Drilling a metering block for PVRC jets

[DusTed74]

Did anyone here ever drill and tap a metering block for PVRC jets? I had an old block so I drilled it and tapped it. It seams to work ok. I was interested if any of you guys or gals have done this in the past.
Thanks............Ted

 

[pishta]

used to drill them out for blow throught carbs. Jets would be a great idea. been done so you can...
Carb Science Series: Holley Power Valves — Explanation And Tuning

 

[RustyRatRod]

Did anyone here ever drill and tap a metering block for PVRC jets? I had an old block so I drilled it and tapped it. It seams to work ok. I was interested if any of you guys or gals have done this in the past.
Thanks............Ted

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Does the PV still screw in all the way and seat? I cannot tell from your photo if it's flush.

 

[DusTed74]

It is a crummy picture,but yes. The hole was counter bored for the jet to set into the pocket. This whole thing took about ten minutes to do with a hand held drill.

 

[RustyRatRod]

It is a crummy picture,but yes. The hole was counter bored for the jet to set into the pocket. This whole thing took about ten minutes to do with a hand held drill.

That's really cool it has enough material to do that. Nice work!

 

[yellow rose]

Every single carb I do has brass in the PVCR. There is no other way to tune that circuit if you can’t change the brass. Well, you can go bigger but the only way to lean out that circuit is to use brass and make the hole the size it needs.

 

[DusTed74]

Its likely posted somewhere to do this. I cant believe how easy it was to do.

 

[Mattax]

I'm lazy. Its one of the last things I do, and only when testing shows the restriction isn't right.
I've told the story before of jetting on the dyno and leaving it on the slightly leaner of the two best pulls.
Short version was it went too lean on the drive home. Had to keep it below 60 mph or it would rev and die. That's when I knew it was right on the line! LOL. Good learning experience.

Current carb may get the primary PVCR's drilled and tapped for restriction.
But here's the current set up. (And yes I had to check to be sure it would clear when tight).

 

[mopowers]

When drilling and tapping for the lower IFR location, how do you ensure the set screw doesn't bottom out restricting flow? Do you cut just enough threads to flush out a 3/16"-1/8" screw?

 

[Mattax]

When I've done any of these restrictions (IFR, E-bleeds) that's what I try to do. When I think its close, test by running a set screw in and see how deep it is. I'm sure there are better ways. Mark W. has mentioned using a nut on the tap as a stop. I haven't tried that. That probably only works when going straight in, like when installing a lower IFR.