• Hello there guest and Welcome to Fox Body Mustangs forum, This forum is intended to be used by enthusiasts of the Fox body Ford Mustangs (1979-1993)!
    To gain full access you must Register. Registration is free and it takes only a few moments to complete.
    Already a member? Login here then!

Stock Rocker Arms - Max Lift?

Middleagecrisis

New Member
What's the general consensus on the amount of lift a stock windsor rocker arm can handle? I know spring pressure is a big factor, but I'm mainly interested in the travel of the rocker before binding occurs.
 

347HO

Member
There's a lot of variables to your question.
Spring pressure is not normally one of them.
Install height
Rocker tip on stem travel
Pushrod length
Pushrod slot
Coil bind
These are off the top of my head...

IMO, anything around .500" net and you'll be thinking about it every time you start this engine.

I would think every automotive forum has more definitive information on this subject.

You can experiment using your mounted rocker ( no pushrod ) and measure the compressed distance to rocker bind using a plunge mic.
Unfortunately you won't know when the pushrod or spring binds.
 

Middleagecrisis

New Member
Good point about using a micrometer to check the amount of travel with the expected lift. I'm looking at a cam that has a split lift of .482/.496 with 1.6 rocker arm ratio. This is B-303 territory and I've known plenty of folks that ran that cam with stock rockers and upgraded springs. I was looking at other cam profiles that were in the .525 lift territory, which drove the question. I'll be very careful with the spring selection to not go any higher than necessary to avoid valve float, or place undue stress on the rocker arm assembly.
 

347HO

Member
The springs are matched to the cam lobe profile, required install height, and rpm. Then valve length, keeper style, rockers, rocker studs/shaft/pedestal are selected to tie it all together.

Max lift is not the only consideration when pairing springs.
More importantly are the lobe ramps.
As lobe ramps become more severe, so must spring tension.

I have a fairly large cam profile, but I had the design of the ramps be "gentle" to the nose and after on a large base circle.
I still have 720# pressure on the nose, and everything else has to handle that to a sustained 8500rpm.

Coil bind and heat are spring killers...
And is why I'm a PAC spring advocate.
 

347HO

Member
I like the fact this kit includes shims to dial in your install height.

I also see they refer to these springs as "pacaloy" or PAC as most people call them. I have full trust in these springs due to the consistency they offer throughout their life.
If you have the capability to measure your springs, do it for your own confidence.
I measure "on the seat", and "net lift".
The exhaust springs will lose tension before intake over time in most cases.

BEEHIVE... Offer some advantages to you. The retainer is smaller diameter, and everything else is lighter so...
These type of springs don't use a damper.

My only reservation from what I see, PAC springs I've used have a very bright, shiny, silvery finish to them. The link shows a different color. If I were to advertise PAC springs... You will clearly see that difference.

In your position, I would go for it... Measure each spring, and if no issues, install them and enjoy.
The price is very low first what you get.

Good luck!
Let us know more when as you go forward.
 
Top