Moparts Tech Archive

Small Block

MP Commando Alum Heads

Heres pics of the Mopar Performance Commando alum heads. These heads are machined from the alum magnum head for use on the older LA shaft style rocker system heads.

This first set of #'s is for the heads before we went for all out high flow #'s

Intake
.200=116
.300=166
.400=213
.500=250
.600=263
.700=273
.800=280
Exhaust
.200=084
.300=115
.400=141
.500=163
.600=177
.700=187
.800=188
---------------------------------------------
These #'s are our final #'s after all the porting had been done. We lost some flow on the low end lifts and gained on the higher lifts.

.200=102
.300=150
.400=201
.500=239
.600=271
.700=291
.800=301
Exhaust
.200=094
.300=126
.400=152
.500=176
.600=187
.700=193
.800=196

Info on the NEW LARGE Port Commando heads

Applications: 1967-‘91 318, 1968-’73 340, and 1971-’92 360 V8 engines and Commando crate motors built up to 1993 (does not fit 1992 & up 5.2L and 1993 & up 5.9L Magnum engines and Magnum crate motors).
Contents: one fully machined aluminum large port Commando cylinder head (bare machined head sold individually).

Specifications:
These heads feature larger intake ports for more airflow. The intake ports flow approximately 268 cfm. The combustion chamber is approximately 50 cc in size. The intake port volume is approximately 188cc and the exhaust port volume is approximately 68cc. The head is designed to use standard length ‘68-’71 340 valves w/ 2.02” intake and 1.60” exhaust. These heads are designed to work with standard 340/360 intake & exhaust manifolds, valve springs, keepers, retainers, “A” engine 5 bolt valve covers, and gaskets. The heads are made w/o any heat crossover passages.

Special Notes:
These heads have special machining that allows the use of a stock “A” engine style intake manifold. The larger intake ports require the use of offset rocker arms to clear the ports. This situation causes the pushords to be very close to the tapped holes for the intake manifold screws. You can see a small portion of the pushrod hole inside the tapped intake screw holes in the head. This hole looks funny, but should not cause any problems since the pushrod itself will not hit the intake screw. It is recommended that a small about of sealant be applied to each intake screw to minimize the possibility of an oil leak in this area. The benefit of this design is that you can have the larger intake ports and use a stock style intake manifold. All other large port cylinder heads require the use of special intake manifolds. The valve cover gaskets will require minor trimming so that they do not rub on the pushrods.

Valve Springs and Spring Mounting Cups: The spring seats on this head are machined to work with a .100" thick spring cup. A spring cup or shim must always be used on any aluminum head so that the valve spring does not damage the aluminum spring seat area on the head. The spring mounting cup should have an OD of 1.65”.

Standard “A” engine valve springs will work well with this head. The recommended springs are listed below:
Part number Lift Range Design Retainer Installed height
P4120249 .430”/.500” Single w/ damper P4452033 1.67”/1.70”
P5249847 .480”/.535” Single w/ damper P4452033 1.68”/1.70”
P3412068 .520”/.620” Dual w/ damper P4452033 1.68”/1.70”

Rocker Arms: The larger intake ports on this head require the use of rocker arms with more offset so that the pushrods will clear the ports. These heads are designed to work with W2 Econo rocker arms and rocker shafts (Mopar part numbers P4876343). Standard “A” engine rocker arms / rocker shafts will not fit or work with this cylinder head. The rocker arm pedestals are cast into the head, so rocker stands are not needed. The use of any other rocker shafts may not provide proper oiling of the rocker arms.

Installation Parts (available separately): A few special parts are required when using this cylinder head:

1) The suggested valve part numbers are P5249185 - intake and P5249187 - exhaust.

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2) Use Magnum head bolt set part number P4876759 w/ washer set P4120459. These head bolts are a different length than standard “A” engine pieces. These longer bolts are need to provide room for the larger intake ports.
3) Use W2 Econo Rocker arms & rocker shaft kit P4876343. Ten 3/8”-16 bolts are needed for mounting the rocker shafts (use grade 8 bolts). Use (8) 3/8-16 x 1.5” long and (2) 3/8-16x1.75” long bolts (use grade 8 bolts). The longer bolts are used in the holes that supply oil to the rocker shafts.
4) Use T/A style pushrods with a cup on the top similar to p/n P4529556 w/ approximately 7.23” length. Measure the exact length required for your application since this may be different due to machining of the heads, block, gasket thickness or other factors.
5) Use valve seal package P3690963.

Mopar tested this head using the parts listed above (and w/ a .509” lift camshaft). The use of different component parts may require modifications to the head for pushrod clearance.

Measure and check your compression ratio and valve clearance when building your engine.

Consult the Mopar service manual for the proper procedure to remove and replace the cylinder heads.

