Archive for the 'Y-Block' Category

Published by tedeaton on 23 Nov 2014

Intake Manifold Plenum Slots

In dyno testing the different intake manifolds on various engines, it’s found that the intake runner and plenum designs are main players in determining what the power curve for a particular engine combination will look like. One intake manifold feature that comes to the forefront on the aftermarket four barrel dual plane intakes is a slot in the divider located directly under the secondary side of the carburetor. These slots came into prominence in the late Sixties with the popularity and use of the Holley three barrel carburetors and that slot was simply required to allow the secondary throttle blade on those carbs to open without interference at the intake manifold. Although the three barrel carbs have been pretty much extinct for several decades, the practice of the intake manifolds being slotted by the manufacturers has remained. When the Blue Thunder intake for the Y engines was introduced, it too had that slot located at the rear of the divider under the secondary portion of the carb. I’ll hence forth refer to that slot as the ‘three barrel’ slot simply due to it working for that purpose.

For the Ford Y-Block engines, the two aftermarket intakes currently available are the Blue Thunder (BT) and the Mummert. In breaking with conventional practice, the Mummert aluminum intake manifold was introduced without that ‘three barrel’ slot in place. The BT intake being introduced a few years earlier has the slot. So that begs the question, exactly what effect does that slot have on the engines power curve if any?

Mummert intake without slot Blue Thunder intake with slot

Click on pictures for larger images.

To test the effect of the ‘three barrel’ slot on overall engine performance, four 1” tall four hole carb spacers are obtained and appropriately modified so they can be dyno tested. While one 4 hole spacer is left stock, another is modified with a slot across the secondary throttle bores. The other two spacers are machined so that they are dual ovals closely matching the dual oval configuration used in the plenums of both the Blue Thunder and Mummert intakes. Again, one of the dual oval spacers has the slot added so it’s across the secondary throttle bores while the other does not. To add another nuance to the tests, the slotted spacers are tested both right side up and upside down just to see if this provides an additional difference to the power curve. This makes for six different test variants which includes the four different spacers and then the two slotted spacers being run with slots down as well as slots up.

4 hole spacers oval slot spacers

Click on pictures for larger images.

The dyno mule is the well tested +060 over 312 with a set of mildly ported G heads. The intake manifold being used for this test is the Mummert aluminum intake which is being used in lieu of the Blue Thunder intake simply due to the lack of a slot in the plenum divider. The carb is the 750 vacuum secondary Holley which has proven to be a solid performer on this engine in past tests. The camshaft is a Seventies era Crower Monarch grind with 238° duration at 0.050” on both the intakes and exhausts and ground on 110° lobe centers. The cam is installed with 2° of advance (108° intake lobe centerline). The net valve lift is 0.459” lift using the Harland Sharp 1.6:1 roller tipped rockers with the valve lash set at 0.019”.

The following chart shows the various dyno results. The *Score is calculated by adding the average torque and horsepower values together, multiplying by 1000 and dividing by the cubic inch (322).

Spacer > 4 holeNo slot 4 holeSlot up 4 holeSlot down Dual OvalNo slot Dual OvalSlot up Dual OvalSlot down
TQ –Peak 340 341 342 338 338 338
HP – Peak 298 303 302 302 302 302
TQ – Avg2500-5500 rpms 324 324 322 323 320 320
HP – Avg2500-5500 rpms 245 246 245 245 244 243
*Score2500-5500 rpms 1769 1772 1763 1766 1752 1751
TQ – Avg2500-3500 rpms 329 324 319 326 316 315
HP – Avg2500-3500 rpms 189 186 183 187 181 181
*Score2500-3500 rpms 1608 1582 1559 1593 1544 1538

In this case, the charts don’t tell the whole story so this is where a series of graphs come into play. The following two graphs show the HP and TQ results for the four hole spacers. There is a pronounced dip in the toque when the slots are incorporated into the spacers versus the dyno runs that are made without the 3 barrel slot in place.

Graph 4 hole HP Graph 4 hole TQ

Click on pictures for larger images.

The next pair of graphs shows the results of testing with the dual oval spacers with and without the three barrel slots. Again, that mid-range dip in the torque curve becomes more pronounced with the slots in place versus without.

Graph Dual Oval HP Graph Dual Oval TQ

Click on pictures for larger images.

