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Valve geometry? #772661 05/05/19 12:26 am
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DavidP Online Content OP
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I'll be replacing valves, guides and springs on my '72.I'm considering using the later valves and the longer adjuster pins. Is the geometry better with the later short stems? Do the guides last longer with these?


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
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Re: Valve geometry? [Re: DavidP] #772668 05/05/19 1:01 am
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DMadigan Offline
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The short stem valves allow you to use the T160 or EF adjusters which have more contact area on the valve which reduces wear.

Re: Valve geometry? [Re: DavidP] #772670 05/05/19 1:12 am
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For several years now every Trident head I have built I have used the mushroom head adjusters.
I think they are an improvement over the standard configuration.
But I am impressed with the elephants foot adjuster that Dave makes and sells and will use them on the next head I do.
Anything to reduce side thrust of the valve in the guide--as guide wear is one of the Achilles heels of the Trident engine IMHO.
HTH

Re: Valve geometry? [Re: DavidP] #772673 05/05/19 1:42 am
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Use Kiblewhite guide and valves - much better quality than stock.

Re: Valve geometry? [Re: DavidP] #772687 05/05/19 5:30 am
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Thanks,
However, I had a look in my '74 parts book and the later rocker arms are a different part number as well. What's the difference there?
I'm OK with spending the money for different pins, but a whole new rocker set is not in my budget.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Valve geometry? [Re: DavidP] #772694 05/05/19 11:44 am
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Nitrided valves and K-liners work really well in my A65. The tolerances can be much tighter and the K-liners are straight and true. Plus you are not pushing guides in and out of the head. The more straight and true and close fitting the guide bore the less the valve rocks and the less wear.


mark
Re: Valve geometry? [Re: DavidP] #772720 05/05/19 4:35 pm
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DMadigan Offline
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I am not positive but I think the difference is the diameter of the pin for the pushrod. T160s use a cup on top and ball on bottom pushrod. Earlier engines (at least to '72) have cup-cup pushrods. The adjuster thread is the same on both.

Re: Valve geometry? [Re: DMadigan] #772728 05/05/19 5:21 pm
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Originally Posted by DMadigan
T160s use a cup on top and ball on bottom pushrod. Earlier engines (at least to '72) have cup-cup pushrods.


It's T160s that have pushrods with a cup top and bottom and T150s that have a cup and ball.

https://www.triumph-spares.co.uk/t150-r3-pushrod-late-type-71-1238

https://www.triumph-spares.co.uk/t160-pushrod-71-3974





Re: Valve geometry? [Re: DavidP] #772731 05/05/19 5:49 pm
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DMadigan Offline
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Sorry, yes, confused. Do you know if the ball on the rocker changed size?

Re: Valve geometry? [Re: DMadigan] #772737 05/05/19 6:55 pm
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Re: Valve geometry? [Re: DavidP] #772749 05/05/19 9:20 pm
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Gentlemen,
The T160 doesn't enter into this. The ball-type valve adjusters and short valves came out in '73.
Reviewing my parts books, the parts numbers for the ball pin, push rods, and rocker spindle are identical for '72 and '74 models. Of course, the adjuster pins are different, but the lock nut is the same, 5/16" UNF. Therefore, the pins are the same thread.
However, the rocker arms are different, at least the part numbers are different. My concern is that there might be some slight difference to the angle of the rocker arms to compensate for the difference in the distance between the bottom of the rocker and the top of the valve stem due to the longer pins, shorter valve stems.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Valve geometry? [Re: DavidP] #772813 05/06/19 10:02 am
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Originally Posted by DavidP
Reviewing my parts books, the parts numbers for the ball pin, push rods, and rocker spindle are identical for '72 and '74 models. Of course, the adjuster pins are different, but the lock nut is the same, 5/16" UNF. Therefore, the pins are the same thread.
However, the rocker arms are different, at least the part numbers are different. My concern is that there might be some slight difference to the angle of the rocker arms to compensate for the difference in the distance between the bottom of the rocker and the top of the valve stem due to the longer pins, shorter valve stems.


Evidence I've been able to find seems to point to the contrary.
I believe "rocker" in the parts books actually refers to rocker assembly, therefore the rocker part numbers could have changed as a result of the different assembly the same as when larger diameter ball pins were fitted.

Re: Valve geometry? [Re: DavidP] #772888 05/07/19 4:10 am
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Excuse me, but there are FOUR INDIVIDUAL PARTS, numbers 23-26 in the diagram, called, "rocker levers." Six parts overall.
As fond as the Brits were of keeping the same part number for later versions, I think it's a safe bet that there is some difference between the two if they adopted a new part number.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
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Re: Valve geometry? [Re: DavidP] #772892 05/07/19 6:29 am
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David

As LAB indicated seems, it's all down the size of the "cahunas" blush

Last edited by Esmerela; 05/07/19 6:30 am.

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Re: Valve geometry? [Re: Esmerela] #772901 05/07/19 10:55 am
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Originally Posted by DavidP
Excuse me, but there are FOUR INDIVIDUAL PARTS, numbers 23-26 in the diagram, called, "rocker levers." Six parts overall.


Yes, triples have four different rocker assemblies, two pairs and two singles.

Originally Posted by DavidP
As fond as the Brits were of keeping the same part number for later versions, I think it's a safe bet that there is some difference between the two if they adopted a new part number.


If part of the assembly was changed due to the different adjuster (as it certainly did when the ball pins were changed, see below) then the part number is likely to have been changed.

