Changing from OEM to Holley 4bbl 650 CFM Carburetor?

[ClydesdaleKevin]

Sent: 6/29/2006 11:51 AM


I had a question or two for you guys...

As you know, I had carburator problems a while back, and had to buy a new Holley carburator in Kentucky, modify the linkage, and get back on the road.

The new carburator is a 650 CFM (cubic feet per minute).

I saved the old carburator so I can rebuild it...which I plan on doing soon.

Here are my questions:

Anyone know what the original carb's CFM was?  It seems I'm a tad underpowered, which on a 413 just shouldn't be!

Second, assuming the original carb was say 750 or higher CFM, will running a 650 hurt my engine?  In other words, would it be like running too lean a carburator?  I would rather have slightly worse gas mileage than have to rebuild an engine!

And finally, anyone know which casting numbers on the carburator body determine what model Holley you have, so I can get the right rebuild kit?

Thanks!

[denisondc]

Sent: 6/29/2006


You should go to this URL: www.holley.com, and poke around on it. At: www.holley.com/TechService/FAQ.asp, the 2nd 'answer is where to look for the 'list number'. ( Holleys also have part numbers, which is not the same as the list number.)
You get to it by clicking on the home page link for 'technical support'. Then on that page is a link in the middle of the page for 'FAQ'. On the first page of the FAQ, close up below the title, you can click on a link for 'carburetor', and they give a means of calculating how big a carb you need. I used 413 x 4000, divided by 3456 and got 478 CFM. My Holley is a double pumper, which the same FAQ says should only be used on a manual transmission. My double pumper has mechanically linked secondaries, so I just avoid pushing the pedal to the floor when starting out.
Once upon a time I found a website that had a listing of supposedly all of the Holley list numbers, showing the CFM, and the specs for each one. My Holley was partly on that list (having been modified a little). I thought that list was on this Holley site, but I dont find it now. Does anyone know where that spreadsheet style listing is found now?
The picture of the carb on my winnie is at:
www.holley.com/0-4779C.asp


And no; other things being equal, running a 650 CFM instead of a larger carb wont hurt anything. If the jets were setup too lean, any size carb could make the engine run hotter - but not because the carb was the wrong size.
A smaller carb might improve your gasoline miles/gallon slightly.
The -list number- is what I was always asked for when I went in to a parts store get the rebuild kit for my carburetor. The problem both times was that their books didnt have my carburetor 'list number' in it. Too old I guess. So I just got the closest-looking set of gaskets. And both times it had all the items I needed. I now have an extra rebuild gasket kit - that I got on ebay, for exactly my list number. I contacted a guy selling the rebuild kits, told him my list number, and he put it up for auction. Cost me about $25.

If you are going to rebuild your own carb, be sure to do the dismantling on a surface where the tiny balls and springs wont get away from you!

[DanD2Soon]

Sent: 7/1/2006

Dave,

Not sure this is what you remembered, but   Holley Avenger Systems&Carburetion.pdf   is a 129 page .pdf of their catalog pages 7-135.  The last 30 pages are a sort-of "spread sheet" type parts listing...link was on the Catalogs Button of the www.holley.com site.

I scrolled it pretty fast, but,  found 3 pages with your 0-4779C shown:
Pdf. pg. 27 / Cat. pg. 33 - Listing
Pdf. pg. 36 / Cat. pg. 42 - Double Pumpers
Pdf. pg. 42 / Cat. pg. 49 - Retrofit Kits

[RV Mech Tech]

Kevin - is your Holley a direct bolt-on or did you need an adapter to install it? - the Holley carbs are very versatile in that they can be fine tuned very easily without disassembling the carb , with the exception of changing the jets or power valve- there are a few adjustments that you can make externally to tune it to your application-  the accelerator pump cam, the accelerator pump linkage, and the vacum operated secondaries (if equipped) can all be adjusted with parts kits from Holley -  if the carb is a direct bolt-on for your engine (if available) then it will be close in adjustment to what you require - if it is a standard bolt on then the above adjustments will be a starting point and may need changing- there are accelerator pump cam kits (little horse shoe shaped cam under the acc. pump linkage) and different rated springs to change the opening of the secondary throttle plates- if you want to try these adjustments you can g to a high-performance  shop and they will have the parts and  HP Books has a tuning guide for The Holley as well-  I have tuned many of these carbs over the years and this is why it is a preferred carb for anyone that wants to try their hand at tuning for stock or high-performance application.