Ted, that is great baseline info for these heads! Can we automatically assume that these heads are going to be used on your EMC motor?

John - Hats off to a job well done! Let's hope Edelbrock will remain in there and do a good job for the Y block.

If an engine were built specifically for these heads with 0 deck, about 10.5 cr and possibly a bit shorter, higher lift cam and mildly ported heads 350+ horse power may be possible with a very streetable "Sunday go to Meeting", not racing, engine. This would back up my paper engine very closely. John you did good. Thanks for the info Ted. The ported heads should shine on your Engine Masters engine. 

Ted, Wouldn't the push rods grow maybe .001" after warm up? we always used the calculation of .003" of growth per foot of material (steel and Iron) for every 100 degrees above ambient temperature for the equipment I set up around the globe. Also I know that the aluminum grows at a much faster rate, the number 1 cause of snowmobile/dirtbike/four wheeler piston failures is the fact that people don't let them warm up before reving them up and the piston grows faster than the cylinder and they get a cold seizure.

I don't have handy the exact growth of the aluminum versus the steel for the same temperatures, but as the steel catches up, might it change that figure?

Can we see some graphs to compare?

Hollow Head (5/15/2010)

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What are the Hp and torque numbers at the same rpm's as tested with G heads? I know the new ones are better at higher rpms but are they waste of money at the lower rpms ?

Can we see some graphs to compare?

Seppo, i initially wondered the same thought, re the Hp @ same RPM and figured the hp or torque nosed over at those rpm,s round the 1st heads results? ted will know for sure.

And with the growth rate on the new heads,that amount Ted mentioned is great point, so initial settings can be allowed for. For all my time rebuilding most earlier engines, i,ve allowed .002" cold set and when engine is ran, its nearly spot on for clearance. so this new figure for our new heads is a big help. regards bill.

It's interesting that there is an improvement, even at lower RPM, with a spacer. I would have thought that the standard heads would be giving close to full volumetric efficiency there. The ram effect obviously doing it's thing with a longer inlet. This is what John was talking about getting an improvement over wider range of RPM.

With more testing to come we will obviously see and get more information. I would like to see the same test done with heads that have had the ports finished to remove the rough casting surface.  

Ted/John,

What are the flow numbers for the intake/exhaust for these heads out of the box versus the g's and where did the biggest improvements in flow come from? Opening exhaust port? changing angle of lower intake port to valve opening? combustion chamber shape and size ect. ect . ect. ?

I will then be curious as to the flow numbers that can be acheived once you guy's start porting them.

I don't get Y block magazine (yes I should) I was also interested in purchase details. Also how long before they're ready for release. 

I ahve not yet recieved my "Y" block mag any one else recieved theirs?? I only live about 50 miles from Bruce, maybe I'll have to drive down.

  And Don, I received my latest issue Friday the 14th.

Piston skirt length and piston to cylinder clearance should be taken into account if you are looking to reduce this clearance below commonly accepted minimum of .035". A short piston skirt will allow the piston to rock more as will additional piston to cylinder clearance.

With regard to pricing ect. We plan to place an order for head castings around the 1st of June. The more deposits we have, the more castings we will order. Deposits of $1,000.00 received before we order castings will result in a final total price of $2049.00 (1000 + 1049) for 2 assembled heads. Orders received after we order castings will be at a higher price.

Anticipated delivery of the finished heads will be late July 2010.

That double-hump in the blue curve looks like it could be annoying as far as the seat of the pants signalling goes.

Cheers... Brian

I do not recall the flow on those carbs but the three carbs combined is not as good as the single 4. The heads were the cork before but with the 3x2 the cork will definitely move to the carb/intake.

Ted is approaching testing these parts the right way. When evaluating parts you must have a base where each item is tried. This is the only way to check what characteristics each part will give. Some minor tuning with jetting and ignition timing is acceptable.

As a guideline you can use the percentage gained by the heads and use that percentage 56Hp(increase)/291hp(base)  19.243% to get your peak against what was tested before with the 3x2 shootout. This peak will change throughout the rev range and should be considered point to point. 

In evaluation part for an engine build you start with an understanding, a desirable outcome and try different parts in different configurations to obtain a desired result. This is something that only top engine builder can afford for one engine not for the entire range of parts available. Not even for Y block.

We are getting a lot of information from some guys who have taken a financial risk to produce a part for something they love. 

a couple of photos for those not familiar with this inlet.

They gave a formula for optimum venturi size related to engine size. I would have to find the formula, can't remember. It was somewhere in the 50 - 55 cubic inch of displacement per square inch of venturi range.

Ted's stock head dyno mule comes in just a shade under that and experience indicates that ported heads will only add 10-15 ft lbs to that engine.

From the testing I have seen stock ECZ-G heads are limited to 285HP +-5. A good port job can take this up to 325-360 depending on cam, compression and displacement.

Porting Y-Block heads can make a substantial difference in HP but will have little effect on torque. All testing was done with either ECZ-G or -113 heads.

To make over 365hp with ported factory heads the testing I've done indicates that the CR must at least 10.5:1 and the cam needs to approach 250 degrees @ .050". Displacement will need to be 330+ cu in.

