472” Hemi, crate engine

[Peter]

Hi guys

Back in 2005-2006 there was 472" Hemi crate engines with 525 hp available from some supplier. It had a Holley 850 double pumper on it, not the double carb setup. Unfortunately I don't have more data or which supplier it came from so I'm asking, does anyone here have any more data/specifications on a engine like that? I guess these engines was quite exposed in marketing back then.

[JS29]

  @Peter  to the forum. 

[RUNCHARGER]

You can get proven Hemi engines from a few suppliers. One of the best is Tim Banning at FHO in Ontario Canada. I have dealt with him many times and his machining and knowledge is always outstanding. 525HP from a 426 Hemi is basically a stocker with a mild camshaft, you can achieve much more for the same money these days.

https://forhemisonly.com/

[Peter]

Thx for the input! Do you know how much is normal to stroke for the 525 hp?

[Cudino]

Mopar Performance had 3 crate Hemis during the mid-2000 era, a 426", a 472", and a 528".  While these weren't shipped with a carb the larger ones came standard with 4bbl intakes and they recommended a Holley 850dp.  I guess these are the crate motors you are referring to.  The 472" was the one with a rating of 525hp, so probably that's the one you're interested in.  For identification purposes this size was stamped into the pad on the top of the crate motor, to the right of the distributor.  I've attaced a picture of a "472" stamp for your reference.  The 472 and 528 had 4.15" stroke (different bores), and the 426" had 3.75" stroke.  Here's an old link with some info:
https://www.jegs.com/InstallationInstructions/300/312/312-P5007630AE.pdf

- Wade

[Peter]

Big thx Wade, seems to be exactly what I'm looking for!

[Peter]

After some investigation I have find the stamp on my engine, it's a 472". Another question, the timing. The documents saying that the 472" shall have only 28 degrees total advance. Since I do the adjustment to the 28 degrees on a higher rpm, any ideas what the value shall be when it just idle?

(Picture is from the documentation)

[BIGSHCLUNK]

My 426 is at 35. She talks back at 36 So 35 it is 

[Peter]

What do you have as initial timing when it idle (without the vacuum connected)?

[RUNCHARGER]

For good performance try for 18-20 degrees of initial advance and 34-35' total advance in as fast as possible without pinging on whatever fuel you are going to use.

[Peter]

Ok, but as you see in picture earlier in the thread, it's a 426" stroked to 472" and the paper delivered together with the crate engine says max 28 degrees total spark advance. It's a quite aggressive cam in these, so it might be the reason it's not more than 28 recommended.

I can set a limit in the distributor so it goes max to 28 degrees but I need to start on something at idle and then work forward from that value so knowing X degrees at idle will help a lot.

[RUNCHARGER]

I've run Hemis since 1980, 426, 472, 528, 572, hot cams, stock cams etc. You will lose 50-75HP and destroy any snappiness in drivability if you set total to 28 IMO. Those things have a low compression ratio too I believe, like maybe 9-1 measured. You can certainly set it at 28 total and then try it at 34 total and actually I would then let us know.

[Peter]

Ok, thanks, just that type of info I needed. Since the documentation says 28 as described, I have been little unsure what applies. Have also watched on Nick's Garage at Youtube, they run both 426" and 472" in the bench and best performance seems to be reached at 34 degrees in different applications on heads, headers etc.

Will see how it goes when I go up to 34!