5/16 pushrods with solid roller

Posted By: mshred

5/16 pushrods with solid roller - 05/05/14 05:08 AM

Can they be ran? What wall thickness is necessary? Solid roller that will see max of 7500rpms, and there is not enough clearance to the lifter bores for a 3/8 pushrod (A 3/8 will rub the lifter because of my offset intakes)...Is .105 wall sufficient? Do I need .120 wall?

Springs are 250 closed, 600 over the nose, and the pushrods are going to be 7.750" long

What do you guys use or what is safe to use?

Posted By: skrews

Re: 5/16 pushrods with solid roller - 05/05/14 05:18 AM

I had Smith Brothers make a set of 5/16 intake and 3/8 exhaust pushrods for my solid roller Indybrock headed motor. Had .712 lift with 245# seat 650# open. Would turn that motor 7300. No issues. Told them to give me the best they could on the intakes.

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/05/14 05:26 AM

Quote:

I had Smith Brothers make a set of 5/16 intake and 3/8 exhaust pushrods for my solid roller Indybrock headed motor. Had .712 lift with 245# seat 650# open. Would turn that motor 7300. No issues. Told them to give me the best they could on the intakes.

Any idea on the wall thickness of the 5/16 ones?

Posted By: skrews

Re: 5/16 pushrods with solid roller - 05/05/14 05:34 AM

Nope. Just told them I wanted the best on the intakes, although they are likely the same wall thickness intake and exhaust.

Posted By: Guitar Jones

Re: 5/16 pushrods with solid roller - 05/05/14 01:30 PM

I'm using Trend 5/16 pushrods in my engine .118 wall thickness IIRC.

Posted By: Triple Threat

Re: 5/16 pushrods with solid roller - 05/05/14 05:18 PM

Smith Brothers 5/16 .120 wall here. 275 on the seat, 600 open. Still going after 225 runs.

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/05/14 06:49 PM

So it looks like a .120" wall thickness 5/16 is probably the best way to go if forced to stay with that size.

Posted By: Streetwize

Re: 5/16 pushrods with solid roller - 05/05/14 06:57 PM

Manton makes a nice 11/32" pushrod.

Posted By: Leon441

Re: 5/16 pushrods with solid roller - 05/05/14 07:05 PM

Was just told about these thicker 5/16 push rods. You can buy a variety of stepped and tappered pushrods. If you know you lengths enter that number on eBay and you would be surprised what's out there cheap. I just got some 9/16 8.300 pushrods with long tapper and short tapper for about what you would pay for lash caps lol.

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/05/14 07:13 PM

Quote:

Manton makes a nice 11/32" pushrod.

I am not sure even the 11/32 stuff would fit. The 5/16 is already very close to touching the lifter bore

I have heard that too thick of a wall thickness on a small diameter pushrod can actually weaken the design...any truth to this?

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/05/14 09:39 PM

Quote:

Was just told about these thicker 5/16 push rods. You can buy a variety of stepped and tappered pushrods. If you know you lengths enter that number on eBay and you would be surprised what's out there cheap. I just got some 9/16 8.300 pushrods with long tapper and short tapper for about what you would pay for lash caps lol.

I will check that out!

Wondering if anyone runs less then .120" wall 5/16 stuff and if it works ok

Posted By: MR_P_BODY

Re: 5/16 pushrods with solid roller - 05/06/14 12:03 AM

Quote:

Smith Brothers 5/16 .120 wall here. 275 on the seat, 600 open. Still going after 225 runs.

Same set up here on my Rampage

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 12:13 AM

The nitrous is what slightly worries me about using such a small pushrod...for some reason I am having serious issues pulling the trigger on this- the 5/16 just makes me feel uncomfortable for some reason, but I have no choice at this point

Posted By: MR_P_BODY

Re: 5/16 pushrods with solid roller - 05/06/14 12:43 AM

Quote:

The nitrous is what slightly worries me about using such a small pushrod...for some reason I am having serious issues pulling the trigger on this- the 5/16 just makes me feel uncomfortable for some reason, but I have no choice at this point

Spring pressure is spring pressure.. if its strong
enough to hold the rev then the PR will

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 12:53 AM

Quote:

Quote:

The nitrous is what slightly worries me about using such a small pushrod...for some reason I am having serious issues pulling the trigger on this- the 5/16 just makes me feel uncomfortable for some reason, but I have no choice at this point

Spring pressure is spring pressure.. if its strong
enough to hold the rev then the PR will

True

I also wonder if my pushrod issue is because I have a factory roller block with a slightly larger lifter boss, or if everyone has the same issue with the Indy stuff?

