power valve
posted before about power valves etc,,thanks for advice
now i know i have 15 inch of vacum at idle,,,not in water , but in driveway.. so i should get 70-80 power valve for primiary side...?? what should knock jets down too??..82 ---84 ..again primiary side. carbs are 1050,,3 circuits,,,,both power valves blocked,,92 jets all around. issue is motors are running fat....547's. yes i know i need to check plugs at idle,,,then mid range check,,then a hard run and check but trying to get started... thanks for advice........ |
Jetting and PV's have nothing to do with being rich at idle. Engines need to be run under load to determine if jetting or PV changes are needed.
If you wanted to install a PV in the primary, a 6.5 is pretty standard, then reduce primary jetting to the 84 range. |
Originally Posted by Griff
(Post 4797415)
Jetting and PV's have nothing to do with being rich at idle. Engines need to be run under load to determine if jetting or PV changes are needed.
If you wanted to install a PV in the primary, a 6.5 is pretty standard, then reduce primary jetting to the 84 range. thanks.................... |
Before you change power valves I would keep the vacuum gauge hooked up and record the readings through the entire rpm range idling and under load in the water.
|
Originally Posted by flashgordon
(Post 4797436)
ok thanks griff,,,,,just want get going on this...i know i will have to run boat ,,,kill motors ,,look at plugs..
thanks.................... |
Originally Posted by TomZ
(Post 4797507)
I'd get the idle cleaned up first so it's not making plugs hard to read when water testing. You'll be far and away more able to tune it if you can get an O2 sensor and A/F ratio meter on it.
and i was planning on taking vacum guage out with me on next run,,,look at numbers mid range etc....maybe i would be better just jetting primary down..?? |
90* adapters are screw in. No big deal to install.
|
Originally Posted by GLENAMY 242SS
(Post 4797774)
90* adapters are screw in. No big deal to install.
thanks............. |
If you`re rich why would you add an unmetered fuel fill to your carbs?
Whomever had no power valves in there had it right. Powervalves belong in cars not boats |
Edit: OP said he's got rich looking plugs. He didn't say at idle.
Don't add in the variable of power valve unless you take out even more from primary, and perhaps secondary too. Power valves add 6 to 8 numbers to the fuel at whatever vacuum you put in the block. So if it's rich with 92's start by taking out some jet. Like 10 or more primary, and 2 or 4 secondary. I think he wanted to lean out the primary side jetting so the PVs only add fuel below their rated vacuum. If I understand things, that gets him more flexibility through the mid range. Really needs AFR gauge. Best $ you can spend. I am learning/fighting this myself right now. Got a lean spot just before (mechanical) secondaries open on mine. oops, don't answer- No Hijacks! |
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