The three day holiday weekend really afforded me a great opportunity to make some headway on this project, and I was fortunate enough to take advantage of it, without a lot of family commitments this weekend. Right now I've caught up some on my original schedule, and it looks like I'm only about three weeks behind. My original plan was to have the car running and driving this weekend, but now I'm thinking that I'll make my first trip to the track on July 26. There are another 2 or 3 track days that I can squeeze in before Drag Week after that point, so hopefully this will give me the opportunity to get the car really well sorted.
Once again I was tied up during the week this week, but on Friday morning I got going right away on the engine. I still had several things I wanted to try on the dyno, primary among them getting the crankcase sealed, and retesting without the 1/2" plenum spacer I had installed last weekend. The plenum spacer was kind of a head scratcher for me. Before installation of the plenum spacer, the dyno data had been showing a vacuum in the plenum of up to 0.6 inches. When I installed the plenum spacer the vacuum during the pull went to zero, but the engine picked up kind of a funny pulsing noise partway through the pull. It also picked up power. I was pretty sure that the pulsing noise was induction noise, but I hadn't heard anything quite like it before, so I wanted to run another test, to remove the plenum spacer and see if the noise went away again. Also this week my new O-rings arrived, which were larger in cross section than the original O-rings; I hoped that they would provide a better vacuum seal around the spark plug tubes for the dry sump system.
Also, over the course of the week I had carefully reviewed all the datalogs from the cam sensors, and had concluded that in all cases, regardless of the sensor and target combination, the right cam was retarding about 3 degrees more than the left cam. Whether I believed the absolute numbers or not, this phase shift between the two cams seemed pretty consistent, and also dovetailed with my original test data from 2006. So, after thinking it over I elected to advance the right cam 3 degrees with respect to the left cam. This put the cams at 105 and 108 for ICL, which was exactly where I had set them when I set the cam timing on the engine stand, before the engine went on the dyno. It kind of felt like all the cam timing changes I had done were a wasted effort after this, but at least the way I've been setting up the cams on these engines over the last 7 or 8 years has probably been correct.
So on Friday I tore the top end of the engine apart, to advance the right cam 3 degrees, check the timing chain tension, give the valvetrain a very close inspection and reset the lash, etc. I also removed the Honeywell sensors from the valve covers and replaced them with Cherry sensors, which were the ones I planned to run in the car. I made sure to seal them with some RTV from the inside, because the Honewell sensors had shown leaks around this area. Thinking about the crankcase sealing issue I decided to take a new set of cork valve cover gaskets and glue them to the valve covers, to help hold the gasket in place when vacuum was being developed in the crankcase. I decided to let the sealer dry overnight so that on Saturday morning I could pressurize the crankcase again and check for more leaks.
I had still also wanted to run a pair of Dominator throttle bodies on my sheet metal intake, so I spent the rest of the Fourth of July holiday (until the fireworks started at 9:30) working on a new top for the intake. First I drew up the design for the top in my CAD software, and then wrote the program to machine a piece of 1/2" aluminum plate to the drawing. While the CNC machine was running I robbed the two Dominator throttle bodies off the high riser in my Mach 1. Around dinnertime I had the plate finished up; here's a couple of photos, one from underneath (the inside of the plenum), and one from on top showing the throttle bodies bolted in place:
To be honest I didn't really think the Dominator throttle bodies were going to help much, because the 90mm throttle bodies flowed 1100 cfm each, but it was worth a try, especially since I didn't have to buy any parts to try it. After I got the top done I took some spare 1" X 3" aluminum angle and welded it together into a box that would fit on top of the intake, then welded the top plate in place. At the end of the day on Friday I was pretty much ready to go with the Dominator parts.
Saturday morning I finished re-assembling the engine on the dyno, without the 1/2" plenum spacer. Then I ran the pressure check again, putting 5 psi into the crankcase. I was pleased to see that the leaks around the spark plug tubes were gone, and also that there were no leaks around the cam sensors. I began checking the rest of the engine over, and then discovered a leak that I hadn't seen last weekend. This one was between the intake manifold and the head. Now, on a regular FE I would never have had to worry about this because this junction is covered by the valve cover, but on the cammer of course this is not the case. I had run a ring of RTV around the ports on either side of the intake gaskets, but as I sprayed a soapy water solution onto the junction between the intake and the heads, I could see that pressurized air was escaping past the gasket and between the ports. And some of these leaks looked pretty substantial.
I dug out the Ford TA-31 and ran a bead of it along the top of the intake manifold rail and down the sides a little ways to try to get this area sealed up. I decided I wanted to let this cure for a couple hours before running the engine, so I took care of a few other things in the shop while I waited. About noon Marc Hunter from the forum came by; he was in Iowa visiting his brother, and had previously arranged to stop up to my place and pick up his FE intake adapter. He brought his brother Ryan with him, and his dog, named Cammer. Best name ever for a dog if you ask me LOL! Ryan owns SCE gaskets and is working on some new FE gaskets, and wanted to show me some of the stuff he was doing and ask a couple of questions. I told him about some SOHC gasket requirements that I would like to see, including a valve cover gasket that isn't cork, and also gave him one of the old Victor Reinz FE intake gaskets, which were far and away my favorite FE intake gasket until they quit manufacturing them. Maybe SCE will start making them now.
