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QRP
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Joined: April 27, 2008
Posts: 1712
Location: NORTH HOLLYWOOD,CA
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 Posted: Wed Mar 03, 2021 12:17 pm Post subject: The weigh-in? chromoly vs HD aluminium? |
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Like the post says.
What's the weight difference between chromoly vs HD aluminum pushrods?
I know there is a lotta variables as to what brand or wall thickness . . etc. etc.
A roundabout average is what I'm looking for.
Since I'm on the subject of weight, why can't "ALL" companies that offer light weight lifters give a specific weight of the so called light weight lifter . . . that is super annoying. |
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Dan Ruddock
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Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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Ohio Tom
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Joined: February 09, 2006
Posts: 1660
Location: Marshallville Ohio
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| Posted: Wed Mar 03, 2021 1:50 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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I have seen HD aluminum PR's yield (the tip pushes in and mushrooms the aluminum). They certainly have their limits.
The only place I can see for HD aluminum is a mild (ramp) cam application with mild springs.
But hey, that's how they did them back in the early days.
They made cams with really soft ramps that would allow the use of soft springs and stock pushrods.
I feel like we need more cam grinds like this now-a-days.
Folks want a high revving motor, but don't want the hassle of top end services. Someone needs to offer a special line of cams that will work with light springs and pushrods.
i.e.: a Quite cam.
One of the oldest performance motors I have worked on had a cam with 318deg duration and only .350" valve lift.
Stock pushrods and shimmed up stock springs. Stock valve heads with dual Solex 40-P11's.
Believe it or not, that thing would rev up and not complain one bit.
Great road racing motor that could rev up all day long for years. |
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UK Luke 72
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Joined: September 07, 2011
Posts: 2867
Location: Little Britain
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| Posted: Wed Mar 03, 2021 1:54 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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| Ohio Tom wrote: |
I have seen HD aluminum PR's yield (the tip pushes in and mushrooms the aluminum). They certainly have their limits.
The only place I can see for HD aluminum is a mild (ramp) cam application with mild springs.
But hey, that's how they did them back in the early days.
They made cams with really soft ramps that would allow the use of soft springs and stock pushrods.
I feel like we need more cam grinds like this now-a-days.
Folks want a high revving motor, but don't want the hassle of top end services. Someone needs to offer a special line of cams that will work with light springs and pushrods.
i.e.: a Quite cam.
One of the oldest performance motors I have worked on had a cam with 318deg duration and only .350" valve lift.
Stock pushrods and shimmed up stock springs. Stock valve heads with dual Solex 40-P11's.
Believe it or not, that thing would rev up and not complain one bit.
Great road racing motor that could rev up all day long for years. |
Have you seen the Webcams Dan Ruddock has ground?
86/86b with added duration for exactly this purpose I believe.
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Dan Ruddock
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Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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| Posted: Wed Mar 03, 2021 2:03 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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You can have a cam that is noisy as hell with mild main lift ramps and a cam that is quiet with harsh beat to hell main lift ramps. The first .015" of lifter movement is what determines how much valve noise you get and after that the rest of the profile can be very harsh or mild. Seen cams both ways.
Last edited by Dan Ruddock on Wed Mar 03, 2021 2:16 pm; edited 1 time in total |
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Dan Ruddock
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Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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| Posted: Wed Mar 03, 2021 2:15 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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| UK Luke 72 wrote: |
| Ohio Tom wrote: |
I have seen HD aluminum PR's yield (the tip pushes in and mushrooms the aluminum). They certainly have their limits.
The only place I can see for HD aluminum is a mild (ramp) cam application with mild springs.
But hey, that's how they did them back in the early days.
They made cams with really soft ramps that would allow the use of soft springs and stock pushrods.
I feel like we need more cam grinds like this now-a-days.
Folks want a high revving motor, but don't want the hassle of top end services. Someone needs to offer a special line of cams that will work with light springs and pushrods.
i.e.: a Quite cam.
One of the oldest performance motors I have worked on had a cam with 318deg duration and only .350" valve lift.
Stock pushrods and shimmed up stock springs. Stock valve heads with dual Solex 40-P11's.
Believe it or not, that thing would rev up and not complain one bit.
Great road racing motor that could rev up all day long for years. |
Have you seen the Webcams Dan Ruddock has ground?
