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Re: Rocker adjusters [Re: John Healy] #284710 11/20/09 3:53 am
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Ron, I would call that valve spring resonance. If one end of a spring is pushed fast enough, the inertia of the spring wire will make the deflection travel down the spring in a wave, much like a "slinky". Obviously, if the resonance is large enough it could cause the valve to loose contact with the adjuster, but not necessarily. Progressive or beehive springs are used to control it. Often, the inner and outer springs have interference to control it also. If a valve has 150 lbs. of seat pressure, it will take quite a lot of acceleration to make the spring leave the collar. This is the reason for having two valve springs at different natural frequencies. Honda has used single springs on valves for some race engines by carefully keeping the natural frequency above the valve train excitation.
Sorry, I never said either had a lash cap. I do not use them except on the 8 valve Rickman Triumph where the roller rockers run on a lash cap that has a shim underneath for differential valve adjustment. The coarse adjustment is on the pushrod. I only said that I do not run different adjusters side by side. Sorry if the picture was not clear enough.
I would expect Nashcar engines to float valves but hard to imagine it was to gain horsepower. Valve opening curves are somewhat trapezoidal and have a duration at full open. Given the spring load, the valve would have to have a whole lot of acceleration to keep the valve train off the cam for long enough to make a difference to power. Even if it did, what is going to stop the valve from hitting the piston? Coil binding?

John, I agree, but mushroom adjusters are not the same as the line contact rockers in your link, they are a spherical so it is a point contact on the valve tip. It would have been simple for Triumph to have put the adjuster on the pushrod side of the rocker and a curved shoe (hopefully with a hardened face) over the valve. Dan Macias modified a couple of rocker boxes to do this on the factory racers.

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Re: Rocker adjusters [Re: DMadigan] #284823 11/20/09 8:21 pm
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So Dave, I went out and looked at a rocker box to see about putting the adjuster on the pushrod side w/thought of modding for cover and all but thought if one were to go this far why not try for a roller tip rather than curved shoe and would there really be much to be gained over the Porsche swivel foot you use now? Are there any roller tipped rockers, for say BMWs or others that could be modded for a Triumph?
So far, this discussion is very interesting and has me thinking that the easiest, most cost effective mods starting with original post would be large dia. barrel shaped pushrods (alum.alloy shafts), Porsche swivel adjusters and beehive style valve springs, followed by a quality valve job & attention to geometry. I still have to look into those beehive springs as I'm not sure of pressures needed for my cams in street application, don't want to wear parts out. Also would like to know if Thundair was using them with stock top retainers? Mark

Re: Rocker adjusters [Re: MarksterTT] #284872 11/21/09 2:47 am
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"It would have been simple for Triumph to have put the adjuster on the pushrod side of the rocker and a curved shoe (hopefully with a hardened face) over the valve"

Triumph did have the adjusters on the push rod side and a line contact on the valve on their late 500 racers. If you want to see one Mick Hemmings has two of them. One he restored and used for vintage racing. The rocker boxes were magnesium and had access covers on the push rod side.

I someone wanted to fit ball adjusters to their triple you can buy the T160 valves off the shelf with stellite tips. But for those of us who remember servicing T160's the ball adjusters, while an improvement, were not that trouble free in service. One would hope that the 911 ones were better made.


Re: Rocker adjusters [Re: John Healy] #284883 11/21/09 5:21 am
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The SOC BMW car engines like my olde '69 2002 have a unique (to me) valve adjuster on the alu rocker arms. The valve end of the rocker is forked with a steel disc bolted into the fork. The hole in the disc is offset. To adjust valve clearamce you loosen the pinch bolt and insert a small pin punch in the holes in the disc rotating the disc for proper clearance then lock down the pinch bolt. A nice design seems to me.

Last edited by dave - NV; 11/21/09 5:23 am.

Dave - NV
Re: Rocker adjusters [Re: Dave - NV] #284896 11/21/09 7:40 am
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Mark, I do not know of any rockers that would be an easy replacement. In that case it would be easier to weld up the end of the rocker, hard face it, and grind a curved shoe.
Roller tips are a big trade-off. A roller will be heavier than a shoe, the friction of the roller on the valve has to be greater than the friction of the roller pin, otherwise the roller will slide on the valve.
John, I believe you about the 500 rockers but why did Triumph not apply it to the road bikes? Certainly could not have been too expensive to do (but then, maybe any expense was too much). The only reason I could think of for not doing on the triples was that they wanted to owner to be able to adjust the pushrods without removing the petrol tank. Adjusters over the pushrods would require removing the tank. That would also have made replacing a pushrod that fell off the tappet when mounting the rocker boxes immensely easier.
The T160 adjusters are similar, if not the same, as Ducati adjusters. The drawback is that the flat on the ball is not very large and the pressure of the ball in the socket causes the leading edge of the flat to dig into the valve, similar to lapping a plate by pushing back and forth, the leading edge takes the most load and the surface ends up convex rather than flat.
I do not remember the stock T160 valves having stellite tips, did they?
Dave, it would be interesting to see a picture of those rockers if you have one.

