TR2/3/3A Valves question

Hi everyone,

I just picked up my cylinder head from the machine shop and I noticed my valves aren't even at the top. Is it a big deal? Could I adjust my rockers accordingly to make up the variances?

Thanks
Chris

Yes, that's exactly why you need to adjust the rocker arms after installation.

You might want to take a look at how badly the intake seats are "pocketed". A little won't hurt, but very much will reduce performance. See the section on valve grinding in the workshop manual, page B26. The book tells you how to cut away part of the combustion chamber around the valve; or oversize valves are available from BFE (and no doubt others).

Stratty said:

Hi everyone,

I just picked up my cylinder head from the machine shop and I noticed my valves aren't even at the top. Is it a big deal? Could I adjust my rockers accordingly to make up the variances?

Thanks
Chris

Click to expand...

The one variance that you can make up before head final assembly is spring pressure,which will vary if the installed spring height is different.
I install the valve,retainer and keepers and measure the gap the spring will sit in.Then I compress the springs in a crude but adequate bathroom scale and drill press setup and see what spring height gives the desired installed pressure,then shim each spring seat accordingly.
Oversize valves Randall mentioned are great to avoid excessive lowering of the valve seat.
But I have never done a TRiumph head.
Tom

Thanks for the response guys. I just took a video of the valves and put it on you tube.

https://youtu.be/sNLk3SXlg8k

https://youtu.be/FgFZnLOUDI0

Your intake valves are noticeably recessed into the head. It is not enough that I would worry about it for a street motor, but I would plan to have seats put in for the next valve job.

Tom discussed the proper way to install valves. As the valve becomes recessed farther into the head, the stem is higher on the other side. The optimum is to measure the desired valve pressure with the valve closed, and then measure what height makes the desired pressure for each spring. You then shim the bottom of the springs individually, so they all have the same resting pressure on the valves. Again, this is optimum...and extremely important for high revving engines where one valve with low seat pressure could float at high RPM and contact the piston. The TR engine is a "non interference" engine, so the valves will never contact the pistons unless the valves break. So, On an average street engine you do not necessarily have to worry about seat pressures if you have no plans to press the upper RPM range.

In finishing...your situation is not perfect, but it is also more common than not on an older street engine rebuild. The work mentioned is above and beyond what the average machine shop will do. If you want seats and shims...you will have to specify that and pay for it. A machinist will normally only recommend either when the head is worn beyond a reasonable amount. Yours is not.

As long as you can adjust the valve clearance with the adjusters...run it as it is.

While you guys are talking valves. How is it that they can install these hardened seat right into the casting of the head? It looks to me like the casting is all on piece and nothing is going to come out of there!!
steve

A special tool centers on the valve guide to cut the original material out of the head so a new seat can be pressed into place and then cut to fit your valve.

I'm with John, just run it unless you need top performance/durability.

Here's a video I just found, which shows the seat installation process nicely. There are big expensive machines often used to cut the seat recess, but this guy just uses a boring head and big drill press.
https://www.youtube.com/watch?v=xJWav8NwgC8

In iron heads the seats install well and stay put. The Jag V12’s had aluminum heads with steel seat inserts that were famous for falling out if you ever overheated the engine.

Thanks John and Brinkerhoff because the last 3 heads I had rebuilt they insisted on putting in the seats that supposed to enable the engine to burn the new types of gasoline without damage to the head. From my inexperienced position, I basically had to yes to the cost without understanding what they were going to do for their money.