I had a choice of putting G heads on my 56 tbird 312 and after much advise from members on this forum I decided to do so. When I checked the casting numbers on this set of heads, I just looked at one of the heads (while mounted on the engine) and just assume they were the same. I know for a fact that the engine run fine with both of these heads. Here is my questions: the head that I checked was ECZ-G (Right). But when I pulled them off I found that the other head is ECG-I (left). Will these heads be okay to run on my 312 block with a teapot carb and rebuilt to stock specs? If so will I see any difference in the right to left banks?
Mixed heads???
- Thread starter cjc56
- Start date
Y-Blockhead
Well-known member
ECG heads appear to be early small valve heads but a ECG-I (maybe a ECG-H??) is not listed in Mummert's list. http://www.ford-y-block.com/cylinderheadchart.htm The ECG-Z head is a large port, large valve head. It will probably run OK with the two different heads but for optimum performance it would be much better to find another "G" head
dmsfrr
Well-known member
An ECG head is from a '55 272. I agree w/ Y-Blockhead, find another 'G' head to use, the engine will thank you.
When looking for a replacement note that the heads are right & left handed. The driver's side head has the threaded water temp sender fitting at the rear. The passenger side head will have a plug in that (front) water jacket opening.
Are the heads from your other/original engine still available? The 'G' heads are the most desirable/expensive stock y-block heads but if someone feels stuck with just one they may let it go for less. Good luck.
When looking for a replacement note that the heads are right & left handed. The driver's side head has the threaded water temp sender fitting at the rear. The passenger side head will have a plug in that (front) water jacket opening.
Are the heads from your other/original engine still available? The 'G' heads are the most desirable/expensive stock y-block heads but if someone feels stuck with just one they may let it go for less. Good luck.
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TedEaton
Senior Member
Performing a cranking compression check on all eight cylinders and determining if there is a significant different in the averages of the readings from the left bank to the right bank will help to determine if there is at least a compression ratio difference between the two sets of heads. If there is no significant difference in readings, then in normal driving you'll likely not see much difference between running those two heads versus running two matching G heads. Even in the G heads there seems to be some combustion chamber volume differences between sets so getting another G head for the ECG side is not a guarantee that any perceived problems will be fixed.
Y-Blockhead
Well-known member
To clarify, the heads are interchangeable side to side but as dmsfrr points out the temp sender bushing or plug may have to be changed to the proper location.
Thanks, Since these heads just had a valve job completed, I think for now I will run the ECG-I(right) and the ECZ-G (left). If this does not work out I still have a set of ECZ-B heads that I will need to have rebuilt. If anyone has any further warning or advise on running these heads together this please respond!