Archive for the 'Y-Block' Category

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.


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.


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.


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.


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


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.

Published by tedeaton on 15 Jan 2014

Y-Block Ford – Dual Quad Testing on Iron Heads – Part I

With the resurgence of the Ford Y engine making a comeback as a viable replacement power plant for more than just mid-Fifties Fords, there is suddenly a demand for both modern performance and old school looks being in the same package.  And nothing speaks old school as well as performance as a dual four barrel setup.  As I had previously dyno tested the different three deuce intakes, the time was now ripe to do a similar test with the various dual quad intakes.  This dual quad intake test becomes much more complex due to wanting to also test a variety of carburetor pairs to also discern if there was a performance advantage to the carbs themselves.  So with a more definitive test in mind, the call went out for as many different carbs and intakes so that an extensive dual quad test could take place on the 312+ dyno mule.

Edmunds 2X4 Intake Fenton 2X4 Intake

Click on pictures for larger images.

And the response was overwhelming.  Many intakes were loaned and a multitude of carburetors were either loaned or donated to the cause along with variety of carb parts and jets.  And a variety of dual quad air cleaners were also provided to do some definitive testing on those.  More on that series of tests further down the road.  And to make the tests go much more smoothly, both Vic Correnti and Tom Drummond stayed for several days to help with the manifold changes and subsequent tuning.  Also showing up during the testing and getting their hands dirty with intake and carb changes were Karol Miller, Randy Gummelt, Joe D. Craine, and Bill Myrand.  Thanks to all for the help as it would have been much more difficult otherwise.

11 Seven 2X4 intakes 12 Twelve 2X4 Intakes

Click on pictures for larger images.

The test engine for this series of tests is Bob Martin’s old 1956 Merc engine that was originally provided as a core for his current engine build.  That core engine was rebuilt and has subsequently been used as a dyno mule for a series of different tests.  This engine is a +060 over 312 with the replacement cast pistons sitting ~.025” in the hole at TDC.  The camshaft is the same cam Bob raced in his ’56 Mercury for thirty plus years.  That cam is a Seventies era Crower Monarch grind sporting 280° adv duration, 238° dur at 0.050”, .450” lift, ground on 110° lobe centers and installed 2° advanced or at 108° intake lobe centerline.  Harland Sharp 1.6:1 roller tipped rockers works the valves.  For this Part I of the 2X4 intake testing article, the heads are a set of mildly ported 113’s and for Part II (scheduled for the next issue of YBM) a set of  Mummert aluminum heads are installed on the engine.  The aluminum heads are thrown into the fray simply to eliminate any questions in intake manifold performance that may be related to a restriction in head flow.  If there is a choke point, it ideally needs to be at the intake so any differences in intake manifold design can be brought to the forefront during the testing.


Karol Miller visit:

Karol Miller had dropped by and when discussing the upcoming dual quad testing and showing him some of the carbs to be used, he pointed out that he had removed most of the choke horn cover from the Teapots that had been used for his record setting Daytona run in 1957.  With that in mind, a pair of 1956 312 L1161-2 Holley Teapots were modified accordingly.  While they do look naked without the choke horns, they do prove to perform better overall than similar carbs with the choke horns in place.  This becomes more evident where the iron heads are changed out to the aluminum units later where head flow restriction becomes less an issue.


Bench marks:

The first order of business was setting some bench marks or base lines for the testing.  This was accomplished by running the engine in a single four barrel format.  And in doing this, it was decided that three bench marks would be established with one being with the 1956 ECZ-A intake, the second being the 1957 ECZ-B intake, and the third being a Mummert aluminum intake.  All the intake manifolds are stock and unmodified while the carburetor used on all three for bench marking purposes is a tried and proven 750 cfm Holley with vacuum secondaries.

An adapter was used to allow the use of the 750 Holley on the Teapot flanged ECZ-A intake and that particular intake was also tested with three different carbs;  a Lincoln Teapot Holley, a 600 cfm Holley, and the aforementioned 750 cfm Holley.  While each larger sized carb did increase the power output, the difference in horsepower between the Lincoln Teapot carb (~500 cfm) and the 750 Holley was only 3 HP which indicates a serious flow restriction in the ECZ-A manifold.  Ford engineering was definitely at the top of its game with the introduction of the ECZ-B manifold for the 1957 models as it was a very noticeable improvement over the previous year’s intake manifold design.

Why three benchmarks?  These would represent three different performance levels depending upon the time frame or era that the dual quad intake testing could be referenced back to.  The ECZ-A intake would represent what the typical performance build would have represented in 1956 while the ECZ-B intake would represent a performance build starting in 1957 and what would be the standard for the next forty plus years.  And the Mummert intake would set the standard for what a dual quad intake would at least need to equal to for matching modern day performance.

