Need opinions on carb vs efi

[encasedmetal]

Hi, I just bought an 85' C10 SWB with a 305/SM465 4sp trans for a daily commuter. I typically travel 60 miles a day and some of it is in heavy traffic/mtn roads. I am currently making plans for what I want to do to the setup and split between throwing a new 600 carba nd aluminum intake on the 305, or putting a FAST efi with aluminum intake on. My main concern is reliability and cold starts- as I'll be driving this everyday even in the winter and I need to get to work. The other option is to LS swap it, but I would have to be very organized and knock the conversion out quick and conservative budget wise (<5K total). What do you think I should do? I've never owned a carbed vehicle before so it's all new to me, which is funny since I tune efi.

[Oberon67]

Originally Posted by encasedmetal

I've never owned a carbed vehicle before so it's all new to me, which is funny since I tune efi.

When I bought my C10 I was deliberately looking for a carburetor, because I'm familiar with carbs, and because I appreciate their simplicity. I specifically didn't want anything with a computer in it. Since you're familiar with EFI, I recommend you go with what you know.

Your concerns about reliability and cold starts are non-issues, however, provided your carb is in good condition and set up properly.

[Front Range]

Basic carb function

This might help

You might enjoy this

[encasedmetal]

Originally Posted by Oberon67

When I bought my C10 I was deliberately looking for a carburetor, because I'm familiar with carbs, and because I appreciate their simplicity. I specifically didn't want anything with a computer in it. Since you're familiar with EFI, I recommend you go with what you know.

Your concerns about reliability and cold starts are non-issues, however, provided your carb is in good condition and set up properly.

so a carb will crank and run just as easy as efi in <10* temps? how much mpg difference do you think there is?

[Oberon67]

Originally Posted by encasedmetal

so a carb will crank and run just as easy as efi in <10* temps?

I wouldn't say "just as easy," but you can routinely get it started in such temps. You will have to treat it somewhat differently, understand its quirks, and if it gets really truly cold where you are, use a block heater.

Originally Posted by encasedmetal

how much mpg difference do you think there is?

Impossible to say; too many variables.

[400/400]

Originally Posted by encasedmetal

so a carb will crank and run just as easy as efi in <10* temps? how much mpg difference do you think there is?

I daily drive my carburated '85 with electric choke. Last winter it had no problem starting up to 20 below. It just needs to be warmed up for a few minutes. The only seasonal adjustments I make to the choke are to the pull off. Once it's consistently below freezing it gets backed off a couple turns.

The big issue with carbs today is finding quality rebuild parts.

[rfmaster]

FAST system is a very nice, but a very expensive EFI solution. FAST is excellent solution in high performance setup.
If you are on the budget, your engine (305) is basically stock and do not mind doing some work retrofitting TBI system from a donor vehicle that offers a low cost solution. Basically JY EFI retrofit can be done for less than $500. Done this many times - for cars, trucks, and boats. The key to swap success is planning and grabbing a complete EFI system from a donor vehicle. Trucks and vans (87 to 92) are easy donors, cars (F and B bodies) are bit more difficult to extract harness from. After market harness (numerous vendors) is a better approach since you do not have to deal with a brittle 30 year old harness and plugs.
ECM (try to find donor with the same engine )
TB with all the trimmings (+complete intake, brackets, bolts, etc)
Harness
Distributor
Coil
CTS (screwed into intake)
Air cleaner Assy
MAP sensor
KS and ESC module
Fuel pump relay
oil pressure switch

Keep in mind that you'll need do some fuel line plumbing and get EFI tanks with internal fuel pump for best results. Use search - we have a thread here documenting details of several swaps performed by board members.

//RF

[cadillac_al]

Back in the old days even old ladies knew how to work a choke and start a car. Now it is getting to be black magic. This country didn't come to a stop whenever it got cold. If you know how they work it is no big deal at all. I try to have my vehicles set up so any woman could jump in, kick the pedal, turn the key and put it in drive and drive away. Back in the day that was common knowledge.

I just changed a fuel pump on my GMC this morning in about 1/2 an hour taking my sweet time. I don't think fuel injection is all that simple.

