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how can I tell if the head has been machined

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bluemiata90

bluemiata90

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I have a 61 TR3. I just took my engine apart for reconditioning and found that 87mm pistons have already been installed. I took the head and crank into the local machine shop and they said it's straight, but is there a way to measure if it's been milled or machined. The head/valves do look to have been reconditioned, but I don't know how to measure the surface. What are the stock measurements. I also found a copper head gasket, is copper the stock head gasket used when an engine is rebuilt. I don't want to get the wrong head gasket and have any problems down the road. The crank journals are all standard measurements, so the crank just has to be polished.
thanks
scott /ubbthreads/images/graemlins/confused.gif
 
Hello BM90,
there are various head thicknesses, UK TR6's had a 3.400" (nominal) head, stamped 516816, TR6 carb and 250 had a 3.535" head stamped 218227 and 5163233 respectiveley and replacement head for America were 3.560 stamped 219019.
The 3.4 head usually gives a 9.5:1 compression on a standard 2.5 engine.
Copper head gaskets were used on early engines but most sets I have come across lately are steel composite. I would have no problems with a copper gasket, but would double check that all the holes line up.

Alec
 
TR4 head thickness is 3.330" unmolested. Measure from the block mating surface to the surface under the valve cover gasket. If yours measures less, the difference is the amount shaved during machining. The desireable hi-port head (TR4A) is marked 511695 on the top of the head on the front side.

Solid copper gaskets (it is obvious when you look at them that they are not sandwiched copper/aspestos but a pure solid piece of metal) can be reused but are expensive to purchase new. Very common is a sandwiched coppper replace gasket - and are inexpensive to replace.

Hope this helps you out. PeterK
 
I am not an expert on the various heads used on the TR3 - TR4A engines. From what I understand, there are three variations on the "high port" head. I have a TR4 with 1 5/8" intake ports. This was used on the later 3's and earlier 4's. I have a measurement of 3.330 hand written in the note pages of my comp prep manual as the stock head thickness. I am not sure where I got that number. I do remember confirming that number on what I think is an unmolested head in my spares pile. But, please do not depend on my reply without additional information.

Mark Richlen
 
There is also a thinner, steel head gasket available. It's often used with the 87mm setup and will boost the compression a little, but might mess with your valve geometry. The steel gasket isn't cheap, best price I've seen is about $100 at British Frame and Engine.
 
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