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Great FE Intake Comparo, Report #4, Part 2

December 3 2006 at 9:10 PM

Jay Brown  (Login jaybnve)

Well, this has turned out to be a three part report. Despite my best efforts, I was not able to finish testing all the multiple carb intakes today. A couple of the guys who were going to help me bailed out, and only one guy showed up, and not until 2:00. Also, I had problems with one manifold that took a lot of time out of the schedule (more on that later). But in any case, here are the results of Report #4, part 2.

Saturday night, after having tested the medium riser and low riser 2X4 intakes, I decided that the best use of time would be to jump right to the crossrams. The reason was that the Mickey Thompson crossram appeared like it would take a substantial amount of time to set up, and since I had until Sunday at noon before I could run the dyno again, I figured that I could use the time Saturday night and Sunday morning to get the manifold set up. After that, the Edelbrock crossram would be pretty easy, and then I could go back to more conventional 2X4 intakes.

Special requirements for the M/T crossram include a two piece distributor, with one part containing the gear on a small shaft plus an aluminum bushing that must be assembled into the engine before the intake is installed, and then a non-stock distributor that actually fits into the intake housing. When I bought my M/T crossram it came with these pieces, but no linkage, so I knew I would have to build that from scratch. I also knew that I would have to use the distributor that came with the M/T intake, and it was a point type distributor. The MSD distributor that I’m using has HEI type terminals on the cap, but the distributor that came with the crossram uses a standard cap, and the HEI cap won’t fit. So, in addition to everything else, I needed a different set of plug wires to work with the standard cap. Finally, I needed some special Allen head or 12 point head bolts to bolt down the intake, because the bolt bosses are countersunk a little bit into the interior of the intake manifold. The manifold features six ¾” pipe plugs that are removed, and then the six middle intake manifold bolts are installed through the holes left by the pipe plugs.

The following photo shows the hardware required to make the M/T intake work:

I got started Saturday night by refurbishing the point type distributor with a new condenser, and also filing one set of the existing points. The distributor is a dual point unit, but I converted it to a single point setup in order to make it easier to set the dwell on the dyno. I also installed a new cap and rotor. Then, I installed the distributor gear and its miniature shaft into the engine, along with the round aluminum spacer. I got the manifold cleaned up, took out the pipe plugs so I could access the bolt holes, added the carb studs, etc.

Sunday morning I ran off to the local hardware store to find six 3 ½” allen bolts for attaching the manifold. Unfortunately, I could only find five, so I ended up using one regular hex head bolt that was 4” long, and machining a sleeve to go over it so that the hex head stood off the floor of the intake a ways, and tightened against the sleeve, which fit into the manifold. Then, I installed the intake on the engine, started all the bolts, and test fit the distributor. It fit just fine. After assembling the rest of the engine, I added the 660 Holleys. Then, I fabricated some linkage out of some aluminum bar stock and ¼” all thread. It was crude, but functional. Finally, I grabbed a spare set of MSD plug wires that I had not yet assembled, and set them up for this engine, with the correct ends for the normal distributor cap. Here’s a couple photos of the setup:

All this took me until 1:00 PM, but I was finally ready to go. After all this work, I was hoping for some good results from this intake. Unfortunately, they were not forthcoming. Here is a plot of the HP/torque numbers from this intake:

From the sounds of the dyno room, the engine did not really like this intake. Three test runs netted about the same results each time, and the engine did not sound strong during the runs. A/F was about 12.5:1, so it wasn’t a mixture issue. In any case, with only 430 lb-ft of torque, and 370 HP, this manifold was disappointing.

