Upgrading 73 Challenger with 318.

[Fordication]

If those are older "X" or "J" heads, they have a CC of 68-70. If they are off a 72 charger, then they have a cc of 73. I wouldn't waste my money on those or the intake. You have to figure out what block you are going to use then go from there. Like I said, if you are going to use your 318, the pistons HAVE to be changed or use the 302 heads. It is cheaper in the long run not to use the 318. Modern hemi, 340 or a 360 would be your choices. As for the intake, an aftermarket intake is the way to go.. aluminum and better flow. Speedmaster also has those on sale for Black Friday, if you can wait that long.

Yes. I am thinking 360 Magnum is the way to go. However, I do like them hemi engines.

 

[66fs]

So, need some advice. My car presently has a 318 in it. I know the 360 is the more powerful engine with greater ability to increase HP. So I may have to replace my timing chain shortly. I was thinking since I am about to remove a ton of equipment I may go ahead and get a new cam, install a pair of ported and polished 360 heads. I know without new pistons I am not going to get a giant increase in power. What intake and size carb should I go with. What would be a good cam for this upgrade? What is the main differences between a 318 and a 360? Thanks

The plan is a sound one. My son has a 73 Dart with a 318. For what you want, a cam change, new double roller timing set, four barrel carb (500 to 600 cfm) and intake, and better exhaust, can make a nice upgrade. I'd skip the heads as that opens up a bigger can of worms, but offers a noticeable power gain. You will also need to update your kickdown and throttle cable bracket.

 

[mrmopar340]

If you change the cam this is a great upgrade. Use a good double roller like Cloyes, no Edelbrock as mine stretched, to keep things stable under thr timing cover.

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[66fs]

If you change the cam this is a great upgrade. Use a good double roller like Cloyes, no Edelbrock as mine stretched, to keep things stable under thr timing cover.

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You do not need a timing chain tensioner if you run a good double roller timing chain. I have a 273 with a Direct Connection double roller chain setup with 300,000 miles on it, installed in the 80's. As of today it only has 1 degree of stretch. No need to complicate things.

 

[mrmopar340]

You do not need a timing chain tensioner if you run a good double roller timing chain. I have a 273 with a Direct Connection double roller chain setup with 300,000 miles on it, installed in the 80's. As of today it only has 1 degree of stretch. No need to complicate things.

We all run what we run. I've got a very stout 340 with a good amount of money in it. It surprises a lot of people. Ounce of prevention or pound of cure. You can't buy Direct Connection parts now so I use what I deem reliable on my motor.

 

[roadrunninMark]

Yes. I am thinking 360 Magnum is the way to go. However, I do like them hemi engines.

Should be able to get one out of the junkyard. Also, if your budget allows, get the modern transmission too. It will cost more upfront and for other items, but the modern transmission and engine will be worth it. If you go magnum, get the overdrive trans. The non electrical version will be easier to get to work. I am putting an 8 speed in the barracuda. As you can see from the avatar, it was just painted. The 318 is being built right now. The trans has already been fitted, some tunnel mods are necessary to maintain the proper position of the engine for the shaker but Holley has mounts that allow you to install the modern combo with minor mods, plus they have the trans mount too.

 

[66fs]

We all run what we run. I've got a very stout 340 with a good amount of money in it. It surprises a lot of people. Ounce of prevention or pound of cure. You can't buy Direct Connection parts now so I use what I deem reliable on my motor.

The Direct Connection double roller was nothing special, probably just a stock OEM / Cloyes 340 timing set.

 

[Fordication]

Ok, so here is what happened since last I talked to you guy. I found the 318 had bad valves. All of my compression was leaking out of three different valves. So I asked the shop to do a standard valve job and they told me they do not do iron heads and it would take 2 weeks if they sent them out and cost me $800. So I grabbed the heads and took them down the street to a machine shop I know of and they did them for $350, had them back to the shop in 2 days. I ordered a new set of lifters, new gaskets and new arp bolts. Gave them to the shop and now just waiting for them to get my car done and get it back to me. 2 valves on one head were lifting and one valve on the other head.

 

[mrmopar340]

Ok, so here is what happened since last I talked to you guy. I found the 318 had bad valves. All of my compression was leaking out of three different valves. So I asked the shop to do a standard valve job and they told me they do not do iron heads and it would take 2 weeks if they sent them out and cost me $800. So I grabbed the heads and took them down the street to a machine shop I know of and they did them for $350, had them back to the shop in 2 days. I ordered a new set of lifters, new gaskets and new arp bolts. Gave them to the shop and now just waiting for them to get my car done and get it back to me. 2 valves on one head were lifting and one valve on the other head.

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Light at the end of the tunnel. Great news on getting it sorted out. Many years of happy cruising ahead sir.

 

[Fordication]

Light at the end of the tunnel. Great news on getting it sorted out. Many years of happy cruising ahead sir.

Not to mention, the bad spark was not the distributor but the connections on the resistor were lose. He crimped down all of the spades and now the distributor is getting a strong spark.