Rebuilding a 65 273..I need some help.

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jdhasa65cuda

jdhasa65cuda

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I have owned a 65 Cuda S 4 speed for 15 years. It came to me with a 68 318 that had replaced the 273 for some unknown reason. It retains the original valve covers intake manifold and carb. I have upgraded the ignition to an electronic ignition and it runs just ok.. the 318 is getting tired. Some years ago when my Magnum RT was at the dealership for service, i wandered into the shop managers office to chat. I noticed a great picture of his 65 Dart drag car with its wheels off the ground as it launched off the line at the strip. We discussed the pic a bit and he told me the Dart had a 273 from a 65 Cuda Formula S. He had rebuilt the engine and used big valve heads on the .60 over engine but it wouldnt idle well at all so he yanked the heads off and used them on some other project and had just stored the engine in his garage. Fast forward 12 years and i saw him recently at the car wash. He said he was retired and i remembered him telling me he still had the 65 273. Well i asked him if he wanted to sell it cause i was looking for a 65 273 to replace the 318. He sold it to me for $300! He said it has very few hours on it and you can still see the cross hatching on the bores... So... I have the solid lifter engine with .60 over TRW pistons installed and the oil pan.. thats it. I have obtained a good set of swirl port 302 heads. But i have no cam. I have been considering buying a Isky E-4 cam and i imagine i will get the lifters from them as well but i am unsure about pushrod length and how to set up the heads, since they were from a hydraulic lifter engine. Am i on the right track? Any suggestions? All help is sincerely appreciated since this is my first engine rebuild. Thanks!
 
Yes you are on the right track. The E4 is a solid cam and their lifters are a good idea. You will want to measure for pushrods but off the shelf length may work fine. The #302 heads are great for the 273. They have similar sized chambers and ports and have hardened valve seats which is a bonus.
 
I'm not sure about the 302 head combustion chamber geometry but a true 273 Commando engine pistons protrude about the deck. The original 65 heads were also closed chamber heads with the proper combustion chamber geometry. 65'
 
Plymouth 65 said:
I'm not sure about the 302 head combustion chamber geometry but a true 273 Commando engine pistons protrude about the deck. The original 65 heads were also closed chamber heads with the proper combustion chamber geometry. 65'
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That was in my thoughts as well..
 
toolmanmike said:
Yes you are on the right track. The E4 is a solid cam and their lifters are a good idea. You will want to measure for pushrods but off the shelf length may work fine. The #302 heads are great for the 273. They have similar sized chambers and ports and have hardened valve seats which is a bonus.
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Will i have to change the rocker arms since i will be using solid lifters? And if so, where should i source them from..
 
jdhasa65cuda said:
That was in my thoughts as well..
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And like Plymouth 65 said, he's not familiar with the 302 chambers. The top photo is the #302 and the bottom is a 273. They are both whin a couple cc of each other.

302Castings019_zpse479835b.jpg


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jdhasa65cuda said:
Will i have to change the rocker arms since i will be using solid lifters? And if so, where should i source them from..
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You will need the adjustable rockers and shafts. They come up for sale here quite often.
 
For confirmation I would verify the piston clearance. The combustion chambers do look very similar. Piece of mind for me. 65'
 
Plymouth 65 said:
For confirmation I would verify the piston clearance. The combustion chambers do look very similar. Piece of mind for me. 65'
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Something you should always do with a wad of clay. There have been members here put 302's on 273's. The OP can search around for the threads. If he wants to know more.
 
Not my own experience, just what I read here. Some have had fitment issues with early stock exhaust manifolds against late model heads. One member cracked a manifold before noticing the contact. Good luck with your build.
 
RedFish said:
Not my own experience, just what I read here. Some have had fitment issues with early stock exhaust manifolds against late model heads. One member cracked a manifold before noticing the contact. Good luck with your build.
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I remember seeing that too. It is on the drivers side manifold only, and is supposedly easy to remedy if it occurs. If I remember right, it is the corner of the head near the rear lower head bolt that is in the way. If it's the bump below the port, you need to be conservative when grinding on the head, because it has been stated here that you can get into the water jacket if you grind too much. A little off the head, and then a little off the manifold would be the way to go about it. I'm in the process of building a 273 with 302 heads....but hoping the Dougs headers don't have the clearance Clarence issues of the manifolds!
 
