74 Challenger EFI and.... Oh yeah Twins

[YellowThumper]

Been enjoying following some real nice build threads here for awhile now. Have my own build going so I will post it up.
History is I have owned this since 84. California car and has been garaged most of its life.
About 3 years into this iteration so there are many details that I will condense and propagate thread getting it up to date.

The car in current state with custom offset and widened rallye's. 15x7 front and 15x8.5 with 275s on rear.


Mike

[RAPIDRICK]

looking forward to this

[YellowThumper]

Car started life as a base model 318/3spd stick with power nothing.
Did not even have a front sway bar.
Over the years I added hood, fender louvers, front and rear sway bars, power brakes, power steering, 360, 4 speed with pistol grip.
Most all of the build has commenced to a degree.
All changes designed and built so the there is no hacking up of car.
Also doing it in stages to keep down time minimal. Change something, mockup something then take it off and put back together to drive.

Current tired 360 will get replaced when it destructs (planning ahead lol) with an Eddy headed 5.9 Magnum.

Converted front accessories to Magnum. Made custom low mount p/s pump bracket.


Modified idler bracket.  Not pretty but functional.


Reason for Magnum accessories is that everything mounts closer to engine to provide more room. Water pump is also 2 inches shorter.

Mike

[YellowThumper]

Converted the Mopar M1 manifold with port injection by drilling in the LA style angled mounting bolt holes.


Because all the new holes are next to existing posts it required the use of thick and notched spacers.



Mike

[YellowThumper]

Converted vacuum brakes to hydroboost unit from later model Mustang. Suprisingly simple. Made an adapter plate that utilizes the factory firewall holes.


Extra hose teed onto existing return line.


Mike

[YellowThumper]

Battery was relocated to trunk.
Relocated starter relay and associated items by making wire extensions and moving them forward closer to the core support.


Mounting box to hold relocated items and fan controller. It gets a top cover plate to hide everything.


Added a jy fuse and relay box. Currently for electric fans and eventually for headlight conversion.


Actually tucks in neetly.


Also moved wiring down to the frame rail to clean things up.


Mike

[roadman5312]

              Awesome work your doing.     I'm watchin this one.   

[YellowThumper]

              Awesome work your doing.     I'm watchin this one.   

Thank you. Lots more to update to get current.
Speaking of...

Here are some pictures in various stages of turbo mockups.
Spare Magnum being used that will eventually make it between frame rails replacing the la.
Turbos are fairly close to final locations. They are symmetrical in the car. Motor is offset. You can also see the 36-1 crank wheel and custom p/s pump bracket.



Early stages with them in car establishing required locations. This was prior to Magnum accessory modification. Headers are all together and about 80% welded. Mandrel bent ss pieces. 1/2" thick flanges. Water jet cut and machined cleaning them up.


Oil pan also has drain bungs added.



Purchased 2 intercoolers and promptly cut their tanks off to make custom ones.


The odd shaping was necessary so they fit in car without cutting it. They mount in front of core support but load in from the rear through radiator opening. Upper and lower piping passes through opening to engine side.


All mounting brackets utilize existing holes.




Mike.

[YellowThumper]

To further clean up bay for more room I removed washer tank and fuel breather canister.


In this view I just tucked line through access plate bud did not like the look. Not pictured I made a new forward section connected underneath and routed it into inside fender well so it cannot be seen. I then added a 180 deg bend up top so open end faces downward and added a fuel filter. This will allow it to breath and also keep out unwanted debris.


I moved the radiator off of the core support towards the motor 2-1/2 inches. More room was available between core support and motor because of the shorter Magnum accessories. This relocation allows the intercooler piping to pass through opening. I also sandwiched an A/C in there. The fabricated mounting brackets utilize the existing rad mounting holes. Radiator sits in a cushioned lower bracket and is cradled by two top caps.

Start of lower portion


Lower unpainted area gets a thick cushion pad. Small bracket farther up is what holds the a/c condenser.


Start of the upper cradle pieces.


Spacer brackets with intercooler outlet showing.


Top view assembled


All cleaned up and painted.


There is a nylon bushing to hold radiator and provide cushion. The intercoolers are temporarily capped off.


Currently using a Chrysler dual fan setup. Having issues with temp controllers so eventually they will be replaced with a custom setup. But they work for now to get me to the end goal.


Mike.

[YellowThumper]

Converted to electric fuel pump with a return line. Magnum front cover has no provision for mechanical fuel pump so regardless I had to convert.
Bent  a 3/8 ss line that loosely follows the original ones path. Currently using the original 5/16 line as the feed with the 3/8 being the return. Eventually when I am ready to squeeze more I will eliminate the small one and add another larger line to handle the flow. That will happen when I convert to an in tank setup.

Bent line. Ss is tough so I also made my own bender for it.




The hanger for fuel pump and filter. Utilizes 2 screw holes and hangs down to be relatively flush to bottom of tank.  In between rear pumpkin and gas tank. Strapped with thick foam to minimize noise and vibration.

Modified sending unit for return line.




This is all you see from behind.


Looking from the ground up.


Regulator has provisions for both the low pressure carb and high pressure efi requirements with just a spring change. It currently is a running driving setup with all the hardware and plumbing required for efi but runs with a carburetor until I add Megasquirt.



Mike.

[msbaugh]

How was the converstion from the slant 6 3 speed stick to 4 speed? Is the floor hump/ shifter location and everything the same dimensions? Doing the same on a 70 challenger but will be a BB

[Joe mama]

That's a great project you have going. It's is gonna be a blast to drive!.

[brads70]

Cool stuff! 

[YellowThumper]

How was the converstion from the slant 6 3 speed stick to 4 speed? Is the floor hump/ shifter location and everything the same dimensions? Doing the same on a 70 challenger but will be a BB

Car was originally a 318/3spd. FYI the /6 was no longer available in the later years. Conversion was no issue for the hump. If I recall correctly drive shaft is the same length also. Just be sure it is correct tail shaft for the Ebody with shifter mounting on tail end.

That's a great project you have going. It's is gonna be a blast to drive!.

Definitely the plan. Something that can do some scorching and be more reliable and convenient to drive.

Cool stuff! 

Thanks but will never reach your cool level.

Mike

[YellowThumper]

Turned up some ss pipe to fab an upper radiator hose.


Welded together with some bends to meander next to and around air compressor and under injector rails.


Made a custom thermostat housing. I have since removed the "Made in China" writing.
Housing on the right is what I started with but quickly shot it down.


Top view. Did not want to go over accessories because hose would become the highest point and cause an air trap.



Making a custom plenum to adapt a Ford dual hole throttle body to a 4150 mounting.

Machined the baseplate


Rolled and bent some plate.


Machined a faceplate. Upper body and faceplate has been fully welded since this picture. Still needs Final weld to baseplate.


Mounts sideways.



Upper cold pipe(s) will route like this.


The two 2-1/2" diameter pipes leaving the intercoolers merge into a single 3" main. The bend was split down the middle and spread out so it fits the tb. Obviously will be adding some filler pieces. I am still undecided on how to connect it to seal. Leaning on some plates that sandwich an o-ring to compress it into the throttle body. Initial intention was to use a silicone adapter but would have taken up too much room.


More to follow. It really has become an obsession.
Mike.