Originally Posted by Esmerela

As LAB indicated seems, it's all down the size of the "cahunas" blush


That certainly seems to be the reason for the change of 'rocker' part numbers between 'small' (1/4") and 'large' (5/16") ball pin rockers from serial NE00262 as described in Triumph Service Bulletin 9/71 (Triple) although the ball pins were available separately they were part of the rocker assembly.

The part numbers listed in TSB 9/71 for 'small' and large' pin 'ROCKER ASSEMBLIES' and 'ROCKER LEVER' numbers in the parts books are the same.


Re: Valve geometry? [Re: DavidP] #772922 05/07/19 4:46 pm
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You do realize that all this about different rocker part numbers does not matter since when you set up the valve geometry during assembly you will have to make corrections by shortening the valve tip, pushrod or raising the rockerbox with shims. Different base, head and rockerbox gasket thickness, variations in cylinder and head height, valve face and seat grinding, et cetera is going to change the geometry.
If you use the stock spherical tip adjuster all this does not matter much since the contact point will dig a pit in the valve tip where ever it needs to be. T160 flattened ball adjusters are a little more restricted in range and have a flat to contact the valve tip. The EF adjusters have the most critical adjustment because the ball has limited range of motion the the foot socket but they have the largest contact area with the valve which reduces the side thrust on the guide.

Re: Valve geometry? [Re: DavidP] #773112 05/09/19 5:44 am
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Thanks,
I guess I'll find out once the new valves arrive. I have decided to go with the later valves and adjuster pins.
I need to get feeler gauges with the bend in them. I remember how difficult it was to get a blade under the adjusters on my '74.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Valve geometry? [Re: DavidP] #773659 05/14/19 6:50 am
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I presume that correct is when the pin is in line with the valve stem at half lift. If this is not the case one must vary the thickness of the rocker box gasket.
Are the copper ones thicker than the standard fiber gaskets?
And, how does this affect the sealing rings on the PR tubes?


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Valve geometry? [Re: DavidP] #773663 05/14/19 7:30 am
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Yes the copper ones are thicker...about as thick as the covseal gaskets you can buy for the rocker boxes - but I haven't actually measured them, must do that one day. You will have to measure up your air gap and then decide what combination of fibre washers under the cups and PRT seals you will need. I actually had to use 4 x aluminium washers as well as the PRT seals and one fibre washer on my last build - but I have custom PRT's. Assemble the head dry with the head gasket in place and just firm up the 4 x outer bolts - have the PRT's in place when you do this. Then lift each PRT up until it fits inside the rocker as far as it will go and measure the gap at the bottom between the PRT and the cam follower block. Then start mixing and matching seals and fibre washers with cups etc until you have a combination that is approx. [from memory] 0.05" to 0.08" bigger than the gap you measured. This 0.05" to 0.08" is the squish you need on the seals = 0,025" to 0.04" on top and the same on the bottom.

Somebody might like to confirm the squish needed?

Re: Valve geometry? [Re: DavidP] #776921 06/20/19 5:01 am
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Got it back together and torqued down. Set the valves and didn't hear that ugly thwack when a push rod comes off its rocker.
The geometry looks good with just the gaskets from Big D. thumbsup
My gasket set did not include the circular gaskets under the bottom cups, so I cut my own. Only starting the engine will tell if it's oil tight.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Valve geometry? [Re: DavidP] #776930 06/20/19 8:53 am
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Originally Posted by DavidP
My gasket set did not include the circular gaskets under the bottom cups, so I cut my own. Only starting the engine will tell if it's oil tight.


Quoted from a 2009 Phil Pick post on TriplesOnLine:

"The 1974 N.V.T. production used a copper head gasket, 71-3941, still with 70-4752 rubbers and 70-4746 bottom cups. However, due to the increased thickness of this version of gasket, a fibre washer 71-1190 was fitted under the bottom cup. Also in this N.V.T. production, a new push-rod tube 71-4000 was fitted, in place of 70-6955. The 71-4000 push-rod tube has a longer engagement spigot than the previous 70-6955, to make engagement into the rockerboxes simpler during assembly.
.
.
.
The most common cause of push-rod tube leaks is over compression of the rubber seals. If any material has been removed from the cylinder block or cylinder head, the amount of material removed will be equal to extra compression of these rubbers. Also, if 71-1190 is used, this will also add to the compression of the rubbers. The fix is to ensure only reasonable compression of the rubbers. There is a thinner rubber available under part No. 70-3547. Often I have found that use of one of these, at the top of the push-rod tube, will ensure a perfect amount of rubber compression. If necessary, mixing and matching of components will often allow fine adjustments."

Re: Valve geometry? [Re: DavidP] #776974 06/21/19 5:25 am
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Thanks,
As I remember my '74 had the composite head gasket when I first took the head off. Copper gaskets were the only thing available for replacement.
I have used a composite head gasket on this engine. The tops of the pushrod tubes entered the rocker boxes smoothly without twisting the seals.
AFAIK the head is unmolested. I'll find out tomorrow if it retains oil when I fire it up.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Valve geometry? [Re: DavidP] #777025 06/22/19 2:54 am
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Rode it a few miles to seat the rings, no smoke, no oil leaks so far.
Re-torque the head tomorrow and all is well. laugh


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Valve geometry? [Re: DavidP] #777567 06/29/19 9:49 pm
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It seems so stupid that when they designed the trident/R3 engine they retained the problematic push rod tubes, (every triumph twin has at least a slight weep in this area) instead of casting tunnels in the barrel

Last edited by Andy Higham; 06/29/19 9:50 pm.

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