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View Full Version : Carb to Fuel Injected????????


scottlippman
08-01-2009, 09:14 AM
Just curious. I've heard some people talk about how I could convert my 351 w/ Holley 4BBL to fuel injected. I believe they are misguided thinking this could be an easy and not too expensive project. Anyone support me on this??? Seems to me we'd have to replace quite a number of major parts. Comments and list of parts to be replaced would be appreciated. Thanks.

JimN
08-01-2009, 11:11 AM
It's not that hard but it's not all that cheap, either. Check a web site for Jeg's or Summit Racing to see that they have.

The MC/Indmar setup isn't made for Ford motors but the parts that are diiferent/additional for the earilier TBI system are:

ECM and its programming
Complete engine wiring harness
ECT (Engine Coolant Temperature) sender
TPS (Throttle Position Senser)
MAP (Manifold Absolute Pressure) sensor
Knock sensor
Distributor (Ignition Control Module is controlled by the ECM, to increase/decrease timing advance when needed and the IC Module provides RPM information to the ECM)

The multi-port system uses crank sensors for RPM info and an injector for each cylinder. The Newest versions use Oxygen sensors and catalytic converters and this would probably be prohibitively expensive.

GM Performance Parts makes crate motors that would be great for this and are complete, from all of the sensors, harness and ECM but they specifically exclude marine use from their warranty. I have seen some sites for engine suppliers that offer a 3 yr warranty on marine motors, though.

Hoosier Bob
08-01-2009, 11:16 AM
You may be able to go TBI for less and much less headache. I believe there are some nice bolton kits avaialble from Edelbrock and such. Keep your carb clean and spend the $$ on something else. If you have to, search compatible systems, Mustangs have a nice setup for the 302 and you may be able to fit. Should be a bolt on install. The GT Fords in the CC's were setup like this I believe. Find a mid 90's CC with the Ford that has been wrecked! Carbs rule!:D

thatsmrmastercraft
08-01-2009, 11:36 AM
Just curious. I've heard some people talk about how I could convert my 351 w/ Holley 4BBL to fuel injected. I believe they are misguided thinking this could be an easy and not too expensive project. Anyone support me on this??? Seems to me we'd have to replace quite a number of major parts. Comments and list of parts to be replaced would be appreciated. Thanks.

Here is the best priced kit that is rather straight forward on the installation. You don't need to be a certified mechanic - just be able to follow directions and have some basic knowledge.

Holley 502-20S - Holley Pro-Jection Fuel Injection Systems $979.9

Throttle Body Fuel Injection, Pro-Jection, Speed Density, 670 cfm, Ford Kit

http://www.summitracing.com/parts/HLY-502-20S/Application/?query=Make|FORD|CID|351|Engine+Family|Ford+small+ block+Windsor

jake
08-01-2009, 12:58 PM
This topic has been discussed a number of times in the past, you may want to search old threads. My two cents, I was considering the same move a couple years ago, but after doing some research on the pro-jection system from Holly (google Jeep off-road discussion boards) it seemed to be the general consensus that a clean well tuned carb is just as good as the projection. It's basically an electric carb, doesn't have many of the features of a true efi system that will bring the drive-ability benefits you are probably looking for.

I rebuilt my carb instead of converted, and with the exception of having to pump it twice when starting cold, I have turn key starts and very smooth idle. I don't think the holly projection system could perform any better.

My conclusion was, if you're going to make the switch, you should either be a mechanic that could do a retrofit of a true efi system you can piece together from used parts (the mustang system seems most common) which would be a great winter project and if you do, please post lots of pics and details along the way, or you might be better off selling your boat and investing a couple thousand extra in a newer model.

**Edit: if you do go forward with the pro-jection, be sure to look for the marine version. You need a return line to the fuel tank and a flame arrestor. The link above is for the street version.

http://www.holley.com/700-21.asp

east tx skier
08-01-2009, 01:16 PM
Keep any fuel that sits in your carb or fuel tank for longer than a week or so stabilized. That is, if you know you're going to have a layup longer than a week or two, stabilize whatever fuel is left in your tank before the last run so that whatever is in the carb is good to sit as well. If you can, during the winter, run the boat a few times and redrain each time. If not, run a little seafoam through the carb in the spring.

As long as you're not letting gas degrade in the carb, the thing will start and run great and you'll spend a lot less money. Really, just stabilizing the fuel is probably plenty with the rest being overkill.

EFI is great, but if you want it, sell your boat and buy one with EFI. It would be the cheaper and more trouble free way to go.

Cloaked
08-01-2009, 01:51 PM
Keep any fuel that sits in your carb or fuel tank for longer than a week or so stabilized. That is, if you know you're going to have a layup longer than a week or two, stabilize whatever fuel is left in your tank before the last run so that whatever is in the carb is good to sit as well. If you can, during the winter, run the boat a few times and redrain each time. If not, run a little seafoam through the carb in the spring.

