Tag Archives: Ted Eaton Specialty

Ford Y-Block Aluminum Head Testing Part I

The much awaited for Mummert aluminum cylinder heads for the 292/312 Ford Y-Block engines are now a reality and have been tested on the DTS engine dynamometer. With no modifications these new heads were found to be worth a solid 56 horsepower increase over the stock “G’ heads with only the heads being swapped out on the test engine. The surrounding parts such as intake manifold, rockers, and carburetor remained the same. These new heads easily outperform the stock ‘G’ heads at the beginning of the test range (2500 rpms) and then simply run away at the higher rpms. Where the horsepower on the original G heads peaked out at 5300 rpms on the test engine, the aluminum heads peak at 6100-6200 rpms. What’s really impressive is that these new heads were ran in their ‘out of the box’ condition with absolutely no tweaking being performed on them before testing. The test engine ended up with 340+ horsepower with the aluminum heads in a “just changed the heads” test. Summarized, 1957 supercharger performance is now available without having to run the supercharger.

Here are some details on the test engine. It’s the same engine that has been used for several other tests so the optimum tuning combination using the stock unported G heads has been pretty well sorted out. The engine itself is a +060 over 312 Ford Ybock, the cast flattop pistons are 0.025” in the hole, an unmodified Mummert dual plane aluminum intake manifold, a 2” carb spacer, and a 750cfm vacuum secondary Holley are being used. The iron heads are a set of unposted G’s that have new valves, a decent valve job, a 0.025” mill to clean up the decks and with only minimal cleanup being done to the ports themselves. The calculated compression ratio with the iron heads is 9.2:1. The camshaft is a Crower Monarch grind with 282° adv duration, 238° @ 0.050” duration, ground on 110° lobe centers, installed 2° advanced (108° intake lobe centerline), and 0.435” lift at the valve with 1.54:1 rockers. Valve lash was maintained at 0.019” hot throughout the testing regimen.

Mummert Aluminum cylinder head for the Y

The aluminum heads were supplied with the combustion chamber volumes being right at 60cc. The iron heads after milling were 65.7cc. The smaller combustion chambers in the aluminum heads boosted the compression ratio to 9.8:1 which is just enough to offset any potential horsepower loss that is realized by the use of aluminum. Aluminum is a less efficient material than iron when it comes to combustion chamber efficiency so the increase in compression ratio with aluminum is necessary to realize the full benefit from port improvements and combustion chamber design.

Mummert Aluminum cylinder head for the Y


To facilitate the installation of the aluminum heads, there were a couple of items that were addressed. First was the need for a slightly longer pushrod. The iron heads used a 7.970” (effective length) pushrod while the aluminum heads required a pushrod that was 8.105” long. Neither length is a custom length though as they are both out of the box replacement pushrods for the Y. The other item was the relocating of a pair of the rocker arms on each head so that the pushrods would be more accurately centered with the pushrod holes in the heads. This was accomplished by machining two of the


Mummert Aluminum cylinder head for the Y

supplied rocker arm pedestals 0.080” on one side only which solved that issue. This modification has been passed back on to John Mummert to determine if adjustments are required on future rocker arm stands that are being supplied with subsequent orders of heads. Other than these two changes, the heads bolted in place using ARP 7/16” head bolts and Best Gasket head gaskets without any other issues. Autolite #3924 spark plugs gapped at 0.035” were found to be optimum.

The tuneup for the aluminum heads required less total timing and leaner fuel mixtures to optimize the power levels. Where the iron head tuneup had already been optimized using 38°-40° total timing, the aluminum heads were initially tested with 32°-33° total timing.

312 dyno mule

With the 1.54:1 rockers, the iron heads made 285.1HP @ 5300 rpms and 336.4 lbft torque @ 3400 rpms. The peak numbers for the aluminum heads were 340.6HP @ 6100 rpms and 357.5 lbft torque at 4400 rpms. But it’s not all about peak numbers either. The aluminum heads are also strong on the bottom end of the scale.

