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Discussion Starter · #1 ·
Hello,

I just wanted to see what the popular consensus is for using a single plane intake vs dual plane intake for a multiport EFI conversion. The engine is a 390 FE engine. I confess I am a little confused by what I read and what has been used in production on some stock EFI cars. If you'll indulge me; the popular opinion is that the dual plane intake for carb or EFI is better for regular street use. OK I can see the benefit for a daily driver. But this seems to be at variance to what GM used for their second gen small block, the LT1/4. We have a 1996 Impala SS and the intake has ~3 inch runners into a large open chamber and that's it. I would say it's as single plane as single plane gets. The car doesn't appear to suffer at the low RPM's. Now of course these cars are ~4300 lbs, come with a 3.08 rear axle gear and has the steep 1st and 2nd gear of the 4L60E transmission. So you can see it's hard to dismiss the use of a single plane intake with multiport for daily driver use if it seemingly works well in this application.

The other reason I went with a single plane intake with EFI ports is there is no dual plane intake offered for the FE with multiport injector ports. Sure it's possible to modify a dual plane intake, but not without a lot of work and skill.

The application this is going into is a 1966 galaxie 500 XL. It should be around 3800-3900 pounds, retains the factory gearing of 3.0 and its C6 transmission. It will be nicely optioned (PS, Power Ford 4 wheel disc brakes, PW, PL, factory AM-FM radio, etc) along with factory air con. Although an overdrive transmission will be in its near future when restoration/modification is completed.

The engine specifications are:

1.) ~396 cid (30 over 390)
2.) Edelbrock RPM aluminum heads (larger valves, medium riser ports)
3.) Rollerized valve train - Advertised Duration 286/290 Crane 349551
4.) Custom made Diamond Pistons 10.5: SCR
5.) FPA headers with 2.5" exhaust and cross over
6.) Multiport EFI with 43 lb injectors. Calculated gross horsepower @ sea level is just north of 500hp at 5600 RPM although that was with a dual plane and a carburetor.

Here's a few pictures of the intake and engine so far.

525660


525661


Pay no mind to the jar of shavings, this intake took a large amount of porting to gasket match.

525662


525663


Pardon the shop, it's a mess :(

This is where I am currently with it.

Thank you for your thoughts and time.

Cheers
 

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The intake isn’t going to bother much of anything in my opinion.

Mote of an issue will be trying to cruise at 15–1700 with that cam. As long as that isn’t your intention, then I’d say this looks like a real nice setup.

What are you using for engine management and spark control?
 

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Had an LT1 in my Willys and the torque curve was just about flat. Had gobs of torque right off idle. With multi port F.I. I think you would want each and every cylinder operating under the same conditions.

I would also like to know what you are using for engine management.
 

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Discussion Starter · #4 · (Edited)
Hello 64nailhead and 39 master,

Thank you for the responses I appreciate them. Interestingly this 390 is a near enough clone of another I previously built for our 1966 LTD. The only thing different about the previous 390 is the intake is a dual plane with a 750 vacuum secondary carburetor using a brand new Duraspark II distributor and I optimized the mechanical advance timing curve. Whilst the car isn't complete I did drive it through the subdivision and it was not lacking any low end torque that's for sure. In fact just under a half throttle stab off the line it spun both rear tyres very vigorously. Being a 1966 it's still a dual range transmission and you can put it in "open dot" drive and all that does is negate 1st gear, so it starts out under the load of second and it was still very peppy. Obviously I don't want to do that as I risk ballooning the rebuilt converter with the increased power levels. But it's night and day difference from the factory Y code 390. My only mistake was not putting fuel injection on from the get go. We are at 6500 feet MSL and our fuel quality available is really poor. In the heat of summer we have nothing but problems with anything carbureted, from the weed whacker to an automobile. Being this high up and with alcohol laden fuel you can watch it boil right in the carburetor on a hot day especially with the air con on. Fuel injection on an old car is really the only way to go for our needs.

Both of these 1966 Fords were originally Y code 390's. For those not familiar, the Y code 390 is the lowest power 390 you could have for a full size. It was the lowest compression, smallest duration and lift cam, single exhaust with a 2 jet that would struggle to crack a tyre loose sitting on wet leaves. It was just your run of the mill plebeian 60's/70's underpowered, underwhelming gas guzzling big block.

For a control system my back up plan is a MegaSquirt. But being an embedded system designer I want to try my hand at designing my own electronic system and firmware. I am piecing the fuel injection components together from examples I've noted in OEM production and of course what's available. Like I mentioned my only concern is the unequal runner length of the single plane. Now because the FE intake is so gosh darn wide interestingly the outer cylinders have the same length runner as a dual plane. It's just the inner cylinders come up a bit short.

Cheers
 

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I built a Megasquirt years ago and ran an LT1 with it. Of course batch fire was the only option so it was one bank then the other. The MS site had lots of info, so much so it was like drinking out of a firehose. Much info on size of injectors and duty cycle. Still have the MS unit.
 

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Discussion Starter · #7 ·
Thanks for the reply. Where are you from?

I'm fervant support of using an MS - very easy and pain free, especially for fuel only.

Good luck - Jim
Hello 64nailhead,

I am from the East Mountains of New Mexico. The MegaSquirt series doesn't look too bad at all to integrate. Of course eventually all our old cars will be getting an overdrive transmission, a 4L80E for the Chevrolet and for the old Fords either a 4L80E or 4R100/E4OD. That's why I am more interested in having a go at designing my own control system as I can integrate the transmission and other custom functions into one unit. I know you can use the CAN to talk to the GPIO board for MegaShift, but then it's getting like piecing a system together from Arduino components and looks like more like a science project than a professional automotive control system :)

Cheers!
 

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Discussion Starter · #8 ·
I built a Megasquirt years ago and ran an LT1 with it. Of course batch fire was the only option so it was one bank then the other. The MS site had lots of info, so much so it was like drinking out of a firehose. Much info on size of injectors and duty cycle. Still have the MS unit.
Hello 39 master,

Yuppers I on the MS unit. Now I do plan on sequential injection for the FE's. I haven't had time to experiment with the distributor yet, but the fall back plan for that is to design and produce either an inductive or capacitive clamp for #1 high tension lead. That's worse case, I would like to differentiate the timing pulse coming from magnetic impulse generator inside the dizzy for #1 cylinder. I bought some extra reluctor wheels to modify. The plan is to fatten up the ferrious non triggering side of #1 cylinder pole. I need to do testing on this idea to see if the signal is distinctly different enough under all operating conditions for the control system to tag #1 firing pulse reliably. Of course it goes without saying the mechanical and vacuum advance will be locked down and fixed so the ECU can control advance.

And to your point of an abundance of information on the MS site and forums, absolutely. I am drawing from that, factory service manuals and my own empirical experience working as a testing engineer for the big 3, Toyota and Class 8 truck companies (semis/lorries).

We shall see how I fair. :)

Cheers
 
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