TR6 TR6 Valve Springs

[DougF]

Anyone using upgraded double valve springs, what are you doing when it comes to the two piece upper collars for the exhaust valves? The springs nest nicely in the intake collar, but on the exhasust side the inner spring does not nest into the collar.
I don't like the thought of the inner spring floating freely and potentially causing problems.

 

[Brosky]

Doug,

I used the uprated springs to match my TH-5 cam from BPNW. I did have custom shims made for the bottom, but the exhaust springs were secure on mine. I would be very careful about a spring digging into the head at high rpms and causing coil bind from wearing a groove in after a period of time.

See pictures here: Head Machining

 

[DougF]

Thanks Paul. I'll have to check the collars on my '74 head to see if they will work.
I'll look into the shims.

 

[Brosky]

Doug,

There are two reasons for shims and both are equally important. One, as I stated, protects the head from having the sharp edge of the spring cut a groove as it sits there and vibrates. Yes, it will cut it and yes it will cut it deeply as one other gentleman on this forum or 6-Pack found out too late. Better to have a shim/spring combo sit there rotating than a spring cutting metal.

The second is a combination of valve spring height and pressure. You want the proper standing spring height as well as the proper pressure holding the valve closed. Too much or too little is not good. Additionally, the spring needs to be able to move the proper amount without "over compressing" and eventually binding, which can cause major failures.

The manual has this information and every cam manufacturer has the pressure specs that they want to have their lobes pushing against.

Always remember, the higher the lift, the tighter the spring compresses and the longer the duration, the longer the spring stays in some state of compression, so you want this all to be done right.

 

[DougF]

Paul,
Thanks for the info. I'll look into shims.

 

[Hap Waldrop]

I dug up this old thread as I stumbled across it actually thru a interent search. I'm re-doing a TR6 engine rebuild that another LBC shop built and the engine only had 15 psi of oil pressure when warmed up, I found the polished standard crankshaft to be way under spec, and way too much rod and main clearence, so I had the crank turned .010"/.010" to my exact numbers in the spec range and resized the connecting rods to get to the clearence numbers I wanted.

Anyway when I got to the head, it needed hardened exhaust seats, and the valve job looked to not done, so that led to a complete head rebuild. When I got to finishing the the valve job, and studying the seat pressures and all that when I honed in on the two piece exhaust valve retainers, these head had already been fitted with bronze guides and new valves and and new dual valve springs. being somewhat new to this engine (I built plenty of 1500s), I noticed that the was no possible way the inner valve spring on the two piece exhaust retainer could possibly locate the inner spring, not good, I knew I had to come up with another option. So I first thought about getting 6 new intake valve retainers, but found them hard to come by, and also notice BPNW had alloy retainers set up for dual springs, so any input into valve retainers for dual springs would be helpful, other than using the two piece retainers with the dual springs, that ain't happening at this shop.

Next issue is after measuring installed valve height and checking seat presure, they were hopelessy low, around 57-60 pounds checked with my Rimac tester, way too low for this engine and this valve size, I want to see something closer to 80-90 pounds. Now the Triumph don't leave the greatest way to shim the valve springs, you need a shim with a ID that is pretty close to the OD of the guide, so it will center itself and stay put. Hours of searching the VSI/Silver Seal valve shim catalog, I could find a couple of shims that might work, but thickness was the next issue, to get from 60 to 80 pounds I need like .080" - .100" of shim. I looked at David Anton's APT site and noiticed he offered .080" shims made for the TR6, so that confirmed I was in the ballpark as for thickness needed for the shim, David and I are friends so I'll for sure will calling him Monday to pick his mind on this issue. Just for grins I started looking thru the fastner bins at the shop to find a flat washer that was somewhere around. 080" - .100" thick and near the right OD to see what that thickness would get me on the Rimac tester for seat pressure, sure enough I was all over 80 pounds with .080" washer and 85 pounds with .100" washer, and thru my search for washers to do this test, that when I found a washer that had a .515" (the OD of the TR6 guide is aprox .505") ID hole, and was .100" thick, I think it is a SAE 7/16" grade 8 washer, and it's OD is 1.100" perfect fo the OD of the valve spring as well, so off to my favortie mom & pop fastner shop tommorow to look for more washers with dial caliper in hand, since I only had the one washer like that. I know it might sound cheesy to use a flat washer for a vale shim, but it the same sort of thing as a shim and a grade 8 unit would be more than hard enough. I had spent hours yesterday thinking about this issue and how to deal with it and as normally my mind was working in high tech mode, but sometimes the answer is way more simple.