So, off came the M/T and on went the Edelbrock XF66 crossram. This intake is noticeably easier to work with, having all the intake bolts accessible from a normal position, and accommodating the stock distributor. With the crossram linkage already fabricated, it was not a big challenge to get the Edelbrock manifold set up, like it had been with the M/T. By this time my friend Kevin had shown up to give me a hand, and we had the Edelbrock manifold ready to run by 3:00 or so. Here’s a picture of the XF66 on the dyno mule:

This manifold showed the most unusual results of any of the manifolds I have tested so far. It made pretty good midrange torque, then DIED, badly, until about 5000 RPM, then rebounded to post respectable HP numbers. Between 4500 and 5000 RPM on the dyno, you could just hear the engine laboring. Speculation would be that there is some kind of a reversion or airflow effect going on here, but to be honest I really don’t know. A/F was right on with this intake, and manifold vacuum stayed at 0 throughout the test, giving no clue as to the source of the huge power drop. Strangely, we had one run where the power did not really fall off like in the other runs; this was run #2, and all of the runs were done with the same conditions, so its difficult to understand what is happening. The following graphs shows the torque and HP curves from the first dyno pull, and then all five dyno pulls we made on this intake. Note that pull #2 didn’t show the fall off in torque and HP like the rest of the pulls:

Comparing the two intakes, the Edelbrock intake makes lots more torque and HP, but it has such a spooky characteristic that I’m not sure which one of these I’d choose. In any case, it seems clear that these intakes are not ideally suited for an engine of this performance level. Here is a graph of the two crossrams together:

It was now about 4:00 on Sunday, and I was hoping to get two more intakes in before shutting down the dyno at 8:00. We decided to do the tunnel wedge intake. So, we tore down the engine again, removed the Edelbrock crossram, and set up with the tunnel wedge. I had the opportunity to test an original Ford tunnel wedge, or a Dove reproduction. I recently purchased the Dove just for this testing, and my friend Kevin owns the factory version. We set them next to each other and looked them over; they were very close. The only real differences that we could see were in the plenum area, where the Dove’s plenum appeared to be more rounded where the runners entered, while the Ford’s was more square. Because I owned the Dove intake, I decided to test that one rather than the factory piece.

I had not yet assembled the bottom plate onto the Dove intake, and this took a little time, but by about 6:00 this evening we were ready to test. At least, I thought so. As I was filling the engine with water just prior to starting it, we had a major leak at the front of the engine. Water was pouring out of the leak slot in the gasket, indicating a leak between the gasket and the manifold. I thought, “Uh oh…”. We tried some sealer into the leak slot, and thought maybe it would hold, but as soon as I started the engine and the water pump started working, it blew out the sealer, and squirted water out of the front of the engine. Here’s a picture:

It was discouraging, but we had to pull the intake back off. We were hoping to see just a bad gasket or something, but what we found was… well, I’ll let you decide. Here is a photo of the water jacket port on the right side of the manifold, which did not leak:

Here is a photo of the water jacket port on the left side of the manifold, which did leak:

Here is a picture of the NAPA MS15166X gaskets that I have been using, placed over the left side of the intake manifold:

As you can see, the water jacket hole extends down past the normal sealing area, and is overlapping into the leak slot in the gasket. So, water was just pouring out through this orifice.

Fortunately, there is an easy fix. Although the NAPA, Victor Reinz, and Fel-Pro gaskets I have on hand all have the leak slot, the Mr. Gasket gaskets that I have do not. Here is a picture of the NAPA and Mr. Gasket gaskets showing the difference:

Working feverishly, Kevin and I reinstalled the Dove intake with the Mr. Gasket gaskets. We finished at 7:30, just in time for a couple of pulls before the 8:00 PM deadline. We filled the engine with water and no leaks this time. After it was warmed up, we made the first pull, and received the following result:

Pretty underwhelming; not even 400 HP. A closer look at the data revealed why. The A/F ratio for this run was around 13.5:1, so the engine was running rather lean with this intake. Obviously there was not enough signal to the carbs to get the fuel flowing. Because I have been trying to keep the A/F numbers fairly consistent during the multiple carb tests, I think I will jet up the 660s and try this intake some more. But tonight, we just flat ran out of time.

Part 3 of this report will cover the further testing of the tunnel wedge intake, plus the Blue Thunder 2X4 intake, and the tunnel ram. I hope to have this completed by the end of this week. Stay tuned…

Jay Brown
1968 Shelby GT 500 Convertible, all aluminum 489" 1030 HP Supercharged FE
1969 XL Convertible, 460
1969 R code Mach 1, 706 HP 511" all aluminum FE, 10.457 @ 127.47, 2005 Drag Week Winner, Naturally Aspirated Big Block
2005 Ford GT, 2006 Drag Week Winner, 12.0 Daily Driver

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