Another 273 commando build .. This one will be a "BEAST"
I came across some good info about the 273 from a guy on another site ................. "DATED 2006 " ....................Quote :
hello, I did some research on 273 . the 180 hp, has an 8.8 cr listed. according to the NHRA specs, which are provided by mopar are; deck hgt. - .011, a .028 gasket, 57.3 cc head will provide a cr of 9.5. the 4 bbl motor, has deck hgt of +.129, .028 gasket, 57.3 cc head, cr. is 11.5. this little motor is a very good runner. in NHRA stk, there is 273/180 motors being run. a 1965 valient with 180/273 runs 13.30,s, in a 1965 plymouth, ran 13.43 @98 mph.
I realize not everyone is into stock racing, but the fact is, these motors can be very quick. many many years ago, I ran a 235/273 dart as a stocker, plus drove it. it ran 13.31 @ 102.30 mph. some people like smaller motors, others like big motors. to each his own. .060 over is about the limit on overbore in these motors. just food for thought.
Here's another story >>>>>>>>>>>>>>>>>>>>>>>>>
Another 273 build
In my opinion, for a good economy engine, the 273 is the better engine between it and the 318. The smaller bore and closed chamber head can be configured to give a 9:1 engine that will require less ignition advance, thus better fuel economy than a larger bore engine with the same stroke. The early 273/318 head has a chamber that is not too unlike the newer '302 casting, although the bowls and ports are different. Small bore and long stroke engines are popular today with the computer controlled fuel and ignition systems. The use of the engine still dictates the type of build, of course.
Building an inexpensive high horsepower 273 is quite a story. I have one built and ready to go for next race season. two years ago, I switched from a factory headed 273 to a W2 headed 318. The 273 was 11.04:1 and had a CompCam292 hydrolic with solid lifters. It ran a best of 12.36 @109 in the 1/4. The 318 has 9.8:1 and a MP .541" lift circle track cam and just ran a 11.26 @119 a few weeks ago. The 318 has quite a bit more horsepower still to be found, but that will have to be looked for later as the 273 is being put back in very soon.
This 273 is a true 11.0:1 assembly with factory 273 heads modified with my porting work and cut down 1.92/1.60 Chevy +.150" long valves installed. The cam is a MP circle track grind with .528" lift. The pistons are an old set of Jahn's cast that stick out of the hole .230" at the dome. Regular iron rings are all I could find, much less afford. The engine has the regular trustworthy 8553 Felpro head gasket. The intake manifold is a Chrysler marine item that is very similar to the original 273 4bbl unit. It did require some coolant flow modifications in order to work on the 273 with a regular automotive water pump. With the same AFB Double Pumper carb that I used on the previous 273 build, I expect to see time slips in the 11.80 range in my 3281 pound Dart.
I came across some good info about the 273 from a guy on another site ................. "DATED 2006 " ....................Quote :
hello, I did some research on 273 . the 180 hp, has an 8.8 cr listed. according to the NHRA specs, which are provided by mopar are; deck hgt. - .011, a .028 gasket, 57.3 cc head will provide a cr of 9.5. the 4 bbl motor, has deck hgt of +.129, .028 gasket, 57.3 cc head, cr. is 11.5. this little motor is a very good runner. in NHRA stk, there is 273/180 motors being run. a 1965 valient with 180/273 runs 13.30,s, in a 1965 plymouth, ran 13.43 @98 mph.
I realize not everyone is into stock racing, but the fact is, these motors can be very quick. many many years ago, I ran a 235/273 dart as a stocker, plus drove it. it ran 13.31 @ 102.30 mph. some people like smaller motors, others like big motors. to each his own. .060 over is about the limit on overbore in these motors. just food for thought.
Here's another story >>>>>>>>>>>>>>>>>>>>>>>>>
In my opinion, for a good economy engine, the 273 is the better engine between it and the 318. The smaller bore and closed chamber head can be configured to give a 9:1 engine that will require less ignition advance, thus better fuel economy than a larger bore engine with the same stroke. The early 273/318 head has a chamber that is not too unlike the newer '302 casting, although the bowls and ports are different. Small bore and long stroke engines are popular today with the computer controlled fuel and ignition systems. The use of the engine still dictates the type of build, of course.
Building an inexpensive high horsepower 273 is quite a story. I have one built and ready to go for next race season. two years ago, I switched from a factory headed 273 to a W2 headed 318. The 273 was 11.04:1 and had a CompCam292 hydrolic with solid lifters. It ran a best of 12.36 @109 in the 1/4. The 318 has 9.8:1 and a MP .541" lift circle track cam and just ran a 11.26 @119 a few weeks ago. The 318 has quite a bit more horsepower still to be found, but that will have to be looked for later as the 273 is being put back in very soon.
This 273 is a true 11.0:1 assembly with factory 273 heads modified with my porting work and cut down 1.92/1.60 Chevy +.150" long valves installed. The cam is a MP circle track grind with .528" lift. The pistons are an old set of Jahn's cast that stick out of the hole .230" at the dome. Regular iron rings are all I could find, much less afford. The engine has the regular trustworthy 8553 Felpro head gasket. The intake manifold is a Chrysler marine item that is very similar to the original 273 4bbl unit. It did require some coolant flow modifications in order to work on the 273 with a regular automotive water pump. With the same AFB Double Pumper carb that I used on the previous 273 build, I expect to see time slips in the 11.80 range in my 3281 pound Dart.
