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From Barn to Road: Breathing Life Back Into a 74 Roadrunner Clone

TK-421

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A week or two back I picked up a 74 Plymouth Satellite Sebring that had been turned into a Roadrunner clone. The owner was planning on restoring the car but that never happened. I know very little of the cars history, only that it's been sitting in a barn for the last 5 years or so and driven "around once a month". Though I suspect it sat for longer periods than that. The car definitely hasn't seen a lot of love.

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Body:
It's not the prettiest thing at the moment. She's got failed clear coat past the quarter windows, on the roof behind behind the 3/4 vinyl top, and on the trunk. The paint on the rest of the car should be salvageable with a good cut and polish. There's rust bubbling in the usual spot, the lower, left rear quarter panel behind the door. The car was blue prior to the black respray. I definitely like the black better but it will likely need a proper paint job at some point. The vinyl top will need replaced. Pretty sure there's rust underneath but it feels like nothing has eaten through the roof.

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Interior:
The interior is in pretty good shape for a near 50 year old car. Not as pristine as the interior of my 67 Cougar but certainly serviceable. It is blue, which I don't much care for. I intend to swap it out for a white, full vinyl interior (with buckets). The dash is, of course, cracked. As is the cap that was placed upon it. The gauge is of the old sweeping tach variety. I'll swap it out for a rallye set when I get the chance. It currently has a column shift auto which I intend to swap out for a floor shift. Interior lights don't come on when the door is opened. I'll have to look into that. The car has AC and the compressor seems to spin alright. I'll have to have it pressure tested. Hopefully, it can be updated to modern fluids without too much trouble. The trunk isn't sealing properly and moisture is getting in. No rust but new weatherstripping is in order.

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Engine/Transmission:
The engine is a mildly built 318. At some point, the engine was given a 4 barrel Summit thermo-quad dual-plane intake that was for some reason paired to a square-bore Eddie carb (1405), a mildly aggressive cam (judging from the slight lope at idle) of unknown grind, and a set of long-tube headers (unknown make). It's also got a Mopar Performance 90 degree adapter for the oil filter. Runs well when it actually runs. Won't stay running once warm, though. The radiator appears to have rust or maybe dirt within the upper portion and appears low on coolant. Hopefully, a good flush will do the trick. The transmission is a 3 speed auto. Not sure if it's a 904 or 727. Rear drive is a 8.25. Not sure about ratio or whether it's got posi.

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Wheels/Tires:
Wheels appear to be Magnum 500s of the 15 inch variety. Widths are unknown. Tires are 215s up front and 275 out back. Both pairs could use replacing but the fronts are in dire need of replacement as they're from 2007. I think I'll bump the fronts up to 225 (or wider if the wheels will support it, the 215s just look so insufficient and thin) and the rears to 285 (seems to be plenty of space on either side of the 275s).

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Good find. Seems to be pretty good shape. You sound like there is a plan to make it look better. Is this a flip you have in mind or a keeper? If it was mine I'd keep it and look at dropping a 360/408 in. Lots of options to make this a big surprise on the street. Good luck with it.
 
Definitely a keeper. I've had a desire to pick up a B-body ever since I saw the Charger on tv in Burn Notice. I prefer the loop bumper Plymouths but those proved too often to be out of my reach both in distance and price. I'm quite happy with the 74, though, even with the less ideal suspension setup.

First order of business is getting it to run reliably and catching up on the much deferred maintenance. After that, a rear disc conversion and new suspension . Interior and paint to follow.

As for the engine, I kinda want to keep building the 318. A larger block would certainly grant more torque at an earlier RPM with more overall potential but I feel like finishing what the original builder started. But perhaps that's overly sentimental. Given what's already been done, all it should really need is some compression. A set of performance heads and zero deck would take care of that I think. Heads, cam, intake, headers/dual exhaust, and zero deck is the formula for about every 400 horse build I've seen. This engine is halfway there.