And here are those bench marks:

ECZ-A Intake with 750 Holley           240HP / 324TQ

ECZ-B Intake with 750 Holley           276HP / 324TQ

Mummert intake with 750 Holley     311HP / 342TQ


1957 ECG-D 2X4 Intake:

First on the list of intakes was an original 1957 ECG-D dual quad intake with the factory supplied L1434 dual quad model 4000 Holleys (Teapots).  With the factory jetting in place (45P/55S), the peak numbers are 285HP@5200 and 336TQ@3600.  Changing the carbs out to the pair of KM modified 1956 312 L1162-2 Holley Teapots netted 288HP@5200 and 322TQ@3400.  Next was a pair of Mike Suter reproduction dual quad Teapots and the numbers for those after rejetting was 273HP@5200 and 319TQ@3400.  And the final carb change for this intake would be a pair of L1094-1 Lincoln Teapots with the numbers peaking at 296HP@5200 and 338@3700.  The Lincoln Teapots required the secondaries being worked mechanically due to the vacuum secondaries not pulling in quickly enough.  Some tinkering with the secondary springs would have likely cured that but there was a chance in the damaging the aged diaphragms so it was not attempted.

01 1956 Ford EDB 9425 C 2X4 intake 1957 Ford ECG 9424 D 2X4 intake

The picture on the left is the 1956 EDB-C intake.  the right hand picture is the 1957 ECG-D manifold.

Click on the pictures for larger images.


Edelbrock #257 Intake (hogged out):

Next on the list was a highly modified Edelbrock p/n 257 dual quad intake.  The plenum dividers had been completely removed and the only divider material that remained was in the runners themselves.  Because the low end torque values were so dismal, this intake was tested only with the Lincoln L1094-1 Holley Teapots.  The peak numbers ended up being 272HP@5200 and 305TQ@3800.  This intake had extreme difficulty in loading the engine on the dyno at 2500 rpms.

Edel 257 2X4 Intake Hogged Out Carter AFB carbs

Click on pictures for larger images.

Edelbrock #257 Intake (stock):

This was a stock unmolested intake and the testing started with the Lincoln L1094-1 Teapots.  The peak numbers for those were 296HP@5300 and 341TQ@3500.  The next pair of carbs was the KM modified L1162-2 Teapots and they peaked at 303HP@5200 and 332TQ@4200.  Carb adapters were then installed and a pair of 625 cfm Steet Demon carbs were bolted in place.  After jetting and other adjustments, these two carbs peaked at 309HP@5400 and 343@4300.

Edelbrock 255 and 257 dual quad intakes  Edelbrock FM255 ported intake

Left picture: Edelbrock 257 intake on top and Edelbrock 255 intake on the bottom.  Note the difference in the carburetor spacing.  The right hand picture is a ported Edelbrock 255 intake manifold.

Click on pictures for larger images.

Edelbrock #257 Intake (ported):

Another intake change and this time to the Joe Craine ported Edelbrock #257 with carb adapters and 2” HVH tapered carb spacers.  The first pair of carbs to be tried would be the Street Demon carbs with the 55P & 72S jetting and the peak numbers would be 320HP@5200 and 342TQ@4400.  Next to try was a pair of Edelbrock 500cfm carbs.  With just the carb adapters and 2” HVH carb spacers, these carbs peaked at 310HP@5300 and 335TQ@4400.  Using the same carbs but removing the 2” carb spacers netted the following peak numbers: 304HP@5300 and 335TQ@4400.  And here are the peak numbers with the Lincoln L1094-1 Teapots w/o the 2” carb spacers: 309HP@5300 and 347TQ@4100.

Edelbrock ported 257 2X4 intake  Street Demon carbs

Click on pictures for larger images.

Iron Head Summary:

With 311 HP being the best single four bench mark number, the Edelbrock #257 intake ported by Joe Craine was able to surpass that.  The remainder of the dual quad intakes tested on the iron heads still proves that adding dual quads to your mid-Fifties era modified Y-Block was a great power adder back in the day though.  And if you were replacing a single four Holley Teapot setup, you were taking giant leaps forward.


And coming up:

The next installment of the Y 2X4 intake testing has the iron 113 heads off the engine and replaced with a set of Mummert aluminum heads.  And this is where the testing gets even more interesting.  While the same intakes that were tested on the iron heads get retested on the aluminum heads, the Fenton, Edmunds, Hogans, the 1956 Ford and Mercury factory dual quads (yes, they are different manifolds), and Edelbrock FM255’s also get throwed into the fray.

Stay tuned and until next issue, Happy Y Motoring.  Ted Eaton.

