Welcome to…………..


The Red Baron’s Mopar Skunkwerks is  dedicated to the retro conversion of  my old car, The Rat Patrol – my 1971 Valiant Charger – amd my current ride, The Red Baron, a 1967 Plymouth Belvedere II RO23 clone –  to a Generation 3  Hemi 6.1 litre engine.

This includes the retro-mod from EFI to carb induction.



It will detail all the steps and modifications  necessary to achieve the conversion..including a comprehensive “to do” list and parts list to assist those who may want to try the same ……..


1st iteration – single carb on Modman intake – woeful tuning issues with intake



2nd iteration – dual quads and plenum divider on Modman – improved peak HP but still terrible bottom end signal



3rd iteration – Edelbrock dual plane dual quad – far superior signal strength – Improved peak HP by 20 rwhp – Improved TQ across range by significant amount – Did show some shortage of plenum volume at track, slightly taller than the Modman requires some skimming for engine bay clearance.






Building a better Rat Trap


Forged pistons – with valve reliefs!!

At the time I first did my conversion, I was in the dark in relation to a few matters which have since come back and haunted me. So I decided to get the motor blueprinted to rectify what were becoming serious issues.

To be clear, the two problems were related in the effect they created, but separate as far as components.

PROBLEM 1 – Piston/Valve clearance.

Factory P/V clearance is tight with factory slugs. Not an issue if you keep the factory cam and factory EFI.


– Most aftermarket camshafts for Gen 3 motors are ground with a fairly late Intake Centre Line. This is to ensure the Piston does not hit the Valve.

 – Not a problem when running EFI, (EFI atomisation is superior) – BIG PROBLEM with carb induction.

 – A problem called ‘intake reversion’ (The intake charge getting sucked back up the intake) can create fuel pooling in the runners.

RESULT – Bores ‘washed’, Excessive oil burning, bore glazing and bearing damage

SOLUTION – If you want to stick with carbs, get rid of the factory pistons and degree your camshaft correctly.


Scoured bearings due to oil overheating and thinning.

PROBLEM 2 – Intake options.

At the time I did my install there were very few intake options, mostly inferior to the factory EFI system.

Most are STILL inferior to the factory intake, whether you use an EFI Throttle body or a Carb.

The OCP dual plane intake released two years ago is by far the best designed off-the-shelf carb intake and has been painstakingly dyno tested to prove its efficiency.

The Edelbrock Dual Quad is an old design, and although works acceptably, my testing showed the plenums were arguably still too small.

Anything else, including the ‘drag pack’ style hi rise intakes, have notable deficiencies in their operation.

RESULT – Poor fuel induction with poor low end response, poor fuel mixtures, you can guess the rest!

SOLUTION – If you don’t want to use the factory intake, use the OCP intake. it can be ordered for EFI or carb applications.



Glazed bore as a result of intake reversion diluting oil


– Well, for a start, no oil burning!

– The cam was retarded 8 degrees, so I expect a significant improvement in induction signal down low and an increase in mid range torque, as well as a more useable power band. I also have the option of going with a bigger cam later.

– The intake and heads are being port matched

– Better grade fasteners are being used and the timing chain is being replaced with a 9 key way double roller.

Stay tuned for progress updates on the rebuild!

Parting the clouds…


One of the big hurdles I encountered when doing my retro fit…and one that I found a hassle when pondering a change to forged pistons, was what were the parts I actually needed!!

The following list is designed to help the guys who may not have the benefit of an experienced Gen 3 engine builder, but need to get some parts lined up on the table to do stuff.

The list is split into four sections – sections –Basic technical specs of a standard stroke 6.1 hemi rotating assembly – Parts to complete a retro fit using carbs – a list of gaskets and fasteners you’ll need for any tear down or cam change – and some parts suggestions for an internal rebuild  for a stroker or just a stronger standard stroke motor.

These lists are NOT comprehensive, but will at least give you an idea of what’s available and who makes what.

signed, your Editor.


6.1 Specs

Bore – 4.055

Stroke – 3.58

Rod length – 6.240

Pins – 2.55”, .9843”

Piston weight – 441 grams inc pin

Retro fit parts list

Ignition ECU – MSD 6-HEMI P# 6013 – This is for ignition only. so unsuitable for use if you want EFI.

ECU to coil Harness – MSD P# 88864 (Requires changes to factory cam and crank sensors to 07-10 5.7 Cam and Crank sensors)

Engine mounts – TTI – MM57A

MP Flex plate adapter – P5153753

ATI Flex plate adapter (Recommended) – ATI915685

Milodon Pan/Sump – MIL31000 – (Note, also available are Weldtech, Canton Mecca, Charlies &  Moroso- (Do your research!,Ed.)

