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jpkarnes
Joined: 03 Jul 2011
Posts: 19
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 Posted: Tue May 19, 2015 2:33 pm Post subject: Low power @ full throttle |
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Hi all,
I must convince that I'm at a loss to figure out why I can't reach full RPM's (at) full throttle. It was running fine until I performed several upgrades including:
1. Switched the .25" rubber fuel hose to 3/8" aluminum tubing.
2. Heads retooled by Ram.
3. Carbs overhauled.
It seems to run fine until about 3K RPM and then "surges" up and down a bit. Any more throttle than that and it runs crappy. The timing is (at) 32 deg (at) 4000 RPM (with no prop on). Any ideas?
John K.
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ronhansen123(at)gmail.com
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| Posted: Tue May 19, 2015 4:45 pm Post subject: Low power @ full throttle |
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John,
I don't think any of your changes should cause that problem directly. You will probably be lean and hot with the Ram head work and need to go to larger jets, but I don't think that would cause surging or roughness. It didn't with me, but I did have to go to larger jets for cooling. Ron at Ram dynoed my engine and he used 30 degrees BTDC at 4500 RPM and got just over 100HP. I don't know if that's significantly different than your timing or not.
I had troubles with mogas (w/ alcohol) getting old and cruddy in a matter of weeks here in California until I switched to avgas. If all this work took a while your gas might have degraded and also your fuel line work might have left some particles in the lines no matter how careful. (Done that.) Some of the air passages in the carbs are no bigger than a toothbrush bristle so it doesn't take much to clog them.
If you have EGTs you can see if both banks are the same. I added EGTs to sort out carb and cooling issues and continue to be glad I have them.
Good luck,
Ron Hansen
601HDS, Stratus/Ram Subaru
On Tue, May 19, 2015 at 3:33 PM, <jpkarnes(at)comcast.net (jpkarnes(at)comcast.net)> wrote:
[quote]Hi all,
I must convince that I'm at a loss to figure out why I can't reach full RPM's (at) full throttle. It was running fine until I performed several upgrades including:
1. Switched the .25" rubber fuel hose to 3/8" aluminum tubing.
2. Heads retooled by Ram.
3. Carbs overhauled.
It seems to run fine until about 3K RPM and then "surges" up and down a bit. Any more throttle than that and it runs crappy. The timing is (at) 32 deg (at) 4000 RPM (with no prop on). Any ideas?
John K.
| Quote: |
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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[b]
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d3dw(at)sbcglobal.net
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| Posted: Mon May 25, 2015 12:15 pm Post subject: Low power @ full throttle |
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Same setup on my HDS. Went to larger main jets and richer needle. Lifted the intake manifolds 1" for better fuel distribution (Ram has the spacers). No problems.
Don
ron hansen <ronhansen123(at)gmail.com> wrote:
John,
I don't think any of your changes should cause that problem directly. You will probably be lean and hot with the Ram head work and need to go to larger jets, but I don't think that would cause surging or roughness. It didn't with me, but I did have to go to larger jets for cooling. Ron at Ram dynoed my engine and he used 30 degrees BTDC at 4500 RPM and got just over 100HP. I don't know if that's significantly different than your timing or not.
I had troubles with mogas (w/ alcohol) getting old and cruddy in a matter of weeks here in California until I switched to avgas. If all this work took a while your gas might have degraded and also your fuel line work might have left some particles in the lines no matter how careful. (Done that.) Some of the air passages in the carbs are no bigger than a toothbrush bristle so it doesn't take much to clog them.
If you have EGTs you can see if both banks are the same. I added EGTs to sort out carb and cooling issues and continue to be glad I have them.
Good luck,
Ron Hansen
601HDS, Stratus/Ram Subaru
On Tue, May 19, 2015 at 3:33 PM, <jpkarnes(at)comcast.net (jpkarnes(at)comcast.net)> wrote:
[quote]Hi all,
I must convince that I'm at a loss to figure out why I can't reach full RPM's (at) full throttle. It was running fine until I performed several upgrades including:
1. Switched the .25" rubber fuel hose to 3/8" aluminum tubing.
2. Heads retooled by Ram.
3. Carbs overhauled.
It seems to run fine until about 3K RPM and then "surges" up and down a bit. Any more throttle than that and it runs crappy. The timing is (at) 32 deg (at) 4000 RPM (with no prop on). Any ideas?
John K.
| Quote: |
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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[b]
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d3dw(at)sbcglobal.net
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| Posted: Mon May 25, 2015 12:17 pm Post subject: Low power @ full throttle |
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Oh...and my Timing is at 30.
jpkarnes(at)comcast.net wrote:
[quote]Hi all,
I must convince that I'm at a loss to figure out why I can't reach full RPM's (at) full throttle. It was running fine until I performed several upgrades including:
1. Switched the .25" rubber fuel hose to 3/8" aluminum tubing.
2. Heads retooled by Ram.
3. Carbs overhauled.
It seems to run fine until about 3K RPM and then "surges" up and down a bit. Any more throttle than that and it runs crappy. The timing is (at) 32 deg (at) 4000 RPM (with no prop on). Any ideas?
John K.
_-=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D _-=3D - The Stratus-List Email Forum - _-=3D Use the Matronics List Features Navigator to browse _-=3D the many List utilities such as List Un/Subscription, _-=3D Archive Search & Download, 7-Day Browse, Chat, FAQ, _-=3D Photoshare, and much much more: _-=3D _-=3D --> http://www.matronics.com/Navigator?Stratus-List _-=3D _-=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D _-=3D - MATRONICS WEB FORUMS - _-=3D Same great content also available via the Web Forums! _-=3D _-=3D --> http://forums.matronics.com _-=3D _-=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D _-=3D - List Contribution Web Site - _-=3D Thank you for your generous support! _-=3D -Matt Dralle, List Admin. _-=3D --> http://www.matronics.com/contribution _-=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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