350 to EFI 305 swap

[Godgunsrocknroller]

Hi, I am buying a 76 4x4 k10. It has a carbureted 350 punched .030 over. It has a 350 turbo transmission and NP 208 transfer case. I wanted to swap out the engine from my 88 1/2 ton 2wd it has a 305 EFI throttle body fuel injection. Would the engine swap work on the two trucks? And also would the 76 be underpowered? What would I need for the swap? Sorry for all the questions, all comments appreciated!

[Godgunsrocknroller]

I forgot to mention that Im doing this swap for better gas mileage. Also the 76 has a 10" lift and 35x12.50x15 tires.

[Lt.Del]

You will get some replies from others, i have never done this, but will tell you the fuel delivery system is different.  The efi is a closed pressure system, requiring much more pressure....fuel pump will have to be replaced...most efi pumps are in the tank.  Your smog stuff, if still needed will have to be modified...charcoal canister, pvc, etc...

SgtDel

[Godgunsrocknroller]

Would it work to swap fuel pumps? Also Im probably gonna run glasspack mufflers on the 76 since it only has headers now, so the smog stuff will stay on the 88. Thanks for your input  

[Godgunsrocknroller]

So far from what ive researched i would need a fuel pressure regulator with a return line for the 88 im putting the carbureted 350 in, and I would need a high pressure fuel pump for the 76 im putting the TBI 305 in. Is this correct?

Also I wanted to know if they make conversion kits from carbs to TBI, since that might be easier than swapping engines. If so where can I get one?

Also what else would improve gas mileage? I was thinking a less restrictive exhaust, maybe a different cam, and these spark plugs I saw that cost $5 each but promise 15% better fuel economy.

Thanks  

[roundedline]

You need a fuel pump to apply the correct amount of pressure for the TBI.  The TBI has a regulator built-in.  I have seen people use the vapor line as the return

I haven't done this, but you could use a Corvette filter from '99 corvette it has a return line built in so you only need one line going to the carb.

I don't know of any coversion "kits" other than this:
www.customefis.com/pontiac.html, but if you already have the engine, there isn't much to get from him..

$5 spark plugs are a waste of money.

How much mileage are you hoping for.  The '87's with TBI got about 17mpg and they use the same engine as the '88-89's.

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project

[Godgunsrocknroller]

Thanks for the reply. I was thinking that instead of swapping engines, im am just going to swap fuel delivery systems. Since 305 and 350 intake manifolds are compatible I am just going to swap manifolds and all the other TBI parts like ECM and all that stuff, and hopefully the distributor is the same for the two engines. I will have to put an o2 sensor in my headers. I found an inline pump that I think was 5lbs psi and cost $37, the guy at the parts store said that the $37 electronic pump along with the mechanical pump would give enough fuel to the TBI. He also said I didn't need to get stronger fuel lines. I'm not sure if hes right though. Also I don't know how to slow down the fuel when I have an electronic in tank fuel pump and carburetion, I was thinking maybe another fuel filter or two to slow the fuel.

I was hoping maybe with my headers and cherry bombs, and TBI I could maybe get 15mpg, but that might be wishful thinking with a 10 inch lift and 35s.

I appreciate any input. Thanks.

[bfofish]

not possitive, but i was told that HEI will not work with a TBI system.all of the TBI's i have seen do not have an HEI.i know my 88 blazer with TBI does not have HEI.

[toplessblazer]

Your 88 manifold is not going to work on your 76 motor. The center bolts on the manifold go into the heads at different angles. 87 and newer small blocks use different intake manifolds than the earlier years and they are not interchangable.  

[toplessblazer]

Not to get off topic here but are you parting out the 88?  

[DnStClr]

Ha ha- There's always somebody lookin for a deal.  
You're in the same boat I am- you also need to consider an overdrive tranny for better gas mileage-
Here's another site about converting to EFI/TBI-

www.affordable-fuel-injection.com/
 

Edited by: DnStClr at: 4/27/06 8:24 am

[Godgunsrocknroller]

So are any parts between my 76 and 88 interchangeable? If not i'm going to have to spend a lot more than I originally planned, those kits are like $1000 dollars! And sorry no i'm selling the whole truck rather than parting it out.

[roundedline]

What parts are you wondering about?  As far as the drivetrain they are interchangeable.  As for at everything else, none of the body or frame pieces are the same.  Steering box may be the same, steering column, and fuel tank sending units (maybe)....

You need fuel injection specific hose regardless of what anyone tells you otherwise.  Regular fuel hose is not made to handle 20lbs of pressure the TBI needs to run.

It would be alot better to swap motors along with all the connectors/wiring going to it.  If you would rather keep the 350, you can oblong the bolt holes in the intake to make it work.

I would put a pump/sending unit from an '87 in the tank (I think the '88 will work, but check) and connect the vapor line to the return on the sending unit.

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project

[cooltoolguy]

the swap would be fairly easy, everything bolts up.  you,need the complete harness along with the ecm.  the tbi computer wants to see 4000 pulse per mile reading so you could get an inline vss to send the signal from your tranny in the 76. (the 88 may already have this) you will need a gas tank, sending unit and fuel pump from an 87 (or put an inline pump in which puts out 18 psi) you can use the origional fuel supply line (with an inline fuel injection fuel filter) just use efi rated rubber hose to make the connections, run return line and a vapor line.
swap over the canister and various other components.  I also believe the exhaust will bolt up too.  the only thing i see that may be a problem is the torque converter lock up,  being the 76 th350 probably has no tcc provisions.  it will be labor intensive and the 88 will probably be junk when your done.

[Godgunsrocknroller]

I really appreciate your guys help, I could never do any of this without it!

So the parts I need for sure are:

Inline fuel pump 18-20psi
Fuel return line
Oblong holes in intake manifold
ECM along with wiring, sensors, etc

I'm not sure if the distributors from the two engines are interchangeable.

Thanks again for the help