You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Measuring Compression Ratio
- Thread starter Ducvelo
- Start date
As long as we are in this area of the Vincent I doubt it can not be agreed the the stock rocker bush retaining method was one of the wost designs in history.... not to mention the bush itself was cheap crap. So the "solution" became the locking rocker nut. Now how anyone
can expect a solid mount by drawing the bush up into an out of round and tapered grove in the rocker tunnel is beyond me. The lost pushrod to spring motion is noticeable and your loss of valve lift depends on how badly the worn radius in the tunnel grove allows the
bush to move. I made the rocker arm solid as a rock by enlarging the tunnel for a rocker retaining device using large needle bearings and the rocker slit proceeds open to the top where there is a 45 degree angle into which a stainless steel wedge fits. the old rocker feed is
now threaded completely through to the tunnel .... a special bolt compresses the wedge and expands the rocker retainer to an almost 360 degree dead tight fit with the entire tunnel wall. You couldn't move it with a Mack truck.... and now there is no lost valve motion.
can expect a solid mount by drawing the bush up into an out of round and tapered grove in the rocker tunnel is beyond me. The lost pushrod to spring motion is noticeable and your loss of valve lift depends on how badly the worn radius in the tunnel grove allows the
bush to move. I made the rocker arm solid as a rock by enlarging the tunnel for a rocker retaining device using large needle bearings and the rocker slit proceeds open to the top where there is a 45 degree angle into which a stainless steel wedge fits. the old rocker feed is
now threaded completely through to the tunnel .... a special bolt compresses the wedge and expands the rocker retainer to an almost 360 degree dead tight fit with the entire tunnel wall. You couldn't move it with a Mack truck.... and now there is no lost valve motion.
Last edited:
No they weren't as the ceramic fusion had not been invented yet. (Concerning Gunga Din)
I forgot to add, Ampco-45 bronze.... the baddest Ni,Al.chrome bronze there is, didn't exist in Gunga Din's time either.... and if it did the Vincent Works wouldn't have paid for it anyway.
A mixed bag of comments follows . First of all please let's not lose sight that Vincents were bravely producing the best and fastest motorcycle in the world with the coming of the Series B Rapide . Period . This wonder in spite of ever being in debt , near collapse . Pretty damn good I'd say . Irving got his sums damn near perfect under these conditions and limitations . A hero to us all .
The original rocker bush layout went huge mileages for many riders at crusing speeds beyond the reach of all other bikes . And replacement bushes were dirt cheap . And rarely failed or mentioned as poor design in the books .
The described system is near Rube Goldburg in its complexity , to my way of thinking way overdone . My own mod in this department was dead easy , cost little and elevated revs while operating near silently . And proven solidly reliable on the drag strip for three years without one failure . Ran it in my street Shadow too with all of the improvements noted above . In my mod the rocker pIn
, slightly larger and a light press in the alloy bush didn't move , while the freed rocker now bushed with oillite rocked freely about the stationary pin . A steady flow of oil reached both sides of the bush , quite easily done , and thus wear was eliminated . Oillite retaining oil never has a dry start . Think about it .
The earlier drag on the alloy bush now eliminated had it lay quietly in the tunnel so that wear in the head ceased .
This system proved faultless at revs up to 7,500 and won many trophies , as well as being trouble free on the road at all speeds , rarely ever needing adjustment or examination . Perfect . Silent running too . And easily acheved for pennies . Sid .
The original rocker bush layout went huge mileages for many riders at crusing speeds beyond the reach of all other bikes . And replacement bushes were dirt cheap . And rarely failed or mentioned as poor design in the books .
The described system is near Rube Goldburg in its complexity , to my way of thinking way overdone . My own mod in this department was dead easy , cost little and elevated revs while operating near silently . And proven solidly reliable on the drag strip for three years without one failure . Ran it in my street Shadow too with all of the improvements noted above . In my mod the rocker pIn
, slightly larger and a light press in the alloy bush didn't move , while the freed rocker now bushed with oillite rocked freely about the stationary pin . A steady flow of oil reached both sides of the bush , quite easily done , and thus wear was eliminated . Oillite retaining oil never has a dry start . Think about it .