But that's a fair ways off. Things can and likely will change. If I happen upon a larger engine I'll probably take it.
 
Nice project, I love this kind of find. You’ll have a lot of fun exploring this car and bringing it back to life!
 
Got the oil changed the other day. Went out and picked up a new filter and fresh oil. GTX 10w-30, same as I use in the Cougar. Lifted the front end a bit and drained the oil. Everything was going smoothly... Until I tried to remove the old filter. With the 90 degree adapter I couldn't get both my hands or band wrench in the small space the filter now occupies. One hand simply wasn't getting that filter off. Stopped by AutoZone to pick up some filter end wrenches but all were either too large or too small for the filter, or had the wrong number of sides. Returned those and picked up a three jaw filter tool for a ratchet. It proved completely useless. No amount of torque or patience could get that to actually clamp on a filter. Just spun and spun.

Took some screwdrivers to the filter and then a pry bar to the driver. All that did was bend the driver and widen the hole in the filter. Threaded a bolt of a decent size through and pried on that. And... the filter finally broke loose. Removed it and readied to throw in the new one. It was a different size, of course. Meant to fit the engine not the adapter. The gasket was maybe 2 or 3 mm larger in diameter than what came off the car. Didn't want to chance it so I went back to AutoZone, returned the useless tool, and picked up an equivalent to what was removed. Oiled up with 5 quarts and let the engine run. Pressure was good, engine seemed healthy... til it died again. Most difficult oil change of my life. The filter was leak tested at factory 8 years ago now (assuming I'm reading the date rate). No telling how long it's actually been on the car but it certainly liked being there.

Also topped off the coolant. Took about a quart. Interior of the radiator is either dirty or rusty. Gonna need a good flush at the least.

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90 adapter is not really necessary on that car.

I read you had big block plans.

Didn't see anyone mention that factory BB cars have different K frames and pass side inner fender sheet metal as well as thicker torsion bars and sway bars.

There is some debate about BB motor mounts still working in an SB K frame.

There is a template floating around to trim the inner fender.
The factory also had a rubber/fiber apron in that area on BB cars.
If you don't do this you will have a bitch of a time getting to the spark plugs.
Headers may eliminate this need depending on brand.
 
The adapter is definitely not necessary. Looks like a regular filter would attach to the block and clear the headers just fine. I'd like to get rid of it but, as I understand it, there's a required metal plate and a gasket or two that is now missing due to adapter use.

I don't have big block plans per se. It's more of a "if a BB conveniently comes along" kinda thing. For now, I intend to continue building the 318. I knew about the different K frames, and thicker sway bars and torsion bars are already planned. Had no idea idea about the fender though. Definitely something to bear in mind.
 
Did some messing around with the ignition components. Took some voltage readings at the coil (pos to neg post).

Key on - 4.3-4.5
Running - 4.5-4.8
Cranking - 6.75
Occasional stumble at idle

From what I've read, those readings are all on the low side (apparently I should be getting somewhere more around 7-9 while running?). It seems that when cranking I should be reading full battery voltage. The battery is new and fully charged so somehow the power isn't getting to the coil. Or maybe I'm testing it wrong? In any case, I made some changes to the system.

First, I moved to coil to the firewall. When it was on the block it was hot enough that I couldn't touch it for more than a couple seconds without it starting to burn. I thought getting rid of some of that heat might help should the coil be going bad. Didn't seem to make much difference though.

While moving the coil I noticed that the wire to the positive terminal was in poor shape. Only about half the strands in the wire were still attached to the terminal connector. A couple of twists and it just popped off. Crimped and heat-shrinked a new connector to the wire.

Also noticed an extra wire (green) on the neg terminal of the coil. The car had been changed over to a 4 pin ecu and dual ballast at some point. I'm thinking the extra wire was a left over from the 5 pin ecu. Pulled the wire, heat-shrinked over the terminal connector, and tucked it away into the harness.

