i8urrice

how difficult of a switch is it to go from a 305 TPI and change it to a carbureted engine? is it something i could handle or is it very very involved.....by very involved i mean...need a lift or power tools?? thanks!

tommyboy

I did mine last weekend. It only costed $1500.00, but I went to the extreme. You will need an 87 up intake. I went with a Holley street dominator. You will need a fuel pump or keep the one in the tank and get a 3 port regulator for input, output and return line. If you run an external fuel pump you will have to pull the tank, modify the sending unit ( remove pump and add to th 3/8 line ) and replumb some of the lines. Go with a holley blue they work good. Next a distributor, I would recommend an MSD billet dist with a 6A or 6AL box and a blaster 2,3 coil. But you could always go to the junk yard and get an HEI. Of course a carb. Then rewire your fans off the radiator so they will work. A radiator hose off an 84 Z28, stock one will not fit, thermostat housing, Holley carb linkage kit, air cleaner. Getting the TPI off is not to bad. You will need a 40 or 45 torx bit. You have to take it apart in pieces, the top, then the runners, fuel rails, then the base. How does that sound ??? I can give you part numbers and pics if needed and also wiring tips.

i8urrice

thanks alot...any other tips would help alot...i've never tried to take a car from tpi to carburetor before....it's either i do that or i'm gonna scrap the car...GM fuel injection systems are horrible

88IROC350TPI

don't do it unless you are having serious problems with your TPI. a 305 and TPI go good together. I spent about $700 converting and you don't NEED an expensive "87-up" style intake, you can modify an older style one and save $50.

I really love fuel injection but I couldn't afford it so I converted to carb ...one day I'm going back to FI. If you have any questions ask me ...Everything went wrong when I did it so I know what works and what doesn't.

i8urrice

ok, how about a switch to speed density system instead of the mass air system.......doing that or switching to a carb....which is cheaper/easier/more beneficial...b/c i either need to make this car easier to work on and faster, or scrap it for something else

Joshua Leslie

you wont need to remove the in-tank pump to run an external(electric external anyway) I did this and run a Holley Stadard pressure, left the pump inside the tank, it still pumps out exactly 6psi as advertised.

i8urrice

but how does it work, if i go to carb...i'm pulling out the ECM....doesn't the computer tell the fuel pump what to do....or is it hooked up to a standard power source....forgive me...i'm used to my mechanical fuel pump on my old charger.....b/c carburetors seem the way to go to easily troubleshoot problems....then i need advice also on removing my smog stuff and the A/C

88IROC350TPI

When I converted I pulled out the back seats and carpetting. There are 3 (I think) wires coming from the fuel pump. Power, ground, and fuel guage. I cut the ground wire and re-grounded it then routed a new wire for the power to the ignition so my fuel pump turns on whenever I turn the key on.

If I was thinking more clearly at the time (it was 2:30AM, had to wake up at 8AM) I would have found the fuel pump relay and hooked it up through that instead of 'hotwiring' it.

I think I should write a add-on to the current TPI->Carb swap manual...

Joshua Leslie

when i converted, the in tank would not work at all, so I hotwired it, shorly after which, it died, weather it was due to age, or bieng hot wired I will never know. it worked for about 3000 miles.

also, i did something wrong, cuz my fuel gauge is always pegged full, im still trying to figure that one out.

89formula#1

hey 88 iroc do u recall wut color the ground wire was for the fuel pump? i know the power wire is tand a white

jeff85iroc

What about wiring what has too be done there.
Like can you just unplug the TPI harness in one peice?and if so
could i plug it in to my 84 vette and put the TPI on there.
PS i know i can put the TPI on the vette but im not sure about the harness.


Thanks



Jeff

x5finger

5finger.8m.com/tpi2carb/tpi2carb.html

Should you decide to get a 3 port regulator, the fuel pump should run on its own w/o any rewiring. The fuel pump is also wired up to an oil pressure sensor. Once there is oil pressure, the fuel pump is turned on. If the pump is not wired through this sensor, if you crash the car fuel can continue to be pumped into the engine bay. FYI, dont try and use a mechanical fuel pump. There is a spot to mount it on the block, but from what I understand the TPI camshaft has no lobe to drive the fuel pump.

Yanking the smog is fun, easy, and rewarding!

As always, the above is IMHO, and your mileage may vary.
-5finger

JRupert99

Fella...

I have been reading your post and the replies.. but i just did a tbi to a carb in a 305. Here is what my buddies and I did. Keep in mind this is the first time we have ever did anything like this.. so the other fellas out there that have the experience... please tell me if i am telling him something wrong. Ok here is what I did. First you have to find an intake manifold, i had to get an aftermarket to fit the centerbolt pattern on the newer style heads. I went with an edelbrock performer. Then of coarse the carb which i went with a 600cfm electric choke. Also you have to change the distributor to one with a coil pack on top of the cap. We did rewire the fan the fan thru the radio fuse in the fuse box, that way the fan comes on with the power. I am also running a performance rpm camshaft as well. You will have to find the fuel lines, i know in mine there were too.. find the one that shoots out gas.. to do this.. just undo them.. and for about one second turn the car on.. youll see one shoots and one doesnt... you can cut them both and the one that doesnt shoot out gas.. just fold over, the one that does shoot gas...you are goign to need a rubber hose and an adapter to put to the carb. The good thing is though.. you can rip all that emissions **** off.. assuming you dont have like e-check or anything.. but you should still be ok. you will have to do some rewiring with the distributor as well. My engine ran and sounded good.. Ok for the guys that know what they are doing.. I just left my ecm fuse in and it ran the fuel pump no problem.. the carb was getting fuel... could this cause a problem later?

gtabadboy

How can i make my fuel pump work without wiring it another way. When i converted from TPI to carb it worked because I kept the computer in. Then I got another carb motor and it wont work. The fuse is good and i jumped the pump and it works. What else could it be. Anyone have pics of how the wires near the FP fuse are hooked up. How can i jump it so that it works. Can I jump the relay so when I turn the key it turns on, is this safe. thanks much.

ATOMonkey

i8urrice you are in way over your head. Take a year off and do a lot of reading and listening. Either that or find a very knowledgeable friend. FI is far superior to carb. Just buying a used accel or LT1 conversion or holley stealth will make the car run like a whole new animal. You should only switch to carb if you absolutely have to. Why ditch the computer? It works the cruise, and a boat load of other things (including the dist).

GTA I just got done with a big long post about what you're doing. Search for that and wiring diagrams. Its not that difficult a thing to do. You just have to think about it a little. Not trying to be a smart ***, just use that stuff between your ears.