Re: Rocker adjusters [Re: DMadigan] #284996 11/21/09 6:50 pm
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The Hiller aircraft museum has a small 2 cyl. opposed aircraft engine with exposed rockers. The adjuster end looks much like a Tri. radiused cam follower locked in place by a step in end of arm. The end of rocker arm is not threaded as the short shaft of follower passes through it and has a lock nut on top of the arm in same location as Tri.. Clearance appears to be adjusted by dropping out follower (shoe) and putting thin shims over shaft, between follower and rocker end. Line contact with adjuster all on same end of rocker arm, a little bulky looking but could be made smaller & lighter for motorcycle use.

Re: Rocker adjusters [Re: MarksterTT] #285089 11/22/09 1:19 am
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Has this been mentioned? Our much loved BSA Gold Stars have excentric ground rocker shafts in the area the rocker pivots. The rockers have a large radiused 'shoe' on the valve end and a pushrod socket on the other.
To adjust valve clearance you merely loosen the locking nut on one end of the rocker shaft, remove the overhead oil manifold and with a wrench on the other end rotate the shaft which raises or lowers the complete rocker.

An issue with this engine (isn't there always?) is the valve clearance is measures at the follower/pushrod junction as there's no inspection caps on the rocker box to allow measuring at the rocker/valve.

BTW, the HD XR750 factory dirt tracker engine uses this same rocker arrangement. There are prolly others, I dunno.

Madigan ... I'll look in the shop for a BMW rocker arm as I've described and send you a photo.


Dave - NV
Re: Rocker adjusters [Re: Dave - NV] #285106 11/22/09 2:20 am
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Thanks Dave. Does the eccentric rocker shaft also move the contact point on the valve fore/aft when adjusting clearance?

Re: Pushrod strength vs weight [Re: phantom309] #286754 12/01/09 6:03 pm
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When I was a kid at a BSA shop they told me to adjust my tappets so you could barely feel any play - so I did. I've never had any problem and they run quiet. If anything you get more lift & performance. Never burned a valve or wrecked a cam.


Re: Pushrod strength vs weight [Re: jim schmidt] #286757 12/01/09 6:19 pm
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I've been setting my unit singles (with excentric shafts) to almost nil clearance for years now with no problems. I wouldn't recommend it for a non-aware rider though. If you were to keep riding it with negative several thou clearance, it could get ugly.


"Beer is proof that God loves us and wants us to be happy" - Benjamin Franklin
Re: Pushrod strength vs weight [Re: jim schmidt] #287322 12/04/09 10:07 pm
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Getting back to pushrods. i just got the motor running again with brand new Manton chromolly pushrods.Based on what i have read here, I set the valves at .002 cold. I rode the bike (A-65) about 20 miles and then took off the cover and checked clearances. Looks like we gained about 8 to 10 thou hot. Guess I will reset by twirrling the pushrods like a Harley. Should be just about right eh?

Re: Pushrod strength vs weight [Re: pushrod tom] #287406 12/05/09 11:11 am
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Hey Tom do you notice a difference? And do you have pictures? What are Manton like and did you weigh them? The ones I made up are 42.5g 1.5oz inlet and 56g 2oz for the exhaust. Using a broken up aftermarket C/Molly set for a V8 ford.


mark
Re: Pushrod strength vs weight [Re: Mark Parker] #287446 12/05/09 3:38 pm
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That would be very hard to get to the pushrods on a triumph to get them adjusted so they just spin.I guess you could make some plugs on the back of th box. Maybe with little fingers you could get way back in the box but not easy.This is what we do with a BMW I race with steel pushrods as he breaks rocker arms with aluminum pushrods, I think they flex then wipp back and break?


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Re: Pushrod strength vs weight [Re: Mark Parker] #287661 12/06/09 7:31 pm
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Mark, Manton Pushrods is in California. Thats what they do. you can googelize them. Great service and a really nice product! They weigh In 47g Ex 56g. Under $40 shipped!
The bike ran well but I want to put on a few miles before I pull the wire. Snowed yesterday so i will get out asap. I will post reults following test rides, fiddling, dyno runs. This motor is different than last year. 11/1 cr, stock cam, 32 amals. I wanted to see how it would work and am also working on a new 'Skunk Works' project. PRT
http://farm3.static.flickr.com/2667/4161555880_43d44413cd_m.jpg Hope this is the picture. I am developing my computer skills just like my BSA tuning skills.....Slowly. Let me know if it comes thru.

Re: Pushrod strength vs weight [Re: phantom309] #287785 12/07/09 4:40 pm
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An easy way to use CR rods is buy tube from Aircraft Spruce P/N 03-00900 and use your ends. When you strip the ends from the Alumni mun rod measure the overall length and cut the CR tube that length. No heat treat is needed as it does not add to the flexure properties. So a 5/16 x .065 wall x 1' is $4.30 plus shipping.

