Tunnel ram or no tunnel ram...

68 HEMI GTS said
That’s your lean cruise. Normaly those are in the .070’s range on a 4150. I’d start .078 as a starting point but, you could remove them initial pay for a drive to see how it acts.Where’s the hole going in your angle channel in the pic I posted? That main body doesn’t even appear to be drilled for a 3rd circuit. So I don’t see it in your blocks or main body. 3 circuit blocks normally look way different. Those are ringers for a 2 circ.

Rat Bastid said
Ok, I’m not sure you are understanding how the power valve works.

It should have been called an “economizer” valve because that’s actually what it does.

Depending on the size of the holes behind the power valve (power valve restricter channel), you can reduce the primary main jet size. And that’s what you want.

You set your cruise AFR with the primary main jets and then you leave them alone forever. You don’t touch them. Once you have the primary main jets sized correctly for cruise (a nice, clean, crisp, lean cruise if you have enough ignition) you can move on to other areas of the fuel curve.

For WOT tuning you now have to add fuel (or remove fuel) from the primary side with the power valve channel restricters. Not the primary main jets. And you control when you get the added fuel from the power valve circuit by changing the timing of when it opens relative to manifold vacuum. The higher the number the sooner you add the fuel through the power valve circuit.

This means you can get a very nice, clean cruise with the smaller primary main jets and still get your WOT AFR correct with the primary PVCR’s and the secondary main jets.

One other thing. I thin you said your T slot restricters measured .049 or close to that. That’s much smaller than anything I’ve ever needed. I’m usually in the mid .060’s to the mid .070’s. You may want to drill out the T slot restricters to .0625 (1/16 inch or 1.5 mm) and see what that does for your tip in lean spot.

You still have 3 emulsion holes open. You have a bit if tuning to do, but once you get it all cleaned up you’ll be surprised at how well a tunnel ram drives and how much more power they make.

My understanding is that PV alows extra fuel when vaccum drops below certain value.
I think I dont have right PV size, only 4.5s and probably need 2.5. My engine idles at 4inHg in gear.
For now it runs smoother with no power valves and bigger jets. I will come back to this for sure.
I bought 6-32, 8-32 and 10-32 taps today. Will need blank restrictors, cant find anything I can use to make them locally. I was thinking to buy brass screws, cut the threaded part, file them for flat screwdriwer and drill them in needed sizes but all I see is steel screws that small.

Before all that I'd like to address the very lean cruise problem. I will verify the size of t-slot restrictors today. My dominator had 0.055" and I had to enlarge them with 1.5mm drill to make it cruise at 14.5:1 afr. I think it was 0.060" hole? It was still very lean but no surging so I left it alone. Plan was to go to 0.065" and it never happened.

My ignition is locked at 34, well its actually locked at 44 but I have programmable box and map sensor to make it work as vacuum advance for crusing. So now its set to 34 flat, I will play with map sensor again ince things run well again.