This next pair of graphs simply compares the four hole carb spacer without a slot to the dual oval carb spacer also without a slot. Low end torque is enhanced with the four hole spacer while the top end horsepower is better with the dual oval spacer. No surprise there. This reaffirms the practice of putting the oval slots in the ECZ-B iron intakes for an increase in top end power.

Graph Dual Oval vs 4 hole HP Graph Dual Oval vs 4 hole TQ

Click on pictures for larger images.

What is obvious on the graphs comparing ‘slot’ versus ‘no slot’ performance is how the addition of a slot does make for a more pronounced dip in the mid range torque values. Based on past experience, that dip or mid-range drop in the torque numbers does look like it can be reduced by simply making the carb spacer taller. For this particular test, the carb spacer height was simply kept at one inch but past testing has shown that the two inch high carburetor spacers are a better choice for optimum horsepower and torque numbers on most Y engine combinations when using either the Blue Thunder or Mummert intake manifolds. There are instances where even more than two inches of spacer works so keep an open mind.

The addition of plenum slots do tend to help the overall performance scores and top end horsepower numbers when used on a 4 hole spacer design. When using ovals under the carbs rather than four individual holes, the same slots prove to be a detriment to the overall score values while top end horsepower values do continue to be higher. The low end performance is reduced with both spacer designs with the slots when compared to the same ‘no slot’ spacers. In summary, not having a slot in the plenum divider does enhance the low end torque values so it simply ends up being a case of exactly what kind of driving is being performed as to whether the intake plenum having a three barrel slot or not is going to be the best for a particular engine combination.

585HP Engine with 2" 4 hole spacer

585 HP with 3″ of dual slotted carb spacers on Blue Thunder intake manifold.  Click on picture for larger image.

Until next time, happy Y motoring. Ted Eaton.

This article was previously published in The Y-Block Magazine, Jan-Feb 2014, Issue #120, Vol. 20, No. 6

Published by tedeaton on 19 Sep 2014

Hi-Volume Oil Pump For the Y

Although I normally wouldn’t advocate a high volume oil pump for a run of the mill Y block (1954-1964 Ford 239, 256. 272, 292, 312), I did run into a situation where the use of one would at least be a temporary fix until a new engine could be built to replace the current one. Because a high volume oil pump for the Y hasn’t been available for awhile, the basic plan called for building one using currently available parts.  Before I actually get into the modifications required to make a high volume pump for the Y, I’ll give some background relating to the engine for which this particular pump was being built and why a high volume oil pump was deemed necessary.

This story starts with a bored to the hilt 312Y (3.925” bore) with old school popup pistons that was assembled by a Dallas area ‘speed’ shop and then this particular engine laying in wait for a number of years before the car was actually ready for it. When the engine was ultimately fired off, the cold oil pressure seemed satisfactory but there was a serious rear main leak so the engine wasn’t allowed to get sufficiently warmed up. This is where I come into the picture as I was approached to help fix the rear main leak. While the pan was off, I casually checked the rod side clearances by merely doing a hand feel of them. And of course I find something to raise some concern; the rod side play on the number one rod journal seemed excessive and upon measuring it, there was 0.081” clearance. The other three journals were acceptable in that they each had 0.025” or less. After some discussion, it was decided to go forward, fix the rear main seal, and get the car on the road with plans to eventually replace this engine at the earliest opportunity. The rear main oil leak was officially fixed at this point but upon driving the car enough to get the oil hot, the oil pressure was dismally low even at highway speeds. Although it’s determined that the excess rod side clearance is not the reason for the low oil pressure, it’s now questionable exactly what other clearances were not maintained within acceptable tolerances in this engine during its initial buildup or if the block itself has some internal problems. If it wasn’t for the low oil pressure, there would not have been any indication that anything was wrong as the engine runs very well with no unusual noises and has plenty of power evidenced by it being able to light up the rear tires at will. All the right parts are obviously there for performance in the form of increased compression, lots of cam, MSD ignition, Blue Thunder intake, Demon carb, and ported heads. But the low oil pressure is bothersome and having a new engine ready to drop back down into the engine bay was still a good ways off. After ruling out the oil pump, the rubber seal at the inlet of the oil pump, oil viscosity, gauges and the oil filter, I suggested just increasing the volume of oil to get the pressure up into a safer zone as an interim measure.

