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The disadvantage the Hemi has is NOT from quench.......it's from terrible valve angles (for a naturally aspirated application) and piston weight...........and the ONLY reason Hemi's do well in Super Stock is because they have two carbs, instead of one like the Chevy's.....

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Terrible valve angles...

2 carbs

In the last few years NHRA has allowed '64 Hemi cars to run 1 carb in A/stock as long as it's a 1964 NASCAR intake. From what I'm seeing they run pretty darn good for antiques.

Your carb answer is a moot point since they never orginally made any single carb drag or street packages and can't be proven.

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The disadvantage the Hemi has is NOT from quench.......it's from terrible valve angles (for a naturally aspirated application) and piston weight...........and the ONLY reason Hemi's do well in Super Stock is because they have two carbs, instead of one like the Chevy's.....

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Terrible valve angles...

2 carbs

In the last few years NHRA has allowed '64 Hemi cars to run 1 carb in A/stock as long as it's a 1964 NASCAR intake. From what I'm seeing they run pretty darn good for antiques.

Your carb answer is a moot point since they never orginally made any single carb drag or street packages and can't be proven.

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However I did pull these from a trash can when after INDY when a Barton motor came apart in an SS car. what strikes me here is the out of the box appearance and far from what I expeceted to see from one of their motors.Later I learned this was not one of their "A" combos and no likely to have the trick stuff.

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The disadvantage the Hemi has is NOT from quench.......it's from terrible valve angles (for a naturally aspirated application) and piston weight...........and the ONLY reason Hemi's do well in Super Stock is because they have two carbs, instead of one like the Chevy's.....

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Terrible valve angles...

2 carbs

In the last few years NHRA has allowed '64 Hemi cars to run 1 carb in A/stock as long as it's a 1964 NASCAR intake. From what I'm seeing they run pretty darn good for antiques.

Your carb answer is a moot point since they never orginally made any single carb drag or street packages and can't be proven.

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It's proven everyday, on race tracks everywhere. The SS/AH combo is a bad hombre, don't get me wrong, BUT, if you let a 427 Chevy weigh the same and get a sheetmetal intake, with two carbs, you might be singing another tune............I am as MOPAR as anybody, but I am also a realist and I know, just because it is a Mopar, does not automatically make it the fastest, or the most powerful. As Wayne said, the HEMI was king in its day, because of shear airflow, but the design itself is not the greatest. If it was, why is it, the wedge engines rule in N/A classes.............Call the NEW HEMI whatever you want, but it is basically a "twisted wedge" chamber and is NOT hemispherical at all.

Monte

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I never mentioned that a HEMI was better and never intended to sound like I did..It's just his point(and now yours) can't be proven because it's comparing apples to oranges.

A HEMI has a number of disadvantages compared to a Chevy..rocker gear weight,piston weight/dome, combustion chamber too large and the exhaust valves on street HEMI style heads moved a few degrees to clear the shock towers.

and no one can go back in time and change what is.

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I recently dyno'ed a 572 Mopar wedge with reverse dome pistons, pump gas and 440-1 heads that required 42 degrees timing for max power.

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Depends what the intended application was , if built for NA set up then i would say that engine is pretty inefficiant with 42* spark lead.

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those hemis were a nightmare to tune due to the massive combustion chambers which slowed flame speed dramatically , the higher these engines were spun the more timing was necessary to make power , there was no 'cut off point' the engine just decided it had enough & hammered the pistons/rings out ,

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We don't call them Hemiroids for nothin Now, if we had a double overhead cam hemi in production that could possibly resolve this debate NOT I was suprised several years ago when I built my first pump gas low compression street stroker motor that ended up making 1.37 HP per C.I. with a set of ported 906 iron heads. I was building and dyno testing a lot of motors then and I had not had a pump gas 426 Hemi make as much HP or torque per C.I. as that low deck wedge stroker did Still haven't That 512 low deck motor had absolutely no quench, 22 CC dished pistons .025 in the hole with a .042 thick head gasket and I used a stock low deck Edelbrock six pak intake and factory vacume carbs. I guess my message is anyone can make power with a wedge, not all of us can do the same with a 426 Hemiroid Maybe Ma Mopar saw the writing on the wall( 426 Hemis don't work as good as the L.A SB do HP per C.I.)) and decided to quit making them(426 hemis) and blame it on the govement emission rules and insurance companys

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You saying you can't make 700hp with a 512 hemi but you can with a 906 head?






I know of one 493 hemi that makes more with stock ex manifolds and stock intake and 2 carter AFBs

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602Heavy- I don't really believe the 572 in question was very inefficient- 840 HP, 757 TQ, 10.9 Comp, .38-.40 BSFC on 91 octane pump gas street motor, gets driven 3000+ miles a year.

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Nice #s. ......i'm only pointing out the fact the engine 'could' be more efficient , the earlier the spark is fired off the more pressure is put upon the piston as it moves toward TDC , 42* is a lot of advance when running 91 octane , not being critical of you're build just throwing out opinions , which don't add up to much anyhow.

I had a 9.5:1 605" wedge that ran 44* spark lead , milled the heads etc & raised CR to 10.4:1 , the engine ran best around 34* advance on 97 octane....faster the burn the more efficient the engine will be.

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Big Squeeze/Monte- I respectfully disagree with your statements comparing Chevy 427 SS vs a Hemi. If both motors were run at an equal HP factor/weight and both were allowed the same intakes and carbs, the Hemi would still spank the Chevy. The only way the Chevy can run with me is because they weigh 150+ lbs less than me (Street Hemi Combo). I could trade my 2 625 carters for their 1 850 Holley, remove the weight and still outrun them. If they were allowed another 400 cfm, same compression, and same race weight, I would still outrun them. The Chevy would have to gain 30-40 HP with the 400 cfm increase in order to make up the weight penalty, not gonna happen. If you wish to compare the Race Hemi version instead, simply look at the AH cars vs the AA chevys- the Chevy motors are rated at way less HP, yet they run .2-.4 slower- do you really think that another 710 cfm (2-780 vs 1-850)would allow the Chevy to make 60-120 HP more? Depending on which version of the Chevy 427 used, they would also have to add significant weight to their combo, so they would need to make even more power. While I do agree that the large surface area of the Hemi chamber creates a longer burn time, the valve layout affords sufficient breathing to eliminate the disadvantage. Now, in the Pro Stock world of unobtanium parts, yes, a head can be designed with all the Hemi advantages and all the wedge advantages, clearly superior to the 55 year old technology that I run.

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I need to fill in with what i always say to my friends complaining about the old american iron motors.... you dont see any chevys/japs run in top fuel.

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those hemis were a nightmare to tune due to the massive combustion chambers which slowed flame speed dramatically , the higher these engines were spun the more timing was necessary to make power , there was no 'cut off point' the engine just decided it had enough & hammered the pistons/rings out ,

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I heard Gartlis tell the story of how he did not want to run the 426 the first year. the 392 had broke 200 MPH and that was his sales pitch for appearances. well after quite a few tries the 426 only went 198. In his attempt to intentionally destroy it and go back to the 392 he bumped the timing to a then unheard of 40 degrees . BAM 207 upped it to 45 hit 213mph

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