As long as you're not letting gas degrade in the carb, the thing will start and run great and you'll spend a lot less money. Really, just stabilizing the fuel is probably plenty with the rest being overkill.

EFI is great, but if you want it, sell your boat and buy one with EFI. It would be the cheaper and more trouble free way to go.Word.

Good advice.

bigmac
08-01-2009, 01:54 PM
I suppose there's nothing wrong with a little SeaFoam in the tank every now and then, but it takes about 3 months for gasoline to undergo any meaningful oxidation.

Bert
08-01-2009, 02:12 PM
Keep any fuel that sits in your carb or fuel tank for longer than a week or so stabilized. That is, if you know you're going to have a layup longer than a week or two, stabilize whatever fuel is left in your tank before the last run so that whatever is in the carb is good to sit as well. If you can, during the winter, run the boat a few times and redrain each time. If not, run a little seafoam through the carb in the spring.

As long as you're not letting gas degrade in the carb, the thing will start and run great and you'll spend a lot less money. Really, just stabilizing the fuel is probably plenty with the rest being overkill.

EFI is great, but if you want it, sell your boat and buy one with EFI. It would be the cheaper and more trouble free way to go.

Good advice but.. all you need to do is stabilize the fuel when put away in the fall. That's all I do. Adding more often won't hurt any thing but is a waste of time. Fuel does not breakdown that quickly.
IMO TBI offers no advantage over a carb. Mine has never given me any trouble and starts fine and runns great from cold.

thatsmrmastercraft
08-01-2009, 03:32 PM
Marine Pro-Jection Throttle Body Injection Part #: 700-21

The Marine 670 CFM Pro–Jection 2D Throttle Body Injection system is designed for all carbureted V–8 engines up to 275HP. It Includes 85lb/hr injectors, Adjustable fuel pressure regulator preset to 21PSI, 12 volt electric marine fuel pump, Adapters for either spread bore or square bore intake manifolds, and the wiring harness is weather sealed and designed for plug and play installation.
Holley Marine Pro–Jection 2D Throttle Body Injection system for engines up to 275HP

Installation Notes
NO LAPTOP REQUIRED Will not support over 275HP Installs on square flange and spread bore intake manifolds. Make sure you have adequate hatch clearance. The overall height of the installed system is approximately 1 inch higher than a carburetor.


Features

* Complete stand-alone system which converts a carbureted engine to fuel injection
* For engine originally with out computer control
* Fantastic Throttle Response
* Greater Fuel Economy
* Increased Power
* Eliminate Fuel Problems
* Die Cast Alum Throttle Body
* Includes a stainless steel flame arrestor (5 3/4 x3)
* Digital 2D computer is rugged and reliable
* ECU provides adjustments for Idle, accelerator pump, main jet, high rpm jet, and choke
* Includes complete detailed installation instructions.

rcnjson
08-04-2009, 02:36 PM
I did the carb to efi conversion a few years ago. My main reason for the change is I don't like carbs. For a stock motor off the shelf carbs are fine and you can tune it fairly easily. When you get into jet changes the carbs is a real pain compared to the efi system.

I used a stand alone system that I bought used on ebay. With the efi system, a pump, and all the plumbing, I was done for under $500. I did it as a winter project so I had time to shop and source the parts. As a matter of fact, I was going a completly different route when I found the efi system that I am currently running. I bought all old ford truck parts and I was piecing together a factory system. Basically doing what everyone has mentioned using factory parts. I am going to use that stuff for another project, 351W powered ice auger or something like that.

Advantages... it rips, I have the only 1980 vintage fuel injected ski boat (factcheck.org), it will run upside-down - huge advantage.

Seriously though, if you are going to run a stock motor you should probably stick with a carb. You can use the weekend that you were going to do the conversion and go out on the boat.

Jason

mikeyg
08-12-2009, 01:15 PM
i have almost 100 hours on the boat this summer on a brand new carb from ski dim and I have to say, that damn thing runs and starts just like it were fuel injected. turn the key and about a half a crank and she fires right up. when putting the boat in for the day i give it one quick pump of the throttle and she fires. no need to rev up or anything. idles as smooth as silk.

kjohnson
08-14-2009, 01:06 PM
I'm not advocating changing your carb, but a friend of mine has a 94 with the throttle body fuel injection. It is much easier to start and you don't have to wait for it too warm up.

CantRepeat
08-14-2009, 03:30 PM
To me, those are the only benefits of TBI change over. No warm up time and no cold idle issues.

ROB
08-16-2009, 08:16 PM
More than double the cost of a brand new carb from Jegs. IMHO it's not worth the money. 3 minutes of warm up before you leave the dock/trailer. I love my new Holley and the boat is running great.

Laurel_Lake_Skier
08-20-2009, 02:40 PM
It is true that most carbureted engines will run better if given a few minutes to warm up......but that is actually a good thing for the rest of the engine. Putting the hammer down on a cold engine is pretty rough treatment for the most of the internal parts even though the engine seems to run fine with the fuel injection systems.