 

[poolboy]

Am I wrong in thinking there is a difference between a "shim" and a collar ?
I thought the collar was just about always necessary to keep a spring from digging into the head, and a shim necessary only to adjust the spring pressure.
I realize that a collar can be customized to serve both purposes, but can't a shim just be added to the traditional set up of springs and collars ?

 

[Hap Waldrop]

Am I wrong in thinking there is a difference between a "shim" and a collar ?
I thought the collar was just about always necessary to keep a spring from digging into the head, and a shim necessary only to adjust the spring pressure.
I realize that a collar can be customized to serve both purposes, but can't a shim just be added to the traditional set up of springs and collars ?

It's more common for most OHV cylinder heads to have recessed pockets for the valve spring to sit in, all the MGB heads are like that, so shimming them is no big deal, the Spitfires and TR6s sit the valve spring on flat area, so no spring pocket to capture the shim and keep it place. A shims only purpose is to increase the seat pressure, so, on Triumph heads you need a shim that locates off the valve guide's OD, since you have no pocket to work with. Some heads have a bottom locating collar if you will to locate the inner spring on bottom, again MG heads have this, but depending on the valve springs used, these are not totally necessary, for example we don't run them MG race heads, and alot of stock heads don't even have them. I heard more than one reference here about having something under a valve spring to keep it from digging into the head, I don't get that, as most cast iron heads even if they have bottom inner spring locator, they do not extend out to the outer spring and the spring its directly on the cast iron head and I've never seen this be a problem, or seen one of our heads get damage to the head from valve spring riding on it, look sometime at how a valve spring is ground flat on the bottom or top, it's made that way for reason to sit flat and not dig in, maybe this is more of issue with aluminum heads, but I never saw any damage from valve spring to our heads. I often though of making a couple of index marks on a given head from the valve spring to the head to actually see how much it moves around under a work load.

 

[TR3driver]

Seems like there is something wrong with this picture, to me. The factory fitted dual springs to some models (eg early PI and late PI/carb) so surely they also made provision to locate the inner spring adequately. My Bentley notes that late PI models used the one-piece retainer on the exhaust, and the Rimmers photo clearly shows the inner spring seat on the one-piece retainer: https://www.rimmerbros.co.uk/Item--i-111870

0.1 also seems kind of thick to achieve just stock spring pressure. Combined with the other mistakes you have found, I'm wondering if those springs are wrong or deformed. Are the original spring seats in place?

I also don't understand the "hard to come by" comment; TRF actually has them on sale at the moment.

 

[Hap Waldrop]

The one piece retainer fits the inner spring perfectly, but not the two piece retainer. No bottom collars were on this head, and I'm not terribly worried about that, I seen and ran way too may examples on race engines without them, a very common happeing for alot of builders using different valve spring packages, and with this engine an the inner spring ID being so close to the guide OD, it can't go anywhere. Moss shows the one piece retainer as N/A, BPNW offers a alloy dual spring retainer, to be honest with you, I didn't even think of Charles at TRF, thanks for reminding me.

As for as the valve springs, they are the new stock dual spring offering that BPNW sells, they were already on the head when I got and you can clearly see they are new, so I have nothing to compare them to, but would love it if someone can provide info there, thats why I'll be talking to David Anton tommorow, most guys on the forum are not building there own heads and have no way to weight valve springs, but Im all ears if you have first hand experiecne with this. There's a few things that come into play with seat pressures, the valve spring being used, the installed height, the size of the valve in a given engine and the cam, 60 pounds is way low for this engine, I'd be afraid the valve would float at higher rpms. I agree that .100" is alot of shim, but that far from the norm on some engines, but if it gets me to the seat pressure I need to be at and I don't have coil bind at full lift, then there's no issue with the thickness of the shim. In fact valve shims are most commonly offered in .060", .030", and .015", and it not that uncommon to use a .060" and a .030 shim together to achieve the desired seat pressure, so .010" more is not that much of a stretch from the norm.




