Rocker arms
Thread Starter
Cruising
Joined: Jan 2021
Posts: 12
Likes: 1
Rocker arms
Hello,
I recently put new heads on my engine and shortly afterwards realized the new heads have valve springs that are a larger diameter than the old ones. I have cast steel roller tip rockers right now that are rated for 1.5” valve springs and the new heads have 1.560” single coil springs. Would the old rockers work or should I purchase new ones?
I recently put new heads on my engine and shortly afterwards realized the new heads have valve springs that are a larger diameter than the old ones. I have cast steel roller tip rockers right now that are rated for 1.5” valve springs and the new heads have 1.560” single coil springs. Would the old rockers work or should I purchase new ones?
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
The amount of lift with the camshaft will be the deal breaker.
If you can get a breaker-bar on the crank bolt, slowly turn the crank until number 1 cyl, Intake valve is at its maximum open point. Or you can use #2 cyl. Which ever is easiest to get at and inspect.
Then take a feeler gauge between bottom of rocker and retainer.
Off-hand I don't remember the minimum clearance. But you should be fine with that set-up.
Edit: Google says 0.020.
Another web site says 0.030
And yet another says 0.060
If you can get a breaker-bar on the crank bolt, slowly turn the crank until number 1 cyl, Intake valve is at its maximum open point. Or you can use #2 cyl. Which ever is easiest to get at and inspect.
Then take a feeler gauge between bottom of rocker and retainer.
Off-hand I don't remember the minimum clearance. But you should be fine with that set-up.
Edit: Google says 0.020.
Another web site says 0.030
And yet another says 0.060
Last edited by HeadsU.P.; Aug 27, 2022 at 09:02 AM.
Thread Starter
Cruising
Joined: Jan 2021
Posts: 12
Likes: 1
The amount of lift with the camshaft will be the deal breaker.
If you can get a breaker-bar on the crank bolt, slowly turn the crank until number 1 cyl, Intake valve is at its maximum open point. Or you can use #2 cyl. Which ever is easiest to get at and inspect.
Then take a feeler gauge between bottom of rocker and retainer.
Off-hand I don't remember the minimum clearance. But you should be fine with that set-up.
Edit: Google says 0.020.
Another web site says 0.030
And yet another says 0.060
If you can get a breaker-bar on the crank bolt, slowly turn the crank until number 1 cyl, Intake valve is at its maximum open point. Or you can use #2 cyl. Which ever is easiest to get at and inspect.
Then take a feeler gauge between bottom of rocker and retainer.
Off-hand I don't remember the minimum clearance. But you should be fine with that set-up.
Edit: Google says 0.020.
Another web site says 0.030
And yet another says 0.060
I installed the rocker with a length checking pushrod and it looks alright to me. But I’m still not 100% sure if I don’t see something that may be a problem.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Looks good to me. Would like to see a shot of a valve closed just because.
What ever clearance you have on that retainer to rocker gap, the other 15 should match unless it's a dual pattern bump stick.
I see an old mark on the stem from checking pushrod length. Pretty much dead center.
And maybe its the camera angle but it appears the rocker stud is not torqued all the way? I see a gap under the head of the bolt. That would concern me.
Either the stud is incorrect length and bottoming out in the hole or really thin guide plates? IDK
What ever clearance you have on that retainer to rocker gap, the other 15 should match unless it's a dual pattern bump stick.
I see an old mark on the stem from checking pushrod length. Pretty much dead center.
And maybe its the camera angle but it appears the rocker stud is not torqued all the way? I see a gap under the head of the bolt. That would concern me.
Either the stud is incorrect length and bottoming out in the hole or really thin guide plates? IDK
Thread Starter
Cruising
Joined: Jan 2021
Posts: 12
Likes: 1
Looks good to me. Would like to see a shot of a valve closed just because.
What ever clearance you have on that retainer to rocker gap, the other 15 should match unless it's a dual pattern bump stick.
I see an old mark on the stem from checking pushrod length. Pretty much dead center.
And maybe its the camera angle but it appears the rocker stud is not torqued all the way? I see a gap under the head of the bolt. That would concern me.
Either the stud is incorrect length and bottoming out in the hole or really thin guide plates? IDK
What ever clearance you have on that retainer to rocker gap, the other 15 should match unless it's a dual pattern bump stick.
I see an old mark on the stem from checking pushrod length. Pretty much dead center.
And maybe its the camera angle but it appears the rocker stud is not torqued all the way? I see a gap under the head of the bolt. That would concern me.
Either the stud is incorrect length and bottoming out in the hole or really thin guide plates? IDK
Thanks again.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Ok, good. I see a nice gap between retainer & rocker.
I also see the spring pocket is milled for a larger valve spring if you choose to do so. But I wouldn't push it.
I usually give the rocker stud a drop of Loctite Blue before installing. Do your studs go into the port? In other words, are threads showing inside the runner?
If so, that's an all-new ball game of issues.
I also see the spring pocket is milled for a larger valve spring if you choose to do so. But I wouldn't push it.
I usually give the rocker stud a drop of Loctite Blue before installing. Do your studs go into the port? In other words, are threads showing inside the runner?
If so, that's an all-new ball game of issues.
Thread Starter
Cruising
Joined: Jan 2021
Posts: 12
Likes: 1
Ok, good. I see a nice gap between retainer & rocker.
I also see the spring pocket is milled for a larger valve spring if you choose to do so. But I wouldn't push it.
I usually give the rocker stud a drop of Loctite Blue before installing. Do your studs go into the port? In other words, are threads showing inside the runner?
If so, that's an all-new ball game of issues.
I also see the spring pocket is milled for a larger valve spring if you choose to do so. But I wouldn't push it.
I usually give the rocker stud a drop of Loctite Blue before installing. Do your studs go into the port? In other words, are threads showing inside the runner?
If so, that's an all-new ball game of issues.
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Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Yes it is. Don't forget to do that.
There is another thread a while back about the Rocker Studs leaking oil into the runner, which is under constant vacuum.
To obtain larger runners, such as over 200 cfm, the runners are hogged out. They grind on them so much that it exposes the rocker stud.
I have a real problem with that. The hogging out supposedly gains more CFMs which in turn is more horse. But at a cost of burning oil, if preventive measures are not taken.
To me, exposing the threads is poor craftsmanship.
I get it if it's an all-out racing engine trying to squeeze every last horse out of it. But for street use, I see daily oil consumption.
And the valve stem seals will get blamed for this oil burning every time.
There is another thread a while back about the Rocker Studs leaking oil into the runner, which is under constant vacuum.
To obtain larger runners, such as over 200 cfm, the runners are hogged out. They grind on them so much that it exposes the rocker stud.
I have a real problem with that. The hogging out supposedly gains more CFMs which in turn is more horse. But at a cost of burning oil, if preventive measures are not taken.
To me, exposing the threads is poor craftsmanship.
I get it if it's an all-out racing engine trying to squeeze every last horse out of it. But for street use, I see daily oil consumption.
And the valve stem seals will get blamed for this oil burning every time.