Who here has done a gen III Hemi swap?

Now that my Montero engine rebuild project is now running and hasn't blown up in my face (yet), I'm riding this wave of false confidence in my abilities, while realizing I don't have any projects lined up for winter. I've noticed that old rwd Volvos are still reasonably cheap, as are Fiat Spyders, ratty 944s, and a handful of domestic rwd sedans from the 80s. Obviously LS swaps are somewhat common for a reason, (probably mostly cost and aftermarket support) but they just don't sound as good as the traditional small block or the modern Hemi due to firing order. Has anyone here tried putting the gen III Hemi into a non-Mopar chassis? Is it nearly as compact as the the pushrod v8s from GM? Any other major obstacles? I'm mostly just daydreaming here, but the only Hemi swaps I've found on youtube involve old Mopars, so there's not a lot to reference. I've seen a few wrecked Durangos and Chryslers on craigslist, and they got me thinking about this stuff, I wish Cressidas were still cheap..what would you do with a modern Hemi and a budget somewhere south of $5k?

I think Gen IIIs are rear sump? Something to think about. They do appear to be relatively displacement dense like an LS, unlike a Modular.

For 5k and a GenIII I'd do a 2WD SRT8 XJ. Figure an A833 and engine management should be sub $3000? I see 2wd Cherokees pretty cheap. Technically Mopar, but I'll call it an AMC product.

Just here for reference, Holley's Midmount accessories bring things in really tight to the long block to make fitment easier:

General Hemi dimensions and fitment talk

The Hemi is about four inches wider.  Height is pretty similar, though, at least with a truck intake on either engine.  There are many internal similarities between the engines (including powdered/cracked metal rods in the good ones)--I have even seen someone use LS swap headers on a 5.7 Hemi.  Lifter problems abound on both engines' versions of cylinder deactivation features . . .

LS is easier, but you probably actually do get more bang for your buck with the Hemi.  I have both.

From what I have seen, firsthand, about the new Hemis eating lifters that eat the engine. NOPE.

I would not say Hemis have bang for the buck unless you have a vehicle that already has one.  I never saw used Hemi engines drop below $2500.  They have... issues, so used ones were either the reason the vehicle was in the junkyard or in high demand. Idling would kill the valve tips or rockers (maybe both) and most Hemi equipped vehicles idled a lot.

When this failure mode first became apparent, it was noted that first generation Hemis had this problem, too, which was part of why Mopar moved away from it.  And second generation Hemis were rare and expensive enough that it did not matter much.

In reply to Pete. (l33t FS) :

What's the commonality between gens 1 and 3 that causes the motor to fail from idling ?

In reply to dannyp84 :

They pump too much up and doesn't drain back. Plus the cam is at a weird angle to the lifters. The 7/8 rods get starved for oil and spin bearings.

The ones in Jeep GC give up a few HP to the truck engines, but have lower profile intakes. 

dannyp84 said:

In reply to Pete. (l33t FS) :

What's the commonality between gens 1 and 3 that causes the motor to fail from idling ?

Not very much lube gets to the tips until higher speeds.  Most OHV engines dribble oil at the rocker/valve tip interface from hollow pushrods that spit up and fill a channel shaped rocker, or forced pressure that does the same.  Hemis don't really have much in the way of gravity assist to lube the tips because the intakes are so high and exhausts so far over, there needs to be more speed to make the crankcase air mistier.

The 426s suffered from it too, but since a fairly large percentage of them wound up as race engines, it wasn't as big a deal.  Plus they didn't have warranties, which kept away the riffraff   And the ones that WERE driven on the street tended to have what we would consider fairly short gearing, spinning 3000+ on the highway.  Small tires, deep gears, and no overdrive.

And now I wonder how Buick nailheads did it.  Their whole valvetrain looked like the intake side of a Hemi.  (Yes the valves were small... it wasn't just a clever name)

I'm planning on putting a 6.4 Scat Pack into an '80 Diplomat coupe.    I expect my swap to be basically the same as most any G3 swap where it was not available as an option.


It's honestly not a cheap swap.  If you are patient, you can find the engine and automatic trans for under $1500.  Look into what it takes to get a G3 Hemi into and running in a standalone setup, though.   It adds up very quickly.    You need to control the engine, and then the trans.   Driveshaft and headers/manifolds.    Usually you need to mix and match front drives.   Oil pump/filter clearance issues.   G3 truck pans are rear sump, car pans are front sump.  Most automobiles like center sumps.  The early G3 is down on power and potential compared to the later Eagle head version.    A833s have gone way up in price, and to get one installed complete is easily $1500 or more.  And then all you have is a somewhat balky 4 speed trans tha needs a long throw shifter when you are done.

