Will a Mummert manifold and the best car headers add any performance to a stock 312? Motor has ecz-g heads, 1.54  rockers, the better exhaust manifolds, Holley 4150. Not sure on bore size, or cam specs but assume cam is stock.  If I can buy 25 HP and some torque it would be worth it, for 10 HP probably not.  Any thoughts appreciated, I've been thru the Eaton test pages (amazing) but none really test an otherwise stock engine so I'd be blind guessing any value.  Thanks

Ted, Redding, CA

I would say at least 25 horses. Probably more. Headers alone probably worth that and they will also increase gas milage. Are you planing on changing the carb as well as the intake? Existing carb should work fine. Biger carb will give more power. I am thinking 600 CFM would be max for stock cam. 550 may work better.

I'm thinking about doing both manifold and exhaust. I just ordered MSD 8383 kit, also the original style wire routing clamps, want to be done with the points.  I have an Offenhauser with 3 94s (I Know, don't say it), but I'm not ready for it. The Holley is 600 CFM and I'll keep it if it stops leaking and will work.  Need to get stuff coming and 25 HP will make me spend, Not going to race anything so would be satisfied at anything over 275, figuring it's good for 240 now when tuned correctly.  That's good news thanks. 

Ted, Redding, CA

Ted

Before anyone can give any advice that has any value we need some more information about the car and just what kind of performance you want to improve. Off the line, top end, on the road?

Stick and how many gears 3,4, or 5? Rear axle ratio? If FOM stock or FMX additions?

The very informative test that Ted Eaton did on exhaust manifolds convinced me that headers made more noise and heat than HP.

The car magazines are for the most part trying to sell the product that pay to advertise so be very skeptic of the things they say.

 So please tell us more. Pete

Pete, I'd like to say all of the above in terms of performance but that will realistically be the subject of another engine.  Basicically I would take any improvement, my thinkng is to produce the best performance from this engine absent cam and head replacement, it runs sound and strong as is and I don't want to rebuild the lower.  That said I don't have a target area just want it to be as efficient/powerful as possible by changing aspiration equipment if it makes sense.

It has a T10 4 speed which like the engine is unknown internally, don't have a clue about the rear end ratio, it works fine in combiation.  Drives like a 56, sounds like a 56 and that is really what I'm after.  It will be a cruiser work in progress for many years is the plan, built to achieve my highest level of enjoyment.

Not sure that helps you much, thanks for helping me through this thought process.

Ted, Redding, CA

That distributor alone should make quite an improvement over the vacuum operated original.

Which intake do you have right now? A Holley 4150 will not mount directly to a '56 manifold. An adapter is required. The later ECZ-9425-B manifold will be a step up, assuming that you don't already have it and not quite as pricey as a new aluminum unit. It responds pretty well to some small mods that are easy to accomplish at home. http://www.y-blocksforever.com/forums/Topic21823-3-1.aspx?


Lawrenceville, GA

Basic answer is, mummert intake, fix your 600 holley, fit ignition you mention, then tune it and you should be in the ballpark and improve from there.

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

Charlie the manifold is an A with a tapered adapter, the homemade gasket was probably good for -5 HP I posted a PIC of it somewhere, but it played with the Holley nicely.  Wasn't thinking about a gain from from distributor but I'll take it, for me the weakest most subject to change part of this engine is the distributor, me and this engine deserve electronic ignition, even to just remain in tune without hassle.

AussieBill, what is ballpark? and why not put the headers on it now?

This is the thinking, headers yes, intake yes, get what I can, going to use the Holley and plug the crossover, hoping it may have something to do with the leak.  When I say leak I mean an annoying manifold stain in the front doesn't really drip, but must at sometime because of staining.

Thanks for thoughts this is helping, ordered some gaskets looking for the rubber valve cover gonna have to search old posts sure I read it.

Ted, Redding, CA

There arent any good headers for the 54-56 in car setup. Fenderwells are still sold (Speedway) if you don't mind cutting your wheel wells. Rams horns will not fit in a car due to steering box and motor mount interference. The later, 57 up, stock manifolds are a bit better and port matching will help. The headers you see currently are basicly just for looks with little or no horsepower gain.

There is a project on the west coast to build some correct, in car headers for our cars. Not sure of the current status. I believe Jardeen was working on the design. Jerry Christensen has a set he made that will fit and do breathe but due to low production numbers they are sort of expensive.

I would suggest you look for the later manifold that will accept the Holley directly, the same with exhaust manifolds. clean up the runners with a grinder and port match them to the heads. Then the MSD electronic ignition. It has vacum advance where the Mallory does not.

Hope this helps. You might want to EMAIL Ted Eaton for his suggestions. He is one of the top Y-Block builders at the current time. He's the one that ran all the dyno tests. Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Ted,

What have you got? You've mentioned a "A" manifold with a leaking Holley, You've mentioned a offy with triple 94's you've bought a MSD 8383 but what dizzy are you currently running.

If you have a standard 56 312 making it more crisp and to boost Hp is really easy and you don't need to spend up big. Really this subject has been handled so may times a simple search will find many posts. A standard 56 will respond nicely to a 57 or later distributor the 8383 is probably better. This will require a carb with timed vacuum or you can run direct but you will need to set the distributor up for it. Really it may only yield 10-20hp but it will feel like much more.

For carb 312 (engine capacity) x 5500 (maximum RPM)/2 (ever second down stroke is a intake stroke)/1728 (cubic inches to cubic feet)  496cfm which is the mean carburetor size for you engine. A smaller carb will give you better economy crisper throttle easier driving and larger carb will give better top end at the expense of bottom end. Remembering a standard cam favors bottom end. If you want to run a 4 barrel a 390, 450, 500 or a 600 with vacuum secondarys is all you need.  A bigger carb will not make it run hard, just the opposite.

Have a look at http://www.y-blocksforever.com/forums/Topic55379-3-1.aspx?Highlight=exhaust+test  unfortunately there is not a lot of headers around for a 56 car. Mummert has one on the way and I don't know if sanderson got a car to get some dimensions off.

If you have a offy with 94's or a "A" with a later holley try them first  with your 8383 and then come back with I want this or that.

cheers

Warren

Grizzly (Aussie Mainline)