What are the advantage's of fancy pancy pushrods?

Status
Not open for further replies.
jimbo

jimbo

VIP MEMBER
Joined
Sep 25, 2004
Messages
1,926
Country flag

Attachments

  • What are the advantage's of fancy pancy pushrods?
    norton pushrods 2.jpg
    66.9 KB · Views: 1,180
  • What are the advantage's of fancy pancy pushrods?
    norton pushrods.jpg
    170.6 KB · Views: 1,102
  • What are the advantage's of fancy pancy pushrods?
    norton pushrods 3.jpg
    658 KB · Views: 1,239
jimbo said:
What are the advantage's of fancy pancy pushrods? I would think the stockers are stiff and light enough?
Click to expand...
These stockers (top picture, used up to 1974) are hollow and indeed light enough however the MK3 stockers (up from 1975) are solid and therefor heavier :roll:
 
Not much point in pushrods that save a few grams when the lifters and springs weigh so much - thats where you can save much more reciprocating weight and reduce wear on the valve train.
 
In my case the advantage is they are the correct length , otherwise I'm all for going with stock push rods on stock motors. Then again why buy expensive fancy pancy anything for a forty odd year old bike to run on the street but lots of us do just that cos we think it might make it better, get another 1/2 a hp when you can buy a missile for a grand and a half. We must be crazy!!!

Ohh next on the list fancy pancy carbs....... how much ? Maybe after the summer!

Jg
 
nortonspeed said:
jimbo said:
What are the advantage's of fancy pancy pushrods? I would think the stockers are stiff and light enough?
Click to expand...
These stockers (top picture, used up to 1974) are hollow and indeed light enough however the MK3 stockers (up from 1975) are solid and therefor heavier :roll:
Click to expand...

None of my Mk3 engines had solid pushrods, however I have seen some solid replacement pushrods that look like stock but weigh a ton. Jim
 
comnoz said:
nortonspeed said:
jimbo said:
What are the advantage's of fancy pancy pushrods? I would think the stockers are stiff and light enough?
Click to expand...
These stockers (top picture, used up to 1974) are hollow and indeed light enough however the MK3 stockers (up from 1975) are solid and therefor heavier :roll:
Click to expand...

None of my Mk3 engines had solid pushrods, however I have seen some solid replacement pushrods that look like stock but weigh a ton. Jim
Click to expand...
so what is your take on the diffs on all the p rods? :D
 
comnoz said:
nortonspeed said:
jimbo said:
What are the advantage's of fancy pancy pushrods? I would think the stockers are stiff and light enough?
Click to expand...
These stockers (top picture, used up to 1974) are hollow and indeed light enough however the MK3 stockers (up from 1975) are solid and therefor heavier :roll:
Click to expand...

None of my Mk3 engines had solid pushrods, however I have seen some solid replacement pushrods that look like stock but weigh a ton. Jim
Click to expand...


As far as I know Norton started using solid pushrods from (late?) MK3 :?
Definitely all new stock pushrods are solid http://www.rgmnorton.co.uk/buy/exhaust- ... do_120.htm
 
I avoid revving my 850 above 7,000 RPM and I use the standard cam. So I have never bothered to lighten the valve train.
 
i used to use maney steel pushrods because i believed the std ones flexed and so compromised the valve timing
the maney steel ones have the same weight as the std ones , the ones from rgm weigh a ton
the info about the flexing of alloy pushrods came from peter williams who strobed them at 5000rpm
if you lighten the valve gear and set valve spring pressure , then steel pushrods makes it worth while
i never expierenced valvefloat ,even on the spint to the line , so it cannot be bad
 
jimbo said:
Jim
Click to expand...
so what is your take on the diffs on all the p rods? :D[/quote]


Well, I have used high speed photography on several sets of pushrods. I have not seen any big problems with flex on any of them.

I would not use the solid aluminum pushrods due to the weight.

I generally use aluminum pushrods in my builds.

I have Maney steel pushrods in my streetbike right now. [just because they were laying around] They are light and work fine.

I don't use anything but aluminum pushrods with an aluminum barrel. I do not like the large increase in clearance when using steel pushrods with aluminum barrels.
 
lynxnsu said:
the maney steel ones have the same weight as the std ones , the ones from rgm weigh a ton
Click to expand...

Which std ones weigh the same as steel Maney pushrods, std pre 1975 (hollow) or post 1975 (solid) :?:

FYI weight inl.rod pre 1975 = 34gr and post 1975 = 46gr
weight ex.rod pre 1975 = 30gr and post 1975 = 41gr

Btw the ones from RGM ( http://www.rgmnorton.co.uk/buy/exhaust- ... do_120.htm ) are std AN rods :!:
 
A 650 Triumph motor with full race cams and standard valve gear will rev safely to 8,000 RPM without tangling the valves . Norton Commandos don't ever use full race cams, and are not revved over 7,000 RPM. So the valve gear goes nowhere near tangling because of the inertia of the bits. With my 850, I have not even lightened and polished the rockers. The only advantage in doing that might be to stop valve float when the springs start to collapse due to age.
 
