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Mustang Technical Discussion > Pre 1973 > Rockers and Pushrods > Community Forums > Mustang Forum Australia - Mustang Tech

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Stallion67
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Since I am about to fit my edelbrock top end kit to my 289 i have realised it did not come with rockers or pushrods. So basically i have two questions..

1 - What are the pros and cons of roller rockers vs standard?
2 - What length pushrods are used in a standard 289 and would these need to be changed?

Cheers,
Tony


Cheers, Tony.

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xpconnor
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I think that the rockers you require will depend on the profile of the cam. Roller rockers are better but you only need them if your cam has an agressive profile. At least that is what I think I have read in my reading the last few days. Other guys will pitch in with more specific detail.


"The Mustang is full of Awesome"

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hybrid
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Roller rockers provide less resistance too, but it's not a huge deal.
If you're putting a new top end on though, I'd be going rollers.

I wouldn't assume standard pushrod length. If you have one of the originals cut it up and make an adjustable pushrod to work out the required length.

Info is in the Tech Shop.


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boofhead
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What head is in the top end package you have? What is the chamber size?

It is most likely you will require adjustable rocker gear as the heads will be using screw in studs. You need to know the size of the stud before you purchase the rockers. You do not need to purchase roller rockers though they are the best option if you can afford them. As I have side you need to consider the stud size (where 3/8th is standard), and the rocker ratio (where 1.6:1 is standard). You may require higher rocker covers when a full roller rocker is employed.

So your options are:

1) Best Option: Roller Rockers. Least friction and side loads.

Many brands and various construction materials and quality. The last 5 performance engines I have build I have used the Ultra Golds. Such as below

www.summitracing.com/i.../make/ford

2) Good option: Roller tip Rockers

A few brands have this style - I have used these on my very mild street engines. It has the roller tip to reduce side loading on the valve stem.

www.summitracing.com/i.../make/ford

3) Standard rocker

I would not personnaly use this style though it is an option and the least expensive.

www.summitracing.com/i.../make/ford

As far as the push rods are concerned you will need moly hardened pushrod that are suited to use with guide plates. Stock 289 is 6.825 You should measure them for the required length though the head manufacturer will gneerally provide the recommended length which will often be close enough and certainly fine for a mild build.

So I assume you have the E Street kit so you have these heads

www.summitracing.com/i.../overview/

Here are the instructions

www.jegs.com/Installat...0-5023.pdf

So a 3/8th stud and they recommend these roller rockers

www.summitracing.com/i.../overview/

also you need a 5/16 push rod of length now the document does not say what size though I have found one magazine article recommended size at 6.250,

www.summitracing.com/i.../overview/

Though this was sized using a roller rocker.

In another article with roller tips were used and they selected 6.75 length which is closer to what I expected to see. While here is one that found 6.95 is the way to go.

sbftech.com/index.php?topic=31983.0

Any way, measure is the best way.

You will need the appropriate spark plugs, e.g, Champion RC12YC .

You will likely need larger rocker covers such as

www.summitracing.com/i.../overview/

which is the set I am running on my Mustang..

Have fun with the installation.


I will someday think of something clever to say.

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Shaunp
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As Boof said you can't guess the rods you need to work it out depending on what's in the engine.
scorpion endurance roller rockers are a little lower then most and will fit under most stock covers, similar price to the Comp cam gold's from memory
The other benefit to rollers is that you average more lift across the duration of the cam, it's only a little but it all helps. A standard rocker is like sled it slides across the valve and it fulcrum on the post. a roller has more of an up and down movement ie less motion is lost.


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Stallion67
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First of all, thanks to boofhead for all the great info!

Yes the heads are e-street and i believe they have a 60cc chamber.

I guess the way forward is to buy the full roller rockers (either the comp cam or edelbrocks) and fit them to the heads. The scorpion endurance rockers would be great shaun if they do fit under the new set of aluminium covers i've already got. Then I'll need an adjustable pushrod to measure before buying a new set of rods.

How do you know how long the pushrods need to be? Is it simply by bolting the rockers on and seeing where they contact the top of the valve stems?


Cheers, Tony.

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hybrid
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It's all explained in the tech shop Stallion.


www.mustangtech.com.au...id=11.html


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boofhead
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I like to use checking springs to do the test. Others use a solid lifter. There are various videos and information around. Some help in the tech section here.

You are basically looking to mark the top of the valve stem with blue marker and then install the rocker to zero lash and rotate the engine and have a look at the mark left by the roller. The finer the line the better. It is also great to have it centred though that is less important than the fine line. Get it to close to a 1/16th Inch as possible and it will be close enough. Here is a video with further information that will provide an idea of what to look for. Note: Its a chev though same process.

www.youtube.com/watch?v=OmzbHgVY3cI


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Shaunp
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Here is one I prepared earlier. Rods are made in 50 thou increments. Rockers are Scorpion endurance units

Checking springs and adjustable rod



Witness mark on the valve.



measuring the rod



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boofhead
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Good picture - exactly illustrates the process.


I will someday think of something clever to say.

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Shaunp
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One more thing you need to also calculate the effect of a crushed head gasket in there as well.


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Stallion67
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When i pull the engine apart I'll make one of those adjustable pushrods. Just have to make sure it is straight.

How do you know how far to bolt down the rocker? Or is there a limit built in..


Cheers, Tony.

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Shaunp
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You may also want to calculate the compression ratio as well, Think the Edelbrock heads are 60cc or larger chambers, if your engine don't have flat top pistons you may drop compression a little too much, you may want to take a cut of the heads.

289 head chambers are like 56cc of similar.


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boofhead
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You have studs so it is fully adjustable hence then you need to adjust the rockers following the appropriate procedure so you get the correct preload on the hydraulic lifters. Do not just bolt them down.

Edit: Here is a video to give you an idea.

www.youtube.com/watch?v=piifbQtCzno

Note: There are many different ways to go about it.


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