Breather Gear Query
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
most of that can be answered with Yes to all the above
compression loss it a big factor and the pistons moving over 4 inches up and down at a great speed think about it at 6300 RPMs what would come out of the plug hole
compression loss it a big factor and the pistons moving over 4 inches up and down at a great speed think about it at 6300 RPMs what would come out of the plug hole
Cruiser
Joined: Jul 2011
Posts: 123
Likes: 1
From: Arkansas
I'm going to have to read up on this subject later. You guys have made me want to learn more.
Speaking of the S&S stuff, this was on the Iron Horse/BSC site. It's a follow up to Englishman's Shovel rebuild. (How many times has that thing been rebuilt ?)
Editors Note (again) I’m confident that this engine will work well as Dan has it set up, but S&S wanted it to be known regarding the breather timing, 10 degrees before and 75 degrees after has been a specification that S&S came up with and has been in print for many years. After additional research was done in 1999, it was found that retarding the breather gear 1 tooth (17 degrees) for an opening spec of 17 degrees after tdc, & closing of 82 degrees after bdc, the level of vacuum in the cam chest and crankcase was increased significantly. This results in better oil scavenging, and less oil carryover. In addition, the hole in the breather gear that sucks oil out of the cam case settling pocket was elongated into a slot rather than a hole to provide more suction time to the settling pocket (and less chance for oil carryover (puking) )
Speaking of the S&S stuff, this was on the Iron Horse/BSC site. It's a follow up to Englishman's Shovel rebuild. (How many times has that thing been rebuilt ?)
Editors Note (again) I’m confident that this engine will work well as Dan has it set up, but S&S wanted it to be known regarding the breather timing, 10 degrees before and 75 degrees after has been a specification that S&S came up with and has been in print for many years. After additional research was done in 1999, it was found that retarding the breather gear 1 tooth (17 degrees) for an opening spec of 17 degrees after tdc, & closing of 82 degrees after bdc, the level of vacuum in the cam chest and crankcase was increased significantly. This results in better oil scavenging, and less oil carryover. In addition, the hole in the breather gear that sucks oil out of the cam case settling pocket was elongated into a slot rather than a hole to provide more suction time to the settling pocket (and less chance for oil carryover (puking) )
Last edited by vanmor; Jun 24, 2016 at 06:47 PM.
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
the setting pocket slot is the only thing they came up with that i can agree with
what they never tell you is to change the timing of the valve with the fixed gear you need to machine the hole < that changes the timing one tooth is too much for a street bike
it is machined in the front top to add earlier / and the bottom to add exhaust length timing
what they never tell you is to change the timing of the valve with the fixed gear you need to machine the hole < that changes the timing one tooth is too much for a street bike
it is machined in the front top to add earlier / and the bottom to add exhaust length timing
Cruiser
Joined: Jul 2011
Posts: 123
Likes: 1
From: Arkansas
So your saying that the slot mod is too much for a stock bike ? Or moving the breather gear timing WITHOUT the slot mod is too much ?
I have older Delkron cases so I don't know if the mod has already been done.
I have older Delkron cases so I don't know if the mod has already been done.
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
the stock breather gear has a round hole in the end opposite the gear - S&S lengthens the hole into a slot and that in turn allows the system to have a longer cycle of vacuum
the cases are not and should not be modded into a slot it does not work that way, BUT the reed type breather by passes all those ideas into a pressure sensitive integral part of the system relying on pressure not timing location - both work reed and the slotted breathers
the cases are not and should not be modded into a slot it does not work that way, BUT the reed type breather by passes all those ideas into a pressure sensitive integral part of the system relying on pressure not timing location - both work reed and the slotted breathers
Cruiser
Joined: Jul 2011
Posts: 123
Likes: 1
From: Arkansas
I ran across a sample of Donny Petersens's book. He states that the biggest reason for the oil problem is that H-D shortened the valve guides in the later heads. To fix it, they added valve guide seals. However, the seals fail due to heat. There was not a oil burning / venting problem til this happened. He says he fixed the problem with longer bronze valve guides and no valve seals.
Interesting.......
Interesting.......
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
he is a flucken idiot -
in 1980 AMF was in charge and they were having DOT issues - the japs took them to court as they had restrictions the AMF did not ----- the guides were lengthened not made shorter and did not have seals this kept a performance cam being installed into a stock motor
AND it did not work out well the AMF motors smoked almost from new
in 1980 AMF was in charge and they were having DOT issues - the japs took them to court as they had restrictions the AMF did not ----- the guides were lengthened not made shorter and did not have seals this kept a performance cam being installed into a stock motor
AND it did not work out well the AMF motors smoked almost from new
Thread
Thread Starter
Forum
Replies
Last Post
