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Contemplating a new engine conversion

Richard Cranium

FBBO Gold Member
FBBO Gold Member
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6:00 PM
Feb 20, 2012
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As the title says, I'm thinking about a new project with a modern engine & transmission in a 68-70 or (possibly a 64-65) B-body. I have very good mechanical skills & can take a B-body completely apart rebuild everything & put it back together, but I have very little fabrication skills. My thoughts would be to take a (basically) done car and do the conversion. I understand that there are a number of retrofit components available for a 5.7 conversion and I have local sources available to get PS & A/c hoses, driveshaft & exhaust made, but is there enough parts available to make this a bolt in project for a person with abilities such as mine?

Also, how much of an issue are the electronics to hook up and make the dash gauges and speedometer work?

Lastly, equally as important; how much can one expect to spend on something like this?

Thanks in advance!
I'm doing a 5.7 with 5 speed auto in a 72 Challenger. My first conversion. I'm using a Hot Wire harness and computer. The dash interface was a big concern. I went with a Dakota Digital cluster and their interface module which so far has made it pretty easy. Also had to build a new tunnel for the transmission. Using a Vintage Air setup too which gave me a lot more room. TTI headers and exhaust.
You shouldn't have any real problems doing it with your skills and knowledge. I'm sure people with more experience with chime in.

I’m also in MA and planning a hellcat swap for my 68’ GTX.
Depending on what year and body you have there are possibly many parts available to make it a mostly bolt in affair.

Holly and a few others make engine mounts, trans mounts, headers and EMS systems.
RMS and a few others can do k-members set up for proper placement of the motor.
A 5-speed Tremec fits most tunnels with little modification if you purchase it with the correct components. (Shifter, bell housing, etc)
A 6-speed, NAG or a few of the other big automatics take more work to fit from what I have seen.
727s are also an option.

As mentioned above using Dakota Digital gauges and and vintage air are also good ways to make it a PnP job if they are available for your model/body.

I will admit that I haven’t physically started my project yet but I think a lot of it is in the planning. Educate yourself and have a good game plan/parts list before you start. That is typical the case with anything in life though.

I’ve been building cars for 25 years and from what I see new hemi swaps are very well documented and supported in the aftermarket these days.
You shouldn’t have much of a problem.
The only thing that will make it more of a challenge is a pre-68’ model year B-body.

My car is a mostly matching number 68’GTX which needs a resto and I don’t know that I care to go to the lengths to make it an original resto.
My other option is sell that car and buy my other favorite which is a 67’ coronet R/T to put the new drivetrain in. The problem with that is there is less aftermarket support for that car than the 68-70 B-body.

What car are you thinking of doing this swap in?
I have a reasonably priced (done) 64 Belvedere wagon available that currently has a 440 & automatic transmission.
That would be cool. A few years ago a couple of old guys drove 200 miles to pickup some parts from me. I was surprised to see them drive up in a 63 Belvedere 4-dr with a 6.1 Hemi.
My doing the Challenger for a friend. Myself I would do a 6.4 in my car.

I'd be looking at just making a nice long range cruising car. The 5.7 I had in my 2010 Challenger had 375 hp & is probably as fast/faster than a stock 440 & still got decent enough fuel mileage.
Good luck with the project! I did same in my 68 and it was worth the effort.
Hardest part for me was figuring out the transmission control and getting it to work properly.
But today it starts, drives, and runs fantastic and gets much better gas mileage that my old 2 barrel 318 and 904 auto ever did!
I was actually able to convert the factory slipstick shifter to a cable shifter for the 5-spd keeping the original console and look.
It's a classic at this point and had a goal of using as much OEM as possible at the onset - read @Darius posts on his conversion journey.
Lots of bolt in parts now that he didn't have available back then, but it's a great read if you want a deep dive
Sound German automotive is your source for auto trans electronics
I think the manual is easier in that less fabrication is required plus there isn't any issues with having to tune the trans. I am putting a crate 5.7 into my 71 Charger, using the stock K frame and suspension but I am using TTI mounts (so that they work with the headers), I am using a Holley mid plate and oil pan as well as a harness and ECU. For a trans I am using a TKX kit that has everything to include the shifter. The majority of this is plug and play without much fabrication at all. I am going to use a Hydroboost brake system and have Wilwoods on all 4 corners. I am making the HB system using a Cummins system. I am going to be running an aluminum radiator but using modern Challenger electric fans.

Point here is that today you can transplant a modern engine into an old car without a lot of fabrication required. EDIT: I meant to add that while it is certainly possible to swap in a modern drive train, it definitely is not cheap. Long gone are the days of dropping in a 440 where a 318 had once been for very little money. That said and IMO the swap is worth the cost and the effort, you get essentially a modern car that looks like an old car (which you love).
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I will do a build thread on here once I begin work on the car, unfortunately I have been building 2 other cars for friends and recently was given a 85 MR2 that I spent some time getting running again. I have been acquiring parts and have most of what I want/need, so hopefully it will go relatively quickly once I get started.
Depends on the transmission. A TKO 5-spd needs a little tunnel work. A T56 6-spd needs a new tunnel and T/Bar cross member mods. I don't know what the TKX needs.
Supposedly the TKX requires little to no tunnel work, part of the reason they developed it. We will see since i am putting one into my 71 as well as a 70 RR.
My 65, I believe needed tunnel work, but with the computer from the engine I can't help but think it would be easier to run the automatic rather than hung pedals and screw with all the parts needed to go stick. Mine has a truck 545rfe, 2005. I will check this out.
I hate the way they look honestly but I would consider putting one in an A-body to make a handling car.
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