426 HEMI crate engine rebuild (mag article)

Does the end result of this rebuild seem reasonably accurate, in your estimation?

https://www.hotrod.com/articles/hemi-crate-rebuild-and-dyno-test/

I'm considering a std bore/std stroke future cruiser deal...a very mild build like this one, this one seems it might be a good influence.

That was a good article except they used a very soft main bearing (972M). Today I would suggest a higher performance (slightly harder, and narrowed) coated main bearing. The mains are the same as any big block so why not? Other than nit picking things like that, the results match what I was getting back in the day when I was rebuilding many crate HEMIs.

One other point: I very seldom used hydraulic roller lifters in a HEMI because the extra mass of the HEMI valve train limited the RPM before valve float. After many years of running Mopar Engines West and supplying HEMIs to people that liked to rev their engines in spite of what they would tell me, my favorite cam combo for a high performance street HEMI was a simple solid flat tappet using solid lifters with the EDM oiling holes added. Then RPM was not an issue, it was much less expensive than a solid roller setup with much less maintenance, and lasted longer too. If you are careful with the spring pressure, and keep the revs down, the hydraulic roller is a good solution.

I was reading the article and it all seemed good until they said they were using lash caps with a hydraulic cam. This is doomed to fail in any engine, not just a Hemi. -- Ray

Interesting, what will fail and why?

My take on why the potential for problems with lash caps is higher with hyd cams is something along the lines of:

If the motor is run to an rpm high enough to incur some type of instability or float, and you have hyd lifters....... the lifters collapse some amount on the opening side of the cam, which means if you get to the point of actually floating/lofting the valves, the potential for an even larger space between the rocker and valve tip/lash cap is created(collapsed lifter is effectively shorter)...... which increases the likelihood the lash caps can come out.

And with the Hemi, the depth of the lash cap is a little shorter than “normal” because of the rather short valve tip length.

That would be my take on it anyway(but, Ray is the one with the Spintron...... so I’m sure he knows what’s really going on).

I can add this........
I recently had some hemi Victor heads here off a build that had a hyd roller cam and it had apparently exceeded the rpm capabilities of the lifters/springs........ and 3 or 4 of the lash caps got tossed....... resulting in a bunch of noise.
Fortunately the motor was shut down before any damage was done.

When a Hemi is tuned right, they rev very quickly. You won't catch it in time with your right foot....Doesn't matter the hp either. Valve float in a Hemi means two valves just hit, and took the head off one of them that just launched thru the rest of the engine...Its not like a wedge. When a Hemi floats the valves, its over with right there....Big mess.....No second chance.

A rev limiter set low enough is critical with one of these engines.

Ray is right. I missed that. Hydraulic lifters and lash caps don't mix. I did build a couple with hydraulic rollers but the valve stems were long enough that I didn't need caps. Still... since the valve centerlines intersect, valve float is to be avoided at all cost...lol...
(Corrected the spelling from my stupid cell phone)

Thanks all....I couldn't ask for better answers, or more knowledgeable sources.

The main changes I would probably make are aluminum heads and solid tappets,
but I'd want the cam on the milder side similar to the one used in the article.

I like the tame overall specs of this one and the end result seems pretty nice.

Regardless of cam or cubes, build it with some compression...They tolerate a lot on pump gas. You can go as much as 12:1 on most pump gas premium....They run so much better with some compression. That 10:1 stuff is for the other engine types...

Cams, to each their own. We have had very bad luck with flat tappet cams for the last couple of years. Nobody around here will build an engine with them anymore. Just remember the more cubes, the more duration and lift the engine will tolerate without sacrificing idle and drivability.

What Dragula said! My 605 runs a roller with 288/292@.050 on the street I love the cam as does the motor.

Well I hope to eventually work my way up to two of them, a 572 and a 426.

The 426 rather tame, the 572 less so.

This is for the tame one....

This dumb idea could take several years to materialize, it may or may not happen
but I'll push when the time is right.

Rich here's an old build that's close to mine except I run a stage V 2 four manifold and aluminum heads.

https://www.hotrod.com/articles/mopp-0310-hemi-426-crate-engine-dyno-test/

KOOL!!!

We had a 484 (+.06/4.15 stroke) street Hemi in a street / strip 69 Barracuda that was a ton of fun. 10.5:1, Eddy heads, and a 1050 4150 carb with a mild roller cam....Car ran 10.26 at +126 with the wheels +2ft in the air....What a blast that car was. That thing sounded so angry, you would swear it was a race engine......Here you go for the sound byte!

https://www.youtube.com/watch?v=mrm62S2Fmow

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Sorry, I thought we covered that a few posts ago, but that one already is.
But......that one isn't the topic here.

The possible future std bore 426 which I was attempting to discuss here...is another thing...

Hey thank you. That's quite a bit more rpm than I'm looking for out of this particular deal, but still good reading.



Hopefully I don't regret getting myself into this mess later LOL.