density has a MUCH narrower cam availability, unless you have some tuning done......



Other than that, you will love the way it feels...

IN fact, if you can snag a pre centerbolt TPI, see if you can snag the cam... that motor has a NICE torque curve...plus, you can also keep that HEI ignition... with both set-ups...

Chase
peteh
08-30-2007, 05:47 PM
"Most people have heard that a mass air flow sensor is more desirable when changing the cam or making engine modifications. But, now that tuners have gained the ability to reprogram the computer chips, it's possible to get a better calibration and cleaner-running engine with the speed density." classictrucks.com

btw 90-91 vettes used waterproof comp.
becareful with distributors, some have gears set up for rolling cams and some are not
use small hei diz with the remote coil. aftermarket coils for the smaller guys are cheaper then the big ones. but stock diz work fine for most people. plus with tpi power levels die at around 4800-5000(i think)
also the room behind the pleneum in a blazer is limited and a small is way easier to put in.
get rid of 9th inj.
Dave G
09-07-2007, 12:40 PM
... snip...
get rid of 9th inj.

You're referring to the cold-start injector, right?

What's the reasoning behind getting rid of it?

I'll post up some pics of the 81Blazer / 86 TPI project we did several years ago, and we're STILL fighting the bugs!
peteh
09-07-2007, 02:28 PM
You're referring to the cold-start injector, right?

What's the reasoning behind getting rid of it?

I'll post up some pics of the 81Blazer / 86 TPI project we did several years ago, and we're STILL fighting the bugs!

The '85-88 units have a ninth injector on the driver side of intake that fired one injector on the side of the intake for cold start only. The fuel then has to travel down each runner under the intake. The '89-up computer fires all eight injectors right on top of the valves so that you get better cold starting.