This article was originally published in The Y-Block Magazine, Issue #115, Mar-Apr 2013

Published by tedeaton on 18 Dec 2013

Y-Block Ford – 3X2 Intake Testing

What started out as a simple dyno test to evaluate the performance differences between the small and large port Edelbrock three deuce intake manifolds ended up turning into a full blown test where seven different 3X2 intakes were compared on an engine in a back to back dyno test.    The other intake manifolds being added to this test included three different intakes wearing the Edmunds brand, a Weiand intake and an Offenhauser intake.  A Fenton manifold was not included in the testing simply due to one not being readily available at test time but there is some information out there pointing to the Fenton manifolds being cast in the same molds as the Edmunds intakes.  But as found in the testing, not all the Edmunds intakes are created equal so the same could be likely said for the Fenton intakes.

Because there was an Offenhauser 3X2 intake throwed into the mix, this was deemed a good opportunity to determine if the Offy intake used in the May 1971 Popular Hot Rodding Magazine (PHRM) Y buildup contributed at least in part as to why that particular Y engine buildup failed to make notable horsepower numbers.  Here are a few of the details of the PHRM Y buildup for those of you that are unfamiliar with the article or perhaps just need the memory jogged.  The engine was a +060 over 312 with popup pistons, ported G heads, and an Engle #324 camshaft with 292° duration and 0.480” lift.  The compression ratio is not noted but is expected to be in excess of 10½:1 based on some of the information given. The Offy 3X2 intake being used for the magazine test was outfitted with Stromberg 97’s with #48 jets all the way around.  Here are the horsepower numbers from that original PHRM build.

2000 rpm         96 hp

2500 rpm         117 hp

3000 rpm         151 hp

3500 rpm         173 hp

4000 rpm         204 hp

4500 rpm         242 hp

5000 rpm         251 hp

5500 rpm         258 hp

6000 rpm         245 hp


Offenhauser 3X2 Intake for Y-Block Ford.  These were all dyno tested on the +060 over 312 dyno mule.  Click on pictures for larger images

But now back to the present.  For this new round of intake manifold testing, a +060 over 312 with flattop pistons 0.025” in the hole with stock and unported ‘G’ heads is being used. This is the same engine that was used for the carburetor test in issue #97 of YBM.  The camshaft is also the same being the 280° Crower Monarch with 238° duration at 0.050”, ground on 110° lobe centers, installed 2° advanced, and has a measured lift of 0.434” at the valve after the lash is adjusted at 0.019” hot.  A set of prototype Harland Sharp 1.6:1 aluminum roller tipped rocker arms are being used at this point.  The static compression ratio is 9.2:1 and 91 octane pump gasoline is being used for all testing.  The headers are the stepped headers that were used for the 2009 and 2010 EMC Y engine project along with the same Magnaflow muffers.  The carbs were dialed in and jetted using the Edelbrock 573 intake and then remained like that for all the intake manifold testing.  Jetting was #48’s in all three carbs.  All dyno runs were performed between 2500 & 5500 rpms.

Edelbrock 573 3X2 Intake with Stromberg 97 carbs.  Edelbrock 553 3X2 Intake that has been ceramic coated. Weiand FM436 Intake Manifold for Y-Block Ford Edmunds DM-424 3X2 Intake for Y-Block Ford

Click on pictures for larger versions.

When it was all said and done, the Edelbrock 573 came out on top at 279 peak hp and the Offenhauser intake was at the bottom of the heap with 251HP.  28 horsepower separated the best from the worst on the 3X2 manifolds which can be considered a bunch.  To validate that the engine was still in good condition and not degrading as the testing was taking place, the first manifold that was run was reinstalled at the end of the 3X2 test session and it confirmed that the engine was still performing flawlessly.

There was still some time left at the end of the day which allowed the new and recently released Mummert aluminum 4V intake to be installed on the engine with a modified 600cfm vacuum secondary Holley.  That change alone upped the horsepower to 292.  Keep in mind that it was only taking ~35 minutes to change each intake which says a lot for the help that was on hand and was a big part in making this test happen in a timely manner.  Pre-planning also helped in that thermostat housings and excess water and vacuum holes on each intake were taken care of in advance.  Intake manifold bolts where they were different were also on hand.  It’s always great when a plan actually works out as intended.

As with any dyno data, much more can be gleaned from it than just the peak values.  By examining the average values, there are other attributes that stand out that can help to clarify additional differences in engine performance.  In order to accurately score or rank each intake manifolds performance, the average horsepower and average torque values for each dyno pull were added together, divided into the cubic inch of the engine, and multiplied by 1000.  Thanks goes to the Engine Masters Challenge group for working out a scoring methodolgy that gives a better determination of how engines with varying parts and/or combinations can be accurately compared to each other.  Chart A (below) lists the manifolds in order from best to worst based on their scores but also breaks down each manifolds performance by peak and average numbers.  The performance numbers for the recently released Mummert 4V intake are also listed at the bottom of that same chart.

