AMC 327 - 443 CID Rambler V8

[amcenthusiast]

'64 AM RV8 heads; fully ported, reworked chambers getting fitted with cut down '73 AM 360/401 valves > to fit stock 1.81" RV8 valve stem spacing; 2.02"/1.65" cut down to 1.95"/1.60"...

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[amcenthusiast]

XRV8 Race Parts dual valve springs for Rambler V8; 480" lift (+.060) -about 120 lbs. seat pressure/280 lbs. open @ 1.9" install height:

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*use SP pn# VK 174R hardened 4G locks only (with 4G valves) or Comp Cams 4G Super Locks (for Mopar)

...do not use pn# VK 174 (non-hardened)

[amcenthusiast]

XRV8 Race Parts reworked '64 RV8 cylinder heads for 443 stroker application; finished, pre-engine assembly, currently installed on running engine:

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(using outer valve springs only for first start up test)

[amcenthusiast]

Honestly, I think it can be seen there is still more potential to be had by further modification to the heads.

eg: 5/16" stems, bronze guides, Chevy LS beehive springs? (for reduced mass/moment of inertia), adapted Mopar RB V8 roller rocker arms with custom made rocker shaft and pedestals etc.

But these 443 heads are 100% DIY by me on a shoestring budget.

Along with Rambler V8's smeared reputation for having 'small/restrictive exhaust ports' (a negative concept I believe is displaced by understanding the more complex positive design attributes of the port), is the overall weight of the engine.

The urban myth proclaims all '56-'67 American Motors Rambler V8s overweight.

(implying poor power to weight ratio to those who know 'race car secrets' or implying 'obsolete', lower technology to those who don't know any different)

One by one, part for part, I can prove otherwise.

Where Chevy Gen1 small block head generic weight is 50 lbs., here are pics I've taken showing my Rambler V8 heads on a bathroom scale:

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-this proves the overall large appearance of a '56-'67 AMRV8 head is due to a generous water jacket, not because the casting is a stupid/low tech thickwall casting.

[Carnut1]

Looks like a double exhaust crossover. Seems exhaust ports with a crossover flow better than ports without a crossover. Probably helps even out the Siamese exhaust ports.

[amcenthusiast]

Keen observation Carnut1.

This will take an exhausting explanation to describe?

[amcenthusiast]

I think my exhaust porting work proves it might be worthwhile to see how 443 CID changes the power output of the engine.

I also think that someone else could do a better job, which leaves more power 'sitting on the table'.

Since the stock Rambler V8 exhaust manifolds don't fit into Gremlin engine bay, I needed to make my own headers.

Since the engine has siamesed center exhaust ports, I did much study to make the best headers possible.

This process led to studying how to make 'best'/true 180 degree tuned headers for a conventional V8 engine.

The last thing I wanted to do was make a stupid set of headers for an engine that already has a smeared reputation for it's exhaust ports.

I think the easiest way I can describe my exhaust system is with another shop drawing.

The drawing will help explain why siamesed center exhaust ports were originally considered to be a solution for a 90 degree dual plane crankshaft V8 engine with 1-8-4-3-6-5-7-2 firing order design error, whereas the goal for making headers was to achieve greater exhaust pulse equilibrium among the cylinders which would have a true independent runner induction system on the intake side, all done to explore higher tuning potential of this particular engine design.

[pdq67]

Wasn't it mentioned earlier that a Cad. head was like the one that you are extensively modifying?

If so, how far off are the bore spacing's and if close can you install the Cad. head on your big Rambler engine?

Seems like if you could make the larger port Cad. head work that you would save some time and work???

Kinda like trying to install an early MOPAR 345", 4.31+", b/s Desoto hemi head or a 4.56+", b/s 354" Chrysler hemi head on a 4.40", b/s SBC instead of carving yourself out a hemi head that will actually fit the SBC..

pdq67

[amcenthusiast]

Hi, this is another good observation. -That's the point though; the Rambler V8 heads are almost copies of the similar year model Cadillac V8 heads > whereas the exhaust port shapes and sizes appear to be the same > both having the exhaust vapor exit the valve pocket through a 'horizontal rectangular' area.

Since these two engines have nearly identical exhaust port designs, and Cadillac made a 429 version of theirs, to know it, serves for sake of encouragement to build 443 Rambler V8 version.

As far as cylinder bore spacing goes, '56-'67 AM RV8 uses same 4.75" bore spacing as AMC's later '66-'91 AM V8.

And this is where RV8 and CV8 differ; the Cad has a 6 bolt per cylinder compared to Rambler V8's 5 bolt per cylinder design.

...but the later '66-'91 AM V8 (with same 4.75" bore spacing) also uses a very similar 'spread out' 5 bolt per cylinder head bolt pattern; the later AMC head is the closest match for a head swap effort.

HOWEVER! All that is beside the point!

The point is to take what's there and figure out how to make the best of it.

...and in this case, that means getting out all the porting tools and spending some time to get the job done.

Some people though, have 1000 excuses for everything.

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Did you know, I am the only person to reveal the *Cadillac to Rambler V8 cylinder head similarity?

I don't like saying it, but this fact alone proves the engine has been unfairly described by stiff necked people.

Like standing between a rock and a hard place, telling the truth about Rambler V8's power making potential transforms into a moral dilemma;

How to build a Rambler V8 race engine becomes an exercise of how avoid railing on those people who insist it can't be done...

...which may be the most difficult task of them all.


