[SD455DJ]

You could get the 350 4-bbl. on non-GTO's, like this nicely optioned Sprint.

Dennis

[Kenth]

Dennis, here is what i have on the 1974 350 units.
7044268/568, 72 jets 43 pri. rods, DB sec. rods #7047806, 1/2 airvalve spring preload, #7029529 power piston spring A, X BODY AUTO. TRANS. 350

7044269, 68, 35, DB 7047806, 1/2, 7037851, A, X BODY MAN. TRANS. 350

[Shiny]

Originally Posted by Kenth

Dennis, here is what i have on the 1974 350 units.
7044268/568, 72 jets 43 pri. rods, DB sec. rods #7047806, 1/2 airvalve spring preload, #7029529 power piston spring A, X BODY AUTO. TRANS. 350

7044269, 68, 35, DB 7047806, 1/2, 7037851, A, X BODY MAN. TRANS. 350

Why is there such a difference in primary jets between manual and auto? 68 vs 72 seems like a big jump. Is this typical?

[65 Lamnas]

Originally Posted by SD455DJ

Thanks for the info! The shaker was functional on the '74 GTO's, but not the TA's and SD455 Formula's. Can you post the jetting for the '74 350 4-bbl carbs?

Dennis

Thanks...didn't know about the '74 GTO shaker.

7044268 49-State AT 72/45 ("I think" the pri rods are 45s, book shows unusual# and I suspect a special taper)

7044269 49-State MT 68/35

7044568 CA same as 7044268 above

Secondary rods (DB) are same for all 3 carbs

[65 Lamnas]

Originally Posted by Shiny

Why is there such a difference in primary jets between manual and auto? 68 vs 72 seems like a big jump. Is this typical?

Not only the jump in jet sizes, but look at the combined flow area when considering jet/rod combo. It's hard to say exactly why the jump, but remember that jets, rods, and PP springs alone are NOT the only components that determine final metering of the primary side. The size of the MABs directly affects the metering, and the airhorns and float bowls are different P/Ns from AT to MT on the non-CA '74 350ci Qjets.

Only way to know for sure is to gauge the MABs, and one can assume they're a bit different which would explain the jet/rod differences.

[Formulas]

Didn't stick cars get the next bigger cam than autos ?... Along with slight bump in compression. .. Different rear gearing... Not as a rule but usually. That changes things a bit..

[65 Lamnas]

Originally Posted by Formulas

Didn't stick cars get the next bigger cam than autos ?... Along with slight bump in compression. .. Different rear gearing... Not as a rule but usually. That changes things a bit..

Not so much after compression ratios dropped with the '71 engines. '70-earlier it was a different story.

[Formulas]

My apologies then.. .. But I don't give anything stock 71 and up to much thought anyways they probably got the upper cam of the year in stick cars that alone can cause minor changes elsewhere

[65 Lamnas]

Originally Posted by Formulas

My apologies then.. .. But I don't give anything stock 71 and up to much thought anyways they probably got the upper cam of the year in stick cars that alone can cause minor changes elsewhere

Don't be silly...there's no need to apologize for anything....It's just information sharing and how we all learn.

Originally Posted by Formulas

Didn't stick cars get the next bigger cam than autos ?... Along with slight bump in compression. .. Different rear gearing... Not as a rule but usually. That changes things a bit..

You ARE CORRECT about the above tho....Pontiac did do this with the MT engines in (at least) the mid-late 60's....no question.

[Formulajones]

Originally Posted by Verdoro 68

I appreciate the detailed info. Interesting that the carbs were the same between a 350 and a 400. I reinstalled the carb tonight and hooked up my wide band. The a/f ratios are definitely in the ballpark - at least with the minimal testing I can do in the driveway. We'll see how it does on the road. Hoping we can get our seats back in time to do some shakedown drives before our drive to Arizona.

Carbs are kinda nice in that respect. It's just a venturi. They'll deliver the fuel the engine pulls through it. Bigger engine pulls harder, smaller engine pulls less. So chances are good you won't have to do much fiddling with it tossing it on a smaller engine unless the thing was way out to lunch to begin with.