As for having something under the spring on a head to keep the spring form digging in, sorry I do not agree with that, and that opinion is based on decades of experience. It's very common in race engine to have a race valve spring that seat and over the nose pressure is at the limit of the most you can have on a given engine, so no shim is used, and because it it a spring that may not be stock OD, no bottom locating collar is not use either. I had to refresh these heads over time and never saw any evidence of the valve spring damging the spring pad on the head, but with this engine that would be a moot point anyway, because there will be a shim on the bottom between the spring and spring pad on the head, so the spring would never touch the head anyway.

Ok, first off, this engine is not a engine I built from the start, but one I'm re-doing for a customer who had it done by a so-called Triumph experts, but the .004" main clearnece and the .003" rod clearence he had , would not let the engine develop hot oil pressure, that's why I'm redoing this engine, because the original builder could not quote his clearences, and that is the only thing I found worng with the engine that would equate to a oil pressure issue. Ok, with that being said alot of the new parts in this engine were not bought by me, but by the original builder, now I did get a detailed list of all of those parts, and where he got them. The camshaft used in this engine is a new (not reground) BP270 suppiled by BPNW, after talks with Leyton at BPNW asking him for cam specs for this cam, so I could degree the cam, he emailed the cam spec page for the new BP270 cam, these cams are done by Piper in the UK, ok to say the specs were vauge would be a enormous understatement, no cam ground on center line was givien, no recommended cam timing was offered, just some goofy deal about where to align the crank gear and cam gear to achive correct timing and even then no quote as to what it should be when checked, and no recommended seat pressure for the springs as well were given, this is why when it comes to cams I use APT, David knows his stuff, and gives you all the correct info to do your job properly, and all his cams and lifters are properly hardened and have the needed Rockwell C numbers, in short I hate to use UK cams in my engines, because they are so vauge with their specs, and normally just don't do things to the level I want, so I use APT anytime I need a cam for these engines. Now I do buy alot of parts form BPNW and find them to be great guys, it's just when it comes to cams ahd lifter, I go to the souce, and that for me is APT.

 

[poolboy]

from Hap " I heard more than one reference here about having something under a valve spring to keep it from digging into the head, I don't get that, as most cast iron heads even if they have bottom inner spring locator, they do not extend out to the outer spring and the spring its directly on the cast iron head and I've never seen this be a problem, or seen one of our heads get damage to the head from valve spring riding on it, look sometime at how a valve spring is ground flat on the bottom or top, it's made that way for reason to sit flat and not dig in, maybe this is more of issue with aluminum heads, but I never saw any damage from valve spring to our heads"

Hap, see the quote below from Brosky. I seem to remember seeing pictures of something like he describes. I don't recall whether the lack of a lower collar was the cause of the damage or just a conclusion that someone assumed.
Maybe Paul can call up the post and have your opinion on the thing once you see the pictures and write up.
Can you, Paul ? Can you find it ?

There are two reasons for shims and both are equally important. One, as I stated, protects the head from having the sharp edge of the spring cut a groove as it sits there and vibrates. Yes, it will cut it and yes it will cut it deeply as one other gentleman on this forum or 6-Pack found out too late. Better to have a shim/spring combo sit there rotating than a spring cutting metal.

 

[Hap Waldrop]

Poolboy, yes I get what Brosky said, and I visited his website as well, his head has no lower locating collars on it either, the shims used on Brosky's head looks to be a VSI/silver seal shim, modified to work on the TR6, it probably the Datsun shim, it comes closer than any of the other shims in their catalog to working on the TR6 head but is only offered in one thickness, and I notice also that is white zinc plated shim, VSI color codes their shims as for thickness, that would make it a .030" shim being it's white zinc plated. Now maybe his head has different springs on it, but if that head used the tow piece retainer with the double spring, the stock replacment offering I have, the inner spring would be neither located on top or bottom, thats why I want a different retainer than the two piece retainer for using with the double springs.

