2x4 Holley linkage question on 427 or 428 FE

[Sal Gerace]

I understand that there are two ways to set up the Holley 2x4 linkage. I would like to know what experiences members have had if they tried both ways or have knowledge of the differances.
1. Linkage set up so that both carbs open at the same time
2. Linkage set up so that one carb opens and the second carb progresses in as the original linkage was made to function I believe.

[Excaliber]

Mine has just a very slight delay before the second carb starts to open. I've considered adjusting the linkage so that both begin operating at the same time. Most important is to make sure both are WOT when it's floored.

Vacuum secondaries. My theory is a better fuel distribution with both carbs in play at the same time.

[mr0077]

With 2 x 390 cfm carbs mine ran best with both primaries synchronized (opening together), but with 2 x 600 cfm carbs it seems to be crisper off idle and at light acceleration with progressive linkage, where the primary opens, then secondary opens, both going WOT at same time). Seems like synchronized opening with the bigger carbs gives it a bit too much throttle area.

[Excaliber]

Good point for consideration Ken. I'm running a couple of 450 cfm's, by the way. Was running twin 660's 'center squirters' mechanical secondary setup to open primarys at the same time, pickup the secondaries about 1/4 throttle at the same time. Man was that brutal, it was 'go or no go', of course the carbs were setup for drag racing so that was no doubt most of the problem.

This may well depend on the type of carbs in question!