Making a high volume oil pump for the Y is not difficult once it’s recognized that the majority of Ford oil pumps have the same diameter gerorotor gear set. A particular nuance to watch out for is the size of the hexagon oil drive shaft which for the Y is ¼” but is conveniently the same size as the Fe (360/390/427), SBF (289/302/351C), and OHV (368,302,332) engines. At this point, the basic plan revolves around using a stock Y-Block gerorotor oil pump housing in conjunction with a longer than stock gerorotor gear set and a fabricated cover that will compensate for the longer gears within the stock housing. The whole key here is to keep it simple, keep it repeatable, and keep it inexpensive. As can be surmised, inexpensive is a subjective term especially when dealing with these older engines.

A high volume oil pump for a 289/302 Ford (Melling P/N M-68HV) was purchased which supplied the necessary longer gerorotor set for this project. Upon comparing the new inner and outer rotors with the stock Y components, the SBF rotors are 25% longer which will effectively increase the oil volume by 25%. Upon comparing the various pump parts, it becomes obvious that the pivot shaft protruding from the SBF inner gear is approximately 1.115” shorter than the one in the Y unit. This makes the stock Y oil pump drive shaft that much too short and is corrected by using the oil pump drive shaft for an OHV Ford engine (368 Lincoln, 302/332 OHV truck) rather than try to relocate the longer center pivot shaft from the Y rotor to the SBF rotor. The OHV oil pump shaft (Melling P/N IS-60A) was merely shortened 0.100” in which to make the total length to the distributor correct. Next on the list is to measure the inside depth dimension of the Y oil pump housing where the rotors reside, measure the SBF rotor thickness, take the difference of these two values, and add 0.003” to the derived value. This is the depth of the hole or recess that must be machined in a new cover to accommodate the longer gear set while providing the prerequisite 0.003” clearance between the gear and the cover (rotor end play). Another option would be to just machine a spacer that would make up this required distance and use the stock oil pump cover but this ultimately creates another place for an oil leak. These engines are already noted for marking their territory so rather than compound the issue, I stayed to the original plan and simply machined a cover with a recess in it to compensate for the longer gear set.

01 internal differences  02 new oil pump cover 03 new oil pump cover

Click on pictures for larger images.

The new cover was fabricated from a ½” thick piece of 4” diameter cold roll steel and machined with a 2.634” diameter recess that measured 0.226” deep. An appropriately sized piece of flat plate steel could have also been used but a bar of cold roll was just conveniently at hand. After placing the machined cover on the oil pump housing and over the protruding rotors, transfer screws were used to mark the location for the cover’s bolt holes and the cover was then drilled to accommodate the required four ¼” X 20 cover bolts. While the pump was completely disassembled, the oil pump relief valve spring was also shimmed with a 0.110” spacer to raise the cold oil pressure limit. Upon assembling the pump, it’s imperative that the rotors turn freely within the pump after torquing the cover in place; if they don’t, the reason why must be determined and corrected.

04 Disassembled oil pump 05 Assembled oil pump

Click on pictures for larger images.

Prior to final assembly, clearances within the pump were checked using the following guidelines.

Rotor End Play: 0.002″ - 0.003″

Rotor To Housing: 0.006″ - 0.012”

Inner Rotor To Outer Rotor: 0.005″ - 0.010″

Torque Specs For The Cover: 95 - 100 INCH LBS

The pump was installed on the engine and did indeed increase the hot oil pressure. The following table compares the engine oil pressure with the stock pump versus the pressures obtained with the hi-volume pump.

Cold Idle Cold & fast idle Hot Idle Hot & fast idle Hot & In 4th gear at 50mph Hot & In 5th gear at 50mph
Stock oil pump 35psi 50-55psi <10psi 23-25psi 27-28psi 20psi
Hi-Vol oil pump 60psi 70psi 35psi 40-45psi 40-45psi 30psi

As mentioned earlier, this oil pump fix was just an interim measure and in no way takes away from the fact that there are issues within this engine that is allowing an excessive amount of oil flow resulting in a loss of pressure. In summary, all this modified pump did was to increase the oil flow to a point that over-rides the amount being lost and in turn gives an increase in oil pressure. But for the time being, the car can at least be driven while parts for the new engine are being gathered up and machined in preparation for a new shortblock assembly.                    Ted Eaton

06 oil pump on engine Click on picture for larger image.

