For my otherwise stock '56 312, I now have the later dizzy installed & bought a ECZ-9425-B intake that I plan on installing next week. I have been searching the forum for anything related to carb preferences, issues, & tuning. I plan on a very mild rebuild in the future, slightly hotter cam, headers, nothing too fancy. I'll never race it, just want a fun weekend nice weather cruiser with good drivability & a bit better performance.

So I see many have good experience with the Holley 390, Demon Jr 525, & the Edlebrock 500's. Opinions vary of course, but generally I am seeing positive results with these. Should I worry that I will outgrow the 390 & wish I would have gone with one of the others? The Demon Jr gets a lot of praise, but I also see some saying they needed to modify the vacuum port for proper distributor advance & also will need to hog out the B intake to match the large carb throats. That sounds a bit scary. Also I worry the Demon Jr being so physically large it wont fit under my T-Bird hood.

Those of you that have been down this path before, if you had to do it again, what would be your choice? For rebuilt carbs, the price differences don't appear to be a huge difference. E'brocks could save me some, but not if it isn't the right choice. I am thinking electric choke & block off the intake's center exhaust passageway with thin sheet metal.

I value your thoughts!

Brian - 56 T-Bird

Woodinville WA

I'm running a 465 Holley, and it is a really nice, quite simple carb. 272, large valves, later dizzy, Pertronix ignition. Doesn't seem to be to much carb. Gary

       

Gary, 55 Vicky, St. Germain, Wisconsin

 

As you know I have the 390 Holley on mine but its only going to be a stock motor.The 465 is a step up and shouldnt be a problem.I put a little piece of tin to cover the exhaust croosover on mine.Worked fine.I also put a 1 inch phenolic spacer under the carb but I understand T-Birds have not as much clearance under the hood.You may have to go to 1/2 inch.

  

I'm running a stock Holley on my 56 TBird and 3 x2's in my 54 so i can't help out on a YBlock. But I run a 600 Edelbrock on my slightly modifed 302 in my 48. I have never had a problem with the Edelbrock in the some 15 years I have run the carb. It ran good right out of the box. I had it professionally rebuilt about two years ago because I had some problems with the way the car was running. Turns out the problem was not the carb and the rebuilder told me the carb was in excellent condition (after charging me $150).

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Brian



Seems like you're in the same boat as me...I am going to buy a 500 cfm carb I guess because I can't find someone who wants to up jump to a 600 cfm...and trade with me.



I have an Edelbrock 1406, 600 cfm electric choke carb that is too large for my 272. Once I put the engine back in my Fairlane and get her running I'll probably order a smaller Edelbrock. The Autolite I've mentioned in other posts, which is on ebay is too much in my book for the gamble of it not working right.



What I'm saying is my Edelbrock will be available if you want it soon. It may be just what your 312 needs.



Cheers



Gord




Gordie T           Long Point, Ontario

I have run a holley 390 and an edelbrock 500 on my 292 (little bigger cam, FOM).  Here are my thoughts:

390 - goo dcarb, easy to adjust, had a n assy defect new out of the box that was a bugger to track down.  Once sorted out, it provided good throttle response, and started very easily - much easier than the edelbrock, especially after sitting for a few days.

500 - Carb is good, but feels a little "sloppy"... by that i mean the throttle response isnt as crisp as the 390.  However, carb pulls noticeably harder at WOT.  The 390 feels like it runs out of breath quickly, but the 500 pulls much harder through the rev range.

Both carbs required a bit of tuning for my application, both are pretty easy to tune.  after running both carbs back to back over several days, the decision to stay with the edelbrock was pretty easy...just plain ole more power, but the 390 worked well.  I think a 600 would be too big (and the math says so too).  Ill probably sell the 390 and try a Road Demon Jr 525.  Rumor has it they have very good throttle response compared to the edelbrock......not sure how much bigger they are than the holley or edelbrock though...

Let me know if you need any other info.

Also, you can get intake manifold gaskets with the exhaust heat passage mostly blocked off - those work fine too to keep the paint on the manifold.

Ron Grove

Wauconda, IL

rgrove - bu tuning on the Edlebrock 500, was that changing the primary jets or what? I am leaning towards that one at the ,moment, but any tuning advice would ve valuable to know as well.

The Demon jr sounds like agreat carb too. I'm just worried about having to hog out the manifold bores to match the large carb primaries & also I have heard they are physically very large. I want my T-Bird hood to close! I also hear with the large primaries & a Ford-O-matic, second gear starts are somewhat difficult. Anyone with direct experience with this carb on a 312 T-Bird?

Brian - 56 T-Bird

Woodinville WA

Hi merry xmas to all  as far as carb,s are concerned I think that a holley is the way to go  the y blk cann,t handel a big carb they don,t have the breathing that a chev has and a holley you can tune it to fit your engine I tried a 6oocfm holley on my 312 and it was to much carb. blk soot out the tail pipe, went to a 390 or 450 holley and it ran great anything you want for a holley to fine tune it you can get it  an anybody with half a brain can tune it

Brian

   I have a 1955 Tbird with an aircooled FOM and a 1957 312 engine. I have used a Holley 1850 AAS ( 600 CFM, vacuum secondaries ) for over 25 years and have never thought of changing it for something else. I did add the electric choke.

   You are right to wonder if you get the 390 or 465 if you may regret it as you probably will. The vacuum secondary carb is self regulating in that the airflow through the venturies draws the amount of fuel out of the fuel bowl that it needs.

 That makes it very forgiving and docile in normal driving.

 Most of the time you are only using it as a TWO BARELL carb in normal everyday driving. Then you want to go fast and you stand on it. At this point you are still on two barrels until your engine RPM and manifold vacuum cause the second two barrels to open and add power. Ask yourself do you want a 390 or a 465 or a 600? Let us know what you decide and if your happy with whatever you choose. Pete

Tuning an Edelbrock usually consists of changing metering rods and/or jets, and/or step-up springs. The manual that comes with Edelbrock carbs is pretty good. It goes over the theory of carburetor operation, and tuning.



I agree with Rgrove about the performance of the Edelbrock. I changed to a Holley 570 from an Edelbrock 600. The throttle response of the Holley is much more crisp. And since I've owned a Holley, I find that it is easier to tune than the Edelbrock - I had always heard the opposite. The Holley is also simply more tunable.



I believe that the only carb that will not be a mismatch to the intake is the Holley 390. You can use an alternative that Steve presented and taper a carburetor spacer, rather than grinding on the intake.

http://www.y-blocksforever.com/forums/Topic21823-3-1.aspx

Either way you do it, you don't want a step in the transition.



I'd go with Holley or a Demon. Since I've not yet used a Demon, the next time I need a carb it will be one of them, just to see what they're like.



Lawrenceville, GA