Where to start - maintenance on a 340

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RoRo7051

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Hey yall.

I'm digging into the 71 Dart Swinger my pops had. It's basically been sitting for 10 years since he passed.

The car runs and sounds pretty great currently.

I'm wanting to go through and complete basic maintenance on the engine such as replacing all gaskets, fluids, filters, etc.

The motor was built by a performance shop over 25ish years ago and the spec sheets have long since been lost.

I know the cam was custom ground and a ton more was done.

My question is this, if something needs replaced how do I go about learning the specs of something like a custom ground cam? Would

The rocker arms seem to have a bit of play in them, I've heard that some is normal, but what about this much?

The car was raced back in the day and has a nitrous retard and delay installed alongside the 6AL ignition. Can those just be disconnected? Is there anything else that needs to be done to remove them? (The nitrous has been removed already.)

Thanks for any help in advance.

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The rockers look normal to me.

You have hydrolic lifters so they will be a tad loose feeling when the engine is not running, once the oil pressure is up the hydrolic lifters pumps up just enough to give you 0 lash (more or less)

As for maintenance.

Go to mymopar.com and get your cars FSM. (free download)

The first section will give you maintenance guidelines.

Sounds like you already have it running and the rockers (oil and such) looks good to me.

You could be proactive and pull the engine and replace all the gaskets etc. Or run it till you find out what leaks more than you can stand.


Good luck to you. I have me dad's 67 Dart Convertible, it makes the car way more memorable when I go for a drive.
 
Removing the delay box is pretty straightforward. The ignition box will be a little harder depending on what distributor it’s running. If you want to remove it you may have to convert back to a factory type electronic ignition or points setup. If the ignition box is working I’d leave it alone. Oh and 10 years isn’t really that long. I wouldn't pull it all apart just yet. Get it running, tune it up and it could be just fine as far as leaks go.
 
Figuring out custom ground cam specs can be a little challenging because the only real way is to pull it out and run it through something like a cam doctor or send it to somewhere to have it profiled. But it’s not really worth the effort. If it runs good and does what you want, run it. If it’s temperamental and the cam is too radical for what you want to do with the car you’ll be replacing it.
 
TT5.9mag said:
Removing the delay box is pretty straightforward. The ignition box will be a little harder depending on what distributor it’s running. If you want to remove it you may have to convert back to a factory type electronic ignition or points setup. If the ignition box is working I’d leave it alone. Oh and 10 years isn’t really that long. I wouldn't pull it all apart just yet. Get it running, tune it up and it could be just fine as far as leaks go.
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I guess I should have added that there is a bit of oil in the coolant and some oil leaking from one head.

My plan was to drain oil and coolant, pull the oil pan, flush the coolant. Then change all gaskets and filters to see if that fixes everything.
 
Replace the easy stuff: air filter element, engine oil, transmission fluid, rear differential fluid, and coolant.

Then drive the crap out of it!! Looks like an awesome car!!
 
When you say a bit of oil, what are you seeing???

I'd drain the oil and change the filter before you run the engine any more. Condensation can foul the oil in a motor sitting that long especially if it sat wih the cooling system not drained.
 
If you have coolant in the oil, and you did a cooling system pressure test, and it shows leakage.

Then I would suspect 3 places, and one concern.

  1. The timing cover has rotted internally and is leaking into the block
  2. The intake manifold gasket
  3. The head gasket.
  4. If the engine was stored with water in it and it froze, a crack could have developed
 
is the oil leaking from the head or from the valve cover? or possibly someplace else?

a little oil in the coolant isn't the end of the world. i'd forego a pan pull and just change the fluids and filter and see what materializes.

cool car, dig that vibe!
 
If you get deep into it, you might want to tighten up the ring gap if it was built for N20.
 
RoRo7051 said:
I guess I should have added that there is a bit of oil in the coolant and some oil leaking from one head.

My plan was to drain oil and coolant, pull the oil pan, flush the coolant. Then change all gaskets and filters to see if that fixes everything.
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I agree with some of the guys above. Establish a baseline, change all the fluids and filters. Replace easy stuff that typically leaks (valve cover gaskets and stuff like that), then run it and see what surprises you have. Hopefully nothing too serious and you can just enjoy it for a while.
 
Bodyperson said:
I think it does. They have a specification for a reason. Im suppose it’s not worth the effort.
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Every engine I build, ok not all but most, get boost of some kind. The rings all get gapped for boost, and I gap them on the big side. They leak down like any other new engine and run just the same off boost. On a 4.030 bore you’re talking about the difference between like .020 ring gap and .028 ring gap.
 
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