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commando57 02-16-2005 03:22 PM

Holley carb interchangeability questions
Can a carb with a metering plate secondary (a 750), be changed to a carb with a metering block by swapping in the metering block from a 600. Both square bore, both vacuum secondary's, both center float pivot. Thanks for reading this.

Max Keith 02-16-2005 03:47 PM

carb interchange

lluciano77 02-16-2005 05:27 PM

Yes they can physically swap, but the metering won't be right. I have seen universal 4150 conversion kits. Those don't make sense. The 1850 and the 3310 have different idle feed restrictions. Also, the PVCR restrictions are different.

You are better off getting a 3310-1 secondary metering plate. It is pretty close. I see them on Ebay frequently. You can get a core 3310-1 for $25 or less.

commando57 02-21-2005 06:33 PM

After some more research
I looked up the 1850 number on Google, info says it is from a 1959 Mercury 383. Anyway, I took off the secondary bowl, (it had an accelerator pump with no actuator arm). The metering block had no power valve or idle screws but it has removable # 72 jets in it. What do I have here? The metering block
has these numbers on it L47772 6501 stamped on it. The list numbers on the
horn are 1850, of course, along with 5752425 and 494. The 1850 is no longer listed on Holley site and the 1850's on Ebay are side hung floats. I will investigate the 3310-1 plates on Ebay. I guess I really need to take apart the
installed carb to get numbers off the plate, to have something to compare.

lluciano77 02-21-2005 06:52 PM

The 1850 is a universal 600 CFM carb. It never came on a vehicle.

You have a primary metering block from a 4777 650 CFM double pumper. It will not work correctly with your carb.

You are better off getting a 4150 style Holley that came with a secondary metering plate. Or put the metering plate back on. You are going to end up with the carb not metering correctly.

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