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Valve Spring discussion

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Brosky

Brosky

Great Pumpkin
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This will probably provoke more discussion, but based on Bill's current engine issues, this is one that bears comments.

I received all of my new internal engine parts over the weekend. Cam, lifters, pistons, bearings, ya-da, ya-da. As I was checking them off of the invoice, I saw the instruction sheet that came with the valve springs, so after I was done, I read it.

Like others have mentioned, the instructions clearly state that the lower valve spring collars should be removed and not installed when these are replaced. As I looked at the springs and a spare head in the garage, that makes absolutely no sense to me. The TR6 engine and hundreds of others were designed to have these collars in place for several reasons. I understand that the new spring makers want the springs to sit properly for height and compression/tension reasons, but in my opinion this is not the answer.

So I called my machinist (who totally agreed with my thoughts) and had a nice discussion with him and this is what I'm doing, based on that discussion. I dropped off the springs and parts. Bob will remove the old springs and collars and measure the thickness of the collars and spring heights uncompressed. After some calculations and following the spring instructions, he will machine a boss or circular relief in the head, that will allow the spring collar to fit down inside, yet will allow the proper spring compression, tension and finished installed height.

Why the extra work? Years ago, I saw the results of leaving these off when a fellow tech forgot to put two on two intake valves on a customer's 4-4-2. After several 1/4 mile runs one night, the results were not very pretty. Luckily, we caught it before a valve dropped and ruined the engine completely.

These springs can do several things without the collars and none of them are good. They can start to cut into the head and that will start a harmonic vibration which will eventually cause excessive valve guide wear, or they can become brittle from getting too hot from binding as they twist and cut into the head and snap along with a few other undesirable results.

My opinion is that if TR6 valve springs were designed to run without them, no engine would have them. Manufacturers are not in the habit of adding extra parts to an engine just for the heck of it. I believe that the cost of machining the reliefs into the head will be much less than the problems that this can create down the road by not doing so.

There may be those who disagree, but I want to eliminate any potential areas that can cause a premature failure to the valves, guides, new cam or anything else in my new engine.

JMHO - you are free to disagree........
 
Paul, I would be very hesitant to go machining any relief into your head because, mainly, I have never, ever heard of this being done to a TR6 head. I am having a problem getting the proper spring pressure without shimming the darn things up. I have two sets of double springs sitting on the machinist's work bench, neither of which can he get the necessary spring pressure. Today, finally Dave at TRF sent me a set of twelve stock collars taped to a piece of cardboard, free, knowing my problem. Will bring them to the machinist in the morning. Thing is, the collar has two levels and looks like the inner small spring will have to sit up.

There has got to be an answer to this situation with the thousands of heads that have been shaved on this planet. Anybody called Kas yet???
 
Bill,

Remember my motto; measure twice cut once. Bob will explore all avenues to get the proper pressure, and spring height or the springs will be replaced with what will work. Cutting is going to happen, but it will only be enough to allow the collar to fit as intended from new. If the springs are not at the proper pressure or show signs of a bind when at full open position, we'll correct that along the way.

I've never heard of it being done to a TR6 head either, but throwing away collars and allowing a spring to sit there with nothing under it to control motion doesn't seem right to me either.

And again, there are springs that are made to be like this, but the reliefs are cut in the heads and the springs can't move out of the slot. They also have different coils at the ends than those used with collars.

I will trust the opinion of a guy who builds very high revving, high HP engines day in and day out to come up with something, even if it hasn't been done before.

If these springs don't fit the bill, (so to speak!) he'll come up with a set that will from his sources.
 
Bill,

The reliefs are partially cut now. We'll just take what we need. I do agree with you about potential bind, but taking out the right amount should get it right.

I wonder if the spring guys feel that everyone who swaps these springs will never do the machining, so they say to take out the collars to cut the corner??

See below:
 
Paul, on my 1500 race engine, I machined a set of lower collars from 17-4 Stainless and heat treated them. When it came time to set the head up, each one was individually cut to a final dimension giving me the correct installed height and pressure.
That engine had a 7650 redline, and saw it on a regular basis.(every upshift).
Jeff
 
Jeff,

That's good enough for me. The collars stay, one way or another. Bob will decide what will work best. I mean at most, I'm only talking about taking an additional, what, .040" to .050" out of the relief?

Granted, not doable with the head on the car, but now is the time for me to do it.
 
Seems to me a building's steel column needs a concrete
footer to keep it from "walking" side to side.

If one column "walks", the moment is transferred thru
the horizontal steel beam into the opposite vertical column.
The second column is then adversely effected.

Kinda like a valve, rocker arm and push rod assembly, I'm
thinking. But heck- I'm the stupid kid on the block.
What do I know?

d :crazyeyes:
 
Are you building a race car or a street machine? I went through this with my engine builder. He helped me with the assembly and steered me away from increased spring pressures. If your building a race motor and worried about valve float with the correct performance parts it can be done. The current tappets being produced today can't handle the increase spring pressures. I had already bought my springs from Moss and we did all the spring tests together from pressure to spring bind. A good and free education! I ended up with the stock outer springs and the new inner springs which slightly increased the pressure. If I remember correctly about 12 lbs. Which was at the high side of the factory recommended pressure.

His philosophy and particularly now a days with the lower quality cam tappets is to leave spring pressures at original factory specks. I also had a reground cam with some repairs to a few lobes and he said that is another reason not to go crazy with spring pressures. He told me about a customer that insisted on a much higher pressures in his MGB motor that his customer was rebuilding himself. (like me). But someone recommend to him as a must if your increasing the performance of the engine to increase spring pressures. So he had to do it and Jesse said he was waiting for a I told you so. Low and behold at the end of the day that guy come walking in his shop with his cam and tappets in a box. Not a pretty sight. That was the clincher for me. Listen to your PROFESSIONAL engine builder.

One last tip is to degree your cam. What a differance that makes.
 
I'm building a street engine, with a new cam, springs and lifters. But I want it built right the first time, so we will take all necessary measurements and do it correctly.

The springs that I got are NOT high pressure springs, but a spring rating recommended by the cam and lifter manufacturer who has been making these cams in England for over 30 years.

The last part that I'm waiting for is the adjustable Vernier Timing Gear, to degree it in properly.
 
It's on the sheet that I dropped at the machine shop. I have to stop Friday, so I'll get a copy.

Actually, I can probably get those mumbers tomorrow. I'll get back to you.

What were your numbers?
 
The Bentley says the double spring should be 85.6 lb. I am right at that.
 
That is the factory setting from the TR6 manual.

I think that is what these are, but there are two other specs, one for the inner compressed and for the outer compressed that I want checked, as well as spring height when fitted, etc.
 
Again, the cool little spring pressure tester the machinist had could dial in the cam settings and check the pressures as well as coil bind. I am sure that your machinist has such a tool.
 
Yes he does. It kind of comes in handy when building Hemi's and racing engines. Coil bind is a subject that he is very familiar with.
 
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