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Rocker arms

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Old 05-03-2018, 09:48 PM
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Default Rocker arms

My Ford build has been on the road for a few years now. I love it, and am just refining a few minor issues with it.
My current focus is on the sewing machine type sound coming from the Cobra roller rockers (1.7). One of the reasons I went with the 5.0 is because of the awesome sound of a properly set up SBF. This minor clatter is starting to really annoy me. It’s quite noticeble when driving next to a wall or in a tunnel etc. Long story short, I have checked the rockers and they are getting worn out with some side to side play and the pins are starting to work their way out.
This engine was the first I ever had opened up, replaced rings and bearings, but assumed the rockers would be fine. The rockers were already on the engine.
So, I’m thinking of going to oem style stamped rocker arms. I may do aluminum heads in the future but that would mainly be for weight savings as I’m pretty happy with the stock power level in such a light car.
I have no idea if the pushrods are original length or if the donor cars owner changed them out.
Looking for thoughts, suggestions or anything helpful regarding changing these out.
From what I read, oem rockers are the way to go for stock power levels, quietness and longevity.
Cheers.
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Old 05-04-2018, 08:01 AM
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Some side to side movement is pretty normal. There shouldn't be any clatter though. Sounds like they are not adjustable. You say the pins are starting to work their way out. By that I'm guessing you mean the rocker arm studs? If so, that means you have the stock pressed in studs. They've got to go. They are generally not compatible with aftermarket roller rockers.

Your best bet is to either go back to the stock type factory rockers, or pull the heads and have the machined for screw in studs.

Your total valve lift and type of springs used should determine which route you take. It sounds like you might have some mismatched parts, so be vary careful how you proceed. If you use factory rail rockers on aftermarket springs not made for them, it could be a disaster.
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Old 05-04-2018, 01:21 PM
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The heads were freshened up with new valves and guides, not sure if the springs were replaced. Rockers are the pedestal style. Not really adjustable except by shimming or changing pushrod length. Basically a stock engine with cobra roller rockers. They are installed properly. "Clatter" is maybe an exaggeration, more like a sewing machine type sound.
So, if I do a little detective work and pull out a pushrod, I should be able to tell if they are stock by the length. What is the length of a stock pushrod?
I suppose at this point I should just go ahead and order new OEM style rockers, and test the fit when they arrive by doing the zero lash, 20 ft lb torque within 1/4 to a full turn and see where I end up. Shim or adjust length of pushrod from there if needed.

Oh the pins I'm referring to are the pins that hold the roller on...they keep shifting out to one side- several of them. I talked to Crane about a fix kit, but they don't offer one and suggested it wasn't a good idea to keep driving on them if they're working their way out. Of course they would rather sell a new set than have me repair these ones, so I'll take that with a grain of salt, though these are definitely past their due date.
Anyone have suggestions for decent oem style rockers?
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Old 05-06-2018, 07:45 AM
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You may want to check this out. https://www.alexsparts.com/6-250-6-272-hardened-pushrods-stock-length-for-sb-ford-5-0-302-gt40-gt40p-ho-engines-w-factory-hyd-roller-lifters/
I used gt40 heads with stock pedestal rockers and a Trick Flow Stage 1 cam in mine. I had to go with longer push rods, which I got from Alex (as well as his valve springs). I've only got about 2k miles on it, but its nice and quiet.
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Old 05-06-2018, 09:19 AM
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Ah, I see now. Agreed. If the pins are coming out of the rocker arms, they need to go. One of them will have a catastrophic failure with little bitty parts spread throughout the engine.

If they're noisy, then the the push rods could be too short. Maybe. Sometimes these components make more noise than we expect, simply because we are sitting very close to them, and there's no sound insulation. And sometimes they're out of spec because of aftermarket parts; like camshafts and lifters. Try this:

With the lifter on the base circle and the engine warm, loosen the rocker arm nut, then tighten it down with your fingers only. This should be zero lash. Is there any up and down movement in the push rod? If there is, the push rod is definitely too short. Can you very easily spin the push rod with your fingers? If so, it might be too short.