Cheers beerchug

A good product for Jim to make available

Last edited by thundair; 12/07/09 4:41 pm.
Re: Pushrod strength vs weight [Re: thundair] #287834 12/07/09 8:57 pm
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From this post, it would appear that whatever combo of alloy vs. steel pushrods or alloy vs. iron cyl/head we're using, the valve clearances will probably (but not necessarily) increase once hot from the cold setting,right? So, say I install steel pushrods, set recommended cold clearance @ .010" (Mega cam) then find out I'm getting a hot clearance of /.018"-.020" should I set my cold clearance @.000-.002" cold? Has the cam mfg. taken the hot vs. cold difference into consideration and if so do they have a hot figure in mind when recommending the cold setting? If so, then they must come up with this clearance based on stock cyl. and head w/stock pushrods right? Will running to little cold clearance when more is recommended be detrimental to cam life? I always thought the clearance was a consideration of cam design and that if I strayed to far off I may be doing harm to opening/closing ramps etc.
I might have just answered my last question, I ckd. my cam timing card and it says "Running clearance .010" and then clarifies that "running clearance is also known as "valve clearance". Am I to assume "running clearance" means HOT since you can't run them cold? Mark

Re: Pushrod strength vs weight [Re: MarksterTT] #287907 12/08/09 7:22 am
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Running clearance is if you are going to run the engine, as opposed to checking valve timing which is usually done with more clearance .020" or .040" being common. All cold clearances, though some manufacturers specify hot, (never seen it for bike motors though). With an iron cyl and alloy head and alloy pushrods relative expansions dictate cold settings. Alloy expands more than steel or iron, so once you go away from factory material clearances need re-assesing. I had an old Datsun on a dyno once and although it had tappet clearance setting them to the recommended clearance for some reason almost doubled the max HP which wasn't much and still wasn't much but was a lot better smile
With an alloy cyl and C/Molly P/rods it only take a couple of minutes running to go from 0 clearence to .006-.008" so I don't worry about burning a valve, which I would think would be the most likely bad result of running too little clearance.


mark
Re: Pushrod strength vs weight [Re: thundair] #287952 12/08/09 5:00 pm
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The Norton steel pushrods don't work that well with alloy cylinders because you end up with excessive clearance (performance loss) even if you set them at 0 cold.

I am looking into aircraft alloy alum pushrods that should be stronger & lighter than stock. I would like to make them available with a BSA lifter cam kit for Nortons - but the aftermarket BSA lifter quality/availability is a problem at the moment - that leaves finding good used original BSA lifters for now.

Anyone have any?

Thundair - have you tested the beehive springs yet?

Jim

Re: Pushrod strength vs weight [Re: jim schmidt] #288054 12/09/09 1:52 pm
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Jim, what happens in the Triumph 650/750 alloy barrel kits from Triples Rule? Why should Norton's have alloy barrel pushrod problems and Triumphs don't. That's not fair.

And where are the A65 alloy barrel kits, there are a lot of them too. Not fair :>

Re: Pushrod strength vs weight [Re: Bodger] #288096 12/09/09 5:41 pm
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Triumphs & BSAs have shorter pushrods and that helps - less expansion. Alloy pushrods don't have the difference in expansion problem. Some racers use the steel pushrods and put up with the extra clearance they get when alloy cylinders heat up. Iron cylinders dont create that problem. Its a bunch of trade offs and Its really each to his own.

Re: Push rod strength vs weight [Re: Mark Parker] #664208 08/17/16 6:22 am
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[quote=Mark Parker]. My long stroke A65 I only want to spinn to 7,000 however it has around 5HP extra with C/molly pushrods and has std valve springs with only 170-180lb seat pressure at full lift and it needs to control the valves past 8,000 so as not to break things if I miss a gear,quote]

Mark,where do you get your C/molly pushrods ?

just to comment on this thread on beehive springs
the advantages - a straight spring will have harmonics
at a certain rpm that can cause breakage, the tapered
beehives don't have harmonics
beehives have smaller retainers -weight
one spring - lighter ,less spring pressure needed

Re: Push rod strength vs weight [Re: jim schmidt] #664212 08/17/16 6:59 am
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Hi Ken

I saw SRM were selling sets. There details are on the site some place.

regards

John

Re: Push rod strength vs weight [Re: jim schmidt] #664217 08/17/16 8:02 am
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I am using a set of SRM pushrods on mine at the moment, I also have a set from Ed V, Both nice sets! If you need specific length becasue of head/barrel skimming, have a chat with Ed.


beerchug
Re: Push rod strength vs weight [Re: Allan Gill] #664225 08/17/16 8:49 am
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I use Smith Bros moly steel push rods in my LSR Triumphs...6 inch rod is 40.5 grams and can handle spring pressures and RPM's far in excess of any vintage Triumph with zero flex..About $8.50 each with fast service..


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: Push rod strength vs weight [Re: jim schmidt] #664707 08/21/16 9:35 am
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Much appreciated fellas, using 750 barrels and head
so std length should be ok ,unless there is a better
length for rocker arm/valve contact with stock valve height

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