Holley Vac Secondary Metering plate

Does anyone know what the metering plate on a 600 & 750 vac secondary Holley is equivilant to in jet size? I have a metering block for a vac secondary to convert it to jets and wanted to get a good baseline to start with.
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I am about to make this mod myself and I was going to go 6 sizes higher then the primaries. I could be wrong on this but im pretty sure that is what a holley book I have said to do.


Blue Fastback

I converted my 3310 750 Holley to a metering block.In my holley book it said it was equal to a .081 jet.If you can give me the number off of your secondary metering plate I can give you the specs.

<font size=-1>[ This Message was edited by: frdnut on 8/20/02 10:31am ]</font>

Hey frdnut
Just to explain a little further..A 3310 (750)has a # 21 metering plate.Now the specs say it has an .081" main hole....Now if you look across at the jet size table,that .081" hole equates to a 74 jet...
Not all the jet no's match up match up with the drill size..
An 1850 (600) has a # 9 plate which matches up to a 67 jet.

gregaust I see what your saying,but its not entirely clear to me what they're saying in the book.They give you the main hole size in the metering plate and the the other chart is comparing the jets to drill sizes,I assumed in case you just wanted to drill out the metering plate.Because I wasn't sure I looked up the jet size for a 750 DP and it was an 81 the same size as the .081 size main hole.Maybe this is just a coincedence.Actually I looked up the 600 example you used and neither of our theories seem to work[img]/phpBB/images/smiles/icon_confused.gif[/img]

I was told by Holly it equals a #74 jet.

Actually now I see the main hole size for the 600 is a .067 and you say the jet is a 67 which would be the same as what I first thought.I guess my question is,is the main hole size the same as the jet size?

It does get confusing but my understanding is the main hole size is actually the drill size in the jet chart.From the drill size you get the jet number.Just an example,the idle hole i believe is the actual size ,so in the same table to keep it consistent the main hole size is the actual hole drill size.I hope that makes sense.
In the lower jets the number equals the hole size but i assume for flow to increase consistently the hole sizes get larger than the jet #'s.
Just a guess but it could have something to do with the area of the hole size increasing rather than just the diameter..
[img]/phpBB/images/smiles/icon_confused.gif[/img][img]/phpBB/images/smiles/icon_confused.gif[/img]