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'48 Plymouth Special De Luxe

6K views 52 replies 6 participants last post by  Second Wind 
#1 · (Edited)
With my work space slowly coming together I'm hoping to start this project soon. I did want to post some pics of the starter project before I start tearing it down. Also being the new guy we will see how my pic post skills are here. Here's to breaking the ice before Jack Frost settles in. I also added a pic of the straight axle I want to use.

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#3 ·
The running board/ rocker panels had some interesting repairs and the fenders need some TLC but it is mostly all there. Yes the axle is just that and it will be used for this project. It came out of a 6 cylinder '50. It has 1-3/4" wide springs so I don't know how well a 440 will go with a spring that narrow. If you look close the tie rod looks really awesome! I think getting the drums off will be a chore too. I see a lot of hours going into the front end this winter. A couple of more weeks and the tear down will begin. I tore down a 440 and hope to have a 727 soon so I can start a mock up. Still trying to decide on a width for a floater 9". A goal would be to have a rolling chassis by spring.
 
#4 ·
With 6 bolt drums, you'll likely need to swap on '49-'54 passenger car drums, or convert to disc brakes. Speedway sells a disc brake kit for these that will let you not only convert to disc brakes, but also 5x4.5" or 5x4.75" bolt pattern. A very good way to go I think.
The 1.75" springs likely wont be too lightweight, but you might find they're too long to keep behind the front fenders. I usually dump the stock springs, and buy shorter 1.75" wide springs around 29"-30" long. Those springs are 70 years old now anyway, so might be work hardened after that long, and no telling when or if they might crack.
 
#5 ·
Thanks for the tip, I will be needin' 'em. I knew that new springs would be in the works it's just that getting the right ones that fit the project. I will definitely be going to discs too because of the braking capacity and the bolt patterns. Since I started this project I have ended up at the Speedway site more often than not. Lots of good stuff there.

On a new note I had a good day today. I picked up a 440 short block and 2 each 727's for $500. Once I get a 9" I can start to make it all work.
 
#6 ·
I used CJ7 jeep springs, others used speedway springs or trailer springs.
 
#10 ·
I will check tonight when I’m home. Maybe I’m off. I can’t remember anything anymore.
 
#14 ·
maybe the rears are 45”? Or maybe cj5 is the application.
 
#15 ·
Now I'm happy. I picked up a 9" tonight complete from pinion to tire for $600. 5:88 gears were not really in the program though. It is an old Speedway Grand Nat. style, so a floater axle complete with brakes. It's 58" wide with offset pinion until I get done chopping it to put pinion on center.
 
#17 ·
I think It would be a lot more supportive than a speedway kit spring. I got mine from Summit racing and I think it was super lift that sold it. I can look it up if you need me too.
 
#22 ·
Hey Mike If you could get me that part number it would help a lot. At least we are talking apples to apples. The axle itself is unsprung weight and doesn't come into play for this part of the equation. Are you running aluminum intake, heads with tube type headers? Or all cast stuff?

Thanks
Mark
 
#21 ·
I did some digging and found out my springs are for a CJA 1940's willys jeep with a 2-1/2" lift. Superlift doesn't sell them anymore but they gave me some names who do. Quadratec, Teriflex, and Skyjacker. Apparently I bought a collectors item. Just FYI. I know you will make the right pick for you.
 
#23 ·
I figured I could make a phone call and get close to what I need. That will happen when I have a block sitting in the motor bay and an idea of where the steering box will sit. Then I can come up with an "eye to eye" dimension and a relationship of the locating pin.....kinda/sorta.

Skyjacker and Superlift???? I haven't said those names in a year or two (cough, cough) :)
 
#24 ·
Another front axle question. Has anyone ever perforated a Chevy straight axle? I am thinking of drilling a series of holes across the width of the axle to take some weight out of it. Maybe even a alternating pattern such as 3/4 than 1-1/4" than back to 3/4" from left to right. The hole size is just for conversation at the moment I would have to do some measuring to see what may be practical for actual hole sizes. Would race tracks allow this?
 
#25 ·
Hi, I am running Weiand tunnel ram and Edelbrock heads, tube fenderwell headers. I ordered the Speedway gasser axle kit with GM calipers and Chevy kingpins. The part numbers are different for the width of the axle that you want. If you are ordering just the spring set, I can take a look and let you know which one is closest. My build is here on the site if you want to take a look.
 
#27 ·
I am hoping to start tearing down the car this weekend or the next for sure. I talked to a motor shop that would be able to help me over the winter. When I stroke this 440 I'm going wide with the holes too so I can't wait to have the next conversation or two with the machinist. For this build I think I might try a front and mid plate built to keep the stress off the sides of the block by not using factory mounts. This Friday I will run two blocks in and see which one will be best to use after sonic checking for core shift. The block that doesn't pass muster will be a mock up block while the other gets machined. That will give me some working room too.

