Hello all,

I recently purchased a 72 240z with the 4 barrel holley conversion on the 2400 engine. The car runs great except for a slight hesitation around 2300 rpm under load. Free revving the engine is smooth and normal and when pushed past the dead spot will run smooth through the rest of the rpm band under load. I have read that a lighter secondary spring might be the problem as the secondary is coming in too early, but wanted to see what the experts have encountered in the past. Thanks for the help!

Welcome Daniel.

I'm afraid you may not get a solid answer to your question, at least not right away. The 4-bbl Holley conversion is not well thought of, generally, and there's not going to be very many people here with a lot of experience with it.

You might want to check with some local hot rod shops - tuning a Holley on a Z can't be all that different from tuning one on any other car.

From my V8 musclecar experience, what you said would be the direction I'd go in. Secondary springs or a vacuum delay valve if they are vacuum secondaries would help with that problem. I just don't know if that applies to a Holley on a L engine.

Thanks for the reply, I'll try to lighten to the secondary spring and see if that helps.