• 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 Block deck height?

Share this page

Bremer

Bremer

Jedi Hopeful
Country flag
Offline
Hello, just doing some engine building math here. There is one dimension that I can't seem to find anywhere, and hope that forum members here can help.
What is the block deck height of the TR2/3/4 engine? I am referring to the distance between the crankshaft center line and the deck (top surface) of the block.

Thanks, appreciate it!
 
I'm no engineer or engine specialist but here is my take. While I'm sure the spec that you're looking for is available somewhere, there is another variable involved with the wet liner engine. The critical distance is from the center of the crank to the top of the liner. The deck must be compatible and the difference or protrusion is given as .003 to .005, I think. The liner height is determined by the machined surface at the bottom, the height of the deck and the thickness FO8 gaskets. The only number I've been concerned with is the liner height.
Tom
 
Hi Tom, yes, you are correct that liner protrusion above the block deck is critical. I would have just added 3-5 thou to the block deck height to come up with the relevant dimension.
I'm looking at possible combinations of rod length and piston compression height, and the block deck height is required to be able to calculate compression ratio (assuming compressed thickness of the head gasket and combustion chamber volume of the head are known).
 
Do you require a published standard spec rather than measurements from an old engine?
 
I prefer the original spec, but a measurement, depending on accuracy, will get me in the ballpark and would be quite helpful.
 
I'll see if I can come up with some kind of mandrel. If so I can give you a number. I won't guarantee the accuracy so it would be good if someone else chimes in. Tom
 
Thanks very much Tom, I appreciate it.
 
I had a go at it without much success. I couldn't true up get the tube I intended to use as a mandrel as it was to big for my little Logan lathe, so I shimmed it. I managed to get the range within about .020 but that's not much use to you. I'll PM with the numbers that I have I have if you want and if I get some idle time I'll try a different approach.

What I or someone else could do accurately is give you the distance from the piston top (standard 86 mm pistons) at TDC from top of the liner or the block but although I have two bare blocks in my shop and one long block I do not have one with the head off and the crank and pistons in right now.

I also wonder if it might be helpful to post you question in the racing section of this forum.

Tom
 
Hello Tom

Could you use a straight edge across the main bearing housing in the block rather than a mandrill?

David
 
Thanks for helping out here David. I'm actually measuring with a 12 inch dial caliper, a decent one that is quite accurate at least up to 3 or 4 inches but accuracy unknown around ten, which is near the deck height but it's the only thing I've got long enough. I did measure from the journal to the top of the block but if I measure from the apex of the cap and then the apex of the block I get a difference of + or - about .010 and that measurement differs from the mandrel measurement by about the same.
I did not use a straight edge and that might make it a bit easier with the caliper.
Tom
 
Thanks very much Tom, appreciate it. I sent you a PM.
I like the idea of measuring piston deck height. If the piston's compression height (distance from wrist pin centerline to top of piston) is known, then all the information is available to calculate block deck height.
 
Back
Top