273 Commando with Hydraulic Camshaft

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superstock64polara

superstock64polara

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Hi all, I have a 67 Barracuda Formula S with a 273 Commando and 4-speed. For whatever reason the previous owner replaced the original cam with a hydraulic stick and stamped non adjustable rockers. I have no idea what hyd stick is in the engine now, the 273 has a really loppy idle so it would appear that it has decent duration at 0.050'. The car seems really under powered, and really soft on torque down low. Other than the hyd cam, the 273 is stock standard, 500cfm AFB, cast iron 4BBL intake, 10.5:1 comp, Prestolite dual point distributor, cast iron headers, untouched 273 1.78 / 1.50 valve heads.

I would like to replace the existing cam with another flat tappet hyd stick and was thinking of a Comp Cams 20-222-3 / XE262H. This will be a street driven car only, I'd like a little lope at idle, and good low and mid-range torque. I would love to hear your thoughts on my choice of hyd stick, or any real world experience you may have of similar 273 Commando builds. Please I only want to hear from guys with real world experience on this. Cheers.

Cam Specs:
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 1,300-5,600
Intake Duration at 050 inch Lift: 218
Exhaust Duration at 050 inch Lift: 224
Duration at 050 inch Lift: 218 int./224 exh.
Advertised Intake Duration: 262
Advertised Exhaust Duration: 270
Advertised Duration: 262 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.462in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.470in.
Valve Lift with Factory Rocker Arm Ratio:
0.462 int./0.470exh.
Lobe Separation (degrees): 110
Grind Number: CRS XE262H-10
478b5a83-aa73-4a92-b252-c72b8e95e957.JPG
 
The stock solid would do very well back in it. The combo was pretty tough to improve upon for a small engine package.
 
If you want comp xe cam I’d go xe250, or similar from another brand.
 
I think the 340 cam would be too big. Just my opinion. If you just gotta stay hydraulic, maybe one of the smaller VooDoo grinds.
 
stock 340 is very close (same) to the stock 360-4 cam through most of the years. I picked up a 360-4 out of a camper special W150 and it had this 340 spec cam in it. 340 auto spec cam was pretty mild. It was used in the police 318-4 motor and those idled for days with all kinds of alternator load on them
 
superstock64polara said:
Hi all, I have a 67 Barracuda Formula S with a 273 Commando and 4-speed. For whatever reason the previous owner replaced the original cam with a hydraulic stick and stamped non adjustable rockers. I have no idea what hyd stick is in the engine now, the 273 has a really loppy idle so it would appear that it has decent duration at 0.050'. The car seems really under powered, and really soft on torque down low. Other than the hyd cam, the 273 is stock standard, 500cfm AFB, cast iron 4BBL intake, 10.5:1 comp, Prestolite dual point distributor, cast iron headers, untouched 273 1.78 / 1.50 valve heads.

I would like to replace the existing cam with another flat tappet hyd stick and was thinking of a Comp Cams 20-222-3 / XE262H. This will be a street driven car only, I'd like a little lope at idle, and good low and mid-range torque. I would love to hear your thoughts on my choice of hyd stick, or any real world experience you may have of similar 273 Commando builds. Please I only want to hear from guys with real world experience on this. Cheers.

Cam Specs:
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 1,300-5,600
Intake Duration at 050 inch Lift: 218
Exhaust Duration at 050 inch Lift: 224
Duration at 050 inch Lift: 218 int./224 exh.
Advertised Intake Duration: 262
Advertised Exhaust Duration: 270
Advertised Duration: 262 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.462in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.470in.
Valve Lift with Factory Rocker Arm Ratio:
0.462 int./0.470exh.
Lobe Separation (degrees): 110
Grind Number: CRS XE262H-10
View attachment 1715570340
Click to expand...
Looks like a Commando. Are you sure? Have you looked at the piston tops with a boroscooe to make sure? What number heads are on it?
 
