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Old 12-24-2013, 05:23 PM   #16
Scooby Newbie
Member#: 209963
Join Date: Apr 2009
Default Observation Report

Ok, spent some time on this today and the results are pretty interesting. For starter, the cams could be swapped with only minimal work. On the right side there is a nice match up between the +165* mark, where the exhaust cam needs to be shifted to, and the spacing of the cogs on the sprocket. In that case all you need to do is move the timing marks, and voila, you have just installed an exhaust camshaft on the intake side. On the left side, you need to drift out the pin and drill a second hole or put a second slot in the drive end of the camshaft. I did not actually attempt this but It looked like putting a new slot in the cam would be the easier DIY approach for those with a vise and a large file. BUT WAIT. it gets interesting. I feel like an idiot for not knowing this:

!!The cam lobes on the exhaust camshaft are not the same!!

The valves are the same, the ports give no clue, but one of the valves on the exhaust side has a much hotter lobe than the other. One has about a .4mm more lift, and a lot more area under the curve and looks pretty hot. and the other has about .5mm less lift and looks like an economy cam. The first lobe has the overlap, the second lobe has almost none. They share identical closing profiles.

This explains why I though though that the exhaust cam had a hot profile. the lobes that I was measuring do! But when you put them side by side I'm not sure if it makes sense to do the swap, especially since you will be putting the two high lifting, high overlap, valves right next to each other. I don't think that they would hit each other, it just looks like you would start dumping mixture into the exhaust for no good purpose.

So, from here: Is this eccentric exhaust camshaft profile universal to the DOHC? Did they use other profiles in the DOHC heads that we might still do this swap with? Is the hot swap here actually to run two intake camshafts?

Time to do a little more research.
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