Part Number P4876310
Description Lg Port Commando
Intake/Exhaust Intake Exhaust
Valve Size 2.020 1.600
Valve Angle 18 deg 18 deg
Ports As Cast As Cast
Inches H2O 25 inches 25 inches Port Volume 188.6cc 67.8cc
Chamber 50cc
Lift
.050" 30.4 23.0
.100" 51.3 61.6
.150" 69.2 81.6
.200" 89.3 94.7
.250" 112.2 107.8
.300" 138.0 121.7
.350" 149.0 134.0
.400" 166.9 146.6
.450" 179.1 154.4
.500" 202.6 159.1
.550" 220.5 162.2
.600" 235.4 165.4
.650" 244.7 166.9
.700" 253.3 171.6
=========================================

LG Port Commando Final Flow #'s

W7Dart
Moparts Master
Reged: 01/19/03
Posts: 761
Loc: State College, PA

Well I've messed around with these things for as long as I am willing to, for now LOL. Just a few observations before we get to the #'s.... These things have a good Exhaust port, Definitley a WEIRD shape, but they don't seem to care much about the shape, I did 3 or 4 different sizes/shapes and all the #'s came out about the same. Alot of flow hiding in the deep closed chamber...... and the Short turn is VERY sensitive. I'd have to say they have the most sensitive short turn of any SB head I've messed with. It really is a very good shape right out of the box, and does'nt liek to be messed with much at all. I tried a bunch of different turns, and one was laid WAY back, and lowered the floor a ton... looked killer, but flowed like Sh%t LOL. Anyhow.....
Here are the intake #'s, as cast, then Port 1 is ported but Factory Chrysler valve job and untouched short turn, and Port 1A is same port only with fresh 3 angle cut and Little Sand roll work on the short turn. The Port 1A is the FINAL #'s for these heads....

LIFT-----ASCAST-----PORT1-----PORT1A-----DIFF
.100"-----52---------65.6--------66.3------+14.3
.200"-----94---------134.2-------137.3-----+43.3
.300"-----140--------202.9-------203.6-----+63.6
.400"-----189--------239.8-------249.1-----+60.1
.450"-----N/A--------248.8-------265.0------N/A
.500"-----229--------262.2-------276.7-----+47.7
.550"-----N/A--------272.6-------281.2------N/A
.600"-----259--------278.4-------285.0-----+26
.650"-----N/A--------285.7-------286.4------N/A
.700"-----274--------291.5-------289.8-----+15.8

Awesome Low and Mid lift... 2.02"/1.60" Stainless Ferrea 6000 Series with straight 45*

The Difference between out of the box and Fully ported is where the Customer can decide whether his $ was well spent on the head porting LOL I think there is just a "LITTLE" HP to be made from the improvements at .200", .300", .400", and .500"

Check out the differences between Port 1 and 1A @ .400", .450", .500", .550"! Most of that was just in the valve job. You can now get a feel for WHY having a good hand done 3 angle valve job is so important on any head. That 277 @ .500" on my bench is better than Any W-2 I have done, way better than any Edelbrock.... Only a W-5, Diamond, and W-8 (all exotics) have been better in the mid lift than this Commando. Yes this head did not go 300, but I think it is there, in the pushrod pinch if you want to push it and widen your intake manifold runners to match. But for the motor these are going on (Road Race Application) I could care less about moving the runner wall and really hogging out the pushrod pinch to get 300 @ an unuseable .700" just to say the heads did it. Should work excellent in their intended application. I'm still dumbfounded by the low/mid lift these things have LOL. That has always been the big disadvantage of a W-2, the Peak #'s are real impressive but the low #'s have never been anything to write home about. In all honesty I believe this set of Commandos even though they are ~15 cfm lower at the high lifts than my old W-2's, I still think these would have made more power on my 416. Oh and here are the final exhaust #'s.....(These are with NO Valve Job)

LIFT
.100"--39.6
.200"--93.1
.300"--144.2
.400"--188.0
.450"--194.9
.500"--203.6
.550"--208.4
.600"--212.2
.650"--214.9
.700"--217.4

====================
comparison numbers from your W2s, W5s, and maybe E-heads

W7Dart
Moparts Master
Reged: 01/19/03
Posts: 761
Loc: State College, PA

LIFT-----COMM----W-2-----W5----EDELBROCK
.100"------66.3-----60.2----70.2-----65.6
.200"------137.3----129.9---146.6----135.2
.300"------203.6----189.0---210.5----197.7
.400"------249.1----232.1---262.9----233.2
.500"------276.7----270.5---301.9----255.3
.550"------281.2----284.9---309.1----265.7
.600"------285.0----302.2---315.7----274.6
.650"------286.4----307.3---315.7----279.1
.700"------289.8----298.8---312.2----287.

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