*Back in the old cave man days, they used to try to smear the reputation of Studebaker V8, calling it 'Caliper V8' -and they even made up stories telling how Studebaker people swiped a Cadillac V8 in the middle of the night and copied it's dimensions with veneer calipers... but the only interchangeable parts are the rocker arms, which was a common swap back then because the Stude V8's rockers are the adjustable type but the Cad V8 rockers are not...

*This feature most definitely has historical significance because AMC/Nash Ambassador/Hudson Hornet rivalry sat between Cadillac, Packard and Studebaker... the Rambler 327 CID hearkens back to Packard's 327 CID inline eight cylinder engine... moreover, the Rambler V8 'deep skirt' main bearing webbing looks to be 'almost a copy of' Packard's inline eight main webs...

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Clear away the smokescreen though and look what happens;

443 'all AMC' cubic inches in a Gremlin:

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[amcenthusiast]

Still not done with shop drawing to explain header/exhaust system design...

...been busy buying a new project car; a basket case '69 AMC Rebel.

...one moment please/be right back

[amcenthusiast]

The concept of how an exhaust crossover might serve to increase scavenging and/or flow is a very interesting study in itself diverging into laws of thermodynamics as applied to heat engines; what engine design/mechanical engineers go to school for.

As I understand it, on a conventional '90 degree' or 'dual plane' V8 crankshaft, the 1-8-4-3-6-5-7-2 firing order has a 'design flaw' because exhaust flow from cylinders #4 & #7 are restricted by immediately chasing #8 & #5 into the exhaust manifold system.

Making a much longer story shorter, by placing an exhaust crossover from #4 to #5, a secondary path is given to provide flow relief which lessens the backpressure experienced by cylinders #4 & #7 (which are otherwise forced to chase #8 & #5)

(by blocking off the 'heat riser'/exhaust crossover, there is reduced heat transfer to the intake mix, however, exhaust flow benefit (provision for alternate 'exhaust flow escape route' for #4 & #7) is defeated)

This becomes obvious by looking at a shop drawing made to describe a conventional V8 exhaust manifold system, also a drawing made to explain how a four into one header works as compared to a 'true 180 degree tuned header' system.

To explain concepts of siamesed center port exhaust ports with 'X shape' exhaust crossover manifold in between becomes a study of sound waves having what is called 'constructive and destructive interference'.

http://www.phys.uconn.edu/~gibson/Notes ... Sec5_2.htm

Moreover, when we study thermodynamic formula for calculating variable pressure and volume of a gas, the schematic diagram of the formula shows a three sided box having a concave roof... which obviously compares to side view profile of Rambler V8's 'section 2' in the shop drawing (the 'mid section' of the RV8 exhaust port)

The pressure-volume math (for the unique 'boxed shape') can be found by digging through the charts on 'HyperPhysics' webpages:

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

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Obviously, there is much more complex engineering involved to design a 'working exhaust port' as compared to an exhaust port which merely functions as a hole for unheated airflow purposes.

As one who who attempts to advocate there is complex engineering involved to explain Rambler V8 exhaust port shapes, the concepts explained by Laws of Thermodynamics is, at the very least, an entertaining study for someone who has an interest in 'heat engine' design.

As I understand it now, there are two sonic focal points (actually four) in the combined RV8 siamese center port exhaust system design. This is even more verbose for me to describe, not having any formal refined text already written at this time.

The potential for amplified constructive sound waves and potential for deconstructed 'dead space' within the RV8 exhaust crossover passageway is evident. Either way, the communication between the cylinders does appear to be highly engineered and complex whether it is used for increasing multiplicity -simply to increase flow rate, or focused, constructive sound waves (as I would tend to advocate; the complex shape of Rambler V8 crossover exhaust manifold is for scavenging improvement). ...I do not believe the obviously complex shapes were designed to reduce thermodynamic efficiency because the mathematical models indicate there is intelligent design.

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Still working on current purchase of 'new' '69 AMC Rebel project car, making plans on how to tow it home... one moment please... we are experiencing technical difficulties...

[amcenthusiast]

Proving why heat is a critical factor when discussing exhaust port design and flow rate:

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[amcenthusiast]

http://www.epi-eng.com/piston_engine_te ... ciency.htm

http://performancedevelopments.com/fuel ... orsepower/

[Carnut1]

Interesting, since these are heavily copied from Caddy I am guessing Caddy did this engineering? At first look the Siamese exhaust is a flow nightmare but after some flowbench work you learn that sometime what looks all wrong actually flows better. Different engineering approaches are used to combat certain inherent flaws in a design. St. Needs a video of this mill running. I am betting it has a very mellow tone at idle and is quite snappy on tip in. Thanks, Charlie

[amcenthusiast]

Hi, thank you for your insightful reply; there is definitely more science concerning an exhaust crossover than what is typically discussed.

So far I've only experimented with 1 1/2" and 1 5/8' diameter tubing for exhaust crossover on this engine.

Yes I believe many of the early US V8 engines had their exhaust system designed this way to help resolve tuning/design errors related to 1-8-4-3-6-5-7-2 firing order.

Still currently working on shop drawings to help explain the custom made headers for this engine; yes it has it's very own sound signature, distinctly different from other 'modern/conventional' V8s.

(intending to show three shop drawings to compare 1) conventional header system 2)180 degree header system and 3) custom header system made for this engine; worked on the drawings last night, but I'm bogged down during daylight working on a '69 AMC Rebel project car)

Here's another good article to increase understanding of resonant interference:

https://courses.lumenlearning.com/physi ... r-columns/