Hi guys,

I have a 4781-1 or -2 that I need a set of metering blocks for. I'm assuming that I need the ones that came with this carb for proper calibration, but Holley isn't showing them. I found a set from AED it says works for the 600-850's but I'm a littl skepticle that this could work right. Any suggestions?

My 750 3310 has a rear metering block from an 800 spreadbore double pumper.

Funny you say that...this thing came with 6213 blocks on it which I think was a 800cfm spreadbore DP. They seem too different to work though.

I went through this with Quickfuel a while ago inquiring about their billet blocks. They said the only diff between the 4776-4781 blocks was in the idle restriction. Using a 650 DP block in a 800 will only lean the idle out a bit, I found this beneficial.

I wouldn't use the blocks from a spreadbore. I also used a spreadbore primary block as my secondary block in my 3310. Then I got a wideband guage. Changing the sec. block to the Holley part definately smoothed out my fuel curve.

Hope this helps.

Funny you say that...this thing came with 6213 blocks on it which I think was a 800cfm spreadbore DP. They seem too different to work though.

Mine works just fine :)
I went 105.8 MPH before the head swap with the 3310 and that metering block.

Don't think it will work with the DP though...the 6213 block has different passage in it for the accelerator pump. Look like a brass tub/o-ring needs to go into it.
http://www.jegs.com/images/photos/500/510/510-26-23.jpg

the block I put on my 3310 is a 62103