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1970 Mustang Retromod - Boss 351

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I know I am getting the cart before the horse here, but I am comfortable enough that we will be pulling home the lucky rust bucket within the week.  I say "we" because this is going to be my son's build.  He is more into cars than I was at his age.  He has his favorites, but also has my sensibility.  His first choice was to build a 1965 Shelby GT350 clone.  1965 fastbacks in decent condition are hard to come by.  After that he wanted to jump into a 1969 Boss 429 clone.  The hardest part of that project was, again, finding the lucky pile of rust that would serve as the platform... and the $20k needed for a motor.  So he has gone to his 3rd option. 

In 1969 the Boss 302 was introduced.  The same year the 351W was introduced with the Mach 1 as a stop-gap measure until the 351C was introduced in 1970.  Had Ford been on its game, the Boss 351 would have began with the 1970 model as it should have given the absolute brute mentality of the engine.

So that is what he wants to do.  He wants to build a "what if Ford had gotten it right" 1970 Boss 351 Mustang.  We have it all planned out:

  • 1970 Fastback
  • Trunk mounted battery
  • Stock front disk brakes (manual, not power)
  • Borgenson power steering using manual linkage
  • Grabber Blue with Boss 302 style graphics (that obviously say Boss 351)
  • Blacked out taillight panel, decklid, and taillight bezels
  • Chin spoiler, decklid spoiler, and rear window louvers
  • Hood shaker but NO twist locks (he hates them)
  • A stout 351C motor (should be around 10:1 compression)
    • Stock block, crank, rods
    • Modifications to help more oil get to the right places - restrictors and lifter bushings
    • TFS Aluminum heads - 72cc chambers, 313cfm at .600 lift (painted blue of course)
    • TFS Roller Rockers
    • Howards hydraulic roller cam and lifters
    • Aluminum intake manifold (gotta figure which one works with the shaker)
    • Holley 650 with mechanical secondaries
    • Original style Boss 351 valve covers
    • Original distributor with Pertronix 2 module
    • FPA coated headers
  • David Kee Toploader - not sure about close or wide ratio yet
  • Detroit Locker TrueTrac, 31 spline, nodular case, 1350 u-joints, and unknown gear ratio
  • Hurst Shifter - hopefully an original 1970 OEM, but new aftermarket is available
  • Black interior, black carpet
  • We really want a gauge cluster with tachometer - might have to go aftermarket though

We are going to make it as much "stock" appearing as we can without obsessing over paint daubs and chalk marks.  Stock external voltage regulation.  We want to use a stock steering pump, but I am not sure if it will work with a Borgenson box.

We are going to go get the car on April 1.  It is incomplete, no motor or transmission.  Interior appears to be complete.  All the glass is there.  Only one piece of rear glass trim.

Buckle up!  This is gonna be wild!

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Love it. A Boss 351 in grabber blue has always been a dream of mine ('71 not '70 obviously)

Yours sounds like a great project. And you can enjoy all the car show folks who will tell you their buddy had an identical '70 Boss 351 back in high school...

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So the car we are building started life as an H-code Mach 1 built in San Jose in May of 1970.  Options on the list are:

  • Power Steering
  • Power Brakes
  • 4 speed transmission
  • 3.25 conventional rear end
  • Sport Deck rear seat (fold down)
  • Grabber Orange
  • Tinted glass

We will retain most of this in some fashion, but the color will be Grabber Blue unless I can convince the boy to do the orange.  It has collision damage to the passenger side which bent the rear axle housing and axles.  The first step is tear down, which wont start for a few weeks while I finish dad's 1969 Dart. Currently the plan is to replace most everything below the roof.  We have most if not all of the trim for the car.  We have a full interior (not the fold down though) except for the dash pad.  We need a windshield, but the rest of the glass is in great shape.  All in all, its going to be a heck of a project, and a heck of a lot of fun.

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I did score my first body panel off ebay.  Passenger side fender.  No rust, but a bit of damage that we will work out.  Its in an accessible area, so hammer and dolly it is.  I drove to central Michigan to get this panel.  The guy had a plethora of old cars.  1968 Cougar with a 428.  1988 Mustang with a 500+ stroker big block.  1967 Falcon with a 572 stroker big block.  1969 Mach 1 Q-code 428 car with 4 speed, 1968 SBF drag car.  And to top all of that off... a 1967 Fairlane with a 427 SOHC engine.  Was a really cool visit!


s-l1600 (1).jpg

s-l1600 (2).jpg

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So we haven’t been standing still, we just haven’t started on it.  Still finishing dads Dart.   I am collecting parts where I can. Mainly when I see a good deal on original parts.  I found a rear valence that needs some work but is in good shape.  I found a grille support bracket as well.  Finally, my Dynacorn floor came in!  Got a killer deal on eBay, and it shipped direct from Dynacorn.




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My dad had a 1969 Dodge Dart Swinger 340 back when he was a senior in high school and freshman in college. He sold it while in college to help pay for college. That was back in 1974. He loved that car, but knew he was better off getting his degree. His car had a 4 speed, bench front seat, signal indicators on the fenders, B5 Bright Blue Metallic with a white vinyl top - NO stripe.

Back in 1997 (I was 20) he wanted to get another car. He searched and searched, and the only one he could find that hadn’t been chopped up to be a race car was in South Carolina. We flew down there and purchased the car. It ran and drove, but the speedometer didn’t work and the gas gauge was stuck on empty. He bought it, and we drove it all the way back to Indiana that night. We timed ourselves between mile markers to keep speed. We stopped every 150 miles for gas. Made it home. It is a real Swinger 340 with a bench seat, 4 speed, T5 Copper Metallic with a white vinyl top and a white stripe. No signal indicators on the fenders. It has since been painted an awful orange, and has signs of body filler on the driver front fender and door.

