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Dual Quad EFI

acm

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Looking for advice on fuel injecting an engine with dual quads.
The engine will be a 421 AMC with 11:1 CR, mid-size roller with 240/250 ish @ 0.050" & low 0.600 lift and a cross ram. I'd consider the engine healthy but not radical.
Car is an old Rebel and will have a T10, 4.88's and weighs just under 3k and will be used mostly as a street toy that will see lots of strip use.
I'm hoping it will have some road manners but do not care about mileage at all.

I'm leaning towards a Holley Terminator due to the retro throttle bodies.
Yes, looks are important on this build. It would be easy to throw a PF4 on it and call it a day...probably would out perform the cross ram too! Really want the old 60's look on this one.

Any input on efi systems for dual quads would be appreciated, especially things that did not work.
TIA
 

acm

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Looked at FAST briefly & you're the only one I know running their stuff.
With the money you saved on a posi, would you mind putting a dual quad set up on the cone crusher and let me know how it works?

It's hard to get decent info off the net these days.
Seems most of the reviews/posts are from folks that should not be allowed to own a screwdriver let alone an aftermarket EFI system. The ancforum would have 50 replies on how I used the wrong thermostat housing and 1 detailed post about the details of how the processor works... don't care about either!

That's why I posted here. Much better chance of someone trying this already & brand of air pump shouldn't matter.
 

beags86

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Well I don't have anything I can add about real world experience with the dual Throttle body's.

I could Google search but I would get the same hits as you.
Funny you say that. My dream for the cone crusher is to run a big inch aluminum small block efi, dressed like a trans am car from the 60s.
Meaning a small block cross ram with two Throttle bodies.
So I am pretty interested to see how this turns out. I have actually toyed with the idea of just tossing it on my car this winter. I can build the engine later.
Quite honestly I think its a kinda a no Brainer. Since the efi will do your adjustments for you, I think you could toss it on and go.
 

acm

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Meaning a small block cross ram with two Throttle bodies.

Pretty much what I'm talking about.
Most of this will be made from spare parts.
Have a 3.8" stroke crankshaft set up for ls style rods, a spare 401 block or two, Edelbrock heads, a T10 set up, a cross ram, 4:56 gears and a bunch of other extra parts hiding around here somewhere.
Only things I'm missing are pistons, new clutch and some sort of fuel delivery system.

I have actually toyed with the idea of just tossing it on my car this winter. I can build the engine later.

I have thought about throwing the cross ram in the car how it sits too.
Only matching carbs I have are Holley 850dp's... think that would be too much for the stock 290?
Also have a mock up motor that might get thrown in while I figure the other 1 out.

20200722_160825.jpg

Quite honestly I think its a kinda a no Brainer. Since the efi will do your adjustments for you, I think you could toss it on and go.

That's what I'd hope but doubt it's that easy. Not sure if the Chevy cross ram is similar to the AMC but the AMC sure has a ton of volume to it, It makes tuning carbs on a street application a bit more challenging.

Also, hoping to keep the car where it is a sway bar & coil over swap to go back to smashing cones when needed.
 

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I'm not worried about plenum volume, I am worried about fuel atomization. How will the fuel carry from the tbi injectors around the curves of the cross ram?

A quick study tell me that its the idea probably isn't great. Cross rams didn't stick around a real long amount of time.
Then gm released that crappy crossfire injection. That didn't stay around long.

But if it runs decent enough I would keep it.

Did you finally pony up the money for motor trend? There is an episode of engine masters that they do some plenum Volume testing.
 

acm

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The injector should take care of the atomization (still have to keep the fuel suspended with the air though).

For the most parts the crossram divides the engine into two halves.
Pretty straight shots to the ports on the AMC one, but the major issue is the large dead area in the middle which will kill atomization, velocity and a bunch of other technical things.
My though is to build a block to fill in this area or to mount an injector on the bottom side for each port, depending how it run.

Anyway, the cross rams are for looks only. Good single plane intake out performs it every time.
Could have the best of both worlds and print an air cleaner assembly that looks like a cross ram set up...:thinking:
 

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Pretty much what I'm talking about.
Most of this will be made from spare parts.
Have a 3.8" stroke crankshaft set up for ls style rods, a spare 401 block or two, Edelbrock heads, a T10 set up, a cross ram, 4:56 gears and a bunch of other extra parts hiding around here somewhere.
Only things I'm missing are pistons, new clutch and some sort of fuel delivery system.



I have thought about throwing the cross ram in the car how it sits too.
Only matching carbs I have are Holley 850dp's... think that would be too much for the stock 290?
Also have a mock up motor that might get thrown in while I figure the other 1 out.

View attachment 346823



That's what I'd hope but doubt it's that easy. Not sure if the Chevy cross ram is similar to the AMC but the AMC sure has a ton of volume to it, It makes tuning carbs on a street application a bit more challenging.

