Building a 273

273Dynamite said
Hi,
im building a 1969 273 with a 904 automatic trans for my 2 door 1949 Plymouth.
its a stock 2 barrel carb i believe 180-190 horsepower. Me and my uncle want to build it to the super commando specs ranking in at 275 horsepower but trying to push it up to 300 horsepower. I acquired a '65 Commando intake #2465726

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View attachment 1715959407 , Im not sure if that will fit on a '69 block. I know i could use the Edelbrock LD4B intake but would like to see if i can use the '65 commando intake. Also have a '64 8 3/4 rear end for the Plymouth, should bolt right in, its an inch bigger than original rear end. Just wanted to see anyone else's input on this build and get any other opinions and options for it. thanks!

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The 273 is a fine Little Engine but if you want the power you're aiming for you could do it easier with a bigger bore like a 318 and no one would ever know it was a 318 cuz the block dimensionally is the same size outside of the cylinder bore...n why not a 360, because the 318 blocks can be had for free many times as are the 273's. The iron intake as far as airflow goes is utterly a pos and heavy. Get a dual plane intake for better low end power and all around better performance. As for what heads to use if you go to 302 heads and don't just use the 273 head which is already a good head you'll find you need a specific amount of work and it's not cheap to make that head perform to its potential. You could just as easily have your closed chamber 273 heads worked and do a little bowl blending to them and way less chamber massaging and be done and have a great flowing head for what it is. Now in regards to heads and power in general...if you were to go to a 318 bore you would open the door to a magnum head which flows way better than all of those little heads including the 302 and then your power goal will be there and then some. Only catch is you need to figure this out before you start buying intake manifolds ,pistons and all this other crap.