Modifying Power Valve Channel Restrictors (PVCR). Drill and tap for removable jets-Rick's Shop
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- čas přidán 5. 09. 2024
- On this video I'll go over drilling and tapping power valve channel restrictors to make them adjustable. This needs to be done if the carb is rich when the power valve opens.
I've always intended doing this. In the past i have used different thickness pieces of copper wire inserted into the pvcr's to reduce the diameter. You can easily calculate the required change in orifice are required by using the current AFR and the desired AFR to eliminate the guesswork. I made a spreadsheet to do the calcs and it gets really close the first time.
If you had the perfect mixture at wot, and if you reduce your pvcr like you did, you need to increase your primary jet size, while leaving the sec. jets alone.
Also, you can calculate the area of the pvcr + pri. jets fuel flow and compare that to the area of fuel flow of the secondaries (for wot), to basically get the carb 'square jetted'
At no time was I ever in the secondaries. During this adjustment.
😮 emulsion holes would have fixed that also by going bigger and mix air at correct level
Some say that it’s the transition slot that adds to rich mix and restrict that.
Looks like you were shooting for about a 13:1 afr on average when the power valve opens up? I got an 1850 Holley on a Ford 390 that the afr goes to 11.5-12 when the power valve opens under light acceleration. Definitely too much fuel I can feel the engine get kinda lazy accelerating when the power valve opens up even on a cooler night when it runs leaner than usual. I bought some 6-32 brass set screws to drill and tap and make the pvcr smaller.
were did u get ur 6/32 plugs
@@butchking154 Mcmastercarr sells them, can also sometimes find them on ebay. Definitely get the brass ones, they are hard enough to drill and not snap a bit off as it is.
@@butchking154 mcmaster-carr can get everything you need there.
Screw the plug into a 6-32 nut and clamp that