FE Power Forums > The Road to Drag Week 2014
The Road to Drag Week 2014 - May 18
jayb:
Once again this weekend things went more or less according to plan. I made quite a bit of progress getting the engine assembled, and now the tough parts of the assembly are more or less complete. I still have some fabrication to do to mount the crank sensor and make an arbor to drive the dry sump pump, but I think I'm on track to get this engine finished up by the end of the month.
The first task on Saturday was to get the timing chain setup put together. I started by installing the cams in the heads, with only the first cam cap in place to retain them. Here's a picture of the right cam installed, but without that first cap in place. Note the numbers on the cam; there is a center dot, and then a 2 and a 4 on either side of the center dot. That center dot should be point straight up with respect to the head surface, or 90 degrees from the head surface:
Here's a picture of the whole right cam installed:
After I had the cams in place I installed the cam gears. The dot on the cam gear should line up with the dot in the previous photo on the cam, and be positioned so that the dot on the cam gear is about 45 degrees from vertical. This is the correct position for the cam gears when you go to install the chain. Here's a photo:
Notice the alignment pin stuck into the cam gear, with the 10-24 allen head screw coming out of it. This pin goes through the gear and into a matching hole in the cam. Advancing or retarding each cam can be done by moving this alignment pin. Currently the pin is in the center position, so this cam is installed straight up. If you move the pin one hole to the right, you are advancing the cam about 3 crankshaft degrees. One hole to the left, and you are retarding the cam the same amount. The 10-24 bolt is installed temporarily, to allow easy removal of the alignment pin (which is 10-24 threaded on the inside). When you move the pin, of course, you have to move the cam relative to the gear, so that the next hole in the cam lines up. This advances or retards the cam. In the next picture, you can see a couple of flats ground into the cam; these are sized for a 7/8" wrench. You can put a wrench on the cam and move it back and forth with the pin out, to get the holes in the cam and the gear lined up. The next picture also shows the rocker shafts and two rockers installed, so that once I get the right cam degreed I can check piston to valve clearance (there are still checker springs on the valves for cylinder 1):
Next I added the timing chain guides and the oil squirters to the front of the engine. The timing chain guides are pretty simple, you just have to bolt the bottom one in place, and then put the top one on after the chain has been installed. Next the chain is installed, and here is where the dots on the timing gears become important. First, the gear on the stub cam should have its timing mark pointed straight down, while as mentioned previously the two cam gears need to have their timing marks about 45 degrees off from vertical, towards the outboard side of the engine. Then you can put the chain in place. The top bolt on the timing chain tensioner must be removed, though, and the tensioner dropped as far down as possible, in order for the chain to fit. The factory chains had three colored links that had to line up with marks on the timing gears. Most of the aftermarket chains don't have those colored links, so I color them myself using some paint markers. The way to do this is to lay the chain on a bench in front of you, and working clockwise around the chain, color one link for the stub cam gear, then count 63 links, then color the next link for the right cam gear, then count 69 links, then color the next link for the left cam gear. You should then have 57 links between the colored link for the left cam gear and the link for the stub cam gear. There are a total of 192 links in the chain. After you have the links colored, drape the chain in place, making sure that the colored links go on the tooth with the dot on each of the cam gears and the stub cam gear. Then lift up the tensioner and install the top bolt, and you are more or less finished. The last thing you have to do is install the top timing chain guide. One thing about the aftermarket top timing chain guides is that the rivets that they use to attached the nylon rubbing blocks to the guide stick up a long way past the top of the sheet metal chain guide, and unless you grind them down pretty far, the timing cover won't fit over them. So you have to make sure that you grind the rivets if you've got an aftermarket guide. When you're done the front are of the motor will look like this:
After putting the chain on I also install some oil squirters, tapping off the main oil galley in each head, to oil the bearings in the tensioner arm and the fuel pump gear. These bearings don't get a normal source of oil, and for race only use probably don't need this modification. But if you are idling in traffic for extended periods of time, then IMO its a good idea to add them. Some people think that these auxiliary oil sources are for the chain, but the chain really doesn't need additional oiling; it gets plenty of splash oiling even at low speeds. But the bearings in the tensioner arm and the fuel pump gear don't necessarily get this oil supply, especially since as they are spinning, because they are throwing oil away from the center of the gear, not towards it. So for extended idling I always like to make this modifications. The photos below show these auxiliary oil squirters; I make them out of 3/16" brake line and squeeze the ends shut so that there is only a .020" or so orifice for the oil to come out. This makes a nice little squirt of oil right at the bearings, without taking too much oil from the main oil galleries.
