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Holley HP EFI conversion

Old 04-14-2020, 09:04 PM
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Default Holley HP EFI conversion

I thought I would start a thread chronicling my conversion from carburetors to EFI. I never had a plan to go EFI it kind of just happened. I found some good deals here and there, purchased couple Holley HP units, EFI intakes, found throttle bodies and then Smitty (articfriends) hooked me up a great deal for injectors and EFI fuel pressure regulators. I am going to be replacing 2 flawless carburetor/intake setups that I have ran for almost 20 yrs. Custom Barry Grant that flow almost 900CFM and have spot on AFR reading throughout all throttle postions.

This might be a slow conversion so bear with me. This will be my first Holley EFI experience and might need to rely on the board for a little guidance. I've only worked with Haltech FX10 and the Fast EZ EFI 2.0. I'm just going to start out running multi port injection. I run Crane HI-6M ignitions currently and eventually would like to have the Holley unit control the timing.​​​​


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I bought 2-36" universal fuel rails and made injector bung holes. This was a 3 step drill process. Initial hole for fuel needed to be drilled, then hole for injector and O'ring to seat into, then a chamfer.
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Tapped the end of the rails for 1/2"NPT and a 1/4"NPT port for fuel pressure.

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Last edited by Rookie; 04-14-2020 at 09:07 PM.
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Old 04-14-2020, 09:10 PM
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This weekend i'm going to start placing sensors in the engine and start on the fuel delivery system.



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Old 04-15-2020, 07:17 AM
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Are you tying the two rails together or feeding them separately, nice work
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Old 04-15-2020, 07:33 AM
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Very nice work! EFI when done right is so nice.
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Old 04-15-2020, 08:56 AM
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Default Efi

Are you installing this in the Scarab, the boat that deserves to ride once again? The boat the world loves? Or in that other junk.
😃
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Old 04-15-2020, 05:39 PM
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Originally Posted by F-2 Speedy View Post
Are you tying the two rails together or feeding them separately, nice work
We can debate the merits of each. I was going to run the front rails from a "T" and join the rear rails together with the pressure regulator bypasses back to the tank/filter head. I've read quite a bit about it and at the end of the day the consensus was that it really doesn't matter.
Oh, BTW the drill bit for the injectors is a 17/32" bit, not really off the shelf at your Home Depot.


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Old 04-15-2020, 05:49 PM
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Originally Posted by RHudson1 View Post
Are you installing this in the Scarab, the boat that deserves to ride once again? The boat the world loves? Or in that other junk.
😃
Ouch! The Panther is getting love also. Just finished new power for that. Merc 420's with upgraded hydraulic roller 500EFI cams. Should be a great combination.
The EFI is going in the other... "junk"


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Old 04-16-2020, 09:22 PM
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Well today we shut down my plant due to a possible (+) Covid19 employee so I had half the day to work on my injection/manifold fuel system. I'm using taller injectors so I can not use the pre-drilled/tapped hole in the manifold. I 3D printed mounts that will connect to the base of the rail and side of the manifold. (carbon fiber reinforced material) All went well until I mounted the rail. I didn't realize the rail location was on a 10 angle to the mounting boss. There is a gap between the mount and where the screw would fasten to the manifold. If I tighten it down there I will push the injector rail forward and the injectors won't sit parallel in their holes. I'm going to have to print new mounts with matching 10 dog leg to match the manifold.
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Old 04-16-2020, 09:35 PM
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Next I spent a couple hours trying to figure out how to plumb the manifold. This did not go well, apparently everything is bigger than planned and took up a lot of space. The regulator will not fit on the back with a distributor inserted. After trying 30 different combinations I came up with mounting the regulator on the back rail and running the connecting fuel line through the middle of the manifold. I looked up my regulator and the spec's say 2 INs and 1 return OUT. (Smitty, can this regulator be used as 1 IN, 1 OUT and 1 Return OUT???) It would make a lot easier to mount the regulator next to the pump and filter.
https://www.racetronix.biz/product.asp?ic=reg-fi886bs
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Old 04-17-2020, 05:32 AM
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Take a look at an old Cutler system. It will show you an option to solve your problem.
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