Decided to adjust the ignition timing at idle. Advanced it a bit. The engine seemed to be running better. Certainly sounded happier. Checked to make sure it would still hot start (at about 160 degrees coolant temp, engine likes to cut out when much warmer than that). All good. Slightly higher idle and vacuum was achieved. After timing and carb adjustment I managed a whopping 5 in of vacuum. Seemed low even for a cammed engine. I have no idea what the cam specs are though so I suppose it might be about right. Already installed a new gasket between carb and intake but checked for a vac leak with some carb cleaner anyway. No reaction from the engine when sprayed. Checked around the intake gaskets, also no effect. Haven't checked the hoses yet but they seem in decent shape.

I read that the ecu can have trouble grounding to the firewall. So I took the ecu off and cleaned the firewall, making sure that bare metal made contact with the ecu. Remounted the ecu. Hooked everything back up.

After all that I took some new voltage readings.

Key on - 5.25
Running - 5.5-5.8
Cranking - 6.75
Occasional stumble appears resolved

So I seem to be getting more power to the coil but still not enough. The engine still cuts out after idling for 15 minutes or so. The ballast is brand new so I doubt that's the issue. Maybe it's the ecu? Maybe a grounding issue somewhere? Not quite sure where to go from here, what else to test or how. I'll have to do some more reading. I'm tempted to start throwing parts at the issue.

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is that a 2 post ballast?

Should be a 4 post in 74
 
is that a 2 post ballast?

Should be a 4 post in 74
Yep. Normally it would be a four post to match a stock 5 pin ecu. At some point, this car got a 4 pin ecu. Looks like a typical Summit replacement. So now it's a two post. If I'm understanding what I've read about 5 to 4 pin swaps, it should be ok.
 
Haven't had a chance to do much with the ignition problem lately. Took the time to start cleaning up the paint some. Paint from the doors forward is starting to oxidize but it serviceable until I can get around to a decent paint job. Rear quarters and trunk will need a respray to look decent. The clear is simply gone on all the upward facing surfaces.

Took a rotary buffer to the front fenders, hood, and driver's door. Think it turned out alright for my first time messing with compound and polish. The car could still use a professional's touch but this'll do in the meantime. Still have the rear quarters, trunk (will need wet sanding first), and passenger's door to go.

Some before and afters...

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Moved the vacuum can from ported to manifold vacuum as per FBO Ignition's website. Didn't seem to do much but I'm sure it'll be feel-able on the road should the car ever actually get on one.

Finally picked up a timing light from Harbor Freight. Found the timing mark on the balancer and put some White Out on it. Checked initial timing and found it to be around 52* or so. Quite high but that's where the engine seems to like it. Backed it down to low 40s. Go too much lower and the engine gets rather unhappy. I suppose the weak spark might be requiring a longer burn and thus more advance at idle. Purchased FBOs ecu and coil kit. It'll be here on Monday. We'll see if that changes anything.

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FBO parts came in yesterday. Because I have no patience when it comes to car parts I installed it around midnight after a late night at work. Had to drill out a mounting hole a bit to get it to match the firewall. Otherwise, it all went together well. Didn't get a chance to run the car till today.

Unfortunately, the car still shuts off after 10 minutes or so. About the only thing left to change would be distributor. Not sure if that would make a difference but I don't know what else I can do. The engine is getting air and fuel. It doesn't even get hot enough to start heating the fuel lines or carb so boiling isn't an issue. Compression doesn't seem to be a problem either. The engine runs fine while it runs.

Have the engine pulling 10 in. of vac at 30* initial. Can pull more around 13-15 in. if I bump the timing up to around 40*.

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Made some progress the other day. It was suggested to me that the choke might be killing the engine if it closes while the engine is warm. The carb requires a manual choke but the prior owner never had a choke cable installed. With that being the case I figured that maybe the choke was closing while the engine was running. I dropped by Autozone and picked up a cable. I installed it and ran the car. I have yet to have the car quit on me since the install. I'm hoping that's the end of the engine stalling.

