Difference between cylinder heads Log Out | Topics | Search
Moderators | Register | Edit Profile

Australian RR Forums » Early Post-War » Difference between cylinder heads « Previous Next »

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

Mark Taxis
Experienced User
Username: mark_taxis

Post Number: 28
Registered: 4-2007
Posted on Friday, 11 June, 2010 - 03:12 pm:   Edit PostDelete PostView Post/Check IP

Can anyone advise me if there is an easy way to tell the difference between a cylinder head for a 4 1/4 and a cylinder head for a 4 1/2 . The reason for asking is that I have a spare cylinder head and I am unsure as to what engine this will fit.
Thanks
Mark
Top of pagePrevious messageNext messageBottom of page Link to this message

Laurie Fox
Frequent User
Username: laurie_fox

Post Number: 81
Registered: 6-2004
Posted on Friday, 11 June, 2010 - 10:08 pm:   Edit PostDelete PostView Post/Check IP

Mark

The studs on the cylinder block are in slightly different positions. At one time your father had some difficulty with several cylinder heads which failed on pressure test. The spare that you have may be OK or it may be one of the failed ones. Your car will have 3/8" studs. Some of the earlier 4 1/4 blocks had 5/16" studs.

Regards

Laurie
Top of pagePrevious messageNext messageBottom of page Link to this message

Mark Taxis
Experienced User
Username: mark_taxis

Post Number: 29
Registered: 4-2007
Posted on Saturday, 12 June, 2010 - 12:19 pm:   Edit PostDelete PostView Post/Check IP

Hi Laurie,
Thank you for the information.
I am not sure of the condition of this head, it looks OK,but it has not been reconditioned so it is a bit of an unknown quantity.
Rgds
Mark
Top of pagePrevious messageNext messageBottom of page Link to this message

NORMAN GEESON
Unregistered guest
Posted From: 86.17.95.149
Posted on Friday, 18 June, 2010 - 11:51 pm:   Edit PostDelete PostView Post/Check IP

Mark

There are indeed some easy ways to tell the difference between the various 4.25 ltr and 4.5 ltr cylinder heads. You will not find these descriptions detailed anywhere else, quite why I really do not know.

The 4.5 ltr rocker cover gasket is longer than the 4.25 ltr. To accommodate the gasket length the 4.5 ltr cylinder head is longer at the rear end. This extra length takes the form of a very noticable curvature at the top of the cylinder head rear wall.

Place your fingers on the very rear face of the head about 3 inch (75 mm) below the rocker cover gasket line, then draw your fingers upwards.If your fingers meet an overhung curvature protruding about 3/8th ( 8 to 10 mm) the head is 4.5 ltr.
On the other hand, if your fingers detect a flat rear cylinder head wall, no real protrusion, then the head is 4.25 ltr.

Failing those tests, a 4.5 head is MORE THAN 8 inches wide, about 8.25 inch from memory.

A 4.25 ltr head is LESS THAN 8 iches wide, around 7.8 inches.

(Message approved by david_gore)
Top of pagePrevious messageNext messageBottom of page Link to this message

Mark Taxis
Experienced User
Username: mark_taxis

Post Number: 32
Registered: 4-2007
Posted on Thursday, 01 July, 2010 - 08:58 pm:   Edit PostDelete PostView Post/Check IP

Many thanks Norman
I will check the head when I am next home
Rgds
Mark

Add Your Message Here
Post:
Bold text Italics Underline Create a hyperlink Insert a clipart image

Username: Posting Information:
This is a public posting area. Enter your username and password if you have an account. Otherwise, enter your full name as your username and leave the password blank. Your e-mail address is optional.
Please quote Chassis Numbers for all vehicles mentioned.
Password:
E-mail:
Options: Enable HTML code in message
Automatically activate URLs in message
Action: