Holley Carburetors – Rebuilding and Tuning?
I am a big fan of YouTube videos, over the last few years I have come to rely upon them for information and knowledge about subjects that are a bit vague to me and they have certainly helped me make some repairs on my stuff. But – I just finished watching a number of videos about Holley carburetors and it seems the only ones that have decent information are those that are presented by Holley themselves. Let that be a bit of warning to you.
Holley carburetors have been around for a very long time but most of us dealing with high performance cars, boats or whatever are probably thinking about the 4150/4160 or 4500 models when the subject comes up. And the main difference between a 4150 and 4160 is simply a fuel plate instead of a jet block on the secondary side of the carburetor. It was a strange method that Holley used to reduce the price of their products a bit but most people usually either skip this one or if they end up with one they change it over to the normal jet block style.
Most of what I see in the videos is someone that has read what to do, but seems to lack the experience of actually doing the work. Whether it is rebuilding the carb or tuning it afterwards, the mistakes are many. One of the things that you must have when working on a carb is patience. Small adjustments, made one at a time with the proper evaluation of what the change has done will allow you to proceed in an orderly fashion. I watched one fellow that was showing how to adjust the idle mixture screws with a vacuum gauge and he never allowed the engine to settle after making a change. He would rotate the screw, look at the gauge and rotate it again. It does take longer than that for the engine to respond – it is not instantaneous. In another video, the person could not understand why he could not get much of an increase in the vacuum draw of the engine no matter what changes he made to the carburetor. Well for one thing, while I was listening to the engine running, I could hear a vacuum leak – but that just comes with experience and listening to an engine that is rolling with the tide so-to-speak and that is a dead giveaway. He had issues that needed to be corrected before he could even get to tuning the carburetor.
So what I want to do and it’s coming quickly with the Monza project getting close to being finished is do my own video on rebuilding a Holley 750 Double Pumper and then another video on tuning it on the Monza’s 355 engine. There are more than a few things to understand about both subjects and I believe I can cover all the questions you might have with doing the work yourself on your own Holley carburetor. Along with that, I would like to help you with any issues you might be having with your Holley carburetor. Contact me at firstname.lastname@example.org and let me know what problems you are running into – I am sure we can get your carb and engine performing correctly.
The Holley 750 that I am rebuilding is an older unit that I have had sitting around for quite some time now. My plans are to change out the main body to one of Holley’s HP units and modify the baseplate with thinner throttle shafts. Now, none of this is required to rebuild or tune your carb, I am just doing it to increase the CFM that I can get out of this carburetor.
Stay tuned – this should get interesting.