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Re: 5/16 pushrods with solid roller [Re: mshred] #1616164
05/05/14 10:20 PM
05/05/14 10:20 PM
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Charlotte, NC
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Use as much diameter and wall as you can stand, if the heads need clearanced then so be it, but if you won't do that then -

Double tapered 5/16"-11/32"-5/16" .120" wall and 5/16"-3/8"-5/16" .145" wall are available.

Wrap some tape on an old straight pushrod and mock up in the long block, keep adding tape until you notice interference, then back off on diameter about .020"-.030" or so at that interference point.

Re: 5/16 pushrods with solid roller [Re: LSP] #1616165
05/05/14 10:26 PM
05/05/14 10:26 PM
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mshred Offline OP
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Quote:

Use as much diameter and wall as you can stand, if the heads need clearanced then so be it, but if you won't do that then -

Double tapered 5/16"-11/32"-5/16" .120" wall and 5/16"-3/8"-5/16" .145" wall are available.

Wrap some tape on an old straight pushrod and mock up in the long block, keep adding tape until you notice interference, then back off on diameter about .020"-.030" or so at that interference point.




It has nothing to do with the holes in the head but the height of the lifter boss because I have a factory roller block.

Is double tapered stronger than no taper?

Re: 5/16 pushrods with solid roller [Re: D-50] #1616166
05/05/14 10:27 PM
05/05/14 10:27 PM
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mshred Offline OP
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Quote:

My intake and exhaust push rods are different lengths.




How much do they differ? I tried to make mine the same length, and with them the same length I get the same lift on both intake and exhaust (lobe lift is the same on intake and exhaust...I thought the different length might decrease lift on one or the other but they are the same )

Re: 5/16 pushrods with solid roller [Re: mshred] #1616167
05/05/14 10:39 PM
05/05/14 10:39 PM
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Charlotte, NC
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Quote:

Quote:

Use as much diameter and wall as you can stand, if the heads need clearanced then so be it, but if you won't do that then -

Double tapered 5/16"-11/32"-5/16" .120" wall and 5/16"-3/8"-5/16" .145" wall are available.

Wrap some tape on an old straight pushrod and mock up in the long block, keep adding tape until you notice interference, then back off on diameter about .020"-.030" or so at that interference point.




It has nothing to do with the holes in the head but the height of the lifter boss because I have a factory roller block.

Is double tapered stronger than no taper?




If talking like mid diameters the taper does not add strength, it only adds clearance.

Pushrods typically want to flex in the middle, that's where the column diameter and wall is needed most.

NASCAR guys use 9/16" pushrods with valve springs lighter than yours on opening and closing load. That should tell you all you need to know about how much pushrod strength means.

Re: 5/16 pushrods with solid roller [Re: mshred] #1616168
05/05/14 10:51 PM
05/05/14 10:51 PM
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PORT ORANGE FL.
gtea1901 Offline
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are you using ball to ball or ball to cup push rods


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Re: 5/16 pushrods with solid roller [Re: mshred] #1616169
05/05/14 10:52 PM
05/05/14 10:52 PM
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Posts: 1,267
North, Alabama
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Quote:

Quote:

My intake and exhaust push rods are different lengths.




How much do they differ? I tried to make mine the same length, and with them the same length I get the same lift on both intake and exhaust (lobe lift is the same on intake and exhaust...I thought the different length might decrease lift on one or the other but they are the same )




7.605/7.640 that is what I came up with.


1.33 60 ft,6.21 at 110.59 in the 1/8, pump gas small block,2950lbs,drag radials,mufflers and driven to track ...
Re: 5/16 pushrods with solid roller [Re: LSP] #1616170
05/06/14 12:29 AM
05/06/14 12:29 AM
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Toronto
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mshred Offline OP
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Quote:

Quote:

Quote:

Use as much diameter and wall as you can stand, if the heads need clearanced then so be it, but if you won't do that then -

Double tapered 5/16"-11/32"-5/16" .120" wall and 5/16"-3/8"-5/16" .145" wall are available.

Wrap some tape on an old straight pushrod and mock up in the long block, keep adding tape until you notice interference, then back off on diameter about .020"-.030" or so at that interference point.




