need advice on a good carb for a 59 312 merc am changing to a four barrel manifold.
600 holly too big? econcmaster 450?
Thanks for any help

Is the engine essentially stock & which manifold?..


Paul

The motor is a stock 59 , it is in my 56 montclair
2 brl. manifold now , am picking up a 312 4 brl manifold this week end.

That would be a stock 4 brl manifold
Thanks 
John

I would say a 450 would be more then enough for a stock motor, 600 would be over kill. I'm only using a 390 on my 292. Out of the box it was too lean and I did have to re-jet it. I'm not sure if Holley jets them for the crappy fuel we have today?

As a general rule, always oversize the carb when using vacuum secondaries.  The reasoning behind this is that the secondaries will only open the amount that the engine ‘demands’ based on the primary venturi flow signal.  That’s assuming the secondary spring or secondary weights depending upon the carb design have not been heavily modified in the wrong direction.  I have dynoed several Y’s now with the 400-465 cfm sized carbs and based on the high vacuum numbers at rpm, they are all undersized.  I recently worked on an original 1955 182HP 272 with the factory Teapot and even it was wanting a larger carb based on the vacuum numbers at 4600 rpms.  I have extremely good results with the 750 cfm sized carbs on the Y engines for all around performance but all these typically have some sort of camshaft upgrade.  The Holley List #1848 465cfm carb does make a good replacement driver carb though for many stock Y's.  For the larger carbs, the Summit 750 carb has been a good choice for many Y builds and I like it better than the 600 cfm version.
 
With all that being said, here are some links to articles that go into detail on some of the carb choices for the Y engines.
Ford Y-Block – Four Barrel Carburetor Testing Using the Iron ECZ-B Intake
Ford Y-Block – Stock or Modified?  Here Are Two Different Builds
Ford Y-Block – Stock Iron Heads Can Still Make a HP to the Cubic Inch

Lorena, Texas (South of Waco)

Holley sell refurbs on eBay.  As good as new, less cost, but a shorter warranty period.  As long as you get it installed immediately to make sure there are not issues out-of-the-box, you won't have any problems.  If you get a Holley, get a street avenger.  It's a more modern carb with a lot of nice features.


Lawrenceville, GA

Thanks to all for all the good info, a friend just gave me a 1.08 autolite. With the stock manifold, I think it will work. He had it on a 390 and didn't hack the program, too small.
Will give it a try first then, do ;what ever is necessary afterwards.
My dampener is splitting on the harmonic pulley assembly. so now on the hunt for a good one. 

Thanks for the help.
John

Check the Damper Dudes or The Damper Doctor. They will rebuild yours.

Will check with the damper dudes, have found it is
Hard to find a new one,
Thanks
John