Fuel Injection

[Joyridin]

Originally Posted by 67 twins

I take it you weren't around when the industry made the changeover. If you were you would know that it was driven by emissions standards.

I worked on those carbs from 1980 on. They were junk. Thankfully everybody switched to EFI regardless of the reason. It was a dream not to have to remove 100 vacuum lines just to see the top of the carb.

[Rickysnickers]

I know this isn't my area of moderation, but the insults and name calling need to stop. State your opinion(s) and reasons for them, if you like, and then move on.

[MARKDTN]

As far as payback financially to switch to EFI (or OD Transmission) you probably will never see a return. But as far as cold staring/Winter, mileage, and overall driveability it's a complete different world.

My '83 K20 I have known since new, I got it with 42K miles. It had a 4-bolt 350 with a Quadrajet and 700R4 transmission and 3.42 gears. Fuel mileage was regularly around 14 around town and maybe 17 on an empty road trip. I put over 100K miles like that. A cam lobe went down so I bought a '90 Corvette Tuned-Port 350. The difference is night and day. I now get 17+ MPG city. Pulling a trailer with the Q-jet you were always hard into the throttle on a hill. With TPI you just barely push it a little more. Cold starts with an empty fuel bowl are a thing of the past now. It barely turns over before it starts year round. Obviously EFI is constantly tuning for optimum air-fuel mixture based on outside conditions, elevation, etc. A carb can't do that. EFI is constantly tailoring your ignition timing to conditions/knock, can't do that with a vacuum advance distributor.

With a carb if you want big power you will suffer drivability issues. It's a compromise. Ask a guy with a street Hemi or blown BB or similar how it really does on the street. They foul plugs and get 4-5mpg. Hard to cool. Now ask a guy with a ZL1 Camaro or CTSV or Shelby Mustang how they run on the street. 550+ rear wheel HP and better than 10 mpg. Plug changes whenever. Cold A/C and cruise. No overheating worries. EFI works.

To the ones that carb LS engines I ask why? The kit to make the ignition work is just about as expensive as a harness. The intake is flat so fuel pooling can be an issue and has destroyed some engines.

If you like a carb, then great. But to say that there are millions running around trouble free today might be a bit of a stretch. Maybe if you only use non-ethanol fuel, maybe. I do in my mower and weed eater but it's not easy/convenient to get. If I had to have a carb it would probably be a professionally built Qjet. I can build/tune a Holley but for everyday driving I think a Qjet is optimum for a carb.

OP-if you want a carb fine. If you want EFI-also fine. For a stock 350 it is hard to beat a TPI system IMHO. If you want a more radical cam you have to be careful with EFI that you pick one designed for EFI. They need good vacuum to work with TPI (or TBI). Good luck either way you decide.

[HalfBrit]

Here's an interesting comparison relevant to the original discussion.
https://youtu.be/8vc4hqhY13Q?si=mqNTb5PG-oJk5vxl

[Palf70Step]

One of the things that may get me to go with EFI, is finding a good carburetor guy/gal near me. It's getting very difficult to find places that have people to work on carbs. I am fair, but its nice to have someone I can go to when I am beyond my brain. I try and use only non-ethanol fuel, but not to worried if I have to use the "bad" gas occasionally, as mine gets driven a good bit so the ethanol doesn't stay long in the tank. AS mentioned, switching will cost more than you'll ever make up in the cost, but it does have some other benefits. For now I like my carb, but it is what I am more familiar and comfortable with.

[MikeB]

I have been using and playing with Edelbrock Performer Series carbs since the mid-90s. Literally dozens of them. That includes conversions to electric choke, and jetting for dual quad setups. Never once have I seen one with deteriorated gaskets or sticky needle/seat. What I have seen is dirty float bowls and clogged brass fuel passages and air bleeds. Some of that may be due to fuel quality, but I suspect most is caused by dirty air filters. That said, I assume their must be some older OE Rochester and Carter carbs out there that don't stand up to today's gas.