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Also installed a new set of spark plugs to relieve the (1 month old) fouled plugs. Nothing special, just some Champion Coppers from AutoZone as that's all they had on hand for the car. I did notice that they are a few millimetres longer than what the prior owner had been using. The car seems a little happier with fresh plugs.

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So, the engine seems to be running reliably enough now. However, it still is struggling under load. It doesn't try to immediately die when put into gear anymore but it is definitely bogging down and will die if revs aren't kept up a bit when coming to stop. I'm thinking it still has poor spark. No air issue now that the choke cable is installed and extra gas will keep it spinning. That would seem to leave spark. With the coil and ECU replaced that would leave the distributor as the only old part left besides the wiring which will have to be checked over.

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It's been a while so it's time for a progress report... Little has been made. But progress is progress.

I worked on the timing some. Set the engine for 36 degree total giving me about 10 at idle which sounds about right. I'll have to recurve the distributor so I can get more at idle. The engine certainly seems to want more at idle.

Set idle with the tach I recently installed. Got it at about 700rpm at idle in park. Drops about 150 or so when put in gear. Had to unplug it though. It didn't seem to like the power source I had it tied too. Had it plugged into the accessories wire running to the radio. This was fine until I turned the radio on at which point the tach started jumping around. Hopefully it's not ruined. I'll have to find a more suitable power wire to tap.

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Did some more work trying to get the vacuum up. Plugged the port to the brake booster. It helped a bit. Did a thorough inspection of the booster line (something I'd previously neglected to do) and it was pretty well cracked at the bend to the port on the intake. Replaced it and plugged the booster back in. Vacuum read a fair bit steadier but not much higher at 7-8 in hg. Let the engine warm some more and did another spray test around the intake seals. Sure enough, it bogged pretty heavily when I gave the rear passenger side a good spray. Guess I wasn't being liberal enough with the spray when I checked last. So, now I've got to replace the intake mani gaskets.

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Since I have to replaced the gaskets I figure I'll go ahead and replace the manifold itself. It's an old Summit dual plane piece which would be fine were it not a spread bore unit (not ideal with my carb being a square bore and all). I've been wanting to use an Air Gap mani anyway. I'm thinking it may help keep the carb cool during my state's desert summers. Might also go for some new valve covers while I'm at it. Those gaskets definitely need replaced too.

Also installed a new carb, an Eddie AVS2 in the 650cfm configuration. Installed nice and easy and runs pretty smoothly. The car certainly starts and runs better when the passenger side jets aren't half clogged. Tuned her up with a vac gauge. Definitely likes the screws in quite a ways, no doubt influenced by the vac leak.

Only other development is that I picked up a rallye cluster. Haven't tested the gauges but the previous owner said they worked when pulled and looking at the good condition the cluster is in I'm inclined to believe him. Hopefully I can get that installed soonish. All it should take is some wire splicing if I read correctly. Also going to need a period style radio to replace the pioneer unit someone installed since I have no intention of cutting into the cluster. Found one at Classic Car Stereos that looks nice. It's listed as being for 71-73 though. Thought 73 and 74 shared the same dash. Guess I'll have to look into that more.

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That should be all. Probably won't being doing much with the car till a new manifold is installed. Maybe I'll take some time to work on the old Goldwing Gl1100 project...
 
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Progress! Well, a little anyway.

Old manifold is off. Coolant passages were covered in rust. Heads didn't look much better but those will also go at some point.

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Plenty of sludge to be found. Lots of scrubbing was needed to get rid of the old gaskets.

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All the old gasket removed. New manifold placed to see how it'll look. Gonna be much cleaner than the old Summit part.

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New gaskets and ARP bits are ready. Just need to put her back together here soon. Then an oil change and some new coolant and hopefully she'll be running again.

Also missed out on an opportunity to pick up a 440 block, forged crank, and oily bits for $125. That blew. I hate living in an automotive dead zone.
 
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