Fuel injection to carburation

[carguy94]

I have a 1987 Chevrolet Silverado R10 with a 350 TBI and its got more issues than I can count. the trucks engine has been backyard mechanic wired and does not run good at all it runs rich the service engine soon light is on and sounds like I have the timing way of and has a radical lope to it. this engine was rebuilt sometime ago and they thought it would be good to put a bigger cam in it but it made it much worse. I had the TBI apart and my pressure regulator is leaking but along with that my drivers bank is running rich compared to the passenger bank. To make a long story short I plan on converting to carburation change the intake distributor hopefully a Rochester four barrel non emission control no engine computer and change the valve train components back to stock. I know theirs a lot more i left out but just wanted some input the engine has to come out its got a chewed flywheel and along with the engine control issues i plan on just overhauling the entire engine and build it to flow with non EFI. i figure i will have to change exhaust components and make a hot air choke work along with a mechanical pump or an electric pump. and sorry for the spelling error my auto correct would not let me spell it correctly is comes out carburation.

Thanks for any input anyone has in advance.

[monte0185]

The biggest problem is going to be the fuel to the carburator. You will need a regulator with a return and as for a fuel pump I just use the in tank pump. You Gound the wire to the computer on the fuel pump relay and provide key on power to the other wire and your in tank pump will provide all the fuel you need. The rest just build like you would any other carb SBC. Oh and no need for the manifold heat flapper thing in the exhaust. a good set of headers would work better probably.

[carguy94]

thanks much appreciated and i do have a set of headers for a SBC to I will go that route and do what you said about the pump in the tank. I assume I should go with a truck that had non emission no EGR and no computer controls with the carburetor.

[monte0185]

Originally Posted by carguy94

thanks much appreciated and i do have a set of headers for a SBC to I will go that route and do what you said about the pump in the tank. I assume I should go with a truck that had non emission no EGR and no computer controls with the carburetor.

Yes definatley. Depending on your budget i would shop craigslist for a cheap aluminum intake and by a New carb like an edelbrock or summit has a decent one for cheap as well. electric choke is nice. Theres tons of stuff out there for SBC's for cheap if you shop around and do your research.

[carguy94]

ok then will do thank you for your input helped me save a lot of time.

[Just call me Sean]

Hotwiring the electric fuel pump is dangerous. '87 block should have a block off plate where the mechanical fuel pump goes.

[monte0185]

Originally Posted by Just call me Sean

Hotwiring the electric fuel pump is dangerous. '87 block should have a block off plate where the mechanical fuel pump goes.

Why is it dangerous? As long as you use a return style fuel pressure regulator and wiring the relay to a key on power its no different than any other electric fuel pump... Plus it saves on a new sender for the tank as well as alot of plumbing work.

[MountainGoat1966]

Electric fuel pumps should have a relay that is operated by engine oil pressure.
If the engine quits due to a wreck, the pump will shut down and not keep feeding fuel to cause a fire.
Or make a fire worse.

[monte0185]

Ok not trying to be an A$$ as i see your side of the argument but What if you have a wreck and the engine is still running and still has oil pressure?? Nothing is situation or fool proof.. Then what about NHRA. they dont require a oil pressure cut off switch for electric fuel pumps. In fact Id say 95% of vehicles with aftermarket electric fuel pumps do not have an oil pressure cut off on the relay for the electric fuel pump. Theres no reason to say it isnt safe cause it dosent have that but it would be more prudent to say that a safer option would be to include some kind of fuel cut off should something like this occur.

But anyway to answer the original posters question. Do your research. there is a ton out there on this very subject and feel free to ask lots of questions. The only stupid question is the one not asked!!

[Just call me Sean]

It's not safe. If the engine is running it's using the fuel. You can't prepare for every situation but you sure don't want to ignore a safety system the factory uses. NHRA have full electrical system cutoff, which would cut off the pump.

[carguy94]

want to thank all you guys for you input it is much appreciated.

[csdineley]

So I did the same thing last year. Actually I had to do it twice now, but I'll get to that. First way I did it, was to get some fuel lines from a '86 and the put a mech pump on my tbi motor. Pull the fuses for tbi. Then I found an intake from an '88 Caprice 350 I also picked up a HEI distributor and Q-jet from the junkyard. Gm changed the intake bolt pattern on the center bolt heads. You can modify a standard sbc intake to work. But I got luky at the junkyard. The only wiring I did was to run a wire to the HEI . This worked very well. Engine fired up on the first time I tried it.
The second time was because I replaced the TBI motor with a Crate Vortec 350. Which isn't setup up for a mech pump. So I had to redo the fuel system. Back to the tbi fuel lines. I cut the ends off. Installed a mallory 4309 fuel pressure regulator. But I don't remember if or how I wired up the fuel pumps. But it all works, and I've been driving almost a year now.

[csdineley]

Also there's no need to change your exhaust for a hot air choke, just get a carb with an electric choke. And if your going carb, no need to change the cam or valve train parts either.

[BigBlocksRule]

Other than a few TBI's I've owned, none of the more modern vehicles with electric fuel pumps use oil pressure relays. I understand Sean's point, but the fact is that the government would force manufacturers to use oil pressure relays if they thought there was an issue.

[Desert1957]

Not sure if the engine has a machined fuel pump pushrod area in the block.

Both my 87 engines cannot run a mechanical fuel pump.

May want to check this before buying any new parts.

TBI engines cannot run any camshaft with "loppy" idle , it plays havoc with the map sensor causing a rich fuel condition and piss poor engine performance.

Desert

[MalibuSSwagon]

A sure sign of a block being provisioned for a mechanical fuel pump is a block off plate installed on the fuel pump mount. The later vortec engines were not machined for a fuel pump mount and therefore had no plate installed.

[bigblue26]

I am doing the same thing right now on my 88 chevy R30 and that's what I did just ran the fuel pump through a regulator. What about the Down Shift relay right next to the fuel pump relay mounted on the fire wall what did y'all do about that?

[csdineley]

Well I have a manual transmission. I don't know anything about the auto's. I thought those relay were fuel pump and one for the a/c?

[bigblue26]

I'm not 100% sure that it's a down shift relay that is just what I found by going through the wiring diagrams. Orginally I thoght it was two relays one for each fuel pump since I have dual tanks. But according to the wiring diagram one relay runs both tanks. So I am a little confused . Also how did you run your fuel lines into the regulator? Did you find an adapter or just have new lines made to go into the female end 3/8 npt of the regulator?

[foamypirate]

That 2nd relay is indeed the kick-down relay for a TH400. If you still have the TH400, you'll need to find a way to set that up, whether with a pedal mounted kick-down switch or one on the carb linkage. Both setups are out there, just need to find them.

[bigblue26]

Thank you that’s what I was thinking if I a use a ratchet shifter would it hurt to not put a kick down on it?

[csdineley]

I got 3/8 to hose barb adapters for the regulator. Cut the ends off the tbi lines and ran a short rubber fi line to connect them.

[Just call me Sean]

Originally Posted by BigBlocksRule

Other than a few TBI's I've owned, none of the more modern vehicles with electric fuel pumps use oil pressure relays. I understand Sean's point, but the fact is that the government would force manufacturers to use oil pressure relays if they thought there was an issue.

The oil pressure switch is the old system. New systems the computer shuts down the fuel pump.

[foamypirate]

Originally Posted by bigblue26

Thank you that’s what I was thinking if I a use a ratchet shifter would it hurt to not put a kick down on it?

If you don't mind manually downshifting for passing gear, it won't hurt anything not to run a kickdown. It's more of a convenience item.

[bigblue26]

Alright thanks for all the help. I appreicate it.