Commando 273 cam specs

[krazykuda]

I was a Design Engineer and am well aware of production tolerances.

Where did you work??? Automotive????

 

[Lamm]

View attachment 1716368894


Here's the specs I have found and use.

1965 180 hp 2 barrel .395 /.405 lift 240°/ 240° duration
1965 235 hp 4 barrel .415 /.425 lift 248°/ 248° duration
1966 235 hp 4 barrel .420 /.430 lift 248°/ 248° duration
Isky E4 .425/.425 lift 260°/260° duration 216° @ .050

I would be interested in the degrees and lifts of the old Isky and Racer Brown cams.

Here's one:
Isky # 390160 / Grind B-603
Intake 35-71
Exhaust 71-35
Lift .448"
Duration 286*

Can anyone tell me more about these?

 

[toolmanmike]

I would be interested in the degrees and lifts of the old Isky and Racer Brown cams.

Here's one:
Isky # 390160 / Grind B-603
Intake 35-71
Exhaust 71-35
Lift .448"
Duration 286*

Can anyone tell me more about these?

Isky's website really sucks. Schneider used to have a few solid small block cams. Small block isn't even listed any more.

 

[toolmanmike]

273 Commando – (rated at 235 Horsepower)
CAM Valve lift: Intake .425 and Exhaust .425
CAM Duration: Intake 248 and Exhaust 248

273 Standard – (rated at 180 Horsepower)
CAM Valve lift: Intake .395 and exhaust .395
CAM Duration Intake 240 and exhaust 240

Comp Cam 20-246-4
Valve lift intake .468 and exhaust .468
Duration intake 270 and exhaust 270

Comp recommended
Comp Cam 20-222-3
Valve lift intake .462 and exhaust .470
Duration intake 262 and exhaust 270

Isky E4 cam
Valve lift intake .425 and exhaust .425
Duration intake 260 and exhaust 250

And how can we talk 273 without a reference to the D-Dart

D-Dart
Cam Valve lift intake intake .495 exhaust .505
CAM Duration: Intake 284 and Exhaust 284

 

[Lamm]

There are a few more Isky camshafts mentioned in this thread.

And here is a camshaft grinded by Racer Brown that was used by the Mopar rally team in the 1960s:

 

[RustyRatRod]

Unfortunately your assumptions don't line up with measured numbers taken at Racer Brown. They are not comparable to the MP cams and I doubt the wear of 50,000 miles would affect duration as it only reduced lift by .010 of an inch on the intake and exhaust lobes. Jim will tell you that Chrysler liked real slow ramps to save on warranty claims.

For a 100% I agree with Chrysler's thinking!

 

[RustyRatRod]

273 Commando – (rated at 235 Horsepower)
CAM Valve lift: Intake .425 and Exhaust .425
CAM Duration: Intake 248 and Exhaust 248

273 Standard – (rated at 180 Horsepower)
CAM Valve lift: Intake .395 and exhaust .395
CAM Duration Intake 240 and exhaust 240

Comp Cam 20-246-4 (what I used)
Valve lift intake .468 and exhaust .468
Duration intake 270 and exhaust 270

Here is Comp recommended for my build
Comp Cam 20-222-3
Valve lift intake .462 and exhaust .470
Duration intake 262 and exhaust 270

Isky E4 cam
Valve lift intake .425 and exhaust .425
Duration intake 260 and exhaust 250

And how can we talk 273 without a reference to the D-Dart

D-Dart
Cam Valve lift intake intake .495 exhaust .505
CAM Duration: Intake 284 and Exhaust 284

That D Dart cam is gettin somewhere! lol

 

[66fs]

Where did you work??? Automotive????

All Over. Production and Skunk Works plus I worked "in plant" while getting my degree. It does not really matter. Good Engineers are pretty much the same.

 

[krazykuda]

For a 100% I agree with Chrysler's thinking!

Yep, slower ramps close the valve slower and less force on the seats...

 

[66fs]

Yep, slower ramps close the valve slower and less force on the seats...

Probably helps with less spring pressure required and less higher rpm valvetrain stress.