That's the preamble.  The rest is over on the FABO forums.  Dad's 1969 Dodge Dart Swinger 340

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Okay, so we are knees deep in disassembly/teardown. The floor is gone.  The quarters are gone. The trunk is gone.  Rear seat support is gone.  Driver wheel well is gone.  Passenger front torque box is gone.  Passenger lower fireball (toe pan) is gone.  Passenger wheel well is crushed and will be gone.  Everything forward of the firewall is gone.  I’m going to have more new sheet metal than old on this thing, but I don’t care.  It’s fun as hell.

It was clearly wrecked in the passenger side.  What we didn’t know when we got it was that, previous to that, it was also wrecked on the driver side.  The whole rear driver body was held together with brazing.  That made a lot of parts that I was planning to save junk.  Actually, right now it’s just the driver wheel well that I’ve lost to brazing, but I have some brackets on there I want to try to save.  They cut out the old wheel well, leaving the flange, and slipped a new one in and brazed it.

I’ve started the frame jig.  I have those measurements. If anyone has any other measurements for other body parts that they’d like to share, I am happy to have all the help I can get!













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I’ve ordered a new cowl, new torque boxes, new apron assemblies and radiator support, new toe pans, new wheel wells.  The driver outer rocker is in good shape, just needs some repair at the very back of it.  Passenger outer rocker has some damage too, not sure if I can save it. I’d love to get some used parts that I can graft in.  B pillars are coming off to be repaired.  Inner cowl/kick panel area needs some help.  Outer cowl pods need patched up or replaced.  Firewall is in good shape.  Roof will need replaced. Roof crossmembers appear solid.  A pillars appear solid.

Man I love this stuff!

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Remember guys, I have a completely (mostly) unmolested 1970 fastback to get measurements and such off of.  I am not without a guide.  It is indeed more than I anticipated, but I genuinely look forward to it.

Yesterday we cleaned and piled up our scrap.  Going forward I hope to clean after each work session so we can maintain some level of clean.

Also, parts continue to roll in.




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All that scrap is gone, and we are close to starting to fit the floor.  This morning we removed the inner rockers (because new ones are included with the floor).  Both torque boxes are removed now as well.  We have some collision damage on the rear passenger rocker that I have to figure out.  It was pretty well smooshed.  If anyone has the back 12-18” of passenger rocker just kicking around someplace, I could use it.





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CJ Pony threw a wrench into things.  I ordered a 2 piece cowl setup (both upper and lower), but they now say they cannot get the lower, and may not ever get it again (I am guessing until they find another source).  They went ahead and send the upper, which I need to send back now.  Found NPD had them in stock, so ordered from there.  We are drilling out spot welds on the cowl while we wait.  The plan is to get the cowl off, then the outer cowl "pods," then the roof and quarter remnants.  We will brace the remaining with angle iron and drag it outside to sand blast and primer

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We have received the quarters, driver wheel well, roof, and strut brackets.  I THINK everything is now present to complete the unibody.

We drilled out the spot welds for the cowl last night.  It was interesting to find that where the 3 panels - upper cowl, lower cowl, and firewall - overlapped each other, they shared a single spot weld that could be released with a single drilling.  Made things a bit easier.

Tonight I am alone, and I plan to get the cowl pods off.  I THINK the passenger side inner panel is in good shape.  I already know the driver side is not.  If that doesnt take all night, I will continue to removing the rest of the quarter panels and getting the roof off.  At that point it will be time for media blast, so I will have to do some bracing.

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No recent pictures, but we are working on getting the floor jigged up.  I am not entirely satisfied with the floor assembly - it is missing rear jig holes.  There are supposed to be holes at the rear of the frame rails BEHIND the spring shackle mounts.  They arent there.  The other two sets of holes lined up well... except for my poor assumptions.  See the attached diagram.

I tried to set the height of the floor based on the points circled in yellow (for fun, the holes that are not there are circled in red, and you can see they are behind the spring shackle mounts).  There are two other sets that are considered the control points for the height, both labeled X.  Why didnt I use them?  Well, the front one has no direct or calculatable distance front to back.  It's just there for the height.  The diagram also makes it look like the front floor support and the front of the rear frame rail are at the same height and parallel to the ground.  The rears are the spring perch holes, which are harder to fasten (not impossible, not even difficult, but I am lazy).  So I used the two sets circled in yellow and I was planning on using the set circled in red.    If I am to use the X points to set height, then there is no way the frame pieces are parallel to the ground.  When they are, the distance to the spring perch mount point is something like an inch taller than the diagram. This will result in the frame sloping down front to back.

So I am going to start over and put the height fixtures at the X points and trim the other posts to be tall enough to engage the holes.  Frankly at this point I know the floor assembly is built correctly, so I probably dont even need to do that.  But I will, because it is part of the experience.


1970 Frame - Copy.jpg

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Tonight we worked on uncovering the last of the unknown areas. We cut the roof off.  The passenger side has some major rot in the structure, but it’s all easy to fix.  The driver side appears solid.  I also did a small patch on the panel that mates to the cowl pod.  That was the only repair I had to make on it.  Tomorrow I want to get the remnants of the quarters and hood removed so I can sand blast and primer.




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