This article was originally published in The Y-Block Magazine, Issue #84, Jan-Feb 2008, Vol 15, No. 1

Published by tedeaton on 17 Jan 2014

Y-Block Ford – Dual Quad Testing on Aluminum Heads – Part II

With the iron 113 heads on the dyno mule, the Edelbrock #257 2X4 intake that had been ported by Joe Craine did exceed those numbers generated by the stock Mummert intake and single four barrel carb combination.  Now it was time to install the aluminum heads on the 312+ dyno mule and see how those same dual quad manifolds would fare.

As a result of changing the ported iron ‘113’ heads to a pair of CNC ported Mummert aluminum heads, it was necessary to establish a new target baseline.  The same stock Mummert intake and 750 cfm vacuum secondary Holley that had been used for the iron head baseline was again used for the aluminum head baseline.  While the iron heads made a peak number of 311 HP in the single four barrel format, the aluminum head baseline jumps to 375 HP with nothing but a cylinder head change.  This does give the dual quad intake testing a much higher target value to aim for.

The dual quad intake testing with the aluminum heads now gets more definitive simply due to the flow restrictions that were taking place in the iron heads being minimized.  This will allow any flow restrictions in the manifolds and carb pairs to come to the forefront.  With that in mind, the same intakes that were run on the iron heads are also run on the aluminum heads.  But added to the fray are also the Fenton, Edmunds, Hogan, and the ported Edelbrock FM255 intakes among others.

Here is a quick summary of how the different intakes performed on the aluminum heads without getting into the various carbs or other variables that were tested on each intake.  This particular list is ordered from worst to best using the best carb combination for each intake that was tested.

1. Edmunds D427                                       330 HP@5400, 343 TQ@3300

2. Ford EDB-C 1956 – modified                  331 HP@5400, 352 TQ@4400

3. Ford ECG-D 1957 – stock                      336HP@6000, 352TQ@3500

4. Ford EDB-C 1956 – stock                        338 HP@5200, 369 TQ@4200

5. Edelbrock 257 – Hogged out                   339 HP@6100, 337 TQ@4900

6. Fenton D427                                               342 HP@5400, 364 TQ@4200

7. Edelbrock 257 – stock                               351 HP@6000, 355 TQ@4500

8. Mercury ECZ-C stock                                357 HP@6100, 367 TQ@4300

9. Edelbrock FM255 stock                            359 HP@6000, 370 TQ@4400

10. Hogans Tunnel Ram                                361 HP@6100, 342 TQ@5200

11. Mercury ECZ-C ported                            366 HP@6200, 375 TQ@4400

12. Edelbrock 257 – Ported by JDC            369 HP@6200, 378 TQ@4400

13. Edelbrock FM255 – Ported by JDC     378 HP@6200, 370 TQ@4600

So with that being said, here are the breakdowns for each manifold that was tested.  The manifolds are now listed in the order in which they were run and tested on the 322” mule engine.

All intakes Click on picture for larger image.

Ported Edelbrock #257 Intake:

Upon establishing the single four barrel baseline value, the Edelbrock #257 intake that had been ported by Joe Craine was the first of the dual quad intakes to be reinstalled on the aluminum headed +060 over 312.  While that particular intake was the best of the lot on the iron heads and actually exceeded the baseline target for those heads, it came up just shy of the revised baseline or target for the aluminum heads.  This intake was tested with several pairs of carbs and here are the results for the best tuneup for each pair of carbs.  I’ll add that jetting changes on two carbs and especially the Teapots can be very time consuming.

L1434 Teapots (1957 2X4 carbs)            332 HP@5500, 365 TQ@3700

600cfm Edelbrocks                                 362 HP@6100, 367 TQ@4300

500cfm Edelbrocks                                 363 HP@6100, 366 TQ@4500

L1094-1 Linc Teapots (60P/82S jets)     369 HP@6200, 378 TQ@4400

Cartger AFB carbs Carter AFB carbs

Click on pictures for larger images.

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Merc ECZ-9424-C Intake (ported):

Next on the list was the hard to find 1956 Mercury dual quad intake.  In looking at this manifolds outward appearance, this one was originally based on the Edelbrock FM255 intake. There was already some prior port work performed on this intake and based on its overall performance, it was a good performer back in the day.  Here are the results with a variety of carbs tested upon it.

