Holley setup and tunning

Hey guys, I just acquired a 670 street avenger with about 1k miles on it. It came off a very mild 350 in a 4x4 used on the street. I will be putting this on my 250 initially just to see what the performance will be.
I know this seems like a big carb, but after talking with Holley, using their carb suggestion tool, and hearing how well the 600 works on 200s I think this may work out well.

Now, is there any specific things you guys would do with this carb prior to installation?

I'm kinda worried about using it for the cam break in and want to make sure I have it set up to run ok for that time period.

Is there any tricks you guys know to help tune these?

What size jets do y'all think should be used?

I'll take any info I can get.

Here are the build specs if y'all need.

250 bored .030
Racetec pistons
CS cam 280/280 110 LS 2 degrees advanced
CI AL head polished w/54 cc chambers
SCR 10.25 DCR 7.98
Intake port matched
1.6 rocker arms
.512 lift
CI dual out header
2.25 exhaust
DSII DIST
MSD 6AL
Blaster III Coil

T5 trans with 3.35 first and 3.00 rear ( 3.55 will be installed a little later)

I know that once I get everything going, I need to check manifold vacuum and adjust the power valve accordingly and then make adjustments on the jetting based off of the spark plug readings. Is there other things I need to be looking at or thinking about before this goes on the engine in a few weeks?

Try jet sizes 2 leaner, primary & secondary.
Get a vacuum secondary spring kit & install the lightest spring in the kit.
Try to get a wideband A/F tester, 14.5 area cruising & 12.8-13.1 WOT.
You will probably have to lean the idle orifice in the primary metering block to keep the idle & transition range leaner.

"...You will probably have to lean the idle orifice in the primary metering block to keep the idle & transition range leaner…."
is a wire placed to obstruct? what sz?

"Try jet sizes 2 leaner, primary & secondary..."
remove current 1s, read stamped numbers and, identify by chart what to order ?

Thanks ~

Bill,

The stock jets are 65 primary and 68 secondary. So I would need 63 primary and 66 secondary?
Just making sure that sounds right to you.

I am looking at AF gauges, but non that I see match any of the interior that I just finished. Is there one that you can wire up and run when tunning and then remove? More of a tool than a permanent fixture inside the car? Which brand would you suggest?

I am going to the parts store tomorrow and picking up some fuel line, carb rebuild kit, jets, and springs. Is there anything else I should pick up for messing with the carb?

Thanks

Instead of a complete gasket set, just get several sets of metering block & bowl gaskets.
The idle orifice I install screw in idle jets, but you have to drill & tap the block to do this. I can do it if necessary, Bill

"...non that I see match any of the interior that I just finished…"
under the hood (could B removed after tune), in the glovebox, center consold, or plug in / plug out from the cabin/drivers seat (pluged like an OBDII 'panel' - unobtrusively)?

more if interested...

I am shopping around for an A/F gauge.

So the carb I have has 65 primary's and 68 secondary's. I plan on swapping the 65s to secondary's and the putting 62s in the primaries. The power valve is a 10.5. They come with 6.5, but the prior owner did not keep it when he had the carb shop tune the engine for him. Considering the specs of my build, should I wait to read the vacuum to change the power valve?
The vac secondary spring was not changed from the stock one. I think that had some to do with the gas mileage issue the guy had with the carb. Plus you can't expect to get very good MPG with a 4x4 with a 3 speed and big mudders on it lol

My plan is to do some as much of the tunning I can to get it running good and then I will be looking for a dyno to do the fine tunning and get some numbers to post up here for you guys.