S2a rocker/arm hangup?

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Maybe a process of elimination, remove plugs, slack off all tappet adjusters so all valves closed turn engine by hand then start adjusting a pair of valve gaps at a time see if they get stiff
You can also remove rocker cover while running rough to watch them all, make video to review at slow speed
 
Maybe~ the pushrods are just a little too long rotating the rockers a little too much in over the head of the valve stem and causing a binding which would delay the valve closing making the engine run rough like valves sticking. I have no bent pushrods which would make sense if the binding is occurring right at the max open position. And why would the pushrods for an 8:1 head be just a little shorter than mine?
 
Samoth said:
Maybe~ the pushrods are just a little too long rotating the rockers a little too much in over the head of the valve stem and causing a binding which would delay the valve closing making the engine run rough like valves sticking. I have no bent pushrods which would make sense if the binding is occurring right at the max open position. And why would the pushrods for an 8:1 head be just a little shorter than mine?
Click to expand...
Still trying to get my head around this.

But the valves will only move as much as the lift on the cam (is it std? for the compression?) I am trying to imagine a cam over pushing a valve to delay closing. It will only move through the travel of the lift, but you need the gap at the valve stem head if you have that how can it push to far?

In 1 of you post you said you "tapped " it and it closed? What/where was the slack at the time?

J
 
marjon said:
Still trying to get my head around this.

But the valves will only move as much as the lift on the cam (is it std? for the compression?) I am trying to imagine a cam over pushing a valve to delay closing. It will only move through the travel of the lift, but you need the gap at the valve stem head if you have that how can it push to far?

In 1 of you post you said you "tapped " it and it closed? What/where was the slack at the time?

J
Click to expand...
The valve was open at the time . I tapped the adjuster nut and the valve snapped shut. So the cam had moved off the peak lobe and the slack was between the pushrod and lifter slide. The valve was jammed in the open position for some reason.
 
Samoth said:
The valve was open at the time . I tapped the adjuster nut and the valve snapped shut. So the cam had moved off the peak lobe and the slack was between the pushrod and lifter slide. The valve was jammed in the open position for some reason.
Click to expand...
Thanks for confirming that.
So what could hold a valve open against its spring?
So I think you can forget the rocker assembly.

J
 
I'm trying to find some shorter pushrods at 7.175 inch length. Rovers North has only my current length 7.1875 or 7 3/16ths. The problem is I had the head milled 100 thousandths, so the currently available rods are all a little longer like mine. If I am right(who knows?) and the rocker jams at the open position, what are my alternatives? Rovers North sugested I could dremel out the pushrod cup to limit the throw of the rod. I have emails out to Cradock and turner engineering.
 
Do all the valves act the same? (I know they don’t)
The length of a pushrod can change up to nearly 1/2 inch with the length of a tappet adjuster can’t it?
So I don’t think your pushrod length is an issue.

J
 
kermit_rr said:
If the rocker/shaft was suitably worn, could the rocker bind on said shaft?
Click to expand...
Hello! The rocker shaft is new and I pressed in new bushings on the rockers and honed them for a smooth but no wobble fit. Maybe they are too tight but they do spin freely.
 
marjon said:
Do all the valves act the same? (I know they don’t)
The length of a pushrod can change up to nearly 1/2 inch with the length of a tappet adjuster can’t it?
So I don’t think your pushrod length is an issue.

J
Click to expand...
yes, that sounds good. I got . them in there with no problem. So that was my original thinking as well. If there is enough room to adjust tappet clearance then there should not be a problem.
kermit_rr said:
Then the valve is bent or the valve seal collapsed/deteriorated?
Click to expand...
I just had the head off and valves apart. they are fine with new seals.
 
Samoth said:
yes, that sounds good. I got . them in there with no problem. So that was my original thinking as well. If there is enough room to adjust tappet clearance then there should not be a problem.

I just had the head off and valves apart. they are fine with new seals.
Click to expand...
Have you put something together wrong? There's only so many possibilities
 
All the brass slides were moving smoothly when my wife turned the engine over by hand and I watched them move. So it is still a possibility that some are sticking enough while the engine is running. So far no bent pushrods!! So I think I'll just put the rockers back on and see what happens.
 
Samoth said:
All the brass slides were moving smoothly when my wife turned the engine over by hand and I watched them move. So it is still a possibility that some are sticking enough while the engine is running. So far no bent pushrods!! So I think I'll just put the rockers back on and see what happens.
Click to expand...
I still can’t get past the slack. The valve spring should move the rocker arm against the pushrod and slider as it follows the cam lobe, while doing so the valve closes.

If you are off the lobe and the valve is still open, it’s the valve or guide surely?
Did we confirm std cam?

J
 
marjon said:
I still can’t get past the slack. The valve spring should move the rocker arm against the pushrod and slider as it follows the cam lobe, while doing so the valve closes.

If you are off the lobe and the valve is still open, it’s the valve or guide surely?
Did we confirm std cam?

J
Click to expand...
or maybe the brass cam follower although they were rising and falling of their own weight without the valve train pushing them. The camshaft is ETC 7128 and can be used on all the petrol and diesel engines up into about 1994. It has slightly more lift but will work in SII and SIIa and SIII engines as well as some others that are newer as I understand it. But it required a shorter pushrod which I have. It still begs the question since I had the head milled that 100 thousandths perhaps the pushrods are a wee bit too long. Okay so they will go in and can be lashed properly, but that doesn't guarantee they are the right length for the rocker geometry does it?
 
kermit_rr said:
Did it work before you stripped it? If so then what had changed?
Why did you strip it?
Click to expand...
Thanks for asking. The engine had been sitting in a barn in dry eastern California heat for, just guessing here, some 20 plus years. I brought it and a transmission back to Washington State to replace my SII engine & trans. Now it's a SIIa and trans to keep me occupied. So I have rebuilt them both starting about two years ago.
 
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