1956 Mercury Carter carbs (vac sec)         347 HP@6000, 353 TQ@4500

L1161-2 Teapots with KM mods                 354 HP@6000, 362 TQ@4400

L1094-1 Linc Teapots (60P/82S jets)       366 HP@6200, 375 TQ@4400

1956 Merc Carter WCFB 1956 Merc Carter WCFB

Click on pictures for larger images.

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1956 Ford EDB-9425-C Intake (stk):

This was the ’56 Ford offering which had the center to center carb spacing much closer together than the ’56 Mercury intake that was just tested.  The rear carburetor sits further forward on this manifold and appears to be more flow restricted as a result.  Here are the results for this intake.

L1268 Teapots (1956 2X4 carbs)              327 HP@5500, 360 TQ@3700

L1434 Teapots (1957 2X4 carbs)              333 HP@5500, 363 TQ@3500

L1094-1 Linc Teapots (60P/82S jets)      338 HP@5200, 369 TQ@4200

 

********************************

Merc ECZ-9424-C Intake (stock):

Another 1956 Mercury 2X4 intake but this time it’s a stock and unmodified version.  Here are the results.

L1434 Teapots (1957 2X4 carbs)            344 HP@5500, 364 TQ@3500

L1094-1 Linc Teapots (60P/82S jets)   357 HP@6100, 367 TQ@4300

Lincoln Teapots Holley Teapots

Click on pictures for larger images.

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Edelbrock FM255 2X4 Intake (stock):

This is the Edelbrock intake originally designed for the ‘55/56 heads and was the predecessor to the highly touted Edelbrock #257.  This intake is also the basic design for the 1956 Mercury dual quad intakes which also posted similar performance numbers.  Here are the results.

L1434 Teapots (1957 2X4 carbs)            342 HP@6100, 358 TQ@4500

GM Carter 1.050” mech sec 4V carbs    356 HP@5800, 368 TQ@4500

L1161-2 Teapots with KM mods             358 HP@6100, 362 TQ@4500

L1094-1 Linc Teapots (60P/82S jets)   359 HP@6000, 370 TQ@4400

Holley Teapots Holley Teapots

Click on pictures for larger images.

********************************

Fenton ‘D427’ dual quad intake:

Here are the results for the Fenton intake which was an unmolested version (no porting).  This intake has ‘D427’ cast on its bottom which leads me to believe that many of the Fenton manifolds were using some of the older Edmunds molds in which to cast them up.

1956 Mercury Carter carbs (vac sec)       324 HP@6000, 357 TQ@3300

L1161-2 Teapots with KM mods               338 HP@5400, 354 TQ@4500

GM Carter 1.050” mech sec 4V carbs      341 HP@5400, 362 TQ@4400

L1094-1 Linc Teapots (60P/97S jets)     342 HP@5400, 364 TQ@4200

GM WCFB carbs GM WCFB carbs

Click on pictures for larger images.

********************************

Edmunds ‘D427’ Intake (stock):

Same drill, just another intake.  This time it’s with an Edmunds intake with the ‘D427’ part number cast on its bottom.

L1434 Teapots (1957 2X4 carbs)             321 HP@5400, 357 TQ@3500

L1094-1 Linc Teapots (60P/82S jets)    322 HP@5400, 351 TQ@3900

L1161-2 Teapots with KM mods              330 HP@5400, 343 TQ@3300

********************************

1956 Ford EDB-9425-C w/mods:

And now back to the 1956 Ford dual quad intake but one that has been heavily ported in the plenum openings somewhere along the way.  The carb openings themselves had been enlarged to accommodate carb adapters to fit later model carbs to it.  This one had also been heavily milled on the intake gasket surfaces which had the port openings smaller than they needed to be.