Posted By: D-50

Re: 5/16 pushrods with solid roller - 05/06/14 01:12 AM

I am using 11/32 x .120 wall and I am running the 360-2 Indy heads. Mine are 7.605 and 7.640 length Manton pushrods.

Attached picture 8135232-I-22leaving(Small).jpeg

Attached picture 8135232-I-22leaving(Small).jpeg

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 01:20 AM

Quote:

I am using 11/32 x .120 wall and I am running the 360-2 Indy heads. Mine are 7.605 and 7.640 length Manton pushrods.

How close are the intake pushrods to the lifter bosses on your setup? Did you open up the pushrod holes in the heads at all to get that size to fit?

Posted By: D-50

Re: 5/16 pushrods with solid roller - 05/06/14 01:27 AM

I bought the heads used and ported by Brett Miller they were probably clearenced already. I do not remember how close they are to the lifter bosses. I am running a 1973 340 block.

Attached picture 8135249-CIMG0081.JPG

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 01:28 AM

Quote:

I bought the heads used and ported by Brett Miller they were probably clearenced already. I do not remember how close they are to the lifter bosses. I am running a 1973 340 block.

Cool. Are you also running different length intake and exhaust pushrods? or did you get the same length for each?

I hope that 5/16 will be sufficient...I just feel really uneasy about this lol

Posted By: D-50

Re: 5/16 pushrods with solid roller - 05/06/14 01:39 AM

My intake and exhaust push rods are different lengths.

Attached picture 8135258-CIMG0081.JPG

Posted By: LSP

Re: 5/16 pushrods with solid roller - 05/06/14 02:20 AM

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.

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 02:26 AM

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?

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 02:27 AM

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

)

Posted By: LSP

Re: 5/16 pushrods with solid roller - 05/06/14 02:39 AM

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.

Posted By: gtea1901

Re: 5/16 pushrods with solid roller - 05/06/14 02:51 AM

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

Posted By: D-50

Re: 5/16 pushrods with solid roller - 05/06/14 02:52 AM

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.

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 04:29 AM

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

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 04:30 AM

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

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 04:31 AM

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!

Posted By: Guitar Jones

Re: 5/16 pushrods with solid roller - 05/06/14 01:04 PM

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

Posted By: gtea1901

Re: 5/16 pushrods with solid roller - 05/06/14 02:34 PM

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

Posted By: 1967dartgt

Re: 5/16 pushrods with solid roller - 05/06/14 05:01 PM

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

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 06:46 PM

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

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 06:46 PM

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?

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/06/14 06:47 PM

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

Posted By: MR_P_BODY

Re: 5/16 pushrods with solid roller - 05/06/14 07:42 PM

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

Posted By: gtea1901

Re: 5/16 pushrods with solid roller - 05/06/14 08:04 PM

Yes I do check me out at stewardperformance.com

Posted By: dogdays

Re: 5/16 pushrods with solid roller - 05/07/14 01:07 AM

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.

Posted By: B3422W5

Re: 5/16 pushrods with solid roller - 05/07/14 02:58 AM

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.

Posted By: MR_P_BODY

Re: 5/16 pushrods with solid roller - 05/07/14 03:25 AM

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

Posted By: fishy340

Re: 5/16 pushrods with solid roller - 05/07/14 03:43 AM

Why go with 5/16 on a indy headed sb motor...kinda like 937 lifter's on a briggs n stratton motor..JMO

Posted By: mshred

Re: 5/16 pushrods with solid roller - 05/07/14 04:02 AM

Quote:

Yes I do check me out at stewardperformance.com

You have a pm!

And guys, I will say it again, it is not by choice that I am left with running 5/16 pushrods. Even if the holes in the head were to be opened up, I am limited by the hydraulic roller lifter boss. I had no idea this would be an issue with the offset intake, otherwise I might have rethought all of this.

I am going to look into getting a pushrod with a tapered end. Gotta be worth something over the 5/16" stuff.