TBI to Carb, Head swap

[diamondstealth]

i've got an 89 350 TBI (full size blazer), i'm thinking of redoing a set of camelbacks, swapping the heads on this motor and bolting on a carb. Everything should swap easy, fuel pressure from the TBI pump (7-9psi?) should work fine without a regulator?? Anyone done this swap?

diamondstealth

1998 Pontiac Trans AM LS1 M6
1987 Camaro IROC-Z
1989 Blazer V10 7" lift

[cheyenne383]

The only reason the TBI pump has 7-9 psi is because it has a regulator, it just happens to be integrated. You can't have any pressure without a regulator, just masses of fuel pumped in that direction. THe easiest way to get a carb to work on an 89 Blazer would be get a mechanical pump and run it, because the vast majority of that body style truck was carbed with mechanical pumps. I've swapped from TBI to a carb before, but why do you want to do this? The TBI set up flows around 700 cfm and there are lots of ways to improve performance without going carb.

As for the camelhump heads, they're leftover trash from the 1960's. Technology owns those boat anchors.

[cheyenne383]

Originally posted by diamondstealth
i've got an 89 350 TBI....1989 Blazer V10 7" lift

:conf: Since when did Chevy make a 10 cylinder 350?

[diamondstealth]

v10 is the model number after 88 for the full sized. the reason i want to go to carb is that the wiring on this thing under the hood is fried. Bought it from a guy that had an engine fire. I've been chasing problems for 2 years now, just thought a carb would be an easier way to get this motor to run right.

These tbi blocks don't have the provisions for a mechanical fuel pump.

I have a set of camelbacks off my old racecar in the garage, along with a holley 750 Dp mechanical, and a weiland intake. I just need to pickup an HEI.

[cheyenne383]

Originally posted by diamondstealth
v10 is the model number after 88 for the full sized

True, for trucks, but Blazers are K/V 5, not 10.

Originally posted by diamondstealth
These tbi blocks don't have the provisions for a mechanical fuel pump.

The original block in that truck should have a pump boss. Vortec engines up until 99 had them, so did TBIs. If not, then get a return style regulator and fab some lines to go from the originals, should be easy, there's not much difference in where the TBI lines go into the back of the throttle body and where the regulator should be for a carb.

[diamondstealth]

As for the block, i know there is a casting area for a pump, but i believe its filled in. it would have to be machined out to except a pump right? Even with the low pressure, i can't just hook the fuel lines to a carb, i still need a regulator?

As for the model, its a v10 blazer 4wd. i've been to parts stores many times, thats what it is. trucks are k1500-3500 instead of k10-30.

[cheyenne383]

Originally posted by diamondstealth
As for the block, i know there is a casting area for a pump, but i believe its filled in. it would have to be machined out to except a pump right? Even with the low pressure, i can't just hook the fuel lines to a carb, i still need a regulator?

No, it's always open,you need to clean it up, but a hone would be fine... should have a block off plate on it, just unbolt and clean it up.

As for the pump, you wont have flow control, so no, you can't just run the pressure line to a carb, you MUST have a regulator. A regulator controls the flow rate, pressure, and also returns extra fuel to the tank.

[diamondstealth]

Hey cheyenne383, i had decided to stick out the wait since i still need to buy a afpr, so i picked up another knock sensor. that made a huge difference. i set the timing back to stock, and it's almost runs like it was new.

question is, i swapped out ignition modules from a 91 truck (actually whole distributor) I'm still getting the trouble codes for knock sensor and ignition module even though it feels like its running 100%. I've unplugged the battery, computer keeps bringing back the codes. is it time for me to pickup a scanner and check it out??