Adjustable Rocker Arms

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Feb 23, 2004 | 04:34 PM

Winchester

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Adjustable Rocker Arms

I'm in need of a little help from all you veterans out there regarding FE rocker arm assemblies. I've been through Steve Christ's "Big-Block Ford Engines" several times (which is an excellent read might I add) and have come across a dillema.

On page 47 it states:

"Adjustable rocker arms are often used in hydralic-lifter engines because their higher ratio gives a slight increse in valve lift. Adjustability also makes it easier to obtain correct valve clearance or adjustment."

Then on page 141 it states:

"Rocker arms used with hydralic lifters have no adjustment provisions because they rarely need adjusting."

I'm in the process of looking for a set of adjustable rocker assemblies for my 390 but I just wanted to clear up this confliction. To me the quote from pg.141 seems to make better sense. Can anybody help me clear this up? Thanx.....

Feb 23, 2004 | 04:45 PM

gtex

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My take: if you're running a mild hydraulic cam, non-adjustables should be fine and will not require as much maintenance.

If you plan to run a larger cam, (I consider .550" lift a good break point) then adjustable rockers will help. Generally at this point you're running upgraded springs and retainers, so the adjustables can help with setting the preload on the lifters.

Feb 23, 2004 | 06:26 PM

Winchester

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Why is it that most of the aftermarket cam manufacturers suggest that you must use adjustable valvetrain?

Feb 24, 2004 | 11:23 AM

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Not sure...... but I do know that when they list their lift figures that they usually do it with the 1.76:1 ratio (adj.) rockers and not the the non adjustables.

Feb 24, 2004 | 04:39 PM

Ratsmoker

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Because they want to sell you their rocker arms! The only time you need to run adjustables with a hydraulic cam is if the base circle of the lobe has been modified to accomodate a bigger lift. I do agree with Greg though. When you run big cams you want to be able to set your preload correctly. I know there are plenty of people out there running the Crane cams with stock non-adjustable rockers.

Just as a note, you will need adjustable rockers with the edel heads unless you have them done correctly by a machinist. The intake and exhasut valves aren't even the same height.

Feb 25, 2004 | 01:09 PM

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The non-adjustable's are 1.73:1 ratio in case you were wondering. The adjustables are prefered by most for their increase in ratio (although it isn't much). As long as everything is set up correctly, I don't see anything wrong with running non-adj. as long as they are in good shape along with the shafts. When a guy gets into the bigger cams they probably aren't as good of an idea but I know a guy who ran non-adj. in a 390 with a comp. 280H cam for a while and he didn't have a problem he just went with the adjustable's later on.

Feb 25, 2004 | 03:53 PM

Winchester

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Is the Crane 941 too much cam for the non-adjustables? Are the standard aluminum rocker stands tough enough as well? BTW this engine will rarely if never see 4500rpm.....

Thanx guys...

Last edited by Winchester; Feb 25, 2004 at 03:58 PM.

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Feb 25, 2004 | 06:37 PM

Winchester

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From: Saskatchewan

Actually it's the aluminum Rocker Stands I was inquiring about. Sorry bout that.....

Feb 25, 2004 | 07:17 PM

#10

Ratsmoker

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Yes, they are tough enough as long as they are in good shape. The 941, from what I hear on here, is not too much for the stock valvetrain to handle. I would call it the limit though.

Feb 25, 2004 | 07:42 PM

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Winchester

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Thanx for all the replies guys, much appreciated. I'm going to give the 941 a try with my existing valve train. Worth a shot at least....

Feb 25, 2004 | 08:14 PM

#12

gtex

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You're probably OK. I ran the crower power Beast, .546" lift on stock vale train. No issues up to and a little past 5500 RPM.

Again, assuming all parts are in good shape. If some parts are near death, then you'll probably figure it with that cam real quick.

Feb 25, 2004 | 08:32 PM

#13

Winchester

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From: Saskatchewan

I've checked out most all of the components and so far everthing is real tight and well with-in spec. Is there any apprehention to cutting down the flow to the rockers by ways of restricting oil flow?