86/86b with added duration for exactly this purpose I believe. |
Yes you are correct, an 86 +3 would have about 240 @.050" and if used with 1.3 rockers would be a very quiet, durable, and gentile combo and you could run berg HD singles with berg retainers. |
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QRP
Samba Member
Joined: April 27, 2008
Posts: 1712
Location: NORTH HOLLYWOOD,CA
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| Posted: Wed Mar 03, 2021 2:25 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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I wouldn't say I'm obsessed with weight but for a current
project / experiment it is at the top of my list.
It's very refreshing that you include all this information in your ads.
Thank you for that.
For years I've always gone with heavy duty everything. This time I'm going in the opposite direction. |
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Dan Ruddock
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Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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| Posted: Wed Mar 03, 2021 2:37 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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| QRP wrote: |
I wouldn't say I'm obsessed with weight but for a current
project / experiment it is at the top of my list.
It's very refreshing that you include all this information in your ads.
Thank you for that.
For years I've always gone with heavy duty everything. This time I'm going in the opposite direction. |
Like to know what the use and what the combo will be. |
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Alstrup
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Location: Videbaek Denmark
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| Posted: Wed Mar 03, 2021 2:37 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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The aluminium push rod issue is just as much rpm related as spring tension related. If the engine regularly sees 6000+ rpm I would recommend going taper PRīs no matter if you use HD sgl or dual springs. The only exception toi that would be if the entire valve train is light weight, and spring pressure at no more than 250 @ 1"
I have a high power 2165 engine out that has TP 60 gr. lifters, thickwalled 3/8" aluminum PRīs, Cryo enchanced Oteva S75 springs w. 240 lbs@ 1" and Ti retainers. It is bumped with a Web 86C ground on a slightly fatter lobe. It hits the limiter at 7200 and sees 7 grand quite often. There is no signs of stress or flex after 3 seasons. So I consider that OK.
It is correct that with more ratio on the rocker arms the weight of the lifter becomes less important, but not so much less that you can just throw "anything" in there. The lesser the weight the lesser "rigid" the rest of the valve train needs to be. Apart from that I agree with what Dan said.
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ekacpuc
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Joined: December 08, 2010
Posts: 1414
Location: ketchikan alaska
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| Posted: Wed Mar 03, 2021 4:44 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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In my search someone pointed out the lifter and pushrod dont travel as much as the rocker side of things (retainers and valves) so its better to reduce weight on the rocker end. By all means reduce weight where you can of course.
I went with beehives this round. I like the light retainer, lighter pressure on spring. Also matched it with a web 252 (266 @ .050 version) from Dan. Also using CB 1.4 rockers.
Havent put motor together yet.
I did see some wear on CB HD pushrods using dual vw springs, web 163 and 1.25 rockers. I didnt see such wear using the ACN pushrods.
Just some thoughts.. pushrods are easy to change. Im starting light/quiet and if I see wear from flex Ill goto chromoly but I dont think I will.
Last edited by ekacpuc on Wed Mar 03, 2021 4:47 pm; edited 1 time in total |
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raygreenwood
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Posts: 21520
Location: Oklahoma City
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| Posted: Wed Mar 03, 2021 4:47 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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| Alstrup wrote: |
The aluminium push rod issue is just as much rpm related as spring tension related. If the engine regularly sees 6000+ rpm I would recommend going taper PRīs no matter if you use HD sgl or dual springs. The only exception toi that would be if the entire valve train is light weight, and spring pressure at no more than 250 @ 1"
I have a high power 2165 engine out that has TP 60 gr. lifters, thickwalled 3/8" aluminum PRīs, Cryo enchanced Oteva S75 springs w. 240 lbs@ 1" and Ti retainers. It is bumped with a Web 86C ground on a slightly fatter lobe. It hits the limiter at 7200 and sees 7 grand quite often. There is no signs of stress or flex after 3 seasons. So I consider that OK.
It is correct that with more ratio on the rocker arms the weight of the lifter becomes less important, but not so much less that you can just throw "anything" in there. The lesser the weight the lesser "rigid" the rest of the valve train needs to be. Apart from that I agree with what Dan said. |
So.....based on your experience and Dan ruddocks comments and Ohio Toms comments....to the three of you....what in your mind constitutes an HD aluminum pushrod?
Is it diameter and wall thickness?
Example: type 4 pushrods are something like 12mm in diameter and an ID of only about 1/4 of that. Hard to mushroom....but at,some point you get flex.
