Folks,
Does anyone know or has tried to open-up the ECG-D intake valve openings / seats to accept the 1.92" intake valves.  These two heads (ECZ-G & ECG-D) appear to have very similarly sized combustion chanbers when looking at them on the bench, only major difference appearing to be intake valve sizes.  Ted? Anyone else?
Regards,   JLB

55 Ford Crown Victoria Steel Top

They are not even close.  ECG-D is 7.6:1 on a 272.  ECZ-G is 8.6:1 on a 272.  That requires about 10cc difference.

What usually limits valve sizing is the relation of the spark plug, and the other valve.  The difference between the valves is .140" so that is about 1/16" increase of the radius of the valve.  Does that look like it will fit?

http://ford-y-block.com/cylinderheadchart.htm



Lawrenceville, GA

Having an abundance of big valve Y heads in which to work with, I don’t have much experience modifying the smaller intake valved heads to accommodate the 1.92” or larger valves.  As Charlie brings up, it would be prudent to first perform some combustion chamber volume checks on both heads and confirm the actual cc’s.  I did look at my notes and the perimeter measurements of the ECZ-G and ECG-D combustion chambers are very similar but it will still take a cc measurement to confirm that the chamber volumes themselves are similar.

Lorena, Texas (South of Waco)

Charlie,
Side-by-side, with loose valves, the 1.92" valves almost completely seat "as-is" into the smaller-valved heads; there also seems to be plenty of clearance between exhaust and intake with the larger valves. So, I don't know what to make of your opposite opinions between you and Ted. And spark-plug clearances look good too, even with the bigger valves.

Maybe my question should be: Is there plenty of casting material around the intake valves to even consider the increase in seat sizing?

Ted, I do not have shop equipment to check conbustion chamber CC's; any other ideas for how to check the differences?

Regards,   JLB

55 Ford Crown Victoria Steel Top

We don't seem to have opposite opinions.  Both of our comments boil down to we're not absolutely sure and you will need to check.

If you have fitted a valve and can see that there will be no issues with the dimensions, then it will work in that regard.  I don't know about material for cutting seats.

To compare combustion chamber size, you simply need to devise some way to compare the volume of one head to another.  The easy and most accurate way, most machine shops offer ccing service.  Take both heads and a set of good valves for each, pay a small fee, and they will measure and tell you.

A cheaper, less accurate way, get a measuring cup with the smallest graduations you can find and see how much water you can fill into each chamber.

An even less accurate way, set the head up on a bench, fill the chamber with water, open a valve and let it drain into a glass.  Mark the level with a marker.  Empty the glass, do the same with the other head.  With this method, you get a direct comparison, but no idea of the actual volume.

No idea if these will actually work, haven't tried it.


Lawrenceville, GA

Charlie,

Thanks for the reply.  I'll wait for a while to see if Ted or others chime-in too.

Regards,   JLB

55 Ford Crown Victoria Steel Top

You didn't say what engine you have in mind for the heads, but if you already have "G" heads, why not just use them and save the time & expense. Also, the ports in the 55-272 heads are likely smaller, ok at lower RPMs but not in the higher ranges. And, if you grind & fit the 1.92" valves you will likely need to port just behind the seats to get any net benefit.. It's your call..         


Paul

Performing cc measurements on the combustion chambers is a basic blueprint activity.  The most basic cc measurements will be accurate within 2/10ths of a cc.  A cc buret is the standard measuring device and almost any liquid can be used for the measurement.  Be aware that the cc measurement needs to be performed with the same heat range spark plug you plan on running for accuracy purposes.

Lorena, Texas (South of Waco)

Folks,

ECZ-G heads are badly rusted in some intake & exhaust ports, ECG-D heads are in good shape; just trying to take advantage of "best of both worlds", so to speak, & thought it might be interesting to try. 

Application is 272 or 292 block previously bored to its present 297 CID size.

Am slowly building a replacement engine for the poor / existing 272 in my 55 Crown.  Just thought that I'd try to "heat it up" a little bit by increasing flow, compression, & using '57 312 cam.

Look, I'm a "home wrencher" with just enough knowledge on the y-block to sometimes be "dangerous" to self and parts (have re-built 5 of them of various sizes including a stock 312 over the years) - which is why I'm soliciting advice here from you experts. Am retired, on fixed income, not wealthy by any means, and can't afford to make any major, costly mistakes; yet; want to "play" a bit.  Besides, I really like the sound of a slightly hot y-block: No better sound than the 1-3-4-8-6-3-7-2 lope.

Thanks for the present and any future suggestions.
Any more advice will be taken gratefully.

Regards,   JLB




55 Ford Crown Victoria Steel Top

Which heads are currently, or most recently have been, on the 297?


Lawrenceville, GA