Acotrel, depends on what you consider to be "full race cams" and plenty of owners are using PW3 cams and the like. "Never rev above 7000" ??? Triumph 650 push rods are particularly short so are less likely to bend/flex. I'm sure your Triumph experience is extensive as you are always comparing them to the Commando. You may be unlikely to "tangle" valves but they surely will kiss the piston if you're not careful and lightened valve gear would be a good idea in this case. IMHO
 
If you have the standard iron barrel and use Maney steel pushrods with a PW3 cam would it allow use to reduce the valve clearance in order to reduce the noise. Or is the clearance for more than just different rates of expansion of valve train components.?
Obviously any change in clearance may effect the valve timing and may require its adjustment also.
 
I have used clearance down to .003" and its fine with hard valve seats on the exhaust that don't eat away (alum cylinders with alum pushrods).

As far as I can tell - flexing and bending is not a problem with alum pushrods in a Norton. I suspect this is false info that keeps being repeated over and over again. The tests I have made show that steel pushrods of the same weight as aluminum pushrods buckle and bend before the aluminum pushrods do - some people tell me otherwise and show me data on paper but real world testing tells a different story. I have never seen the alum pushrods fail and I have revved them into valve float range with dual racing springs many times (when I was roadracing). I use stronger aircraft alum tubing now.
 
maybe the steel p rods would be needed with this cam? :shock:

http://www.ebay.com/itm/Norton-Commando ... 3V&vxp=mtr

Specifications
•Duration: 276 degrees @ .040 - L.L. .388" - Cam lift at TCC 168" intake. 145" exhaust
•Timing: 36btc/64abc (in); 64bbc/32atc (ex) - lash .016" in. .016"ex
•Timing at .40" cam lift with stock lifter
•Lobe center 104 degrees (intake) 106 degrees (exhaust)
 
toppy said:
If you have the standard iron barrel and use Maney steel pushrods with a PW3 cam would it allow use to reduce the valve clearance in order to reduce the noise. Or is the clearance for more than just different rates of expansion of valve train components.?
Obviously any change in clearance may effect the valve timing and may require its adjustment also.
Click to expand...

If you use that set up, as I have, I called Steve and he advised me to reduce the clearance by half, that is to 5 1/2 thou.

You don't do it to reduce noise, though it might, but rather to set a correct clearance based on the combined expansion rates of all components and it differs simply because the steel rods expand less than the alloy ones.
 
jimbo said:
maybe the steel p rods would be needed with this cam? :shock:

http://www.ebay.com/itm/Norton-Commando ... 3V&vxp=mtr

Specifications
•Duration: 276 degrees @ .040 - L.L. .388" - Cam lift at TCC 168" intake. 145" exhaust
•Timing: 36btc/64abc (in); 64bbc/32atc (ex) - lash .016" in. .016"ex
•Timing at .40" cam lift with stock lifter
•Lobe center 104 degrees (intake) 106 degrees (exhaust)
Click to expand...

No more than with another......it is a 4S, nothing 'exotic'
 
SteveA said:
You don't do it to reduce noise, though it might, but rather to set a correct clearance based on the combined expansion rates of all components and it differs simply because the steel rods expand less than the alloy ones.
Click to expand...

I was going to get some last time I had the head off to but as i was removing the head an base gaskets to increase compression (JS 3thou head gasket now used) as an experiment to see if improved the motors performance (it did) i was unsure of the length of rods needed. My rods are around 0.030" shorter than standard (done before my ownership) and i was unsure if taking 0.052" out of the height of the engine assembly would mean further changes to length (seems to all be ok though). So i put them back as they were now the motor is running well an no leaks (yes i know it tempting fate to say things like that out loud :D ) so no reason to pull it apart just to change pushrods if by the general opinion there is little or no benefit to be had. I personally can't tell much change in tappet noise once the motor is up to temperature an i new the cam as know to be "louder" because of clearance it runs at so i may get some Maney parts if i remove the head in future but there will need to be an other reason to pull it apart
 
I used the kibble pushrods in my 750. It makes me feel good they are in there, but that is probably about it. I dont have anything to compare it to, but the bike flies and there is not much tappet noise (could be due to other things). It seemed easier to locate the pushrod ends when putting the head on.
 
Status
Not open for further replies.
Back
Top