312 test mule on the dyno

As with any combination, carburetor spacers are always a player and the Y-Block combination in this test was no exception. Although spacer height was maintained at 2”, the differences in performance between the four hole design and the tapered design are worth noting. The two graphs demonstrate the performance curves between the iron and aluminum heads and also between
the two different carburetor spacer designs as used in the test.

Before removing the heads from the test engine, a set of 1.6:1 roller rocker arms are installed and this results in another significant step up in performance. A variety of intake manifolds are also tested just to see how these heads respond to some of the older intake manifolds that are still being widely used today. Among these are the Edelbrock #573 3X2 setup that was deemed the best performer in the recent 3X2 intake test as well as a factory 1957 ECG-D dual quad intake with a pair of factory dual quad Teapots. More on this in the next article. Until then, happy motoring. Ted Eaton.



Originally published in the Y-Block Magazine, July-August 2010 issue, Issue #99, Vol 17, No.4

Addendum: It was found at the end of the intake manifold testing session that the oem damper ring on the 312 dyno mule engine had slipped giving erroneous values in regards to the ignition timing settings. Testing on the EMC engine found 38° total timing to be optimum on that particular combination.

Engine Masters Challenge Y-Block Entry for 2007

The idea for entering a Y into Popular Hot Rodding’s Engine Masters Challenge competition was prompted by discussions on the Y-Blocks Forever website.  I sent off the application form and was ultimately assigned the alternate #15 position which meant as the participants within the first thirty competitors either dropped out or failed to qualify then the alternates would be moved up the list.  I realized early on that actually making the competition from alternate #15 was a very slim chance based on what I had seen in previous year’s competitions but would give it a go.  There were some heavy hitters actually placed after myself in the alternate list so that did give some consolation.

Upon looking at the rules, the 312 had an inherit advantage in that it was in the lower spectrum of cubic inches required for the competition.  300 was the lowest manufacturer cubic inch allowed so the 312 was allowable whereas the 292 wasn’t.  Where the Y is strong is actually in the stacked intake port design.  These ports, being what they are, allow each runner length to be equalized and therefore the overall torque being much more pronounced or peaked.  Where runner lengths are varied on other engines due to ports being spaced differently across the length of the head, the torque band for the various cylinders is thereby different and the overall torque of all the cylinders when averaged together is thereby softened or the peak torque reduced.

emcy-blockleftview-1.jpgIf there was any one area in which the Y was handicapped for this competition, it was in the head department.  Aftermarket heads were permissible as long as factory intake and exhaust patterns were maintained.  There are no aftermarket heads for the Y, so a pair of ‘113’ heads were picked out for this combination.  They did not have to be made overly big in port volumes to support a larger cubic inch engine and therefore are more efficient for the smaller cubes.  The heads were set up with a custom set of Ferrea valves and topped off with Comp Cams beehive valve springs and Dove 1.6:1 roller rockers.  Considerable work went into the exhaust porting so that the camshaft could be ground the same for both the intake and exhaust durations.  The camshaft selected for this particular engine was a custom Isky grind with 270° advertised duration, 242° duration at 0.050″, 0.547″ net lift at the valve, and ground on 107° lobe centers.  The cam was installed at 105° intake lobe centerline.  A Rollmaster chain assembly spins the camshaft while Smith Brothers pushrods work the Dove Manufacturing 1.6:1 roller rockers.

Frank Rice shipped me a C2AE block that was a 312 marine engine originally.  This block had the better main webbing but upon sonic checking it, core shift was one of the worst ones I’d seen.  Because I was minimizing the amount of overbore, offset boring to re-center the bores within the casting was not an option.  The other option for a block was to take one of the 292 blocks lying loose and boring the main journals to the 312 size and then boring the cylinders to the desired 312 size.  The rules required factory journal sizes so using the 292 mains on a 312 crankshaft was not an option.  I used Frank’s block for this project though as it saved having to bore a set of main journals to the 312 dimensions and was still an excellent block for this particular project.  Thanks Frank.

