drpimento

Hi fellas. I'm going to adjust my fuel mixture, I think I'm running rich. I went out and bought a vacuum gauge. Where do I attach it to my Holley 4160?

Vetterodder

It would have been helpful if you'd given more info about the engine, carb, manifold, etc., but I'll take "generic" stab at it by making some assumptions about what you might have.

The manifold vacuum port is on the passenger side near the front and just below the float bowl. Depending on the year and model 4160, there may or may not be a ported source above that on the metering body but that's not the one you want. If you're running full manifold vacuum to the vacuum advance, it will be hooked up to this port and should remain connected while you adjust the idle mixture. If you need to use this port, they sell plastic tees to tap into it the vacuum line. Most manifolds have a plugged vacuum source behind the carb that's usually plugged. Any auto parts supply should have the fitting to connect it to your guage. Depending on which of the many different 4160 series carbs we're taking about, it might be easier to hook the guage up to the manifold rather than the carb. Keep in mind that the mixture adjustment that you are making involves only the idle mixture.

drpimento

Oh yeah...it's a 67 327/300hp base engine and it has the 600cfm 4160 I'm pretty sure. What you described helps a lot, thanks.

SWCDuke

If the carb is OE or OE equivalent it has a full vacuum advance system, so teeing into the vacuum can signal line should give you a true manifold vacuum reading.

A 327/300 should pull about 18" at 500 idle speed in neutral.

Duke


[Modified by SWCDuke, 10:08 PM 10/23/2003]

drpimento

I misread the service manual when I set my idle and thus set it to 700 when I adjusted my timing. :bb The 700 is for the rpo k-19 option which I don't have. I'm thinking that could be part of my problems. Thanks.

JohnZ

I always put a vacuum fitting in the threaded hole in the manifold just behind the carb to use for my vacuum gauge, and put a rubber cap on the nipple when I'm not using it for tune-up; Paragon has lots of different ones - just get one with one more nipple than you need (if you have Powerglide, A/C, power brakes, etc.) and cap the extra one. :thumbs:


[Modified by JohnZ, 11:07 AM 10/24/2003]

Paul L

John,
Can you pull vacuum by removing the power brake hose and attaching the gauge hose at that nozzle?

JohnZ

Yup! :thumbs:

Paul L

Thanks!