Also, hoping to keep the car where it is a sway bar & coil over swap to go back to smashing cones when needed.
The injector should take care of the atomization (still have to keep the fuel suspended with the air though).

For the most parts the crossram divides the engine into two halves.
Pretty straight shots to the ports on the AMC one, but the major issue is the large dead area in the middle which will kill atomization, velocity and a bunch of other technical things.
My though is to build a block to fill in this area or to mount an injector on the bottom side for each port, depending how it run.

Anyway, the cross rams are for looks only. Good single plane intake out performs it every time.
Could have the best of both worlds and print an air cleaner assembly that looks like a cross ram set up...:thinking:
Or.... how about one of those cross rams that opens into two. You mount a tbi unit inside. And then have two fake carbs on top?

I've actually seen this done with an 871 blower.
Pointless as hell. Lol.


What about a port injection with some nozzles by the intake ports? Just use the cross ram for air?
 
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beags86

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Anyway. Back to legit engine talk. I would think any block might slow down the air speed enough to cause the droplets to fall out of the air?
I would think some sort of runner setup would be more of the route to go.
 
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acm

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Here's a couple shots of the manifold.
20200722_160825.jpg

20200722_213752.jpg
20200722_213902.jpg
20200722_213906.jpg 20200722_214054.jpg
20200722_214102.jpg

Pics aren't great or in any order but you get the idea.
Room to add stuff is limited and the bag of bolts in the back part of the plenum is a rare factory secret...
I like the article for the port injection. I looked at doing something similar but I'm to cheap to cut up a 2k intake and this is a re-pop.

20200719_190209.jpg
 

acm

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Honestly I would be tempted to pop on the dual Throttle bodys and run it. I bet it would run fine.

Very funny... I agree dual throttle bodies are the way to go and now we are back to the OP.
Which system to use???

Have you used the FAST system on an engine with a healthy cam?
Can you use a laptop or is it just a hand held tuning unit?
Spoke a little with Heath, he suggested the a specific Holley set up... just can't remember which one (this old age bit blows!)
 

beags86

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You got the lsa of your cam?
Efi likes no more then 110 lsa. 112-118 being better.

No , I haven't used it with a healthy cam. The chevelle has a decent cam in it. But i don't have a cam card. And I don't know the exact specs.
But my ear says it's not a slouch.

I guess it comes down to budget to. If your unlimited budget i think the holley is the way to go.
For me I can add a ez efi Throttle body for 600 bucks. I am sure when I do mine thats what I'll be limited to with two kids Going to day care.

Anyway I would probably guess heath told you to use the terminator kit. You can even get the TB in gold to look like a carb.
Screenshot_20200723-092613_Chrome.jpg


Here's another write up to read on the terminator system.

https://www.efisystempro.com/efi-pro-hangout/building-twin-4bbl-throttle-body-engine

Seems that staying away from the sniper is probably the best idea.

(Oh yeah, the twin tb kit i showed there isn't available from holley thats a third party putting that together. )
 
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acm

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Definitely staying away from the Sniper line. Chanook stuff...
The Term X & Dom lines are supposed to be made in the good ole USofA!!!
& look at what Holley just released.
Screenshot_2020-07-23 Holley.png
With the gold throttle bodies, in the famous words of @max 02, it'd look tits!!!
I looked at the kit you linked. Pretty cool stuff.

As far as the cam goes. Don't have one yet for this motor. Still need to port the heads, get some data from that and then get a cam ground. Nice thing with the crazy off brand engine is the .904" lobes. You can do some pretty steep ramps and still keep the valve train somewhat happy.

I am thinking about throwing the cross ram, headers and a fuel system on the 290 to work out the kinks before dropping in a real motor.
The trunk is rusty, so big hole for an EFI cell should work nicely.
Not real sure that the headers I have will clear the suspension. Which will suck because they were too pricey to be shelf art.
It would also be nice to see if the hood will close after all the shenanigans...
 

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Definitely staying away from the Sniper line. Chanook stuff...
The Term X & Dom lines are supposed to be made in the good ole USofA!!!
& look at what Holley just released.
View attachment 346874
With the gold throttle bodies, in the famous words of @max 02, it'd look tits!!!
I looked at the kit you linked. Pretty cool stuff.

As far as the cam goes. Don't have one yet for this motor. Still need to port the heads, get some data from that and then get a cam ground. Nice thing with the crazy off brand engine is the .904" lobes. You can do some pretty steep ramps and still keep the valve train somewhat happy.

I am thinking about throwing the cross ram, headers and a fuel system on the 290 to work out the kinks before dropping in a real motor.
The trunk is rusty, so big hole for an EFI cell should work nicely.
Not real sure that the headers I have will clear the suspension. Which will suck because they were too pricey to be shelf art.
It would also be nice to see if the hood will close after all the shenanigans...
This that car will all that fancy schedule 40 pipe suspension?
 
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