holley power valve

[Snake]

Almost ready to rebuild my 3310-2 ,now its power valve picking time.My vacuum reading is 7 in gear @ idle so I think a 3.5 should be in the park,my MP purple sure gives a low vacuum signal for sure but works great when I get on to it lol.Anyone running a 3.5? right now my 600 holley has the 6.5 and at idle sometimes the pv opens and closes and feels like a miss.Whats your thoughts on this.PS my engine is well:burnout::burnout: tuned.

 

[Abodybomber]

Holley book used to say two inches below main metering under load,(put a vac guage on it sready state cruising/drop two.Personal experience,try your 3.5/see how it hits.Better to go up a jet size or two than have your power valve dump fuel.3310,great reliable carb good luck.

 

[Snake]

Thought I would double check with the holley techssssssssss and they say ya go with the 3.5 in my case.

 

[stumper]

Rule of thumb is half your manifold vacuum at idle - rounded up if needed. 3.5 should be just about right.

 

[Snake]

Rule of thumb is half your manifold vacuum at idle - rounded up if needed. 3.5 should be just about right.

looks like in the past I had it wrong,was always taught 2 steps down from the reading.Just the other night i saw a Holley tech vid that said half of said reading is the proper way to do it. if 3.5 dont open on time I will try next size up.