L1434 Teapots (1957 2X4 carbs)               321 HP@5400, 354 TQ@3500

L1161-2 Teapots with KM mods                329 HP@5400, 352 TQ@3300

L1094-4 Linc Teapots (57P/82S jets)      331 HP@5400, 352 TQ@4400

********************************

Hogans 2X4 Tunnel Ram:

This was a unique piece that falls in the sheet metal intake category and had been drag raced previously on the Church Brothers 1955 Thunderbird with much success.  On their iron headed engine, it had made a best of 490 HP but when replaced by a nicely ported Blue Thunder intake with a single four barrel carb, 510 HP came to the forefront.  While the Hogans intake is in the shop to see what can be done to its innards (plenum mods) to get it back on par with the single four intake, it is being run again with its ‘as supplied’ plenum with a myriad of carb pairs as part of this dual quad test.  Here are the results.

L1094-1 Linc Teapots (60P/82S jets)    311 HP@6200, 307 TQ@5100

L1094-4 Linc Teapots (57P/82S jets)    324 HP@5900, 324 TQ@5200

Street Demon 625 cfm carbs                   350 HP@6100, 345 TQ@4900

L1161-2 Teapots with KM mods             354 HP@6000, 329 TQ@5300

Predator 930 cfm variable venturi        356 HP@6100, 352 TQ@5000

L7996 450 Holleys w/mech secs           360 HP@5800, 344 TQ@5400

L4224 660 Cntr Sqtr Holleys                 361 HP@6100, 342 TQ@5200

Hogans intake Hogans Intake Hogans Intake Hogans intake

Click on pictures for larger images.

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Stock Edelbrock #257 Intake:

The Edelbrock 257 has long been considered to be the gold standard of YBlock dual quad intakes.  Here are the results for the stock Edelbrock #257.

L1434 Teapots (1957 2X4 carbs)           328 HP@5500, 353 TQ@4200

1956 Mercury Carter carbs (vac sec)     331 HP@6100, 352 TQ@3400

L1094-1 Linc Teapots (60P/82S jets)   333 HP@6100, 354 TQ@4200

L1161-2 Teapots with KM mods             344 HP@6100, 353 TQ@4400

GM Carter 1.050” mech sec 4V carbs    345 HP@6100, 358 TQ@4400

Street Demon 625 cfm carbs                   351 HP@6000, 355 TQ@4500

********************************

Edelbrock #257 “Hogged Out”:

On this particular intake, the plenum dividers under each carb had been completely removed which played havoc with the carburetor signal.  This intake had been run previously on the iron heads and was the worst performer of the manifolds tested on those heads.  It did not fare much better on the aluminum heads while low end throttle response proved to be even worse with the better flowing aluminum heads.  As a result, dyno pulls had to be started at 3500 rpms rather than the normal 2500 rpm start.  While one pair of carbs were run on this manifold in an inline setup, a pair of Offenhauser crossram adapters were also utilized and tested in an effort to help save the manifold.  Here are the results.

Inline: Street Demon 625 cfm carbs      272 HP@5100, 293 TQ@4600

Crossram: 660 Holley cntr squirters     339 HP@6100, 331 TQ@4500

Crossram: 625 Street Demon carbs        339 HP@6100, 337 TQ@4900

Those open plenums were not at all happy with the carbs sitting directly above them.  Installing the crossram adapters which both lengthened the runners as well as shielded the bottom of the carb directly from the ports was worth an easy 67 horsepower.  Even with a 67 HP gain, that manifold still comes in at the lower performance end of the list and still lower in output numbers than an unmodified #257 intake.  The lesson here is to be cautious in porting these manifolds as it is quite easy to go the wrong direction when attempting to increase the power levels.

Crossram intake Crossram intake Crossram intake

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Ported Edelbrock FM255:

With the results being much better with Joe Craine porting the Edelbrock 257, it was decided to also see what Joe could do with the Edelbrock FM255 intake.  The stock FM255 actually performed better than the stock 257 so it stood to reason that a ported FM255 might also perform better than a ported 257.  Here are some of the results.