In my experience the bearings in the roller lifters fail and drop the forks of the lifter on to the cam. The needle bearing and the cam shavings circulate and kill the rest of the engine. You have a very short warning when you hear a lifter tick that does or does not go away as the engine warms up.

Pete. (l33t FS) said:

dannyp84 said:

In reply to Pete. (l33t FS) :

What's the commonality between gens 1 and 3 that causes the motor to fail from idling ?

Not very much lube gets to the tips until higher speeds.  Most OHV engines dribble oil at the rocker/valve tip interface from hollow pushrods that spit up and fill a channel shaped rocker, or forced pressure that does the same.  Hemis don't really have much in the way of gravity assist to lube the tips because the intakes are so high and exhausts so far over, there needs to be more speed to make the crankcase air mistier.

The 426s suffered from it too, but since a fairly large percentage of them wound up as race engines, it wasn't as big a deal.  Plus they didn't have warranties, which kept away the riffraff   And the ones that WERE driven on the street tended to have what we would consider fairly short gearing, spinning 3000+ on the highway.  Small tires, deep gears, and no overdrive.

And now I wonder how Buick nailheads did it.  Their whole valvetrain looked like the intake side of a Hemi.  (Yes the valves were small... it wasn't just a clever name)

Early Hemis and the 426 had cast rockers that oiled through the rocker shafts.

The 426 Street Hemi had a 12 month/12,ooo mile warranty.  (Which may have been shortened to 6 months by 1970 due to how many of these cars went straight to the track)

"Scuffing" on the ends of the valves in the 426 was due to the small valve stem diameter, as per Pete Hagenbuch, one of the engineers for the Street Hemi.   

 

Russian Warship, Go Berkeley Yourself said:

A833s have gone way up in price, and to get one installed complete is easily $1500 or more.  And then all you have is a somewhat balky 4 speed trans tha needs a long throw shifter when you are done.

They're only balky when you treat them nicely. With a wave of the foot over the clutch pedal and an arm like you're shutting a door in the wind they shift like butter. Very very cold butter. In a cement mixer :)

I find it sad that people are still fixated on the Gen III LS.  A 250k mile engine is not "cheap" at any price.  Move on to Gen IV, people.  Lifter and cam swaps are not hard with the engine out.  LS3 should not be the only Gen IV people use.  The 4.8s didn't even come with the stupid weird lifters with jack 'n the box springs.

As for the Hemi, my 6.4 will do the lifter click/tick once in a while.  I don't care, in or out of warranty.  The thing moves a 6300 pound truck like it's a Datsun B210.

How expensive is a TR-6060 from a Challenger?  I  know they're physically enormous, but getting something that's already setup to play with a Hemi with no issues (and has a nice double overdrive to boot)

In reply to psteav (Forum Supporter) :

I'm seeing 1500-1800 on car-part.com

rustomatic said:

I find it sad that people are still fixated on the Gen III LS.  A 250k mile engine is not "cheap" at any price.  Move on to Gen IV, people.  Lifter and cam swaps are not hard with the engine out.  LS3 should not be the only Gen IV people use.  The 4.8s didn't even come with the stupid weird lifters with jack 'n the box springs.

As for the Hemi, my 6.4 will do the lifter click/tick once in a while.  I don't care, in or out of warranty.  The thing moves a 6300 pound truck like it's a Datsun B210.

My friends who follow competition drifting tell me it's a waste of time and money to use anything other than an LS3 when building a competitive car, which is a little bit disheartening because one thing that's cool about drifting is the diversity of chassis and engines. Sounds like as long as you don't idle your 6.4 excessively it'll be ok.

When talking about low RPMs causing damage to lifters, are we talking idling for extended time, 1500 rpm cruise, or something else ?

In reply to No Time :

I think its extended idling. Cop cars do it for hours, and that's where I heard of issues.

In reply to Appleseed :

Thank you. I was wondering what my level of concern should be on the one in my Grand Cherokee, and seems like it's low.

Engine Masters (the TV series) did a great comparison between different hemi swaps.  If its something you are considering, its worth the watch.

In reply to 93gsxturbo :

Yeah, I  was thinking of that episode. The Apache heads flow like 330cfm on the intake!