Milodon Pick up – MIL18331

Milodon bolt kit – MIL85025

Milodon splash tray – MIL32010

Milodon pan gaskets – Mil40750

Mahle splash tray – OS32363

Milodon Oil dipstick – 22064

Lokar flexible transmission dipstick

Lokar universal accelerator cable

Lokar universal kickdown cable

Manifold – Carb(s) or 4V Throttle Body

  •  OCP Dual Plane Single
  • Edelbrock Dual Plane Dual Quad – (Small plenum volume, responds well to spacers)
  • Ritter Drag pack (Requires scoop – 7.5” high)
  • MP Drag Pack – (Requires scoop – 9” high)
  • Indy Modman – Dual or Single (Recommended for use with supercharger only)

Air cleaner, Aluminium Radiator, Hoses, Electric Fans

PS delete pulley (Bouchillion)

Headers – TTI long tube or Jeep SRT factory may fit

Remote oil filter set up or Dakota filter mount

TTI oil boss block off plate – 0200-FBP

Idler pulley – 0489172AA, Screw – 06508247AA

Tensioner – 04861660AA, Screw – 06104221AA

Jeep 6.1 Nippondenso Alternator pre 2011 – 56044380AC, 56044380AH,  (Use with external regulator) – The Jeep alt. provides for better inner guard clearance.

Fasteners and gaskets

Main Cap oil pick up stud # 6506333A

Main Cap bolt #6506272AA M12X1.75X91.2

Main Cap oil pick up stud # 6506333A

Main cap side bolts #6507697AA M8X1.25X45

Mopar Head Gasket 6.1 #5037592AC

Head Bolt #6506334AA

Head Bolt #6510280AA.

Screw-Connecting Rod #6509243AA

Head Gasket Sets – #Fel-Pro HS26366PT

Intake Gasket (Ports only) – Cometic #C5197 – Cometic Aramid Fibre

Intake Gasket inc Factory valley – MAHLE Original #MS19674

Exhaust Gasket – Fel-Pro #MS96964

Lower end gasket kit – #05170861AC

Std/Stroker rebuild parts.

Pistons – Probe SRS forged – #14868 – 491 grams inc pins – 9.88 comp  – Rings – Total Seal ring pack – CR 1001 60 (1/16,1/16, 3mm).

Piston Kit – Mahle HMI220055F01 forged inc metric ring pack (1.5, 1.5, 3.0) – 429 grams – :10:1 comp

Piston kit – Wiseco K0112xs forged inc metric ring pack (1.2, 1.2, 3) – 460 grams – 11:1 comp

Piston kit – Stroker – Wiseco K471X05 forged inc metric ring pack – 445 grams – 10.5:1 comp

Camshaft – Crower camshaft degreeing bushings – 720007, 720008, 720009 (Use these with aftermarket pistons with valve reliefs ONLY)

T Chain – Manley 73205 DR 9 Key way – (Use with aftermarket pistons with valve reliefs ONLY)

Rear seal without retainer – #C5203 Cometic

Front seal – 53021585AD or Timken SL260028

6.2 / 5.7L – NON-MDS Lifter 5038784AC.


11.7 – a win in my book…

Three Years ago I was talked into replacing my broken LA stroker with a Gen 3 hemi.

I figured why not? Easy I assumed.. Run 11s easy I assumed….

Well if you’ve been following…you’ll know it ain’t been easy – but I succeeded through trial, error, bloody pigheadedness and some light bulb moments!


If I had my time again…id have gone straight to a hood scoop and a drag pack intake – not because its the best way to make HP with a carb….BUT three years ago it was pretty much the only efficient way. Other intakes on the market were inefficient, or needed more than one carb.


If I had my time again…Id know to try to replicate the factory EFI intake….looong runners…and a decent plenum.

So instead…I used stacked spacers


Now thanks to Joe O’Cone’s OCP intake, the resto mod is a lot easier… But that wasn’t around when I started.

Cam calibration is still a thorn in the side of those doing this mod.  Unless you use custom slugs..it’ll bite you on the backside!

I plan on contacting Modern Muscle next year to see what can be done to defeat Piston/Valve issues without swapping slugs.


And then there’s port matching..but now the Eddy dual quad is available with 6.1 ports…for a mere $700 US…..

Until then..I have my 11.7 timeslip to keep me warm 🙂


Dyno Data is IN!

A while back I promised that I’d do a genuine comparison between the Indy Modman intake and the Edelbrock 5.7 dual quad dual plane.

I experienced significant tuning issues with the Modman running both single and dual carbs – (333 RWHP) and it only really worked half way decent when I installed a full height divider (346 RWHP)

After much testing and trialling of the INDYtm intake which yielded only moderate improvements, I bit the bullet and purchased the EDELBROCK  / MOPAR PERFORMANCE Dual Quad Dual Plane AIRGAPtm. 

