273 or NOT 273?

[fat-360]

Not even close. I ran 1.88 intake J heads on a 273. My favorite engine of all time.

So how did it go?

 

[Dartswinger70]

Cometic will make whatever you want.Matt Steen told me that. Pistons are now commonplace.

I think its good the 273 is gaining the support. Maybe they are all that's left? 318s being gobbled up etc.

 

[Dartswinger70]

273 head is the same as 318 in port volume. If you put a 340/360 head on a 273, you’ll lose so much airspeed,compression,and shroud or crash valves etc.
The 273 doesn’t flow enough air to warrant big heads, 170ish cfm (stock) puts the engines peak horsepower potential at just over 6grand.

I was faced with putting a set of J heads on a stock 318 bottom end. An old head mechanic at the time (around 2003) warned against the loss of compression etc.

 

[66fs]

So how did it go?

With 4.10 rear gears it would fry good street tires all the way through 1st, 2nd, half way through 3rd, and break them loose again going into 4th. But that gets old in a real street car. 64 Barracuda, 4 speed, 10.95 big block clutch and pressure plate, no lightening. So 3.23 gears went back in and the 4.10s were traded off. On trips, It would cruise at 100 mph all day long. You could wind it up to 100 mph and shift into 4th gear. All while getting mid 20's mpg with 2.76 rear gears on long trips. That 273 would stop pulling a little before 7,000 rpm.

 

[fat-360]

I was faced with putting a set of J heads on a stock 318 bottom end. An old head mechanic at the time (around 2003) warned against the loss of compression etc.

I’ve done that. Milled ‘140 off the heads,so much so that we were touching the outside of the inlet seats(1’88). With the mopar 655p/n cam 120psi on a compression gauge…

 

[toolmanmike]

#920's.
Very similar to the #302's except no eyebrow between the valves. The top photo is with a original 273 steel shim head gasket. It looks like quite a bit of room for larger valves.

 

[Newbomb Turk]

#920's.
Very similar to the #302's except no eyebrow between the valves. The top photo is with a original 273 steel shim head gasket. It looks like quite a bit of room for larger valves.

View attachment 1716340458

View attachment 1716340459

You can fit a 2.100 and a 1.600 valve package in there.

Certainly it would be nice(r) if the exhaust valve was only 1.550 or even better 1.500 but those sizes fit in those heads.