Or......is it alloy? There is a huge difference in hardness and stiffness between something like a 6061 and 7030.
Or is it treatment and structural design?.....meaning is the alloy post production hardened and or....is the shape structured for strength like the tapered pushrod?
Or some of all of the above?
Ray |
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Alstrup
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| Posted: Wed Mar 03, 2021 5:33 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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Sadly I for one do not know enough about metal and treatments, but I would say all of the above. The combinations I refer to are tested and found bad, ok or good.
The type 4 PRīs are crazy strong, but they cant handle much lift. Thatīs why they do not get reused more in the type 4 world
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jimmyhoffa
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Joined: February 16, 2014
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| Posted: Wed Mar 03, 2021 5:50 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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Ekacpuc what sort of wear did you see on those CB hd pushrods?
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Dan Ruddock
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Joined: October 25, 2012
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Location: Sarasota, in my adopted state of Florida
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| Posted: Wed Mar 03, 2021 5:56 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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| Alstrup wrote: |
Sadly I for one do not know enough about metal and treatments, but I would say all of the above. The combinations I refer to are tested and found bad, ok or good.
The type 4 PRīs are crazy strong, but they cant handle much lift. Thatīs why they do not get reused more in the type 4 world |
I used t4 prs in a t1 engine with .575 lift back in the early 90s. I removed the stock ends and put full ball ends on, stollen from a set of cm pushrods. Worked fantastic, quietest performance valve train I have ever heard. Used waterboxer big mouth tubes. Bugguy1967 is doing the same thing right now after I told him about the idea. I will post a pic of one of the pushrods. |
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raygreenwood
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| Posted: Wed Mar 03, 2021 6:11 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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| Dan Ruddock wrote: |
| Alstrup wrote: |
Sadly I for one do not know enough about metal and treatments, but I would say all of the above. The combinations I refer to are tested and found bad, ok or good.
The type 4 PRīs are crazy strong, but they cant handle much lift. Thatīs why they do not get reused more in the type 4 world |
I used t4 prs in a t1 engine with .575 lift back in the early 90s. I removed the stock ends and put full ball ends on, stollen from a set of cm pushrods. Worked fantastic, quietest performance valve train I have ever heard. Used waterboxer big mouth tubes. Bugguy1967 is doing the same thing right now after I told him about the idea. I will post a pic of one of the pushrods. |
Cool!
Most of the type 4 cam kits come with custom cut to length chromoly PR kits. Strong...yes. but also will never be as quiet. And....never quite as tightly adjusted as I can get with the stock type 4 for runnning stock D-jet (I adjust my valves hot to minimum hot lash setting).
So for something just a bit hotter than stock but still "stockish".....web 73 or Raby 9550/9590 cam, stock 66mm stroke, 42 x36 valves and about 8.5:1 compression and single HD-ish springs......I really could just get away with stock type 4 PR's.....if the length/geometry is correct?
Ray |
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ekacpuc
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Joined: December 08, 2010
Posts: 1414
Location: ketchikan alaska
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| Posted: Wed Mar 03, 2021 6:12 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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| jimmyhoffa wrote: |
| Ekacpuc what sort of wear did you see on those CB hd pushrods? |
When I go home for break Ill see if I can find one and post a pic. Was your typical ring around the shaft from the pushrod flexing/deflecting. |
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Dan Ruddock
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Location: Sarasota, in my adopted state of Florida
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| Posted: Wed Mar 03, 2021 6:16 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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| The ball ends added extra length over the stock ends. |
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bugguy1967
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| Posted: Wed Mar 03, 2021 6:27 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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| Alstrup wrote: |
Sadly I for one do not know enough about metal and treatments, but I would say all of the above. The combinations I refer to are tested and found bad, ok or good.
The type 4 PRīs are crazy strong, but they cant handle much lift. Thatīs why they do not get reused more in the type 4 world |
[youtube]
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bugguy1967
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| Posted: Wed Mar 03, 2021 6:31 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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For the OP: 88-100 grams versus 55g. The lightest I have gotten aluminum dual tapers was 40g. The narrower you build your engine, the stronger your pushrods become.
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Alstrup
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| Posted: Wed Mar 03, 2021 6:38 pm Post subject: Re: The weigh-in? chromoly vs HD aluminium? |
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Dang Bugguy. Thatīs nice. Good idea Dan. I never went in that direction due to lack of tips. Might wanna look into that.
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