The wait is over as the new Mummert aluminum heads have now been run on an engine with the following results.  56 horsepower increase over the stock heads!!!!!!  In their first day, a total of 24 pulls were made with the aluminum heads to test a variety of timing, carburetion, carb spacer, jetting, and exhaust changes.  The aluminum heads themselves were tested as delivered and used in the ‘out of the box’ configuration with no porting being performed.

The engine used for the test is a +060 over 312 with the cast flattop pistons 0.025” in the hole and stock G heads that had only a good valve job with hardened seats installed and a 0.025” mill to clean up the deck side of the heads.  No port work.  The compression ratio calculates to be 9.2:1.  The engine is running the factory 1.54:1 rockers, Mummert single four intake manifold with a two inch four hole spacer, and a 750 cfm vacuum secondary carb.  The camshaft is a Crower Monarch grind ground on 110° lobe centers, 280° advertised, 238° @ 0.050”, and 0.430” lift at the valve after the lash is set.  Prior to the head test, a 465 Holley, a modified 600 Holley, and a 750 Holley were all tested and the 750 simply shined above the rest.  The 465 just gives up earlier and the 600 fell in behind the 750.  These same carbs were used with the aluminum heads with the performance order being the same but much more pronounced.

To keep the tests reliable and truly comparitive, both the iron and aluminum heads were ran back to back and on the same day.  The engine was ran first in the morning with the iron heads to get some baseline numbers.  The dyno numbers for the G heads are 286.1 HP @ 5300 rpms and 336.4 lbft torque @ 3400 rpms.  Although there was a 290HP number on one of the pulls, it was disregarded due to the water temperature being on the cool side.  These are still respectable numbers for stock unported G heads.

It took just a bit over two hours to swap out the iron heads to the aluminum versions.  The engine was then started, heated up, stopped, and allowed to heat soak.  At this point the valve lash was rechecked.  As an FYI, the heads grow about 0.004” from ambient to hot so setting the valve lash at 0.015” initially nets 0.019” hot.  After a series of dyno pulls to determine what the engine preferred for new ignition timing and fuel mixture attributes, the numbers for the aluminum heads are as follows:  340.6 HP @ 6100 rpms and 357.5 lbft torque @ 4400 rpms.

The new heads do like leaner fuel mixtures and considerably less total timing.  They are definitely more efficient.  Whereas the iron heads liked 38-40° total timing, the aluminum heads are happiest with 32-33° total on this particular combination.  Intial testing shows an Autolite 3924 spark plug being a good middle of the road spark plug to start out with.  Spark plug gap for the tests was at 0.035”.

With the 2” four hole carb spacer, the aluminum heads outperform the iron heads at all rpm ranges.  With the 2” tapered carb spacer and below 2800 rpms, the iron heads are only marginally better in torque than the aluminum versions, but after 2800 rpms, the aluminum heads simply run away from the iron versions with the best peak horsepower numbers.

With ‘out of the box’ aluminum heads and no port work, 1957 supercharged performance is now available without having to use the supercharger.  There is still some more dyno testing yet to be performed after which point the heads will be pulled off of the engine and disassembled.

Iron heads w/4 hole carb spacer:     238.3 HP, 315.8 lbft TQ  (averages)

Alum heads w/4 hole carb spacer:   270.8 HP, 331.9 lbft TQ  (averages)

Alum heads w/tapered carb spacer: 271.7 HP, 329.5 lbft TQ  (averages)

This was a core engine that was already 0.060" overbored and simply rebuilt to use as a dyno mule.  The block decks were straight so they were not cut upon on this latest rebuild which kept the pistons at 0.025” in the hole.  The deck side of the heads were cut 0.025” though to give a surface that was smooth enough to seal with.  The iron 'G' heads used for testing had considerable rust on the sealing surface before preparing them for use.  This particular short block was originally put together in the Seventies with the current pistons and it would appear that only a cleanup mill was performed on the block decks at that time.

The intake manifold fit was fine on the aluminum heads and no additional work was required as such.  The iron ECZ-G heads had been milled ~0.025” and the same intake manifold fit fine on those also but I typically don’t start to see a problem with manifold fit until at least 0.045”-0.050” is milled from the heads and/or decks.  I didn’t ask John if the aluminum heads were machined with composition gaskets in mind or if machined to the original ‘steel shim’ head gasket specs.  Regardless of how they are machined, everything fits up just fine.  On an unmachined and stock Y block and using the stock cylinder heads and composition gaskets, the heads will sit ~0.020” higher than stock if no milling of the heads or decks takes place.

The similarity in rpm torque bands between the single four and the three deuce intake testing was indeed related to the fact that the same heads were used for both but the camshaft also plays into this as well.  Had the camshaft been a different grind but remained the same for both the 3X2 and single four tests, the peaks would have changed from the camshaft that had previously been used.  But testing with some specially tailored four barrel carbs as well as some different exhausts on the iron heads has had some dramatic effects on low end torque production so it’s still the total combination that must be considered.

It was interesting to note that the peak horsepower of the dyno mule engine went from 5300 rpms with the iron heads to 6100 rpms with the aluminum heads.  Same camshaft, same intake manifold, same carb spacer, same rocker ratios, same exhausts, and same carburetor.  By switching only the heads, the differences in torque production as well as the usable rpm ranges could be definitively evaluated.

Time constraints has put any additional 3X2 testing on the back burner for the time being.