[Oberon67]

Originally Posted by cadillac_al

Back in the old days even old ladies knew how to work a choke and start a car. Now it is getting to be black magic. This country didn't come to a stop whenever it got cold. If you know how they work it is no big deal at all. I try to have my vehicles set up so any woman could jump in, kick the pedal, turn the key and put it in drive and drive away. Back in the day that was common knowledge.

This.

[Dead Parrot]

How good of shape is the current 305? What mileage are you getting now? Your 60 miles per day roughly equals 15,000 miles/year. You should figure your gas costs with the current setup vs your expected gas costs with whatever you might want to consider going to. You can then figure a rough number of years to break even on your investment.

A lot of folks will bad mouth a 305 but one in good shape is a good motor for a daily driver commute vehicle.

As for cold/hot starts, my carb equipped truck starts just fine if it is 100+ or below 0F. Just make sure the choke is adjusted properly, the exhaust riser valve(if equipped) is still working, your THERMAC system is present and working and the PVC system works. A lot of folks take those off and install and open air cleaner, "to make more power", then wonder why their vehicle sucks as an all weather daily driver.

[encasedmetal]

Originally Posted by Dead Parrot

How good of shape is the current 305? What mileage are you getting now? Your 60 miles per day roughly equals 15,000 miles/year. You should figure your gas costs with the current setup vs your expected gas costs with whatever you might want to consider going to. You can then figure a rough number of years to break even on your investment.

A lot of folks will bad mouth a 305 but one in good shape is a good motor for a daily driver commute vehicle.

As for cold/hot starts, my carb equipped truck starts just fine if it is 100+ or below 0F. Just make sure the choke is adjusted properly, the exhaust riser valve(if equipped) is still working, your THERMAC system is present and working and the PVC system works. A lot of folks take those off and install and open air cleaner, "to make more power", then wonder why their vehicle sucks as an all weather daily driver.

305 feels strong-pretty sure it has 157k miles and carb hasn't been rebuilt. I just bought it monday so no idea on the mpg yet. I'm ignorant due to lack of experience with carbs-I'm not afraid of them at all-I just find it weird that I have to pedal the truck 4-5 times for it to crank in the morning and it's 50* outside or is that normal? (again, remember my lack of experience here). truck still has egr and all vacuum system to my knowledge.

[daddyjeep]

Alright Casedmetal, since you are obviously very familiar with EFI this seems like a no brainer to me. They don't put carbs in vehicles any more for a reason. I agree with a couple of the previous comments that a properly tuned carb that is not worn out works just fine even in the cold. A carb, no matter how good it is, can not compete with fuel injection for cold starts. I changed my Jeep to TBI years ago and it was the best thing I could have done to it, well before I changed it to a MPFI V8, now that is the best thing. If you are considering the FAST system you should probably strongly consider a 5.3 swap for the same money, maybe less. That was the mistake I made with the Jeep. I spent a bunch of money on the Howell TBI system and should have just went with a more modern V8 powerplant from the start. I had half the money in my V8 swap than I did upgrading the old I6.

[Oberon67]

Originally Posted by daddyjeep

They don't put carbs in vehicles any more for a reason.

Two reasons, actually: Fuel economy and emissions.

[Tom]

Originally Posted by Oberon67

Two reasons, actually: Fuel economy and emissions.

And performance. And adapability. No jets to change when you go up 10,000ft mountains. No carb'd engine is going to be running the 10:1+ compressions we run these days as it requires knock sensors and constant fine tuning to adjust everything.

Its like this: carbs are simple and easy to adjust. They work.
EFI is more cost and setup, but then it always just works, really well.

[Oberon67]

Originally Posted by Tom

And performance. And adapability. No jets to change when you go up 10,000ft mountains. No carb'd engine is going to be running the 10:1+ compressions we run these days as it requires knock sensors and constant fine tuning to adjust everything.

Yes, those are indeed advantages, but Detroit in the 1970s and '80s would never have adopted EFI across the board just for that. It took the government strong-arming them through regulation to force the move to EFI systems.

[Dead Parrot]

Originally Posted by Oberon67

Yes, those are indeed advantages, but Detroit in the 1970s and '80s would never have adopted EFI across the board just for that. It took the government strong-arming them through regulation to force the move to EFI systems.

