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04-18-2013, 07:22 AM | #41 |
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Join Date: May 2010
Location: NC
Posts: 2,975
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Re: not enough backpressure?
What kind of intake are you running, the intake makes a big difference in jetting the carb. But by the sounds of what you are saying I'm thinking ignition problems.
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04-18-2013, 08:45 AM | #42 |
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Join Date: Apr 2011
Location: Glenmoore Pa
Posts: 1,644
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Re: not enough backpressure?
The intake is a Burns single downdraft. I have been thinking ignition also thats why i went through the ditstributor, everything inside of it checks out good unless the centrifigul advance just isnt going far enough and i need to advance it more to start. I was also pondering the possibilty that it may be the power valve is too weak but its just a thought. I just added the air cleaner so i will test drive it again later to see if that made any difference, but i doubt it.
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04-18-2013, 11:00 AM | #43 | |
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Join Date: May 2010
Location: Windy City
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Re: not enough backpressure?
Quote:
To complicate the issue, in addition to the main jet size in a 94 you have one of many power valves, each with different vacuum actuation profiles. The problem may very well be the PV. There is also a known problem with later manufacture power valves improperly fitting in 94's. You stated the rear two plugs oily, not the front two. You may have an intake gasket leak. I'd start there. Now, to figure which jets and power valve to use, your best bet is to temporarily install a wide-band AFM. The HAMB has a lot of 94 tech threads, you might look there. |
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04-18-2013, 11:10 AM | #44 |
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Join Date: Apr 2011
Location: Glenmoore Pa
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Re: not enough backpressure?
MikeK i tried the Hamb but i couldnt get a good thread on the 94 with on a Model A. The jet changes i used were simply the ones I had. I had the PV fitment issue in an older set of 94s but this one it fit in fine. Im thinking of just removing it and plugging it for now. I think the stock PV is rated somewhere around 8 which is what is in there now.
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04-18-2013, 11:10 AM | #45 | |
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Join Date: Jun 2010
Location: New Jersey
Posts: 1,471
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Re: not enough backpressure?
Quote:
That is not a muffler, it is an expansion chamber and not all 2 strokes have them. They effectively act as a supercharger and can be very RPM dependent. They are designed for fuel and air to be pulled into the exhaust and then reflected back into the cylinder after the piston has covered the intake holes. To my knowledge on a 4 stroke less backpressure will require a richer fuel mixture, other than that I know of no other negative effects. |
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04-19-2013, 08:37 AM | #46 |
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Re: not enough backpressure?
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04-19-2013, 05:33 PM | #47 |
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Join Date: Apr 2011
Location: Glenmoore Pa
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Re: not enough backpressure?
Problem Solved! Swapped on my known good, shop use Stromberg and shes runnin like a champ! Im gonna take apart the Holley at some point and try to figure out whats goin on. Thanks everyone for the help.
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