I'm trying to determine a good starting point for primary & secondary jets/rods for my Q-jet on my new engine.

Here are the details of combo: 383, 10.1:1 CR, RPM intake, the cam is a hyd flat tappet 230/236 (at 0.050") and 274/286 (advertised), 110 lsa, gears are 3.73's with 29" tires/TKO600, long-tube headers & dual 2.5" exhaust with h-pipe, D.U.I. distributor "all-in" at 3k, probably 14* to 16* initial timing. The car will be driven in a spirited manner.

The Q-Jet is one of those Jet Performance "Stage II" 750 cfm carbs. They claim it was setup for engines up to 9.5CR and 220 duration cams.

Thanks for any help.

What's in the carb now?

On the secondary side you'll probably want a set of DA rods and a G hanger as a good starting point for a reasonably stout combo like that.

Primary side there are differences in the way some later QJets have to be jetted to work right (like the Edlebrocks that use later "M" style metering rods with larger .035" power tips). Knowing what they put in there for starters is helpful before making a blanket suggestion. Usually a primary jet around 76 is a good starting point (most V8 QJets come stock around 72 or so). Primary rods are the wildcard with B style (early divorced choke carbs), K style (round choke built into the side of the carb) and M style (many later 80s-up style QJets, as well as Edlebrock QJets).

I think the Stage 2's and the ones before that were mid 70's units....so I'm thinking about if the choke is on it, which I think they were.

Some rods can be had from GM, other parts from Eddy-brock.

Got mine together and she's running WAY better than ever. Wish I had done this YEARS ago.....:rolleyes:

OK guys, thanks for commenting. The carb is a mid 70's vintage and it has the round choke on the side - I guess it is a K style.

The secondary rods are currently DA's & the hanger has an "L" stamped on the top of it. I have not opened it up to look at the primary jets (yet).

The carb ran real nice on my low-compression 400 with a 280/280 cam (Magnum 280H), but I couldn't rev that engine very high. This new 383 may see 6k between shifts.

Here is the response I received from Jet Performance when I emailed them my new engine specs:

"Unfortunately, it will need internal modifications also. You can jet it up on the primary side, secondaries will need different rods also. We dop offer recalibration services on your unit. "

What "internal" modifications could it possibly need besides primary jets?

Dunno what they do, but Damon has mentioned some light opening up of the air bleeds. EVER SO SLIGHTLY.....

If you pick up a Q-Jet (Rochester) rebuild book, it'll go over quite a bit. Worth reading for a few nights and hopping back online to do research to take notes like I did. :)

Just open 'er up and see what's in there first. Simple things first, then get more complex if necessary.

Don't you dare swap out those secondary rods. You hold onto them- you can't buy them any more and they're some of the best secondary rods you can lay your hands on for a performance application.

Thanks guys. I feel a little better now. I'll start tweaking once I get her fired up (fingers crossed).