Another consideration is the 'EFI computers' in the 70's were little more then basic logic chips and discrete transistors. And they were expensive to produce. Today, a computer that can make hundreds of adjustments per second to a multi port EFI system while reading the results in real time can be made for a few dollars in the quantity the auto makers order them in.


As for having to pedal it several times, choke may be out of adjustment. Check it before starting in the morning when it is still cool. Should be closed or nearly so.

[encasedmetal]

Originally Posted by daddyjeep

Alright Casedmetal, since you are obviously very familiar with EFI this seems like a no brainer to me. They don't put carbs in vehicles any more for a reason. I agree with a couple of the previous comments that a properly tuned carb that is not worn out works just fine even in the cold. A carb, no matter how good it is, can not compete with fuel injection for cold starts. I changed my Jeep to TBI years ago and it was the best thing I could have done to it, well before I changed it to a MPFI V8, now that is the best thing. If you are considering the FAST system you should probably strongly consider a 5.3 swap for the same money, maybe less. That was the mistake I made with the Jeep. I spent a bunch of money on the Howell TBI system and should have just went with a more modern V8 powerplant from the start. I had half the money in my V8 swap than I did upgrading the old I6.

I totally understand where you're coming from with the doing it right and not spending the money twice part. My apprehension there stems from time of install (it is my daily) and all the little conversion parts needed for the swap add up quick. a 5.3 motor is cheap, but the rest needed for the swap ain't. hmmm...

[Oberon67]

I have always preferred manual-choke systems because the automatic chokes add complexity, and because I'm kind of a control freak... I prefer manual transmissions for the same reason.

But, yeah, given a carb and a working choke, most any Chevy can be made to start. You just have to know what you're doing, and there was a time when it was common knowledge.

[tucsonjwt]

To clarify, a carburetor in good condition will start in any weather, but EFI will start quicker and run better during the first few blocks due to much better fuel control and computer assist.

I had a long conversation on the phone with an east coast Qjet rebuilder and he told me that a routinely driven carburetor will not need adjustment or rebuild. Most of the problems he sees are from hobby vehicles or boats which are driven rarely and load up with gunk.

However, I still think a manual choke is the best option for any vehicle with a carburetor, so you can control air/fuel mixture yourself, based on engine performance.

Having said that, if I had $5K laying around I would still go with a 5.3 in a late model truck. As stated above, I think I have had 8 new vehicles with a 5.3 engine and they are nice, but not trouble free. We are still driving 30+ year old trucks and a 5.3 engine does not make them new trucks. I applaud anyone who wants to do the swap, but I just think that this is a job for someone who is really into old squares, has a lot of skill, and does not have to worry about emissions laws in their state (AZ considers engine swaps "tampering" with original vehicle equipment. Others posting here say they can get through emissions with a late model engine, but when you call the AZ
DMV you get a different story.)

[Firebirdjones]

We don't have any testing at all in Prescott (Yavapai) but Maricopa and Pima does (Phoenix and Tucson) One of the big reasons I bought a house up here.
However the late model engines do pass with emissions removed in those counties tested. All they are testing for as of right now is a simple OBDII plug in and scan of codes. Those codes can be switched to "no report" The car scans clean.

Right now, we don't have the goofy laws that California has in place that affect the retro engine swaps.

[EmeraldFlame]

I reccommend this Fitech EFI unit it will bolt onto the 4 barrel intake

http://www.summitracing.com/parts/fi...a7MaAgzr8P8HAQ

[RodsGreen10]

Originally Posted by EmeraldFlame

I reccommend this Fitech EFI unit it will bolt onto the 4 barrel intake

http://www.summitracing.com/parts/fi...a7MaAgzr8P8HAQ

I don't recommend the FiTech.

[RodsGreen10]

Originally Posted by EmeraldFlame

I reccommend this Fitech EFI unit it will bolt onto the 4 barrel intake

http://www.summitracing.com/parts/fi...a7MaAgzr8P8HAQ

I don't recommend the FiTech.

[68post]

The original and properly working induction system will work better and likely get better mileage than an aftermarket carb with an aluminum intake.

F.I. seems a large expense and more hassle than necessary for what now is a minor issue to solve.
A well sorted dual exhaust would probably gain more mileage than F.I. alone.