At the conclusion of this test, there was sufficient data to determine if the Offenhauser intake in that original 1971 PHRM test was a major contributor in why that particular engine performed so poorly.  Although the average horsepower and torque values were slightly higher on this new test, the original test did have subtly better peak numbers which I’ll attribute to the differences between the compression ratios and the cylinder heads.  The heads used in the original test were ported versus the stock and unported G heads being used in this test.  The compression ratio as well as the larger camshaft being used in the PHRM test should have also contributed to much higher numbers versus the 9.2:1 CR in this test and the smaller Crower camshaft that was being used.  But overall, the results were quite similar.  In summary, the Offenhauser intake had much to do with the dismal performance of the Y in that original test.

Chart A – overall performance evaluation
3X2 Intake Peak HP Peak Tq Avg HP Avg Tq Score Order in which tested on engine Overall Perf Ranking
Edelbrock ‘573’ 279.3 336.0 235.8 312.8 1703.7

1 & 8


Edmunds DM-425 266.5 336.1 231.2 308.1 1674.7



Edelbrock ‘553’ 270.1 334.1 231.0 307.5 1672.4



Edmunds DM-424D 260.1 338.6 229.7 307.3 1667.7



Weiand FM436 266.2 332.1 229.3 305.6 1661.2



Edmunds Ford 424 261.9 330.4 227.3 303.0 1646.9



Offenhauser No part # 250.8 311.5 215.6 287.1 1561.2



Mummert 1X4 intake w/600 Holley 291.9 346.0 244.8 323.7   1765.4


Not a




Chart B breaks down the horsepower results of each manifold using the same rpm format as was published in that original magazine article.  Had any other brand of three deuce manifold been used in that 1971 test, the results would have been much better.

Chart B –   all values horsepower
rpm Original PHRM Test This Offy test Edel573 Edel553 EdmdsDM-425 WeiandFM436 EdmdsDM-424D EdmdsF-424
2500 117 132 139 141 144 140 147 143
3000 151 176 188 188 190 188 193 187
3500 173 208 223 222 224 221 225 213
4000 204 230 252 242 244 245 245 240
4500 242 244 269 263 257 257 254 250
5000 251 251 275 267 259 265 252 250
5500 258 242 275 263 257 258 247 249
Avg 199.4 211.9 231.6 226.6 225.0 224.9 223.3 218.9
Ranking   7 1 2 3 4 5 6








Looking at the dyno data from the perspective as to which 3X2 intake manifolds would be the best from a daily driver point of view and not as a drag strip performer, only the torque numbers in the 2500-3500 rpms range were examined.  This did change up the order somewhat but the Offenhauser intake in this case still remains at the bottom of the heap.  No matter how the Offy intake was examined, it remained the poorest performer of the group.  Chart C summarizes the data and rearranges the various 3X2 intake manifolds in a best to worst ranking when only the torque values in the 2500-3500 rpm range are being considered.

Chart C – Lowend performance evaluation –  values are ft/lbs torque
rpm Edmunds DM-424D Edmunds DM-425 Edelbrock 553 Weiand FM436 Edelbrock 573 Edmunds Ford 424 Offy
2500 309 303 296 293 292 294 277
2600 320 314 308 306 305 306 287
2700 328 323 316 316 313 314 294
2800 334 329 322 322 321 319 300
2900 336 332 327 327 325 323 305
3000 337 333 330 330 328 326 308
3100 338 334 332 331 330 327 310
3200 338 335 333 332 333 328 311
3300 339 336 334 332 334 330 311
3400 338 336 334 332 335 330 311
3500 337 336 333 332 336 330 312
Avg 332.2 328.3 324.1 323.0 322.9 320.6 302.4
Order   tested  6  7  3  4  1&8  5  2
Overall   scoring order  4  2  3  5  1  6  7
Revised  scoring order  1  2  3  4  5  6  7













Torque Graph for Edmunds Edelbrock Offenhauser 3X2 Intakes   Click on graph for larger version


Edmunds "424 Ford" 3X2 Intake for Y-Block Ford Edmunds DM-425 3X2 Intake for Y-Block Ford Dyno Testing the 3X2 Intakes Dyno Testing the 3X2 Intakes

Click on pictures for larger versions

Special thanks goes out to those persons who loaned their 3X2 intakes for this testing.  If not for the generosity of these people, this test would not have happened in the detail in which it did.  With this particular test completed, future testing of some other variables are already being planned.  Cylinder head testing and exhaust system testing are in the works.

That’s all for now.  Ted Eaton

This article was originally published in the Y-Block Magazine, May-Jun 2010, Issue #98.


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