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Originally Posted by Eliminated572
(Post 4515007)
Pro systems built me two 1150 dom carbs last year. 3 circuit. He had the intermediate circuit very soft. Power valves were the high flow style (I had a ton of PVCR). Clean idle, clean cruise (around 13.5), just a hint of fattening up when the PV's opened. Otherwise they were perfect. I monitored via O2's...I quizzed him on the 2 vs 3 circuit debate in marine. He laughed and responded that it's 2016. Old days are well past us... FWIW they can and do work. [ATTACH=CONFIG]563200[/ATTACH]
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Originally Posted by mike tkach
(Post 4514853)
mercury marine would have used a smaller cheaper carb but they spent the extra money for a reason.on engines like the sc525 fuel distribution is not real good but the dominator 1050 helped.the sc525 came with 7.5-1 compression ratio and a whimpy hyd flat tappet cam,without boost it would not get out of it,s own way.the small 177 blower would not move enough air with a 4150 carb,it made less than 500 hp so the dominator was the answer.
Seems like to me that carbs for blower motors are ofter chosen to avoid any restriction in the inlet of the roots blower. Guys often run two 850s with a 6-71 or ever two 1050s with a 8-71.... I've read that they often pick up boost by using larger cabs and eliminating the restriction. Using the chart for my motor ~460 ci and 7.5 psi, we actually land on a 1050 cfm carb.... Like merc with the 525 sc, I'll be about 100 cfm over the recommendation... This is how I came up with an 1150.... [IMG]http://i1198.photobucket.com/albums/...ps34r35fmt.jpg[/IMG] Edit: Forgot to mention; at high elevation guys often over carb and jet down. Not sure that it always works out but I'm gonna try it... |
Originally Posted by mike tkach
(Post 4514853)
mercury marine would have used a smaller cheaper carb but they spent the extra money for a reason.on engines like the sc525 fuel distribution is not real good but the dominator 1050 helped.the sc525 came with 7.5-1 compression ratio and a whimpy hyd flat tappet cam,without boost it would not get out of it,s own way.the small 177 blower would not move enough air with a 4150 carb,it made less than 500 hp so the dominator was the answer.
Mike I was surprised as well but thought I'd throw it out there. Evidently prosystems thought otherwise. Not sure but I still have the build sheets for 454/177 builds. |
Originally Posted by 89Force235
(Post 4515047)
Thanks, good to know that they can be made to work. The big question remaining is how does a guy make the "intermediate circuit very soft"?
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When I changed from 850 boost referenced to Nickerson built 1050's on B and M 174's in my 311 Formula I picked up 400 RPM. Had to buy a set of props.
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Originally Posted by f311fr1
(Post 4515320)
When I changed from 850 boost referenced to Nickerson built 1050's on B and M 174's in my 311 Formula I picked up 400 RPM. Had to buy a set of props.
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Originally Posted by mike tkach
(Post 4515312)
remove the air bleed from the circuit.the oriface is big&pulling air instead of fuel.
Also, would you remove the air bleed restrictor all together or start putting larger bleeds in until it leans out? |
i would remove the bleed and see how it responds,then go from there.
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Originally Posted by mike tkach
(Post 4515325)
i would remove the bleed and see how it responds,then go from there.
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Originally Posted by 89Force235
(Post 4515326)
Would you bother with running a PV on a 3 circuit? If so just the primary? or both?
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