After a quick tour of the shop and some more technical discussions I got back to working on the engine, while Marc and Ryan hung around waiting for me to be finished so they could see the engine run on the dyno. I still had to wire up the new Cherry sensors I'd installed in the valve covers, and this took about an hour to finish up. Finally around 2:00 or so the engine was ready to go. It fired right up as usual, meaning that I hadn't screwed anything up with the cam sensors (which is always a possibility LOL!). A couple of minutes into the warm up it dawned on me to look at the crankcase vacuum, and lo and behold, I had close to 10 inches of vacuum running at only about 1500 RPM! Boy I felt good about that; all the chasing around of the vacuum leaks had paid off. I was pretty sure that significant crankcase vacuum would improve the power output of the engine, so after the warm-up was complete, I made another 5500-7500 RPM pull. The first thing I noticed during the pull was that the noise from the previous few pulls was gone; removal of the plenum spacer seemed to have eliminated that sound. After the pull was over and we looked at the data, sure enough the 0.5 inches of manifold vacuum was back. So the plenum spacer definitely helped the power output, and caused the new noise. But on this pull, I was a little disappointed by the power numbers. It seemed that the crankcase vacuum had not improved power at all! This was a surprise, given the size of this engine and the low tension rings I'm using. A review of the data showed that 10 inches of vacuum was all I was getting. I figured that I could use up to 20" or more, so after talking it over with Marc and Ryan I decided to adjust the vacuum relief valve on the engine to stay shut until a higher vacuum level was reached. I started the engine to run another pull, but now the crankcase vacuum was reading much lower, maybe only 1-2 inches. I was confused by all this, but I ran the pull anyway. Towards the end of the pull some smoke starting coming from the right side of the engine, indicating a valve cover leak. The engine didn't seem to care, though, and made the same power as the pull before. After looking at the data we went back out into the dyno room and I checked the valve cover bolts. Sure enough, some of them were really, really loose. This is one reason why I would like to see a rubber or composite valve cover gaskets for the SOHC; the cork gaskets get hot, shrink, and then start leaking. Then, as you tighten down, the same thing happens a few more times. Finally after you've tightened them a few times the cork splits and you have to ditch the gaskets and start with a new pair. A better gasket for the valve covers would be a real help for these engines.
After tightening the valve cover bolts the crankcase vacuum came back. Marc and Ryan had to make the return trip to Iowa; two really nice guys, and it was my pleasure to have them visit. After they left I took a short break and then went to the next test, which was to install a 1" plenum spacer on the intake. I figured if a 1/2" spacer was good, maybe a 1" spacer would be better. I was curious what the engine would sound like with a 1" spacer, but when I ran the test it sounded the same as with no spacer at all, and the power was back down a little, plus the 0.5 inches of vacuum was back in the plenum. So it seemed like the 1/2" plenum spacer was optimal for this engine.
At this point, I decided to install the new plenum top with the Dominator throttle bodies. Here's a picture of the engine with these installed:
As mentioned previously I didn't hold a whole lot of hope out for this combination, but I thought I would give it a try. Boy, was I mistaken! The Dominator throttle bodies picked up a solid 20 horsepower over the entire RPM band, 5500-7500! A huge, huge power improvement. Boy, was I happy to see that!
It was getting towards the end of the day Saturday, and I had wanted to run some more experiments with the Dominator throttle bodies by adding some plenum spacers, but I was running out of time to do that. I decided to jump to my last test. During all the testing with this engine I was seeing about 0.85 psi in the dyno's exhaust system. Usually there is power available when there is pressure in the exhaust system; in fact, I documented some of this in the miscellaneous testing section of my book. So, for the last test I disconnected the exhaust system and ran the headers open in the dyno room. When I started the engine, I immediately had to put ear protection on; that thing was LOUD. I ran the pull, and anxiously downloaded the data and... no improvement. Nearly identical numbers to the previous pull with the exhaust system connected.
So the dyno results this weekend were all rather surprising to me. First, no power improvement with vacuum in the crankcase. Second, a big power improvement with the Dominator throttle bodies. And finally, no power improvement with open headers over the dyno exhaust system. I would not have guessed any of these outcomes. I guess all this shows is that you have to test this stuff to really find out the truth.
Sunday morning I spent working on the car. It felt pretty good to get my hands back on it; it has been two years since I've really done anything with it. I got it positioned in the middle of the shop and spent some time pulling the pumpkin, because the car currently has street gears in it and I need to put in a set of pro gears. Shortly after noon my friend Kevin R came by to give me a hand pulling the engine off the dyno, and putting it in the car. We attached the engine and transmission together, along with the Gear Vendors overdrive, and had it muscled into place by 4:00. Here's a photo of the engine in position:
Right away I could see that my hood scoop is too low, but I have some plans to address that, including getting a pair of Accufab Dominator throttle bodies, and reshaping the plenum box to make it wider and shorter, so it has the same volume but a lower profile. I have a lot of work in front of me on the left front corner of the engine compartment, to fit the dry sump tank and accessories, but I think I can get all this done in the next couple of weeks. I'm shooting for a test and tune at a local track on July 26; we will see what happens.