In that last photo you can see the bolt just to the left of the primary timing gear that goes into the block's water jacket. You need sealer on the thread of this bolt, and all around it, to ensure there are no leaks here.
When it comes to tightening the chain, there are a lot of different theories about this out there. Several years ago when Earl Wade was still alive I spent quite a bit of time on the phone talking to him about this topic. Earl basically said that he liked to keep the chain pretty tight, and he suggested the following way to monitor it. Earl said to paint some blue machinist's dye on the top of the tensioner arm. If the chain gets too loose, it starts hitting that tensioner, and you can easily see the marks in the blue dye when that happens. Here's a couple of pictures of the tensioner arm on this engine; in the first picture you can see some witness marks where the chain has been hitting the arm, and the second photo shows what it looks like after the top has been painted with the blue dye:
Before the chain can really be tightened, however, the front cover has to go on the engine. The reason is that if you tighten the chain before that you can pull the nose of the stub cam off by several thousandths of an inch, and make it really tough to install the front cover. In fact I have been told that some of the stock, cast stub cams have actually been broken this way. So, before proceeding with any chain tightening its time to install the front cover. Unfortunately I'm out of time tonight, but I'll add to this thread in the next day or two with the latest progress on the engine.
cjshaker:
Dang, that's a lot of gasket surface area to seal up!
I noticed how close that chain was to the tensioner in that first picture. The machinist dye is a good idea. Also seems like that top guide could be longer. That is a long stretch of chain for that short of a guide. The 4.6/5.4/5.0 engines use a slightly rounded guide that is designed primarily to combat the "whipping" action of the chain, and it's much shorter than that SOHC top section. I'd guess that that is where a lot of the cam "movement" comes from at speed. Have you ever noticed witness marks above that top section of chain?
edit: I see there are nylon rubbing blocks on the top surface of that upper guide, but they do little to "guide" the chain. Just primarily try to limit the jumping motion I suppose. It would be interesting to see that section of chain in super slo-mo at speed.
cobracammer:
Hey Jay! Awesome post. This will really help me out with the timing portion. So, I think you have to advance one side and retard the other correct? (Something like 4 degrees?) can go just quickly go over how many degrees the Passenger/Driver side gets?
Thanks again!
Drew Pojedinec:
That is just too much chain :P
How does everything stay balanced and the harmonics not get crazy with all that? I'm no expert on SOHC engines, but I work on and fix industrial engines that often run for well over 50,000 hours, I just don't see how that setup could be made to run 100,000 miles without major adjustment issues and problems. You'd need to either design a gear to gear system or have the tensioners be more self tensioning for any sort of longevity.
Just cuz it's interesting, what Cat puts on the end of the camshafts in our C32 engines:
Either way, thanks Jay, this is super interesting.
Drew
cobracammer:
--- Quote from: cjshaker on May 18, 2014, 10:45:26 PM ---Dang, that's a lot of gasket surface area to seal up!
I noticed how close that chain was to the tensioner in that first picture. The machinist dye is a good idea. Also seems like that top guide could be longer. That is a long stretch of chain for that short of a guide. The 4.6/5.4/5.0 engines use a slightly rounded guide that is designed primarily to combat the "whipping" action of the chain, and it's much shorter than that SOHC top section. I'd guess that that is where a lot of the cam "movement" comes from at speed. Have you ever noticed witness marks above that top section of chain?
edit: I see there are nylon rubbing blocks on the top surface of that upper guide, but they do little to "guide" the chain. Just primarily try to limit the jumping motion I suppose. It would be interesting to see that section of chain in super slo-mo at speed.
--- End quote ---
Seeing that the Timing chain is set to be a "whisper" space from the chain guides, I would venture a guess that the chain hits the nylon blocks often? I would think if the chain moves enough to mark the machinist dye on the tensioner arm, that the nylon guides are being hit quite frequently by the chain?
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