For this block, I went one step further in that I had it cryogenically treated.  This ‘cold’ treatment was performed by Cen-Tex Cryogenics of Waco, Texas.  The idea behind this was to make the cylinders walls harder and potentially wear better.  Hard to say just how much more benefit this treatment provides but I couldn’t see it being detrimental and at this point, I’m going for any potential benefit that I can for this particular engine.

The pistons themselves are a custom set from Wiseco which have a left and right specific dome tailored specifically for the Y-Block Ford combustion chamber.  Rules limited the compression ratio to no more than 10½:1 but the smaller cubic inch of the Y still required a domed piston in which to achieve this.  The compression ratio would have been too low otherwise without the dome.  The domes on these particular pistons are configured such that turbulence is created in those areas of the combustion chamber where the head overlaps the decks.  The rules also did not allow gas porting for the rings.  I got around this by using a Dykes style top ring which fits the rules but has superior sealing characteristics in lieu of not being gas ported.  The second ring was a 1/16″ plasma moly design while the oil ring was a low tension 3/16″ unit.  The 10½:1 compression ratio was good for the E85 fuel being used but would not have been suitable for 91 octane pump gas.  E85 fuel is not readily available in this part of the country so tuning a carburetor for this would have taken some time but was doable. The bore was finalized at 0.022” over stock which fit within the max 0.035” overbore restriction and gave a final displacement of 316 cubic inches.  Past dyno experience and calculations indicated an attainable 395 peak HP @ 6200 rpm, 375 lbs-ft peak torque @ 4200 rpm and a flat curve for the torque to give a good average number.  Due to the rules requiring factory journal sizes, I was restricted to using the factory Y rods.  No bolt in aftermarket rods are readily available at this point in time.  I used the C2AE rods as they are slightly longer than the C1 rods and simply fully prepped these with new ARP bolts, bushings, and a resize.

Because pan evacuation or vacuum pumps were not allowed, this permitted me to take advantage of the crankcase breather on the block whereas most blocks do not have this option.  I also added two extra breathers to each valve cover to insure that excessive pressure was not a hindrance to piston movement under load.  The Engine looks achaic or old school with the original side breather on it though but it was put back on specifically for a performance advantage in this particular instance.

Rules required no modifications to the oil pan.  Aftermarket pans were accepted but unfortunately there’s not an off the shelf pan for the Y.  Rules also prohibited the use of truck pans or I would have used one of the HD pans I had sitting here.  Because modifications to the pan were not allowed, I did get an okay from the rules committee to use a windage tray that sandwiches between the pan and the block.  I subsequently built a windage tray that used directional screening and this simply fit in place with a pan gasket on each side of it to seal it in place.  One side of the tray acts as a wiper against the crankshaft and rods.  If I pull it out of the engine or build another, I’ll get some pictures of it and submit to the Y-Block Magazine.  Nothing fancy but every little bit has to help.  The oil pump is the gearotor style.  I still think there’s a slight advantage to using this style pump over the gear style in both power and pumping even though both are rated the same as far a volume goes.  An ARP oil drive keeps it turning.

The Ford Y-Block oiling system is already a ‘side-oiler’ design similar to the later produced 427 FE side-oilers.  The main bearings are fed directly from a proprietary oil gallery in the side of the block and then the cam bearings and rocker arms are fed from the mains.  Rocker arm oiling for this family of engines is normally by way of a grooved camshaft on the middle journal or a camshaft that is crossdrilled in the center journal which alternately feeds each bank as required.  I opted to machine a groove in the block in the center cam journal hole which connects the three holes located there and then this modification is sealed in place with the installed center cam bearing.   This provides a solid flow of oil to the heads which I restrict at the rocker arm pedestals with a 0.046″ orifice.  The overflow tubes at the ends of the rocker shafts are left intact so that they can free flow which provides ample lubrication for both the distributor gear and the timing chain.  This also insures that the rocker shafts are purged of air and that the oil remains cool thus warding off any potential sludging or oil degradation that may occur as a result of stagnation.