As for EFI, I did a conversion 8-10 years ago using a FiTech system on a friend's 383. It took a while to get it dialed in, but mostly it was just a learning curve for us. What I liked about it most was the immediate startup, falling into a smooth idle. Literally like a new car!

I'd convert my truck's 350 to EFI, but don't want to mess with a new gas tank, or whatever is required for a 69 truck w/o a return line. And whatever I did I wouldn't want a noisy external pump. That, plus I recently sold my trusty old 1406 and replaced it with an AVS2. The guy who bought my 1406 later said he stole it from me because it works so well!

[67 twins]

Originally Posted by Joyridin

I worked on those carbs from 1980 on. They were junk. Thankfully everybody switched to EFI regardless of the reason. It was a dream not to have to remove 100 vacuum lines just to see the top of the carb.

Well there is your problem. A carb should have two vacuum lines. One for PCV one for vacuum advance.

[franken]

These are just my opinions, not presented as fact.
The OP may want to spend a bit of time reading both the good and bad about FI. It doesn't like sketchy wiring/grounds, etc. The components can be unreliable and the whole thing is expensive.Typically, aftermarket systems are TBI so they're a lot like a carb, but computer controlled.
A tuned carb works well, as does tuned EFI--then again who has the skill to tune either.
I doubt there are huge mileage or performance improvements from EFI and that these come from better head design.

[MikeB]

Originally Posted by 67 twins

Well there is your problem. A carb should have two vacuum lines. One for PCV one for vacuum advance.

I think our member Joyridn was just kidding, but I found this diagram from an 82 C10 I used to own. Looks like more than twenty hoses, but "only" seven connected to the carb. I actually had it all figured out at one time!

[Steeveedee]

I worked as a mechanic in that era. As long as one has the vacuum diagram(s), it's all good.

[Joyridin]

Originally Posted by Steeveedee

I worked as a mechanic in that era. As long as one has the vacuum diagram(s), it's all good.

I remember working on a roughly 81 Mazda RX7 that had the engine replaced and wouldn't start. I think half the weight of the engine was rubber tubing and solenoids.

Tryng to figure out if it was a computer issue or an actual carb issue was never fun.

[Steeveedee]

Originally Posted by Joyridin

I remember working on a roughly 81 Mazda RX7 that had the engine replaced and wouldn't start. I think half the weight of the engine was rubber tubing and solenoids.

Tryng to figure out if it was a computer issue or an actual carb issue was never fun.

Yeah, the Japanese never shied away from making things complicated. I remember adjusting the idle speed on a Toyota by turning a screw in an electrical box under the dash.

[Orange Crate]

I helped someone tune their carb. Lots of laying on top of the radiator support, smelling like gas. FI is tuned with a laptop in the cab. Everything can be tuned, acceleration, deceleration, idle fuel, fuel flow at any manifold pressure, warm up fuel, idle air control, ignition advance, cold advance and more. So I would say that the most valuable part of FI is the ability to tune (in the cab). Maybe that is valuable to you also.

[CastIron]

To answer the OP's question- we all have out own opinions, but it is up to you to decide. That being said, here's my opinion. I have a 69 C1500 that I installed a 350 crate engine in about 10 years ago. It had a 307, and I didn't want to use the tiny 2 barrel it had on a 350. I just happen to have had an Edelbrock Performer intake and carb off of another truck. So I took that apart, made sure it was clean, and installed an electric choke. After engine break in, I changed some needles and adjusted the idle mixture a little better. I haven't touched it since and it never fails to start and run smooth. (a thick gasket cures the hot soak issues)
Basically, I just used what I had. That was worth it to me. I saw no need to change to FI, knowing it wouldn't make much difference on that engine.
Disclaimer: I usually take the easiest route on my own cars. I have spent over 30 years working on cars professionally, more than half at GM. I have a very clear understanding of FI and I'm not afraid to work on it.

[weq92f]

.