The earlier drag on the alloy bush now eliminated had it lay quietly in the tunnel so that wear in the head ceased .
This system proved faultless at revs up to 7,500 and won many trophies , as well as being trouble free on the road at all speeds , rarely ever needing adjustment or examination . Perfect . Silent running too . And easily acheved for pennies . Sid .
The oiling system is simplicity itself . The two oil drillings in the alloy bush are cleared out with a drill bit . Now a tiny rotary burr
In your Dremel tool is used to create a small trench from each side of the inner oil feed holes , coming in from the opposite side for each , these allow the oil to gush against both sides of the bush in the rocker bore . Takes but moments . The edges of the bush are eased back to easily accept the incoming oil .
The stationary pin now seals off the original flow against it while the new short trenches direct the flow towards the bushed rocker . All is rosy .
So still does the alloy bush lay that it soon sticks up in the light burnt oil deposit , so motionless it gets ever quieter . Sid .
In your Dremel tool is used to create a small trench from each side of the inner oil feed holes , coming in from the opposite side for each , these allow the oil to gush against both sides of the bush in the rocker bore . Takes but moments . The edges of the bush are eased back to easily accept the incoming oil .
The stationary pin now seals off the original flow against it while the new short trenches direct the flow towards the bushed rocker . All is rosy .
So still does the alloy bush lay that it soon sticks up in the light burnt oil deposit , so motionless it gets ever quieter . Sid .
There's a bunch of people wanting specific details concerning why this bike goes fast...... removing lots of little losses can add up to one big gain. So now we know having the valves following the cams at 100% adds a bit of power.
As far as that other set up goes you couldn't mean wearing deep grooves where grooves shouldn't be is a fine design feature? Maybe if you rode long enough the rocker would pop out of the top of the head! The only heads I've seen without rocker
tunnel DAMAGE were new heads. My usual fix was sleeving the tunnel with bronze.... it is now true and round. Choosing a tight fitting bush and rocker lock nut and now the assembly can pass as a good repair
I have yet to hear that flexing in the valve train was a good thing. Now if I get in the mood I may speak of the special Russian submarine developed titanium push rods and custom light weight adjusters
As far as that other set up goes you couldn't mean wearing deep grooves where grooves shouldn't be is a fine design feature? Maybe if you rode long enough the rocker would pop out of the top of the head! The only heads I've seen without rocker
tunnel DAMAGE were new heads. My usual fix was sleeving the tunnel with bronze.... it is now true and round. Choosing a tight fitting bush and rocker lock nut and now the assembly can pass as a good repair
I have yet to hear that flexing in the valve train was a good thing. Now if I get in the mood I may speak of the special Russian submarine developed titanium push rods and custom light weight adjusters
Last edited:
No wear occurs . The small grooves connect the existing feed holes inwards to reach both sides of the rocker , very short distance . Had no ill effects , went faster because the reciprocating weight of the pin is eliminated , they sit still . The rocker itself only moves . I used Royal Enfield 125 pins , a thou . larger in diameter than Vincent pins for the new pins . Be sure the new pins do NOT protrude past the alloy bush sides , make then slightly shorter , and nicely round off it's edges so they can't dig into the tunnel wall . Really it worked marvelously well and the benefits are as described . Our race twin Lola has this set up .
Perhaps Rips system likewise was an improvement , I've no personal knowledge of that , but this method was my own creation , among many , and did exactly as I thought it would and without machining skills or much outlay . Sid .
Perhaps Rips system likewise was an improvement , I've no personal knowledge of that , but this method was my own creation , among many , and did exactly as I thought it would and without machining skills or much outlay . Sid .
Sid, I am talking about the wear to the rocker tunnel ...... not grooves in a stock rocker bush.
Last edited:
As for pushrods I tried a set of alloy rods with pressed in steel ball ends , light as a feather . Still have one of them 55 years later ! Had one ball peg break off so went back to the original rods . I've heard that one piece pushrods made from a modern hard alloy , 7071 ? , work fine , the ball ends integral . The cups in the followers are often undersized or rough so be aware of that and deal with it . Sid .