It has nothing to do with the holes in the head but the height of the lifter boss because I have a factory roller block.

Is double tapered stronger than no taper?




If talking like mid diameters the taper does not add strength, it only adds clearance.

Pushrods typically want to flex in the middle, that's where the column diameter and wall is needed most.

NASCAR guys use 9/16" pushrods with valve springs lighter than yours on opening and closing load. That should tell you all you need to know about how much pushrod strength means.




Yea, I know that really one should try to fit as big of a pushrod in the motor as possible...My problem is that 5/16 is the biggest I can fit.

I read on either Manton or Smith Brothers web sight that they say tapered is stronger as it reduces harmonics or something to that effect, but not sure how true that is or if it has been proven. I would imagine if it was true everyone would run tapered pushrods

Re: 5/16 pushrods with solid roller [Re: gtea1901] #1616171
05/06/14 12:30 AM
05/06/14 12:30 AM
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mshred Offline OP
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Quote:

are you using ball to ball or ball to cup push rods




Ball ball...T&D rockers with 1.6 ratio and MRL solid roller lifters

Re: 5/16 pushrods with solid roller [Re: D-50] #1616172
05/06/14 12:31 AM
05/06/14 12:31 AM
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mshred Offline OP
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Quote:

Quote:

Quote:

My intake and exhaust push rods are different lengths.




How much do they differ? I tried to make mine the same length, and with them the same length I get the same lift on both intake and exhaust (lobe lift is the same on intake and exhaust...I thought the different length might decrease lift on one or the other but they are the same )




7.605/7.640 that is what I came up with.




So a .040" difference. Cool, thanks for sharing man!

Re: 5/16 pushrods with solid roller [Re: mshred] #1616173
05/06/14 09:04 AM
05/06/14 09:04 AM
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You do know you can clearance the lifter bore if you are so worried about it right?


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Re: 5/16 pushrods with solid roller [Re: Guitar Jones] #1616174
05/06/14 10:34 AM
05/06/14 10:34 AM
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PORT ORANGE FL.
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I make a one piece 3/8 .120 wall push rod that I can put a longer taper on the lifter end to clear.


stewardperformance.com
Re: 5/16 pushrods with solid roller [Re: gtea1901] #1616175
05/06/14 01:01 PM
05/06/14 01:01 PM
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Hilltown Pa
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Open up heads where pushrods go through. I ran 3/8 pushrods with my Indy 245s


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Re: 5/16 pushrods with solid roller [Re: Guitar Jones] #1616176
05/06/14 02:46 PM
05/06/14 02:46 PM
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Quote:

You do know you can clearance the lifter bore if you are so worried about it right?




I know lol...It's just the engine is already assembled and this would involve taking it ALL apart to do that so that I don't make a mess

Re: 5/16 pushrods with solid roller [Re: gtea1901] #1616177
05/06/14 02:46 PM
05/06/14 02:46 PM
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Quote:

I make a one piece 3/8 .120 wall push rod that I can put a longer taper on the lifter end to clear.




You make pushrods?

Re: 5/16 pushrods with solid roller [Re: 1967dartgt] #1616178
05/06/14 02:47 PM
05/06/14 02:47 PM
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Quote:

Open up heads where pushrods go through. I ran 3/8 pushrods with my Indy 245s




It's not the hole in the heads that is the problem, that I would do no problem. Its the lifter bosses in my block- they are taller as it is a factory roller block, so the clearance is very tight there

Re: 5/16 pushrods with solid roller [Re: mshred] #1616179
05/06/14 03:42 PM
05/06/14 03:42 PM
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Romeo MI
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Quote:

Quote:

Open up heads where pushrods go through. I ran 3/8 pushrods with my Indy 245s




It's not the hole in the heads that is the problem, that I would do no problem. Its the lifter bosses in my block- they are taller as it is a factory roller block, so the clearance is very tight there




Is the engine still on the stand... if so.. pull it
apart and make it right

Re: 5/16 pushrods with solid roller [Re: MR_P_BODY] #1616180
05/06/14 04:04 PM
05/06/14 04:04 PM
Joined: Nov 2004
Posts: 89
PORT ORANGE FL.
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Yes I do check me out at stewardperformance.com


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Re: 5/16 pushrods with solid roller [Re: gtea1901] #1616181
05/06/14 09:07 PM
05/06/14 09:07 PM
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In general, a tapered pushrod should be more expensive and difficult to make, so that could be why some aren't running them.
However, making the pushrod larger diameter in the middle will make it stiffer than if it is the same smaller diameter for its entire length. It will also help the harmonics, that is true. So, it's better all around.