Ignition is an MSD distributor using the MSD wires and MSD Digital 6-Plus controller.  Sparkplugs are a set of 18mm NOS Autolite BF32’s that I had been saving for a rainy day as these are getting more difficult to find.  These plugs have been side gapped and indexed to the individual cylinders.  There’s a forthcoming article about how to do this in an upcoming issue of the YBM.   Intake manifold is a Blue Thunder unit that’s been simply port matched to the heads.  Otherwise it’s stock other than what’s being called the 2nd design manifold.  Based on what Gary Burnette has passed on to me, the 2nd design intake flows as well as the 1st design intake after being extrude honed.  Carburetion for gasoline is handled by a Holley 750 cfm HP series carb with vacuum secondaries.  Backup carb is the 650 cfm Speed Demon carb which has been a proven carb on my Y powered roadster.  I lean heavily towards the vacuum secondary carbs due to them being very optimal in flow on a day to day basis as the secondaries only open up as required for a given engine demand.   Testing has shown similar results on the Y with both the 650 and 750 cfm carbs and this has to do with the vacuum secondaries simply opening less on the larger carburetor to get the same amount of power output.  For E85 fuel, I would simply get a alcohol specific carb in the 650 to 750 range and have to work with it to get the tuneup right.

The tech at the EMC competition ultimately called and said that the Y would not be allowed into the competition with the mushroom tappets.  Didn’t matter if it was a factory lifter, rules were specific against mushroom tappets.  As a result the engine was not run and instead relegated to the back of the shop.  But because I was entered into the competition as an individual and not as an engine choice, I was free to change engines and remain in the competition.  As a result, I readied a 427 Tunnel Port engine I had for the competition.  Standard bore, factory steel crank, an Isky flat tappet camshaft, a single plane TP intake, MSD ignition, and that engine was ready to be called up.  But I was simply too far down on the alternate list to be a player.  Do all this again?  Not at a number fifteen on the alternate list for sure.  Definitely way too much work with not much to show for it and especially with the engine being disallowed due to the original tappet design.

Note that this article was actually a response from Ted to one of the topics I’ve been working up for the “Top Ten Y-Block Stories” for the March-April issue of Legendary Ford Magazine (condensed from this).  But the volume and the depth of his response was an article in itself and I know you will enjoy it as much as I did.  Shown at the ßbottom-left is the Y-Blocks Forever picture by Jim Culver of Randy Gummelt’s blown 770 HP Y that took the World Y-Block E.T. mark to 8.15 @ 162 mph in Columbus at the 2005 Y-Block Nationals.  The motor was prepared by Ted Eaton and Lonnie Putnam – but that’s another one of the expanded “Top Ten” story’s for Bruce’s Y-Block Magazine this year.        Bob Martin

Originally published in the Y-Block Magazine, Jan-Feb 2008, Issue #84,  A shorter version of the text was published in Legendary Ford Magazine, Mar-Apr 2008 Issue.

Rocker Arm Geometry

Rocker arm geometry is an area that’s very often overlooked when modifying an engine for increased power output and/or efficiency. Besides the obvious advantage of reducing valve stem and guide wear by minimizing the “scrubbing” action that can take place when the rocker arm geometry is optimized, the maximum or advertised lift at the valve for a given camshaft profile can also be obtained. The method in which the rocker arm geometry is altered will vary depending upon the valve train design. There are basically two rocker arm support designs where the rocker arms are either a ball (fulcrum) and stud arrangement or are shaft mounted. To adjust the rocker arm geometry on the ball and stud style, the length of the pushrod itself is altered in order to change the pivot point but when dealing with a shaft mounted rocker arm such as on our venerable Y-Block or an Fe Ford, then the height of the pedestal stand holding the rocker shaft must be altered.

In the case of the Y-Block, rocker arm geometry whether it’s good or bad, doesn’t change when the heads and/or deck is machined. The relationship of the rocker shaft to the valve stem tips remains the same and the pushrod length only needs changing when required by lieu of the lash adjuster being outside of its usable range. On an engine using the ball and stud arrangement for its rocker arms, any machining done to the head or deck surfaces can necessitate a change in pushrod length to maintain the existing rocker arm ratio.

