I'm looking for advice for a carb for my newly rebuilt 292. I upgraded to a four barrel intake, but at the time I didn't realize there were two choices for intakes. Yes, I ended up with the older style with the smaller bolt pattern. So, now I think my options are limited. I've heard that there are adapters that allow for the larger bores to be bolted up, but I don't know if they flow all that good. Any thoughts?

 

There is enough meat there to bore the holes out and re-drill the Holley pattern. Is it a steel or aluminum unit?

Garbz

 

Really? Has anyone ever tried that? It's steel.

 

I think I remember trying to match up a phenolic spacer of the later Holley bolt pattern to the older A intake, and the bore spacing and mounting holes just werent going to work. But you have the carburetor and intake so it is easy enough to check. The carb will have to be above the intake 1/2 to 1 in. to allow the larger throttle blades to open and not interfere with the top of intake, so that puts the adaptor back at the front of options.

An adaptor between intake and carb should provide quite a bit of additional flow capability, compared to the 2V carb. Massaging the intake's bores with a die grinder will help some too. However if the 4V carb is a 600 Holley or Edelbrock, it is going to be too big and not work well.

 

Why go to all that trouble? Sell the "A" to some unsuspecting soul on e-bay or CL for $50 and trade up to the "B" manifold for $100-200.

FYI: Check out the manifold test on Y-Blocksforever to see how well the stock "B" manifold tests out.

 

If it is the '56 ECZ-9425-A manifold, it is not a bad manifold. Get an adapter and either open up the bores in the adapter and manifold to match the carb, or taper the bores in the adapter to provide a smooth transition from the carburetor into the manifold.
As has been said, don't over carb it. Don't go much larger than 500cfm on a stock Y.
If it's not the A manifold that you have, you'll be better off finding a B manifold.

 

Thinking about it, I figured this is how I ended up with an "A"

Sorry, I couldn't find the link at y-blocksforever

So, I ran out to the barn to see what I had and praise the Lord, it's the ECZ-9425-A. Where can I get the adapters? I'm not having any luck searching Summit's on-line site, unless I'm not searching right. My Y is bored to 60 over, so is an edelbrock 600cfm too much carb? Seems like even the Holleys that are compatable (at Summit) are 600cfm.

 

Yes, 600 cfm is too much. But if you want to find out yourself go for it.

 

I think the link he's referring to is:
3X2 Intake Manifold Testing - Results.
It shows how the B manifolds compare to many of the 3-2 intakes. The 4 barrel intakes will be tested and compared in a couple months.

Adapters can be had at Speedway Motors, among others. One or both of the following might work. Find out before you order.
Universal Carb Adapter - Tapered Port
Flathead Carburetor Adapters

RE the carb, a vacuum secondary model of 600cfm or larger might work but you'll get better throttle response with a smaller carb. A lot of the Y-block guys like the Demon Jr 525, and the Holley 390 and 465. And there is the Edelbrock 500 but it would not be my preference.

 

Of all the carbs I've messed with, the good ole' 4100 is still my favorite.

 

Heck no, that's why I'm asking you guys for advice. I'm not looking for a race car feel, just a little more response.

Ok, that's pretty helpful. I checked these all out and may opt for one of these. Interesting about the Edelbrock, I've never owned one but listening to all the hype, one would think it's a great performer and easy to adjust.

Sorry, I haven't been able to find this model, but I'll keep looking.

I noticed that most of the carbs have vacuum operated secondarys. Don't know why, but my '69 Bird with a 4300 motorcraft carb always gets gummed up and stops working. I probably don't drive it enough!

 

The 4100 is an autolite carb, it's pretty much a 4bbl version of the 2100. You won't find one new, just rebuilds of used ones. There's a few pages online that cover rebuilding and tuning them. They're a pretty simple carb. I'll dig you up some links if you need them.

 

Ok thanks for the info. I'll try to check it out too

 

The 4100 is a good carb, too. In dyno testing 4v carbs on the Y, it was found that the 4100 may actually work out best for a street Y.

I think the Edelbrock carb is a lot of hype. I really don't have much experience with carbs but I do have experience with an Edelbrock and a Holley. My 1st aftermarket carb was an Edelbrock because I heard how easy it is to tune, the thing about changing jets without spilling gas. With that edelbrock, I had a problem with the secondaries they wouldn't open when the engine needed it and resulted in a lean spot. No combination of jets, metering rods or springs cured it. Apparently it is a problem that comes up occasionally and the fix is to grind on the secondary flapper counterweight. I didn't want to do it so I tried the Holley Street Avenger. In hours I had it tuned and running better than the Edelbrock did in the several years I had it. Obviously I wasn't tuning on it for several years but it amounted to much more than a few hours. On the Holley, jet changes are easier, secondary adjustment is easier, float adjustment is easier, cornering performance is better. It is ,hands down, a better carb in my opinion. But I encourage you to try any and all carbs that you can because there is nothing better than firsthand experience and because what doesn't work for one might work for another.

 

I had the same issue last year. The POS sold me a "A" manifold but listed it on ebay as a "B". I found a low priced ($80) 390 CFM Holley 4bbl from a pinto upgrade for it and got that. Cost me about $50 to rebuild it right myself and about $70 to tune her dead on.

I still got the A manifold laying in my shed. I too tried looking for an adapter for slapping a square holley on it. Another FTE guy who just bought a blue thunder sold me his "A" for a fair deal. People kept saying they dont make the adaptors no more. I seen one on ebay last summer. Of course I did not buy it for the $10 they were asking.

Another option is to buy a teapot. I seen one on ebay the other day for $50. You would have to rebuild it to run it though. There are some drawbacks to the holley teapots but if you are just setting it on a stock engine in a vehicle you only drive casualy I dont see them being an issue.

The largest CFM I could see on any Y block ever is 600. That sitting on a race engine. A 390 or 450 CFM on a stock or mildly modified engine would do well. Tuning the holley carbs is very simple, and critical to proper operation. I found a ton of help and advice from the guys in the Y block section of FTE and will thank them again.