Holley 4160 tuning

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mbrooks573

mbrooks573

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Hey guys, just rebuilt the 273 in my 66 cuda and need a little help getting the holley tuned in. Basically a stock rebuild: Comp Cams Duration 250/260, Lift .432/.444, factory intake and exhaust, used a holley 390 CFM I had. Car idles and cruises great but does stumble a bit when I get on the gas. Overall, throttle response is not a crisp as it should be. Holley carb is at factory settings and I haven't changed any jets. Anyone tuned the 390 for a stock 273 rebuild with success? Thanks for the suggestions!
 
start with the accelerator pump setting .015 gap at WOT , cam setting correct ? then to the nozzle if you have a .025 try a .028 . take a vacuum reading adjust the power valve according to idle and launch readings
 
As above – timing/ignition first.
Our 4160 had a horrible hesitation which I could not figure out. Problem went away when we switched to HEI.
 
CARBURETOR RULE #1: 90% of all carb problems are ignition related!!!

As others have said, make sure the timing is set somewhere reasonable like 10-12 degrees BTDC.

Make sure the distributor is in good shape. A leaking vacuum advance will cause exactly this symptom. Make sure the mechanical advance moves freely, and has been recently lubed. If you are still running points, make sure they are in good shape and the DWELL is correct. Cap, rotor, wires and plugs should be new and correct.

Check the other obvious stuff like vacuum leaks, screwed up PCV,etc...

Then, start monkeying with the carb. The Holley website has some really good info. Start with float levels.

CARBURETOR RULE #2: If nothing you do to the carb seems to fix the problem, the carb isn't the problem. See Rule #1.

You do know that the original AFB was 500 CFM right?
 
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