6 cyl swap
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6 cyl swap
I have a 78 4.9 that I am wanting to swap over to EFI. I HAVE A 94 donor truck with a 4.9 to rob the efi stuff off of. I know about the fuel delivery issues, but what else do I need to be aware of. Has anyone ever done this and how difficult is it.
Thanks
Jeff
Thanks
Jeff
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From: Boise, Idaho
It's definitely been done before.
Things you'll need to be aware of:
The heads are different. The EFI is set up for a fast burn. You'll most likely want to stay with the EFI's head.
The fuel pumps are different. The carb has a low psi fuel pump on the block (you'll need a block off plate for it), and the EFI has a high psi fuel pump in the gas tank.
The EFI block has 16 bolt holes for the split manifolds whereas the carb block has 13 bolt holes. DO NOT drill extra holes (there are water jackets behind them). Just skip the 3 extra bolts, they were mainly there to increase installation speed in the factory and aren't necessary.
Other than that, it's just all the bolt ons, oxygen sensor, and your fuel computer.
There might be one or two other things, but that's about it.
Things you'll need to be aware of:
The heads are different. The EFI is set up for a fast burn. You'll most likely want to stay with the EFI's head.
The fuel pumps are different. The carb has a low psi fuel pump on the block (you'll need a block off plate for it), and the EFI has a high psi fuel pump in the gas tank.
The EFI block has 16 bolt holes for the split manifolds whereas the carb block has 13 bolt holes. DO NOT drill extra holes (there are water jackets behind them). Just skip the 3 extra bolts, they were mainly there to increase installation speed in the factory and aren't necessary.
Other than that, it's just all the bolt ons, oxygen sensor, and your fuel computer.
There might be one or two other things, but that's about it.
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More HP, better starting, better driveability, last longer (no running rich on start up to wash down the cylinder walls, the main reason you can put 200,000 plus miles on a gas burner today.) When I was a kid people couldn't believe it if you got 100,000 on a engine
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From: Boise, Idaho
The carb 300 is known for going hundreds of thousands of miles. Many have 300,000 - 500,000 miles on them. That's not an issue.
I can understand about the rest though (although some would say its negligible), except for more HP. Do a little work on the carb version and you can easily get more HP than the EFI.
I can understand about the rest though (although some would say its negligible), except for more HP. Do a little work on the carb version and you can easily get more HP than the EFI.
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
The carb 300 is known for going hundreds of thousands of miles. Many have 300,000 - 500,000 miles on them. That's not an issue.
I can understand about the rest though (although some would say its negligible), except for more HP. Do a little work on the carb version and you can easily get more HP than the EFI.
I can understand about the rest though (although some would say its negligible), except for more HP. Do a little work on the carb version and you can easily get more HP than the EFI.
Post Fiend
Joined: Jan 2007
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From: Almost Heaven
The carb 300 is known for going hundreds of thousands of miles. Many have 300,000 - 500,000 miles on them. That's not an issue.
I can understand about the rest though (although some would say its negligible), except for more HP. Do a little work on the carb version and you can easily get more HP than the EFI.
I can understand about the rest though (although some would say its negligible), except for more HP. Do a little work on the carb version and you can easily get more HP than the EFI.
You can easily build a carb'd 300 to make good power. Why don't you yank the motor and build it, even mildly? Cam, headers, 4BBL, that kind of thing? Col Flashman claims to push out 300 horse, 400 foot lbs and get rediculously good fuel mileage to boot.
I'd love to have a built 300 in my truck. Sorry, but the EFI's 145 horse is just unimpressive and doesn't merrit not being able to build the motor for more power without really diving into your savings.
My opinion, which you didn't ask for; Keep the Carb and build it for more power!
It's worth noting the EFI version doesn't have the low end grunt the carb'd does.
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Talk about diping into savings. What would it cost to build one like Col. Flashmans. I have a 94 donor truck setting in the driveway that I gave 100 dolllars for. I plan on using all of the parts off of it that I can. Fellows I am not a kid anymore the HP thing dont impress me like it used to. The heaviest thing I pull with this truck (other than my sorry old butt) is a 14' john boat. I don't want to buy all the carb. go fast make big HP goodies. 4 Bl intake + holley 390 + cam + headers = more than I want to spend. I guess when you get right down to it I am just a tight wad.
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From: Boise, Idaho
Col. Flashman's engine was an extreme example of what is possible. His was a fresh from the start fully built, while being fully rebuilt, by a professional and was, I *think* about $4500.
I put a 4bbl, intake, and full exhaust on mine from engine to tailpipe including exhaust manifolds for about $800. Keep in mind that included things like a new cat, muffler, exhaust piping, and other stuff that's just regular lifetime of a truck maintenance.
However, in your case, it sounds like the EFI will do just what you need and you have it sitting in front of you. I'd probably go ahead with the EFI swap. With that in mind though, hopefully all the sensors and stuff are in good condition or you'll be putting money into it again pretty soon to get it to run right.
You will also have to do some exhaust work since the EFI uses a split manifold setup and the carb uses a single.
I put a 4bbl, intake, and full exhaust on mine from engine to tailpipe including exhaust manifolds for about $800. Keep in mind that included things like a new cat, muffler, exhaust piping, and other stuff that's just regular lifetime of a truck maintenance.
However, in your case, it sounds like the EFI will do just what you need and you have it sitting in front of you. I'd probably go ahead with the EFI swap. With that in mind though, hopefully all the sensors and stuff are in good condition or you'll be putting money into it again pretty soon to get it to run right.
You will also have to do some exhaust work since the EFI uses a split manifold setup and the carb uses a single.
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