Also picked up a torch set and an air compressor today.

(note to oneself.....get the darn snowblower ready for use too!)
 
#28 ·
Sometimes Bigger is Better

I've been meaning to ask this. With anticipating upwards of 650 HP have you thought about going with a 12" wide tire especially since you're going to be tubbing it anyway. Radir offers a 12:00" X 15" X 32" cheater slick. When I built the 428 for my 53 I wanted to run them but they were about an inch to tall for the radius on my wheel wells and I didn't feel like like redoing the radius so I had to stick with 10:00" X 16" X 29 1/2" cheaters although I have thought about a pair for my Willys pickup because the fiberglass rear fenders can obviously be easily trimmed to fit.
 
#29 ·
I may go wider I was just looking for a starting point. This is an area that needs a lot of thought yet especially with weight and gearing in mind. I will be looking at the width when I get the axle under the car. The 9 inch has a 5:88 gear in it now. Seriously doubt I will run that. It will be tubbed for sure and then I need to look at rules for a fuel cell or hang a tank out front.
 
#30 ·
I have the motor ordered and should see it in about 2 months. I tore down the car this last weekend and final got the body divorced and out side. I have a lot of clean up up and rearranging to do now but for right now the project looks like these pics.

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#31 ·
After talking to my motor builder some more. The plans are changing.

48 Plymouth Custom Special - 4dr suicide style
Starting new build from scratch with plans of:
1950 Chevy straight axle with steering box
Ford 9" rear with 4.10's or 4:29 gear
Mopar 440, 512 CID stroker estimating 680 - 700 hp on pump gas (now a 400 motor on 110 octane)
727 auto (Now a T400)
30 or 32 inch X 10 wide tires ( the biggest things I can fit)
guessing at finish weight of 32-3500 pound car ( hoping for 3200 pounds)
hoping to run in the 10's
 
#32 ·
Hi Mark

am I missing something from your latest post? The only thing I see different is that you added "is the biggest things I can fit" to your tire selection. I reread it it a couple times to make sure I wasn't missing something else. I know in my last comment on your thread I asked if you'd thought about a 12" wide cheaters from Radir wheels because of the horsepower you're anticipating.
One last thing, have you thought about going into your settings and adding a signature to your posts so members see your name, just a thought. :cool:
 
#34 ·
am I missing something from your latest post? The only thing I see different is that you added "is the biggest things I can fit" to your tire selection. I reread it it a couple times to make sure I wasn't missing something else. I know in my last comment on your thread I asked if you'd thought about a 12" wide cheaters from Radir wheels because of the horsepower you're anticipating.
One last thing, have you thought about going into your settings and adding a signature to your posts so members see your name, just a thought. :cool:
I updated and clarified some info in a post. I had been contemplating tire size so I did not respond to that part, sorry. And you are right, I think I have everything in my signature but my name. I will fix next,
Mark
 
#35 ·
My motor guy is big on Mopar so I have to trust him and he has built motors over 2000 HP. It will be normally aspirated. There will be some really big Indy heads. If I got it right the ports are so big they rerouted oiling because oil lines come out of block at sending unit and/or oil pressure port at back of block and feed oil into heads with the external lines. We talked about a lot so I don't remember valve sizes. I told him to pick the cam because I wouldn't have a clue. I told him this thing won't be on the street and if I need to run a vac pump to stop this thing I will. I think he got where I was coming from from then on. The motor will spin 7K. Sitting on top will be an Indy tunnel ram and a Dominator 1050. I am leaving the space under the motor open so I will have a really high capacity oil pan. There will be no motor mounts but will have 1/2" front motor plate and 1/2" mid plate, both aluminum. The mid plate will convert to the T400 trans.

In the end I told him I want to see VERY GOOD documentation of what I am coming home with. I think this thing will be home in 2 months. He said a month I asked for 2 months for prep time.

The T400 he said is a lot better of a choice when running a trans brake. After a couple of pictures he showed me I said OK. He will pick converter. I mentioned 3500 stall but we kind of passed over that.

Finally I about busted my back side this weekend to make some serious progress with the great weather we have been having. By Sunday night I stripped the car down and took a few pertinent measurements along the way. So right now I have I rolling chassis to clean up. Still need to clean up and organize work area too. Then I will chop the front stub off and start to graft in new frame rails ( probably 3 X 3 tube 1/8"wall) for the motor and straight axle. I still have not decided on front springs yet I think mostly because I was not firm on rear tire size yet as well as the time to talk to someone.

The goal for this next year will be to get a new rolling chassis together and make some runs with it. I can do so and not get into building a cage or making a pretty body. Although I would like to get a tilt front end working. I think it will come apart again anyway for suspension changes because I bet I don't get it right the first time.
 
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