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Basic roller rocker info, with photos 
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Post Basic roller rocker info, with photos
thanks to this forum and the great people here, I've learned a lot about these robust 240 and 300 engines. Some of the same basic questions come up over and over and it's nice to have a good resource to refer to.

Here, I am putting down some simple information regarding roller rockers, what they do, and fitment issues. These are oversized valves made for the 240 by SI Industries. They have stock length, stock 1/4" tips, and stock 1.7" spring height for the springs. The cam here is an Isky Mile-a-Mor, which has a 0.415" lift on the intake/exhaust. Lift on the stock cam is about 0.4" with a difference between the intake/exhaust.

Roller rockers can improve valve train functioning. Their main advantage to me, a simple daily driver guy that wants stepped up performance and economy compared to the OEM engine, is to reduce friction and increase longevity of the valve and valve guide. The only full aftermarket roller rocker that I know of still in production for the 240/300 is the Harland Sharp S4002, with a 1.6 ratio. That's the roller in the photos. Others have made BBChevy rollers work, and there are a number of ratios available. The geometry of the 300 head may be different than this early generation 240 head.

Friction is reduced by using needle bearings on the fulcrum point, and a roller tip on the valve stem. The roller tip allows the rocker to transfer force to the valve tip in a way that reduces side loading. The side loading of the valve stem in the valve guide increases friction and wears out the valve faster. Side loading occurs as the OEM rocker tip 'scrubs' across the valve tip.

Additional benefits, for the performance minded, are the ability to run high lift cam lobes and heavier spring loads, and maintain consistent functioning in the higher rpm range.

The geometry of the early 240 valve train is quite interesting. The lifter centers for a cylinder are approximately 2.07" apart. The pushrods maintain this 2.07" up and down motion via the use of built in valve guides. The following photo shows the general arrangement:

Image

Note the tight clearance between the pushrod and pushrod guides in the cylinder head. The pushrod can move freely in the plane of the valve, but not laterally. On the OEM rocker or roller rocker setup, there is only one orientation that the rocker can assume.

The the valve train in the 240 head is less than ideal--the valve stems are 1.9" apart on the same cylinder. Since the pushrod only goes up and down (no lateral movement), there is a 'scrubbing' that takes place between the valve stem and the rocker tip to absorb the side movement. The after market roller reduces the scrubbing--much like how a tire has less 'scrubbing' when a steering wheel is turned at 5mph than when at a standstill.

Here's a photo of how the Harland Sharp 4002 roller rocker and OEM rocker sit on the stock valve height/spring setup. Note how the roller shows a definite off-center in the front and back sense. In subsequent photos, note how the roller also has an off-center in the side to side sense. Naturally, this will vary somewhat according to the cam and rocker ratio.

Image

Note also how this photo show the approximately 7/16" height difference between the OEM and Harland Sharp Ford 240/300 roller. It's this adjusting nut on the top of the rocker that creates valve cover interference with the stock cover. The lock itself is inside the adjusting nut.

This photo shows the valve at rest. The roller should start off-center.

Image

At full compression, the roller should pass through center and be fairly close to center. This is the point of peak spring tension and the roller should not be too far off center.

Image

John in Fresno


Last edited by 66 E100 Pickup on Mon Jan 14, 2008 6:35 pm, edited 2 times in total.



Wed Dec 26, 2007 2:18 am
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This is SUCH good info I'm making it a sticky. Well done!
Thanks,
Joe

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Wed Dec 26, 2007 12:45 pm
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Just the kind of stuff we want and need :!:

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Wed Dec 26, 2007 4:57 pm
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thanks guys for the kind words :D

I found today that the #1 valve stud (the roller in the photo above) is bent by 0.040". The roller just didn't seem to be riding as squarely as it should, and when I measured the other pairs, I found out why :shock:

Still hoping someone will send me some spare BBC rockers of different ratios so I can test fitment and post photos. PM me.

John


Last edited by 66 E100 Pickup on Mon Jan 14, 2008 6:35 pm, edited 1 time in total.



Wed Dec 26, 2007 10:57 pm
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So are you still using the stock pressed in studs or did you have your head upgraded to screw in studs?


Sat Dec 29, 2007 1:32 am
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stock press-ins. Spring pressures are only about 220 psi at full compression. My goal with this under 4000 rpm set up is good low end torque, high mpg, and good engine longevity.

The machinist wasn't concerned at all with the press-ins under these conditions. There's only about 30 psi more than the stock set-up. Hopefully I'll never have to update otherwise. It may be that the roller fulcrum has partially evened up the score.

John


Sat Dec 29, 2007 2:57 am
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And if you REALLY want to boggle your brain with rocker arm regalia just check out THIS site!


http://www.mid-lift.com/INTRO-ML-BKGRND.htm

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Tue Jan 01, 2008 10:24 pm
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This post deals with the Chevy InLine 6 rocker upgrade. Thanks to one of the members, I received a 1.75 ratio Ch**y rocker. The swap out of the stock Ford 1.6 rocker with a higher ratio yields a low budget improvement in the potential volume of intake and exhaust flow, thus giving more performance across the rpm range. The Ch**y rocker also comes with the stock 3/8" locknut for a true bolt-in affair for early 240 heads.

