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Discussion Starter #1
What is the difference between the two? And can I run non blower carbs on a blower and can i run blower carbs on a naturally aspirated engine?
 

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What is the difference between the two? And can I run non blower carbs on a blower and can i run blower carbs on a naturally aspirated engine?
You can do anything you want..its a free counry....J/K :happy: Will they work correctly? No...Blower carbs are boost referenced [power valves] and jetting is generally set richer than N/A carbs. Trying to run blower carbs on a N/A engine will not have the power valves properly referenced to the demands of the engine.
 

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Heres the deal with blower carbs. You will have to determine if you need a referenced PV or not:

Referenced PVs are big in cars because you spend the vast majority of the time in a low RPM unboosted condition. If your boat is a light boat, with a large HP to weight ratio and a slow driven blower, then referenced PVs may be desirable in that application.
If its a cruiser or large out drive, and you spend a large portion of your time in a boosted or close to it condition, then PVs are next to useless.

When the PV is referenced, a 4.5" PV will open when the manifold vac is less than 4.5". Thats very easy to do in a large boat, specially if the blower is setup to make fairly serious boost.

If most of your time is in or near boost, then the PV is open all that time. Why have one.

The PV does not add fuel at idle. So if you go from idle to boost or close, I say forget the PV.


If you do not run a PV, just jet the thing about 6 sizes larger to start, and go from there, keeping an eye on the plug readings.
If your do decide to run a PV, IT MUST BE REFERENCED OR IT WILL REMAIN CLOSED ALL THE TIME AND NOT ADD ANY FUEL WHEN THE ENGINE GOES INTO BOOST. The idea behind the PV is to add fuel when the engine is in or near boost.
YOU MUST REFERENCE THE PV!!!!

PS, why did you even bother with the question about using blower carbs on a N/A deal? It only added to the confusion of your question. The anwer is yes you can. You simply hook the reference hose to the intake manifold and it will act perfectly normal. BUT, the carb will calibrated for a blown deal and probably be rich as hell, and the PV will be a pretty low number and be open more than normal.


Your throughly confused now aren't you?:D



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Discussion Starter #5
No i am not confused i have always blocked pv on any carb ive ever had! My Father taught me how to tune holley carbs and we always pv delete and go up on jets. I really appreciate the info this is my first blown engine build and its been a learning experience for sure! The reason i asked about running blower carbs on a na engine is because the blower i bought came with two 600's and i will be selling them but a friend of mine was wanting them but his eng in na. thanks for your input!!
 

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No i am not confused i have always blocked pv on any carb ive ever had! My Father taught me how to tune holley carbs and we always pv delete and go up on jets. I really appreciate the info this is my first blown engine build and its been a learning experience for sure! The reason i asked about running blower carbs on a na engine is because the blower i bought came with two 600's and i will be selling them but a friend of mine was wanting them but his eng in na. thanks for your input!!
I was confused and I wrote that mess.:D

If the 600's have a tube somewhere on carb either like the upper on like this:


Or under the bowl like this:............. then the carbs are referenced. If not, then they are simply jetted richer.




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