JDMopar said:
I remember seeing that too. It is on the drivers side manifold only, and is supposedly easy to remedy if it occurs. If I remember right, it is the corner of the head near the rear lower head bolt that is in the way. If it's the bump below the port, you need to be conservative when grinding on the head, because it has been stated here that you can get into the water jacket if you grind too much. A little off the head, and then a little off the manifold would be the way to go about it. I'm in the process of building a 273 with 302 heads....but hoping the Dougs headers don't have the clearance Clarence issues of the manifolds!
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I don't remember a separate thread about that clearance issue but I do remember reading about it many times. It is probably buried in a thread.
 
RedFish said:
Not my own experience, just what I read here. Some have had fitment issues with early stock exhaust manifolds against late model heads. One member cracked a manifold before noticing the contact. Good luck with your build.
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This is correct. Check for clearance with the original drivers side manifold. Check the manifold and the exhaust port on the head. Be careful grinding on the exhaust port as there is coolant under it. Not a fan of aluminum rocker arms on a street car, but I know people that run them. I'd run stock 273 rockers and shafts. An Isky E-4 is good but you can do better. The last one I bought, was a custom cam from Racer Brown. Stock pushrods should work fine. Sounds like it will be a really nice combination in a 4 speed car. Not sure if the original 65 manifold would be the best since you are running 66 up heads. What is the casting number on the intake?
 
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Yep, there are a lot of posts about it. It wouldn't be a bad idea to start a thread with photos.
 
What about the original 340 4 barrel cam with this combination? It got slightly more duration and lift than the original 273 Commando cam. Any thoughts? 65'
 
Headers are the best solution. OEM manifolds do not flow well The left manifold on early A has extra 90 degree crook at the bottom end. Someone compared it to pooping through a straw. LOL
 
Plymouth 65 said:
What about the original 340 4 barrel cam with this combination? It got slightly more duration and lift than the original 273 Commando cam. Any thoughts? 65'
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Slightly? The 340-4 cam was pretty radical in a 340. It would be a monster in a 273. You better have a 4 speed and a good clutch. You could use that cam. I wouldn't.
 
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RedFish said:
Headers are the best solution. OEM manifolds do not flow well The left manifold on early A has extra 90 degree crook at the bottom end. Someone compared it to pooping through a straw. LOL
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I laugh every time I hear that. :rofl:
 
Plymouth 65 said:
What about the original 340 4 barrel cam with this combination? It got slightly more duration and lift than the original 273 Commando cam. Any thoughts? 65'
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In general the 273-4 cam 248°/.425
340-4 speed cam 276/284° .444/.453
 
The 340 auto cam was smaller (same as the 360-4 cam) The 273 manifolds were actually pretty good for the CID of that motor. even the cheesy Y design to the single exhaust was good engineering for that sound but they really cheaped out on the Y tube diameter, there is a major kink in most of them. if you could mandrel that Y fitting youd wake any 273 up. Its the same with the slant and its anemic 1 3/8 (almost) headpipe where it bends. Open it up to super six 2.25 and voila, instant gratification.
 
The stock exhaust manifold is not that bad. I ran J heads and those manifolds with a stock 340 cam. Ran great. I won't deal with headers.
 
pishta said:
The 340 auto cam was smaller (same as the 360-4 cam) The 273 manifolds were actually pretty good for the CID of that motor. even the cheesy Y design to the single exhaust was good engineering for that sound but they really cheaped out on the Y tube diameter, there is a major kink in most of them. if you could mandrel that Y fitting youd wake any 273 up. Its the same with the slant and its anemic 1 3/8 (almost) headpipe where it bends. Open it up to super six 2.25 and voila, instant gratification.
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The Hi-po exhaust was bigger. Acurite LTD has it. It's only money. $1100 LOL

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Yup, the Y headpipe, extension and muffler had a different part number.
 
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