The higher ratio rocker moves the pushrod more towards the center of the head:

Image

The pushrod is close, but does not touch the end of the slot. Since the pushrod lift is the same (according to the cam lobe), the additional valve lift is gained by forcing the valve side of the rocker to move more, in proportion to a 1.75 ratio versus the stock. As an example, the stock cam intake lobe has a 0.233" lift. With a stock 1.6 rocker, the valve lift will be 0.233" x 1.6 = 0.3728". With the Ch**y rocker, the valve lift will be 0.233" x 1.75 = 0.40775".

The valve tip and rocker contact point appear to be very well matched to each other, identical in appearance to the stock:

Image

It should be noted that the best way to achieve greater valve lift is to use the proper cam profile for the desired performance, and 1.6 to 1.7 ratio rockers. The 240/300 engines are blessed with a dozen or more choices of cam profiles, all the way from stock, to "RV" torque/mileage types, to agressive street engines, and all out race applications.

Many Ford sixers would not recommend using these high ratio rockers with high lift cams (>0.26" lobes) or high pressure springs as this will increase wear at all contact points--cam lobe, lifters, pushrods, fulcrum, and valve tips. Any compressed spring pressure of over 250 psi should also get a screw in stud replacement.


Sat Jan 05, 2008 12:50 am
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Incorporated into FAQ.


Fri Jan 11, 2008 11:02 pm
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A little trick is to chamfer the sides of the push rod guide holes. Not widen the holes just make sure there is not a sharp edge for the push rod to rub against.


Sat Jan 12, 2008 10:46 am
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John's excellent photos have cleared up something that I have been wondering about.

It appears that the angle between the valve stem and the rocker stud is very nearly parallel if not exactly so. This means that using a longer-than-stock valve, such as the Chebby units will not have an adverse effect on rocker arm geometry. All that will be needed is a proper length pushrod.

The 300 Ford valve train geometry is opposite of the bent-eights, partly because of the "U-flow" head ports. The 300 has the valves angled to be much closer to parallel with the pushrods than most V-type engines.

My conclusion is to go ahead and run whatever valve you desire (within reason) and let the valve stem length fall where it may; it won't be as big an issue on the 300 compared with many other engines.
Joe

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Sat Jan 12, 2008 12:32 pm
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This post tackles the big block chevy roller fitment. It should be noted up front that these rollers come with a variety of options, which include stud size, ratio, and offset. The basic "crane gold" number is 13750 for the 7/16" stud, 1.7 ratio, and 15750 for the 3/8" stud and 1.7 ratio. Custom ratios can vary all the way from 1.55 to 1.80. For more info on the part numbers and options, take a look here:

http://www.cranecams.com/index.php?show ... =4&prt=108

So why bother with a chevy product on the 240/300? Quite simply, very good used sets can be had on e-bay for half the price of new Harland Sharps. And, the myriad of ratios allow a very custom build.

Thanks to an interested member, I received a fairly standard 1.7 ratio 13750 to mount up in my 240 head. Looking first at the dimensions of the Crane Gold (right) vs the Harland Sharp, it's easy to see why the Cranes are a popular choice:

Image

The distance from the fulcrum to the roller tip centerline is basically identical between the two. This should mean that if mounted at the same height, the roller should ride and perform very similarly to the HS 4002.

Looking at the head on profile, it can be seen that the 13750 fulcrum does not have the same mounted height, but the smaller roller compensates for the lower fulcrum height so that the geometry ends up pretty close.

Image

When mounted, the roller tip does indeed sit very well on the valve.
Image

It should be noted that in all these "mock-ups", full spring compression is not achieved. Since these are hydraulic lifters, some lifter compression and bleed down does occur.

With due diligence, it appears that the BBC roller, in it's basic configurations, will adapt well to early 240 head builds that are stock, or minor in deviations from stock.

John


Sun Jan 13, 2008 1:44 am
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Valve stem, valve guide, and pushrod are not parallel. I am quoting from memory, not looking at a blue print, but as I recollect the angles were 12, 8, and 8 degrees.

I can't check because I'm in Florida training to ride from Key West to Canada.


On my bicycle. 1,668 miles.

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Mon Jan 14, 2008 3:06 pm
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Excellent goal! Who is organising this?


Mon Jan 14, 2008 6:16 pm
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THE FRENCHTOWN FLYER wrote:
Valve stem, valve guide, and pushrod are not parallel. I am quoting from memory, not looking at a blue print, but as I recollect the angles were 12, 8, and 8 degrees....


Which is a whole bunch closer to parallel than most V-8's so a slightly longer-than-stock valve shouldn't be much of an issue.
Joe

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Mon Jan 14, 2008 9:16 pm
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Post Re: Basic roller rocker info, with photos
Where did these pictures go? Any chance we can get them back?


Sat Feb 02, 2013 12:07 am
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Post Re: Basic roller rocker info, with photos
clintonvillian wrote:
Where did these pictures go? Any chance we can get them back?

I was also wondering this as I plan to throw on some Harland Sharp roller rockers on a 240 head in the summer. Pictures would be appreciated.

Since the Harlands are oversized, what valve cover would be tall enough? I'd assume a Clifford but that is pretty expensive for a simple valve cover. I'd like to retain a factory-looking valve cover if possible.

Also, I'm a little unclear on this. What mods are required to install 1.6 roller rockers? Would I need to fiddle with rocker mounts, springs, or pushrods?

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Thu Feb 20, 2014 4:11 am
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