Fig A.Rocker arm geometry is generally optimal when the travel or movement of the rocker arm tip on the valve stem is minimized. To understand how to achieve correct geometry, it must be understood that the rocker arm tip itself travels in an arc. At zero lift, the rocker arm tip is expected to be closer (or inboard) to the plane of the pivot point and as the valve starts moving down, the rocker arm tip starts moving outboard. If the geometry is close to ideal, then the rocker tip will be at its most outboard position at half or mid lift at which point the rocker tip starts moving inboard again as the valve reaches full lift. Simply put, ideal rocker arm geometry is achieved when the rocker tip is sitting on the valve stem tip at the same position at both zero lift and full lift. In a perfect world where the rocker shaft pedestal stand locating holes, the valve guide, and the rocker itself are all machined to exact specifications, the rocker tip is expected to be sitting slightly inboard of the valve stem center at both zero and full lift while the rocker tip will be sitting the same distance outboard of the center of the valve stem at exactly mid-lift. But because of variances in manufacture, getting the rocker arm to sit on the valve tip in the desired location while optimizing the rocker arm geometry doesn’t always happen. In these cases, lash caps may be utilized to increase the area on the tip of the valve stem in which to increase the working area but in other cases it may require another style of rocker arm of the same ratio. Depending upon the scenario, compromises may be made in which optimum geometry is not achieved in order to allow the rocker tip to be sufficiently located on the valve stem tip.

Now that it’s clear that the rocker tip must be sitting on the valve tip at the same location at both zero lift and full lift, then it’s easy to assume that the rocker arms pivot point most be raised or lowered if the rocker arm tip contacts the valve stem too far inboard or outboard at zero lift in relation to where the tip resides at full lift. In the case of the Y-Block with its shaft mounted rockers, this involves altering the height of the pedestal stands so that the rocker shaft can be moved in the appropriate direction. If the rocker arm tips are sitting too far inboard or closer to the shaft versus where the tip sits at full lift, then the pedestal stands need to be longer or sitting taller. Conversely, if the rocker arm tips are sitting too far outboard as compared to where they reside at full lift, then the pedestal stands need to be shortened. In extreme cases, altering the height of the shafts can require an appropriate change in pushrod lengths to insure adjustability at the rocker arm for valve lash adjustment.

Fig A.There are several different methods in which to measure rocker arm geometry. Without any measuring tools available, a visual observation of the rocker arm movement while the valve is going through its range of motion can prove quite adequate. Using a dye or magic marker on the valve stem tips to indicate the path or length of travel on those tips while varying the height of the rocker shaft can also indicate better or worse rocker arm geometry. Measuring the actual valve lift can also be performed as maximum valve lift occurs at “perfect” geometry and if the rocker is above or below this ideal point, then the valve lift starts decreasing logarithmically by the amount that the geometry is incorrect. There are tools available to facilitate measuring rocker arm geometry and one of these is a dial indicator on a fixture that actually measures the relationship of the rocker tip and with the edge of the valve stem at both zero and full lift. Regardless of the method used, the end result remains the same where the contact point of the rocker tip with the valve stem at both zero lift and full lift are being made the same.

As delivered from Ford, the rocker geometry on the Y engine is reasonably close with the stock lift camshafts. As the stock camshafts are replaced with those with increased lift, then it becomes necessary to machine the rocker shaft pedestal bases so that the shaft itself sits lower to re-achieve a more ideal rocker arm geometry. Because of the variability in the various rockers from the different manufacturers, it would be difficult to have a set amount that would need to be removed from the stands for a given amount of lift. Even using aftermarket or replacement valves with different than stock valve stem lengths will dictate checking the rocker arm geometry and correcting as deemed necessary. Due to all the variables involved, it would be prudent to at least check the rocker arm geometry on an engine as it’s being assembled especially when new valves, rocker arms, and possibly rocker shaft assemblies are being replaced.. T.E.

Originally published in Y-Block Magazine, Sep-Oct 2005, Issue #70.