• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR2/3/3A TR3/4 cylinder head differences

Share this page

Marvin Gruber

Marvin Gruber

Yoda
Country flag
Offline
Pulled the head off a 65 TR4 today. It had a stuck intake valve. Car had been sitting some time. After I had the head off and the valve out, I began to notice some differences in the heads. I pulled out a TR3 head I thought I might use, thats when I found out the TR3 valve stems are all the same size but on the TR4 headed (stamped 511695), the intake valve stem is quite a bit smaller than the exhaust valve stem. That got me going, I dug out two more heads with the same number stamped on the front right side corner. I thought those were head serial numbers. One head had the numbers stamped upside down from the other two. Are the heads stamped with 511695 the so-called "big valve" heads. I have a good 66 TR4A engine with the same 511695 stamped on that head as well. It has the dual exhaust manifold on it and pretty sure that is all original and correct for the car. I am now thinking that the engine in this 65 TR4 I am working on is not the original engine for this car.

Marv
 
The smaller exhaust valve stems started in the middle of TR4 production, CT21471E according to the Moss catalog. But there are 'conversion' valve guides available to fit the smaller stem valves to the early heads.

Actually quite a few different heads used at one time or another, check out TeriAnn's article on them:
https://www.tjwakeman.net/TR/FAQ_heads.htm
 
Check the CT number stamped onto the side of the engine block on the flat area just to the rear of where the coil is mounted. If that number is close to the Comm. No. (VIN), then I would assume that the block is the original one that came from the S-T factory when new.
 
Back
Top