93' Blazer TBI to carb conversion questions

[rcrahn]

Looking to help a friend convert a 93 Blazer 5.7 TBI engine to carb. He wants to have a vehicle without computer.

How difficult is this to do?
Any articles,videos or threads on doing this?

Appreciate any help

[Ziegelsteinfaust]

It is easy to put the carb on, and get it to work. But it will not be right out of the box. You will have to learn how to tune it to get it where it needs to be.

Also you will need a regular distributor. I like initial timing at 15*, and all in with 36*.

The fuel tank is tricky since you have a electric pump in the tank. People have removed the tbi pump, and spliced in a carb pump.

The only wire you need to run a carburetor engine is a switched hot to the distributor. Make sure you have a multimeter as you decide on which one to get. Maybe there's a write up, but I buy pre smog vehicles for fun myself. You can just run a switch from the fuse block through a switch to the distributor if you have too.

I would avoid any carb over 600cfm on a stock engine unless were doing a q-jet. It makes tuning more difficult for the novice or un obsessed type. Even then there are a sequence of steps that you need to do to achieve the best possible results. Use a air fuel ratio gauge to do it easier. Reading plugs is a part, and I hated it.

Lastly remove the computer harness carefully incase you want to go back.

[Ziegelsteinfaust]

If you watch Roadkill. Look for the Idaho tater truck episode.

It is a good visual of how a average guy can dial in a truck, and not go insane.

[ChevyTech]

Does it have an automatic or manual transmission?

The automatic transmission in a 1993 Blazer is shifted and controlled by the computer.

[sweetk30]

and tbi is stupid easy and hardly go bad . also fuel mileage will prob go down .

[Texasdeere]

It's fairly easy to do. The factory TBI set up was very simple (archaic) but pretty good when new. Never that efficient or a great performer stock. But if you are having a lot off problems and feel more comfortable with a carb, go for it!

I am about to do this to my 88 dually with the 7.4

Once the throttle shaft start to wear out it isn't ever going to run right. No new replacement throttle plates available and the re-bore kit is expensive.

Holley makes a carb that accepts the factory throttle poss sensor for the later transmissions.

Both fuel lines (in and return) are right at the back of the tbi

You will need a carb, hei or no-computer dist, intake manifold, and a fuel press reg with return. You will also need to run a signal wire for the fuel pump relay.

There are a bunch of good youtube videos on this with the small block trucks.

Watch a few of those and you will be all set.

[b454rat]

In 93 it’s called a”4l60” but not “e”. It’s still a 700r4, uses a cable, not electronic.

[bluex]

Use the large pink wire at the coil to power the HEI. The white wire in the same plug goes to the tach. The oil pressure an coolant temp (sensor in the head) go straight to the gauges. You can get rid of the rest unless its needed for the transmission. The A/C signal is an input to the pcm just so it knows to bump the idle up. You can get rid of that side of it also.

[95 S_Trucker]

Originally Posted by b454rat

In 93 it’s called a”4l60” but not “e”. It’s still a 700r4, uses a cable, not electronic.

1982-1989, 700R4

1990-1992, 4L60

1993-2010, 4L60E

The 93 has an electronic controlled transmission(if its automatic), and it is controlled by the PCM.

[speedygonzales]

Y'all are debating a tranny question that chevytech laid to rest on the same day the OP posted.

Which was a month ago and hasn't been on since to check for answers. It does not seem likely he will be back here looking for anything.

Be that as it may, the unit in question can still be set up old school and it could still use the PCM to control the tranny by using a carburetor that has a provision for a TPS.