1956 Mercury Carter carbs (vac sec)    347 HP@6000, 359 TQ@3300

L9776 450 cfm mech sec Holley           349 HP@6100, 354 TQ@4500

L1434 Teapots (1957 2X4 carbs)           350 HP@6000, 362 TQ@3400

GM Carter 1.050” mech sec 4V carbs   353 HP@6100, 359 TQ@4400

L8007 390 cfm vac sec Holley               353 HP@6100, 360 TQ@3400

L1094-1 Linc Teapots (60P/82S jets)   361 HP@6100, 370 TQ@4400

L1094-4 Linc Teapots (57P/82S jets)   361 HP@6100, 371 TQ@4400

L1161-2 Teapots with KM mods             362 HP@6100, 362 TQ@4400

But this is where things get interesting.  It’s observed that the mechanical secondary carbs have some severe reversion coming back up through them when loading the engine at 2200-2500 rpms.  To alleviate this, a 2” HVH tapered carb spacer is installed under each carb. But going with what Joe Crane had seen in some air flow testing, the spacers were tested in both the conventional right side up configuration and upside down.  The upside down configuration looked like a better fit to the four holes existing in the carb adapters that were being used to accommodate using modern carburetors on the teapot flanged intake.  The spacers being upside down peaked at 372 HP with the 660 cfm carbs.  Regardless of looking better, the spacers being right side up while using the same carbs netted 378HP.  That’s a 6 HP change that didn’t cost anything but the time it took to reverse the spacers.  It becomes obvious at this point that there is no end to the number of variants that can be tested.

With the same L9776 450 cfm Holley carbs reinstalled but with the upside down HVH spacers now under them, there is an eighteen horsepower increase.  That’s pretty substantial for just a pair of carb spacers being installed.  The pair of 660 cfm center squirter Holleys are then bolted on with the spacers being tested in both positions and the performance again steps up another notch.  Here are the final numbers for both sets of these carbs.

L9776 450 cfm mech sec Holley   367 HP@6100, 350 TQ@3300

L4224 660 cntr sqrtr Holleys        378 HP@6200, 370 TQ@4600

The Offenhauser crossram adapters worked so well on the ‘hogged out’ Edelbrock 257 intake that it was decided to also try them out on a manifold that was already at the top of the field.  In this instance and on the ported FM255 intake, performance went backwards.  Here are the numbers.

Crossram: L4224 660 Holley cntr sqrtrs    352 HP@6200, 357 TQ@4500

******************************

Stock ECG-4224-D 1957 Ford:

And this manifold completes the dual quad testing.  It’s tested only with two different pair of model 4000 Holleys (Teapots).  Here are the numbers.

L1434 Teapots (1957 2X4 carbs)    326 HP@5500, 355 TQ@4100

L1161-2 Teapots with KM mods     336 HP@6000, 352 TQ@3500

*********************************

In Summary:

Although I was on the trail of a couple of Edelbrock M254 intakes to also include in the testing, getting either of the intakes here for the test just didn’t happen.  The M254 2X4 intake was designed for the smaller port Ford 239 and Mercury 256 heads so I suspect it would have really been flow restricted on the aluminum heads.  Without actually testing that particular manifold, I can only guess that its performance would have been on par with the Fenton and Edmunds intakes.

One thing that became clear throughout these tests was what worked for carburetor pairs on one intake manifold did not necessarily work for another intake.  While the Lincoln Teapots performed quite well on some of the basic low rise dual quad intakes, they failed miserably on the tunnel ram.  On that particular intake manifold, two different sets of Lincoln carbs were used and both sets simply would not throttle up properly.  It’s a good guess that there was just enough reversion from those short and straight runners to be upsetting the metering in those particular carbs.  The carbs essentially sit right on top of the runners on that particular setup.  But the pair of 1956 Teapots (List #1161-2) with the Karol Miller modifications shined in that particular application.  Still trying to figure that one out but the internal secondary vacuum signal has been altered significantly on the KM modified Teapots which may be compensating for any reversion taking place.  The 660 cfm center squirter Holleys also worked very well on that intake as compared to some of the other carbs tested but that was the application for which they were specifically engineered.  But on the throttle up, all eight barrels were wide open on the 660’s versus only four barrels initially open on the vacuum secondary KM modified Teapots.  Lots to think about.

So there you have it.  Most of the dual quad intakes that were available for the Y have been tested and compared against each other.  Only in the best of circumstances did a dual quad setup exceed those performance baseline values established by a stock unported Mummert single four barrel intake.  Porting definitely works but if running aluminum heads, you do have your work cut out in getting the air flow numbers high enough in the dual quad intakes to match the cylinder head flow.

The next installment of the dual quad testing will cover the results derived from testing the various dual quad air cleaners.  Stay tuned and until next issue, happy Y motoring.  Ted Eaton.

This article was originally published in The Y-Block Magazine, Issue #116, May-June 2013.

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