Here's what many forget when comparing and or replacing a solid with a hydraulic, or the other way around. A similarly ground hydraulic will "act" about 10* bigger on the duration @ .050 than a similarly ground solid. That's why you can end up with a dog if you go with say a 230* @ .050 hydraulic where a 230* @ .050 solid was. Especially in the case of a 273, since it's a small cube engine. If it was mine, I'd try my best to scrounge up some original solid adjustable rockers and pushrods and change it back to a small solid like it was designed for. The Comp 270S might be a good choice. It's 224 @ .050......still maybe a tad big, but you can easily counter that by installing it down around 103 or 102 instead of 106. That would help make up for any lost bottom end torque. I am sure there are other small solid grinds out there......that one just came to mind.
 
RustyRatRod said:
Here's what many forget when comparing and or replacing a solid with a hydraulic, or the other way around. A similarly ground hydraulic will "act" about 10* bigger on the duration @ .050 than a similarly ground solid. That's why you can end up with a dog if you go with say a 230* @ .050 hydraulic where a 230* @ .050 solid was. Especially in the case of a 273, since it's a small cube engine. If it was mine, I'd try my best to scrounge up some original solid adjustable rockers and pushrods and change it back to a small solid like it was designed for. The Comp 270S might be a good choice. It's 224 @ .050......still maybe a tad big, but you can easily counter that by installing it down around 103 or 102 instead of 106. That would help make up for any lost bottom end torque. I am sure there are other small solid grinds out there......that one just came to mind.
Click to expand...
Isky E4 is a bit bigger than the stock Charger 273 cam. As close as you can get without having one custom ground .
 
toolmanmike said:
Isky E4 is a bit bigger than the stock Charger 273 cam. As close as you can get without having one custom ground .
Click to expand...

I started to mention that, but I'm not familiar with the specs.
 
toolmanmike said:
Looks like a Commando. Are you sure? Have you looked at the piston tops with a boroscooe to make sure? What number heads are on it?
Click to expand...

It's a 273 Commando mill with 10.5:1 pistons and 2658920 heads. I don't know why but someone's swapped out the adjustables and solid stick for stamped rockers and a hydraulic cam. Ideally I'd love to go back to a solid but at this stage a nice hyd flat tappet stick makes more sense.

Unless someone has some 273 adjustables rockers they would like to sell?

IMG_1437.jpg
IMG_1466.jpg
 
They probably listened to to many Chevy guys and read too many magazines and forums. The ductile iron small block Mopar adjustable rockers are rock solid as long as the adjusters are in good condition OR you replace them with the Crane adjusters and lock nuts.
 
don't put a comp chevy cam in your mopar or an antiue Isky one grind fits all cam - your mopar is bot a y block ford
run a compression check b 4 doing anything
let's see where you are at
highly doubtyou have a real 10:1 motor
lunati voodoo is best choice but which will depend on all the factors
 
What rear gears and tires size you running?

I'd measure the lift on that cam to get a ruff idea what you have now.
 
Hipo pistons are one of the most important pieces for the 273 commando.
You need to verify this. Nothing else really matters till u verify.
 
Have you tried tuning the distributor curve and carb to get the most of what you got.
Engine looks fairly stock unlikely the person put a way too huge of a cam in it, you might be expecting to much from the little 273.
I tried to figure out what you have now, no point swapping cams only to pick something that's similar to what you got now, If you looking for bang for buck and don't mind deep gears go 3.91 plus, 3.23 might be ok behind 360 plus engines but are pretty high for a 273.
 
Wyrmrider said:
don't put a comp chevy cam in your mopar or an antiue Isky one grind fits all cam - your mopar is bot a y block ford
run a compression check b 4 doing anything
let's see where you are at
highly doubtyou have a real 10:1 motor
lunati voodoo is best choice but which will depend on all the factors
Click to expand...


The biggest reason why the Isky E4 is used so often is the lift and duration is similar to the stock specs. Most off the shelf solid lifter cams are designed for race engines. When you are building a 273 you don't have much choice unless you have one ground for you. Pistons are the same way. Not many choices unless you have them made.

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 lift 260° duration 216°@ .050 l/c 108°
 
we sold lot's of isky e 4s
they also came in the trunk of a hi po 312 57 t-bird
I'v never cam doc'ed the 273 solid cams
definately do not want a race cam on the street
withot the adjustable rockers it's a lot of money to go back to solid
let's see the compression
 
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