Running an original MSD Atomic I throttle body injection..no need for laptop, it's all done with the unit's plugin hand held controller/monitor. These are the settings:

Initial:
Displacement = 402
Cylinders = 8
Camshaft = "Mild"/"Medium" (3 choices stock/mild/large)
Fuel Pump = PWM, w/ regulator, fuel pressure = 42 psi
Air pump = NO
Idle RPM target = 700
Rev Limit = 5900
Timing Control = Disabled


Advanced

Fans - 1 = 190 F., 2 = 200 F.
A/F Targets = Idle 14, cruise 14, WOT 12.8, Nitrous OFF, Boost 11.9
Pump Squirt = 20%
Power Valve Enrich = %15
Nitrous Control = Disabled

Tuning this consists of dialing in the mechanical blades on the TB to get to a target idle while monitoring the IAC action to give it good authority on maintaining idle...want the action to be low 10-20 or so. Then it's a matter of adjusting Pump Squirt/Power Valve over time while driving it in various situations...level cruise, decel, accel, stop/n/go, idle over about 4 cold starts. If after this, blade adjustment is needed again (or major change in a setting), all the learned maps have to be erased and started over (learning) from scratch. This is called a comprehensive reset.

Time consuming yes, complicated...no. I fought a hunting idle on cold start for a while which turned out to be vacuum leak...once past that, it's been solid.

Hth,

-Kevin

[MikeB]

Originally Posted by weq92f

.

Running an original MSD Atomic I throttle body injection..no need for laptop, it's all done with the unit's plugin hand held controller/monitor.
-Kevin

Pretty cool that the old MSD Atomic is still working well!

What are you EFI guys using for fuel tanks and pumps?

[weq92f]

Originally Posted by MikeB

Pretty cool that the old MSD Atomic is still working well!

What are you EFI guys using for fuel tanks and pumps?

.

Original Master Kit pump, rear tank. Pump is external, mounted at tank bottom and plumbed with return.

-Kevin

[Rickysnickers]

I have a Pro Flo 4 system on my truck. Works well and easy to use. For fuel system, I have an aluminum, under the bed tank. It has an Aeromotive Phantom 340 in-tank pump.

[binford]

I did fuel injection as I live near sea level and travel to 7,000 + feet in 60 miles.
I got tired of adjusting the carb for a altitude.
I would want something that did the timing as well too.

I installed a 1992 TBI and distributor. Learned a ton. Now days their are systems like FAST or Holley Sniper that have a wide band O2 sensor.

My carb was toast and got like 6 mpg, TBI got me 12 mpg and I could start the truck without the happy dance on the gas peddle. In fact I can start it from outside the truck.

[68isgreat]

I converted to a new (rebuilt) 1990 350 tbi setup for ease of tuning and mpg, and because I couldn't afford a new LS and didn't want a used one. It runs fantastic with no tuning issues after I set it to zero degrees base timing. I did have to buy a new ecm computer and chip, because the one I had was the wrong one. All that said, I'm at the bodywork stage and haven't driven it yet, and hope to have it on the road by August. Fingers crossed. If I had a carbed engine already that ran well, then I would probably save up for a new conversion to EFI and attendant trans conversion (I went with a rebuilt 700r4 so I can have overdrive). There's nothing about carbs that appeals to me other than relatively low cost. Just my two cents.

[LS short box]

On my latest LS swaps I've used Tanks Inc EFI gas tanks. They supply the tank that bolts in with no mods along with the sender and 255 Walbro internal pump as a base kit. I use a C5 FFR. -6 SS line. They have worked very well.

[MARKDTN]

Originally Posted by MikeB

...What are you EFI guys using for fuel tanks and pumps?

On a square body you can use an '87 TBI tank (both long or short bed versions are available) with a '89ish IROC fuel pump. That one is easy.

On a 68-72 I used an '87 TBI Blazer tank with that IROC pump on a SWB but it required some frame mods and the filler neck was strange (I never saw it finished, I delivered it with no bed and he had a '96 stepside bed installed). On other vehicles to use an original tank I have used an '88 Ford truck external pump (no kicker pump). I did a '66 Mustang with EFI and used a Tanks Inc. tank with internal Walbro pump.