Edelbrock 1406 Jetting

[Matthew Osmond]

I've been looking at a few forum posts looking for what people have found with tuning and jetting their carbs, and maybe I'm confusing information, but some people seem to be maybe using different jets for the secondary side?

Unfortunately working long hours and the car being parked for the time being I don't have a ton of time to mess around and fine tune the carburetor, I do have the chart for reference

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I am currently in position 1 but I find it has a hard time getting going off idle, cruising around in the idle circuit seems decent but could be a bit better, would the best number to try first be #2 or #23?

I have a 1985 GMC K10, SBC 350 / SM465 / 4.10 rear end, 35" tires, around 800 to 1000 feet elevation. Camshaft is stock, swapping to 1.6 rockers for the time being, ported vortec heads, long tube headers, there's no timing tab so I'm not sure the initial timing unfortunately.

 

[potent rodent]

go with number 2 that will be 1 stage rich on mine iv got 95 jets front 98 in the back with the silver spring i think its the number 8 , u will want to try diff spring set up that fits your vac

 

[Matthew Osmond]

go with number 2 that will be 1 stage rich on mine iv got 95 jets front 98 in the back with the silver spring i think its the number 8 , u will want to try diff spring set up that fits your vac

I ended up going with #2, went 1 stage rich on the secondaries, and used the heaviest step up spring since I'm pulling 21"Hg at idle, and it was a massive difference.

Unfortunately when I went for a drive it was sounding like a diesel there was so much valvetrain noise, so I adjusted the valves again and put the exhaust manifolds on, and I think I messed something up on the starter and it just free spins now, so it's down for the next few days unfortunately!

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[75gmck25]

For off-idle transition - pull the carb and ensure the transfer slot exposure looks like a square when the throttle linkage is back to idle. Then just leave the idle speed screw set there. Reinstall the carb and tune the idle mixture screws for best vacuum or best idle speed. Do not touch the idle speed screw. Now take it for a drive and see if it comes off-idle better.

For mid range throttle transition - as already suggested, switch to the 8” or 7” step up springs. This will make it transition to power mode a little earlier (as vacuum drops) and smooth out the transition. When these springs are wrong you will get the mid throttle power loss that caused the 1406 to be nicknamed “Edel-bog” carbs.