Rocker Arm Studs
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Rocker Arm Studs
Hello!
I am new to ford I6's, about a 2 weeks new when i bought an 84 f150 4x4 with a 4.9l. it has been running fine and seemed to be running OK last night when i parked it. I did rev it up a little, but no more than I have before or that you would do driving, maybe 4k. this morning I went to start it and it sounded weird like it had no compression, it finally kinda came to life but you could tell it was not firing on all cylinders and there was a loud tapping noise, not like a rod though.
I took the valve cover off and noticed one rocker arm was off the pushrod and valve, and another very loose (the source of the tapping i'm sure) upon closer inspection i noticed the studs that the the rocker arms bolt to were lifted up or pulled out. the one with the arm off was up about 1/2 inch, the other about a quarter. you could clearly see a clean area from where they were originally.
guess my question is how are those studs installed, and what would cause them to pull out? i have looked at new heads and the studs are not there?
thanks!
Clawless
I am new to ford I6's, about a 2 weeks new when i bought an 84 f150 4x4 with a 4.9l. it has been running fine and seemed to be running OK last night when i parked it. I did rev it up a little, but no more than I have before or that you would do driving, maybe 4k. this morning I went to start it and it sounded weird like it had no compression, it finally kinda came to life but you could tell it was not firing on all cylinders and there was a loud tapping noise, not like a rod though.
I took the valve cover off and noticed one rocker arm was off the pushrod and valve, and another very loose (the source of the tapping i'm sure) upon closer inspection i noticed the studs that the the rocker arms bolt to were lifted up or pulled out. the one with the arm off was up about 1/2 inch, the other about a quarter. you could clearly see a clean area from where they were originally.
guess my question is how are those studs installed, and what would cause them to pull out? i have looked at new heads and the studs are not there?
thanks!
Clawless
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From: Spokane, WA
The problem with pressed in studs is solved by having the head tapped for threaded studs and use them. Some engine builders do this routinely as part of a rebuild to circumvent the problem with pressed in studs.
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From: Spokane, WA
Pretty much so. While you are at it have a valve job done and specify a 30* back-cut on the valves, mill the head enough for clean-up and a mild port/polish job if you have the resources. Consultation with a machine is in order.
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From: Boise, Idaho
Fortunately, removing a head from an '84 isn't that difficult of a task. Unbolt the intake/exhaust manifold combo as they'll come off in one piece, pull stuff out of the way, and then remove the valve cover. Unbolt the head and be thankful it's not EFI, or you'd still be back working on the intake/exhaust.
Stuff's just going to be really heavy.
It does sound like you revved it too high. 4000 isn't exceptionally high, but many never rev above 3000 or 3500, especially with a stock carb setup. The revs probably pulled your rocker arm stud out.
x2 on the rocker arm studs tapped and threaded. Any other headwork while the head is out is optional, but highly recommended. If you have extra funds, you'll be glad you did as the head is a big bottleneck in performance.
Stuff's just going to be really heavy.
It does sound like you revved it too high. 4000 isn't exceptionally high, but many never rev above 3000 or 3500, especially with a stock carb setup. The revs probably pulled your rocker arm stud out.
x2 on the rocker arm studs tapped and threaded. Any other headwork while the head is out is optional, but highly recommended. If you have extra funds, you'll be glad you did as the head is a big bottleneck in performance.
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Rocker Arm Studs
So, I stopped by a machine shop today and talked with them. Then I went home and pulled the head, your right it was relatively easy. I went ahead and ordered a rebuilt head, the figure I got from the shop, with having all the work done that should be done when its out, was more that several remans I found.
It also has 3 bent push rods, 2 were from the rockers with the pulled up studs and one was not. Any recommendation on new ones? I cant find anything but sizes, nothing specific to the 300. Never really went this far before on a repair before so I'm guessing that's how the come?
I'll keep that in mind on the RPM. This all kinda makes me a little leery towing a boat with this thing now.
Thank you for your help! It will be running again in no time!
Clawless
It also has 3 bent push rods, 2 were from the rockers with the pulled up studs and one was not. Any recommendation on new ones? I cant find anything but sizes, nothing specific to the 300. Never really went this far before on a repair before so I'm guessing that's how the come?
I'll keep that in mind on the RPM. This all kinda makes me a little leery towing a boat with this thing now.
Thank you for your help! It will be running again in no time!
Clawless
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From: Boise, Idaho
Below 3000 RPMs is where the 300 makes it's power, so don't worry about RPMs too much. However, I push mine to 4000 on occasion and have never had a problem, 4500 - 5000 is generally where people start losing piston skirts and stuff.
When I said you revved it too high, I wasn't meaning past the 300's capabilities. I was meaning more that if your rocker arm stud was loose, a run at 4000 is what made it finally pull out.
I've seen push rods for the 300 a couple different places. Try rockauto.com. I've never replaced mine, but that's where I've found them for sale.
Glad pulling the head wasn't too much work.
When I said you revved it too high, I wasn't meaning past the 300's capabilities. I was meaning more that if your rocker arm stud was loose, a run at 4000 is what made it finally pull out.
I've seen push rods for the 300 a couple different places. Try rockauto.com. I've never replaced mine, but that's where I've found them for sale.
Glad pulling the head wasn't too much work.
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From: DeKalb, Ill.
Those are bigger concerns than your engine. Don't be afraid of pulling a boat.
The 300 is pretty much done creating power by 3500 rpm.
Keep it within that range and you shouldn't have any trouble at all.
Murph.
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From what I've heard, the "general" rule is that you can reuse headbolts one time. But you never know if they've been reused once before.
If it were me, I'd just replace them all for the peace of mind knowing I've got fresh, brand new bolts holding the head to the block.
If it were me, I'd just replace them all for the peace of mind knowing I've got fresh, brand new bolts holding the head to the block.
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It's alive!!!
It's Alive!!! Ok it's late but I couldn't wait till Sunday. I started when I got home from work, and fired it up at 1:00. It actually runs better and sounds much better. I wouldn't be surprised if it was having issues before I bought it. Now I need to change the oil and hope its clean, no water.
In any event, that you all for your knowledge and help and the courage to do this, it was fun and provided the oil is clean, a lot cheaper than than dropping off somewhere.
thank you!
Clawless
In any event, that you all for your knowledge and help and the courage to do this, it was fun and provided the oil is clean, a lot cheaper than than dropping off somewhere.
thank you!
Clawless
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