Now tighten the nut down with a torque wrench. It should only take less than one turn of the nut to get to spec.
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Old 05-06-2018, 10:42 AM
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Hello Brad, Do the below rockers look the same, these are the Crane - Cobra 1.7 rockers that even carry a F0RD part number

these are pedestal mount and really are only good for the factory cam, we always used 1.6 on the intake and 1.7 on the exhaust, this seems to give the best power for a stock cam. Not sure why your roller tip trunions would back out but I would not risk these parts creating havoc in your engine. Do you hold her at 6250RPM for extended periods? Just wanted to help with a picture to help with identifying the problem, I suggest new roller rockers.
Attached Thumbnails Rocker arms-miata%2520-37-.jpg  
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Old 05-06-2018, 11:24 AM
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Hey Deano,
Yes those are what I have- on my build blog under "Engine Build" you can see pics, and one even shows the pin pushing out the side. At that time I just pressed them back in, but everytime I've had the valve covers off I notice they still keep backing out. Assuming previous owner of my engine only changed rockers, do these normally just use stock length pushrods?

Why would you suggest rollers vs stamped for my application? Remember, I want quiet and longevity. Seems a lot of folks are only getting 20k miles or so out of a set of rollers. And goods one are pricey. I've no doubt they may have a slight advantage as far as reducing friction and heat, but I guess everything is a compromise.

How is your build coming?
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Old 05-06-2018, 01:20 PM
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Hello Brad,
I don't want to open a can of worms here, but YES those particular rockers were meant as a "bolt and go" upgrade for the stock 5.0. Now I agree you should never "bolt and go" so some checking may be in order and if I remember correctly one of our fine members posted a step by step process on your build page for checking push rod length when you first started your engine. All pointless as you should NOT be using those rockers if they are failing, I do know that Summit does sell stamped rockers in 1.6 and 1.7 ratio's, or at least they used to. I will dig out 16 used stock stamp steel rockers / pedestals for you and send them your way if you like as I should have a few stacks of them in my back room off of my drag car engines. one set is from an 89 and the other from a 91. Just trying to help a fellow enthusiast and save your ride from catastrophic failure and well I just have the parts kicking around. I will try and dig out the pieces today and send you a PM and pic if you want,

my project has been sitting for a bit as I purchased a '48 *****'s CJ2A that I am bringing back to life, then I will get back on the Miata. Hoping to update my build page and get back started next month. My M3 is currently filling my need for speed ATM, LOL.

Talk soon
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Old 05-06-2018, 08:54 PM
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Yes, I remember Dennis posting the proper torqing for the pedestal rockers....which is exactly what I did. Valve closed, zero lash and 1/4 to 3/4 turn to click 20ft lbs.
I’ll gladly pay shipping and a 12 pack of Buds if you’re wanting to unload a set of your stock rockers.
I did find a set on Summit made by Crane but haven’t pulled the trigger on them yet.
Cheers.
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Old 05-14-2018, 10:56 AM
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Default Rocker Arms

Hello Brad,
Apologies on this late response, I have searched through all my parts and I can NOT seem to find any of my stock 5.0 pedestal mount rockers. I found a second set of Cobra 1.7 rollers and two sets of 87/88 460 pedestal rockers but unfortunately no 302 stuff. I know I had two sets put away but alas either they were used up by a fellow enthusiast or I am suffering from old age blindness,lol. Didn't mean to hold your repairs up and I will make sure I have parts in hand before I open my mouth again, hehe.

Have a good one, wished I had better news.
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Old 05-14-2018, 10:23 PM
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Ya, no problem Dean. I went ahead and ordered Comp Cams OEM style stamped rocker arms. Installed them, but they needed nearly 1 1/2 turns to get to 20ft lbs. So picked up some shims today and got them all to 3/4 of a turn to 20 ft lbs. Not sure they’re any quieter....they sure weren’t on first start, what a racket but they quieted down after a few minutes. Car seems to drive the same. Still chasing down a couple exhaust leaks.
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Old 05-15-2018, 02:10 PM
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OK, now I think I may be nuts. I drove the car a bit, pulled into the garage and could hear a slight ticking- mechanical type noise. I grabbed a piece of rad hose and listened to the valve covers...yup, there's a bit of mechanical noise but not exactly the sound I'm hearing- seems to be coming more from the middle. I listen to a fuel injector. Bingo. I think the sound I've been chasing all along has simply been noisy fuel injectors. And it's probably all very normal. Me, not so much. lol.
Oh well, good to be rid of the worn out roller rockers anyways. Car goes in tomorrow to my exhaust guy to address a couple exhaust leaks. Then it's first track day next Thursday.
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