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Discussion Starter #1
Here is my setup

2004 FXDX
95 JUGS
SE HTCC PORTED HEADS
SE 257 CAM
BAISELY SPRING
THUNDERHEADER 2-1
MIKUNI 45
SE AIR CLEANER KIT
3:37 GEARING

Will a Woods key help with this? I like the SE257 but would like to see it kick in just a bit earlier, it seems to be around 2800 right now. the gearing helps, though. Any thoughts?
 

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dotrpaul said:
Here is my setup

2004 FXDX
95 JUGS
SE HTCC PORTED HEADS
SE 257 CAM
BAISELY SPRING
THUNDERHEADER 2-1
MIKUNI 45
SE AIR CLEANER KIT
3:37 GEARING

Will a Woods key help with this? I like the SE257 but would like to see it kick in just a bit earlier, it seems to be around 2800 right now. the gearing helps, though. Any thoughts?
I assume you're using the HTCC pistons.

Assuming that is the case, you are around 10.5:1 CR, you have to be mindful of the threat of detonation/pinging with pump gas. If you advance the intake valve closing, you will build more cranking cylinder pressure.

How are you adjusting ignition timing?
 

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Dotrpaul, you can't use the key, it's for gear cams. Thay do however make a 4* advance gear for the chain cams.

Totenkopf, can you elaborate on the building pressure thing when you advance the cam timing, gotta be real basic, I know nothing about how this works or why. The reason I ask is that I have a 4* gear and was thinking about using it with my (old grind) tw37 chain cam.
Any additional info appreciated. Thanks, adx
 

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When you advance it, the piston is still at the same spot and has more time to build compression. Just the same if you retard it. The valve closes later allowing more compression to escape.
 

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adlerx said:
Dotrpaul, you can't use the key, it's for gear cams. Thay do however make a 4* advance gear for the chain cams.

Good catch! I was wondering if anybody was going to say anything about this. There is this option though, which I believe is what you have......
http://www.woodcarbs.com/camgears.htm

Totenkopf, can you elaborate on the building pressure thing when you advance the cam timing, gotta be real basic, I know nothing about how this works or why. The reason I ask is that I have a 4* gear and was thinking about using it with my (old grind) tw37 chain cam.
Any additional info appreciated. Thanks, adx
Howdy adx!
Well, you're gonna get a real basic explanation, cause that's all I know! :D
See comment and link above in your quote.

RK05 basically has it. The earlier you close the intake valve, i.e. in your case 42* to 38*, that is 4 more degrees of rotation that the piston can build pressure in the cylinder. The higher that cranking pressure is and depending on combustion chamber shape and piston design, i.e. HTCC in 95" especially, all of those angles and concentration points, heat and other factors like crap gas, can precipitate detonation/pinging. Valve timing of the intake and exhaust openings and closings with the amount of overlap between the two and the timing of such that they have can all be varied to operate in the motor most efficiently at different rpm points. For example, low, mid and high rpm, depending on what the mission is of the motor. In my mind the intake closing is one of the most important in determining what the cam is going to be like though.

Also, remember how a diesel engine works with no spark plugs? high compression and low octane fuel. You just need an initial way to start it (glow plugs) and then it runs on it's own.

Hope this helps! and if you can find one of the threads here that one of the guys put together that describes cam timing very well, those are great to read and get a handle on what is happening.
 
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