Only a moderate change in tuning was needed, the mid range and WOT needed leaning by one step on the step-up rods, and the pump shot set back one step.

Below is the dyno chart ( same dyno..similar atmospherics) showing three (3) runs – 


Dyno Dynamics Dyno Chart

 – The BLUE line was the Modman with divider – this netted a 11.9@ 114mph

 – The MIDDLE RED is the EDDY – same carbs – 360 rwhp

 – The Upper RED is the Eddy with twin 1″ 4 hole spacers. – 368RWHP

(Dyno Dynamics Dyno Chart)

-The Eddy had a home port match to the 6.1 heads.

-I think this proves conclusively that the Modman is a JUNK NA intake.

-My guess is that the carbs are losing about 15 rwhp to the EFI….

Going steady with Mopar and EDDY!!


After much testing and trialling of the INDYtm intake which yielded only moderate improvements, I bit the bullet and purchased the EDELBROCK  / MOPAR PERFORMANCE Dual Quad Dual Plane AIRGAPtm. 

Only a moderate change in tuning was needed, the mid range and WOT needed leaning by one step on the step-up rods, and the pump shot set back one step.

The difference has been staggering…with an enormous amount more mid range and far more responsiveness.

Ive found it impossible to get an accurate GTech 0-60 time because the car just smokes the bags all the way through 1st and well into 2nd gear.

I wont be able to provide any statistical comparison until I get it to the track…but Im confident my 60ft issue is no longer going to be induction related……Hooking up may be another challenge!!!!


Eddy dual quad


Indy Modman MISERY!!

To speak plainly, Indy Cylinder Heads should be ashamed in releasing such an ill-thought out product on the market, without comprehensive testing including track time.

Peak HP on engine dynos maybe one thing, but its highly doubtful even Indy are aware of what an average performer this piece is in carburreted format.

If you plan on buying a Modman…I’d recommend you use it in an EFI or Forced Induction role.

Single 800 AVS - second best MPH but appalling lean out off the mark - shooter drilled to .040th helped a little

Single 800 AVS – second best MPH but appalling lean out off the mark – shooter drilled to .040th helped a little

The following is a detailed chronology of my efforts to get the Indy Modman intake to work efficiently on my Gen 3 HEMI.

 All tuning changes were validated both on the same dyno and at the track in similar DA.

 I have been tuning Carter and Edelbrock carbs for thirty years and am fully aware of the processes required in re-calibration and enhancements.

1st tune – Single 800CFM AVS Thunder carb

333 RWHP – 110.8 MPH – 12.4 sec qtr – 1.94 60ft

Comment – Lean bog very apparent on launch


2nd tune –  Drilled pump shooter to .040th – 1.91 60ft

Comment – No bog if I rolled on the throttle, but sluggish response


3rd tune – Pro Systems 830 cfm – 50cc Primary pump shot, 30cc secondary

No dyno – 109.8 mph – 12.4 sec – 1.84 60ft

Comment – No bog but sluggish 60 ft


4th tune – Twin Edlebrock 500cfm Performer carbs – drilled shooters to .040th

No dyno – 111.1 mph – 12.39 sec – 1.91 60ft

Comment– Slight bog unless I rolled in the throttle


5th tune – Twin Edelbrocks with twin Brodix turtles inserted in plenum

Comment – No change


6th tune – Twin Edelbrocks with full height divider along length of plenum – increased initial timing from 15 to 21 deg .  Converted linkage from progressive to 1:1.

348.7 RWHP – 114.3 MPH – 11.9 sec – 1.82 60ft

 This has been the best result achieved. The 60 ft is still woeful for the mph and HP.

Dual quads 1:1 linkage

Dual quads 1:1 linkage


  – Traction not a factor in any testing.

  –  No modification of air bleeds with Holley, just jetting.

  –  The Modman plenum volume results in a significant loss of signal and requires a MAMMOTH pump shot to overcome the overall plenum volume requirements.

  – The full height divider I ran was also ½” wide, serving to occupy some plenum space as well as improve the signal.

 – The car 60 footed better when I rolled on the throttle than when I rugged it in every scenario.

 – Stalling up had a negative effect – often resulting in a bigger bog.  I have determined this was because stalling uses up some of the ‘tip in’ travel hence a smaller pump shot.

 – The cam I ran was a HR with 219@.50 – It does not require a big converter , nor really high gears, so this was not contributing to the issue .

The divider that showed biggest gains. Hard to believe this lump of metal improved MPH by 3 mph!

The divider that showed biggest gains.
Hard to believe this lump of metal improved MPH by 3 mph!