Note I added a addition to the post I made on the first page here, I thought I was adding it here, but I actually added to that post

 

[poolboy]

Thanks, Hap, for the reply, but I wasn't really talking about what Paul had done to his engine. I'm sure it was in capable hands during his rebuild by " His Majesty's .."shop.
No, I was refering to the incident that he cited about the springs digging into the head. There was a post by another individual (with pictures) and I wanted you to see it, in light of your comments about the likelihood of something like that happening.
I don't know if the head was damaged from the lack of a collar or not, but that seemed to be the conclusion that most of the posters came to.
If Paul can dig up that thread, I'd like your opinion, just out of curiosity, nothing more.

 

[Brosky]

I apologize, but I just got around to reading this. Several things need to be cleared up.

Hap, I won't disagree with your experience, but there were not one, but three individuals who had issues with springs digging into TR6 heads. I will look for the threads when I have a few minutes to spare. With that being said, I don't know what springs that they installed or why the collars were eliminated when they did their work.

As far as mine goes, the shims that were put in mine were machined down on a surface grinder by Bob Mason at Mason Racing Engines when he did all of the other work. He did not use the stock collars as the new springs would not work with them. I got the springs and the cam matched, per the recommendations of Greg at BPNW. Bob spoke to him at length prior to doing any work on the engine and got the recommended spring pressures and that is why the shims were machined down from their stock thickness.

One of the first questions in their discussion was what Bob was planning to use under the springs, to replace the collars. They both agreed that there should be something there to take the place of the collar and to prevent the spring coil edge from digging into the head.

Bob did all of the machining and assembled the head and long block assembly and Erik put it all together and back in the car.

 

[Hap Waldrop]

Paul, I won't have to worry on the head I building due to fact I too will using a shim under the spring to achieve the seat pressue I want, so I'll have a buffer between the spring and the head. Now I don't know what the lower collar looks like on a TR6 since I have none to look at, but if they are like the ones used on a Spitfire then they locate the inner sping on the ID to center it and then fit into the ID of the outer spring which without a shim would still leave the outer springs bottoms in direct contact with the spring pad on the head, now maybe the TR6 use a lower collar that goes all the way out to the OD of the outer springs, and if so that would sure explain alot to why my seat pressues are so low, and why I need so much shim, BPNW does offer a uprated high lift cam valve spring set and I'm betting they would net more pressure, but I found the way I need to go to get these springs to seat pressures I need. Also just to refresh what I said, I've seen plenty of examples on MG race engine where no shim, no locating collar was used, because the springs were non stock daimaters and the needed no shim, because the spring alone was enough, and in those heads, upon many tear down and refreshes I never saw any damage caused to those heads in the spring seat areas.

Paul, on your head, from the pictures on your website that is clearly a VSI .030" shim, I can tell from the color of the shim, and if Bob had to surface grind them thinner, then you needed less than .030 shimming to get where you needed to be and with neither of us using the lower collar, I'm betting you have the higher pressure springs BPNW offers, and the ones I had to use on this head (they were new and already there) are the stock replacment springs.

 

[Brosky]

Hap, I don't doubt what you said, since I pointed out that he did have to machine them to get the proper pressure, so you know the parts used by machinist's like yourselves, better than me.

In so far as the bottom collar, it kind of looks like an upper collar, turned upside down, for lack of a better reference. I may have my old ones and some spare springs in the basement. If I can find them, I'll post a picture.

 

[Hap Waldrop]

Cool Paul, I like to see one, actually the OD of it would tell me what I wanted to know.

 

[Hap Waldrop]

Well, I talked with Phil at APT yesterday, and ask him to educate me more about the TR6 lower collar, according to him, its like the Spitfire and Spridget ones I described, being that is locates the inner spring, and then fits into the ID of the outer spring, meaning if no shims were used the outer spring would sit directly onto the spring pad of the head.

 

[Brosky]

It looks like that is correct. I would still like to find mine, as I seem to remember them coming out all the way. But TRF does use the shims as shown here:

TRF Head Rebuilding

 

[poolboy]

I had a dozen each of these included with some TR6 spare parts. The springs were labeled V 550 ?
Just thought I'd post this photo for comments.