Cab Franc is the weaker and softer brother to Cab Sauv. It will blend well with Merlot but not sure about the Zin so much. Cab Franc is also prone to vegetal odors (especially green bell pepper) if it is not picked ripe.
It might hold up to a stronger grape, the other day I had a Saperavi, Cab Franc blend, and it was really good. Saperavi on its own is a lot stronger than Cab Franc, but the Cab Franc wasn't over powered.
I LOVE East Coast Cabernet Franc, as long as it has ripened well. Under-ripe gives it an almost green pepper taste and nose, but well ripened Cabernet France has a soft tobacco taste and nose. And, the East Coast growing season gives it a softer, near Pinot like body.
Cab Franc is one of the Bordeaux grapes, so it blends well with merlot. Zin? Zin might overpower it.
your blend with Zin will depend on percentage. some statement right. anyways what I am trying to say as that only 10% for example of Cab Franc with Zin can still be a better wine than without. try bench trials to see. a 50/50 blend probably would not work
Thank you for that yeast suggestion. I have GRE and D21 on hand for my Cab Franc grapes I get tomorrow afternoon. I'm waiting to see what the brix is (we had a lot of rain at the end of last week so I know that the brix dropped a bit). I am worried since we are in Southern PA that I may get less than optimally ripe Cab Franc and don't want to have to blend the batch with other wines for the next 5 years to use it all. Assuming I will taste the green characteristics up front so I can make my yeast decision.
Edit: pH 3.47, 22 brix (1.091), TA 6.0 g/L, might add some simple syrup to bump it up to 13.5 to 14% final ABV, assuming it goes to .990-.994 final gravity. Definitely some greenies left in there, though they taste pretty good, just tart.