On the street, no one would ever guess that these issues were to arise at the track..until I did some street tuning on drag radials.  It was only then I noticed the car struggled to turn the tyres on the street until tune #6.

 This problem manifested even worse at the track.



  • NO intake should perform better with a plank of metal inserted into the plenum.

The Modman is a show/supercharger intake – pure and simple.

It may function better with a large cube motor – but as it runs a plenum that is 5x the volume of a normal single plane M1, I would still recommend experimenting with a divider.


So here’s a summary of the issues I’ve confronted. 

I’ve linked the problem to the page where I’ve covered it in my blog


ENGINE POSITION –Using these adapter mounts you can expect an extreme pinion angle, a crooked engine and very little valve cover clearance on the right side inner guard (as viewed from the driving position) with an A body installation.

The problem lies with the left side mount – the pedestal is too high – pushing the motor up at the front and across .

FIX – In Australia you can use the Hemi 6 cylinder K frame and mounts devised by Elko/Valiant spares, OR

FIX – Use Andrew Dunnet’s K Frame/Mount conversion kit which is superb

FIX – Have the left side TTI mount modified, OR

FIX – Centre the engine,

FIX – Make a custom K member

Left side mount - pedestal stands too high for a level motor.

Left side mount – pedestal stands too high for a level motor.


STEERING BOX CLEARANCE –  Thought I’d  found a solution with Street and Performance shorty headers.  These work a peach on the left side…but foul on the aussie steering box and are probably NOT going to work on a R&P  conversion.

FIX – In Australia / NZ  – Simple answer..budget for custom headers.

FIX –  In the US – Use TTI headers and the Dodge RAM truck Hemi manual trans starter motor.


Fabricated right side header


MILODON PAN GASKET – Variety of issues – Stud hole not large enough, splash trough not deep enough, etc

FIX – Do what I did…use the FACTORY splash tray/gasket and trim the ears off it and drill two extra holes to match the Milodon pan.


If it leaks – then COMBINE with the Milodon cork rail gasket for a happy marriage between the tin pan and pan rail.

 OIL FILTER – The TTI adapter mounts foul on the TTI block off plate.

 FIX – Some small grinding required.


FIX – Run a Dakota angled filter mount – a shorty filter and some grinding is required.

 In any case, clearance for remote oil hoses is tight between the auxiliary oil ports and the Alt. 





The early 5.7 AND 6.1 Car Alt sits too low and fouls the A body frame rail

 FIX – Provided the engine mount problems are fixed…the Jeep Cherokee 6.1 Alt provides more clearance to the inner guard.


 FIX – Buy a March pulley kit system


FIX – Clearance the inner fender fold.

REGULATOR CONNECTOR – The modern G3 Alt. has a twin post external regulator socket. 

 FIX – Connect one to the F(-) and one to 12V switched.

CURRENT – The G3 Hemi Alts can make 150 or 160 amps – This will fry the old factory ammeters at full load. 

 FIX – Fit an extra “shunt” wire that runs from the Alt. post to the starter relay – this “splits” the current and makes it highly unlikely your car will ever draw enough load through the existing Alt wire to cook your ammeter.   Use 10 or 12 gauge wire.



COMPATIBILITY –  The 6.1 runs non-compatible senders to the later MSD Hemi 6 ECU harness.

 FIX – Buy later 5.7 Cam and Crank sensors.


BRAKE BOOSTER (Aussie only)

 COIL PACK INTERFERENCE – The aussie  V8 brake booster is not a happy marriage with the coil on plug valve covers. Basically any re- positioning of the booster in the bay, or cutting of the booster bracket, will still not allow enough room to be able to remove either the #6 or #8 coil packs for plug removal.

 FIX – Relocate the booster to a remote system, The MC will also need to be re-positioned on a off set bracket as coil pack clearance is necessary, OR

–  Use the offset bracket from Elko / Valiant Spares and a Hemi 6 booster

FIX – Run a Hydro booster


Off set brake booster bracket available from Elko / Valiant spares – includes new dust boot, all linkages and bushings.


CLEARANCE – The two rear most pan bolt lugs on the left side interfere with the body of the Mopar mini-starter.

 FIX – The two left rear-most oil pan bolt lugs cast into the block must be trimmed back to allow clearance for the starter when using the Mopar mini starter.


 FIX – Use a 2005 Ram starter. (This may interfere with  TTI headers)


 INLET/OUTLET – LOCATION AND DIAMETER – There is no direct compatible radiator for the A Body / G3 6.1 conversion.

FIX – Champion makes a “B Body 6.1 radiator”  P# CC1643 – however although on the correct side – the inlet / outlet pipe diameters are reversed.

 They ARE on the correct side however– so ………… 

Fix – Use Gates universal hoses – 1 x p# 25526 (13″), 1x p#25527 (15″)