A smaller diameter pushrod needs to be quite thick, and it doesn't get weaker as you make the wall thickness larger. But the last 25% or so of the diameter (the part in the exact center)does very little to increase resoistance to bending, which is what you're really after. So on a 5/16" pushrod, any wall thickness over 0.117" isn't adding appreciably to the strength, just the weight.

The statement above that pushrods need to be as large a diameter as you can fit is right on. It's in the Strengths of Materials book under "columnar loading".

Some years ago, Subaru switched to overhead cams from pushrods. The design of the Subaru engine makes for extremely long pushrods. They used exactly the same camshaft profile from pushrod to OHC, and gained quite a bit of power. This was attributed to lack of pushrod flex getting the valves to open much closer to the camshaft specs.

R.

Re: 5/16 pushrods with solid roller [Re: dogdays] #1616182
05/06/14 10:58 PM
05/06/14 10:58 PM
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Portage,michigan
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Quote:

In general, a tapered pushrod should be more expensive and difficult to make, so that could be why some aren't running them.
However, making the pushrod larger diameter in the middle will make it stiffer than if it is the same smaller diameter for its entire length. It will also help the harmonics, that is true. So, it's better all around.

A smaller diameter pushrod needs to be quite thick, and it doesn't get weaker as you make the wall thickness larger. But the last 25% or so of the diameter (the part in the exact center)does very little to increase resoistance to bending, which is what you're really after. So on a 5/16" pushrod, any wall thickness over 0.117" isn't adding appreciably to the strength, just the weight.

The statement above that pushrods need to be as large a diameter as you can fit is right on. It's in the Strengths of Materials book under "columnar loading".

Some years ago, Subaru switched to overhead cams from pushrods. The design of the Subaru engine makes for extremely long pushrods. They used exactly the same camshaft profile from pushrod to OHC, and gained quite a bit of power. This was attributed to lack of pushrod flex getting the valves to open much closer to the camshaft specs.

R.




Well stated and right on.
When Best Machine built my old 422w5 motor Chuck Millen gave me a great lecture about using as big a pushrod as will fit. With my X block we used 3/8 on intakes and 7/16 on the exhaust.
That motor was built circa 2004 and is still campaigned by the current owner. It has seen hundreds of 7500 rpm laps and never any pushrod issues, ever
Those same Manton's specced at the above diameters are still in the motor.

Regards the OP, we're it me, I wouldn't use a 5/16 pushrod in a roller with significant spring pressure. Probably would not have used that block that so limits your choices.
Might get away with it, but, IMO, that is tan extremely weak link. And weak links generally rear they're heads at some point.


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Re: 5/16 pushrods with solid roller [Re: B3422W5] #1616183
05/06/14 11:25 PM
05/06/14 11:25 PM
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Romeo MI
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Well stated and right on.
When Best Machine built my old 422w5 motor Chuck Millen gave me a great lecture about using as big a pushrod as will fit. With my X block we used 3/8 on intakes and 7/16 on the exhaust.
That motor was built circa 2004 and is still campaigned by the current owner. It has seen hundreds of 7500 rpm laps and never any pushrod issues, ever
Those same Manton's specced at the above diameters are still in the motor.

Regards the OP, we're it me, I wouldn't use a 5/16 pushrod in a roller with significant spring pressure. Probably would not have used that block that so limits your choices.
Might get away with it, but, IMO, that is tan extremely weak link. And weak links generally rear they're heads at some point.




I wouldnt recommend a 5/16 if a 3/8 cant be fitted
in the area but I HAD to go 5/16 due to the area..
I messed up by not getting offset intake lifters but
so far the 5/16 are working fine to 7400 rpm and that
might be going up

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