Adjustable rockers for the late Rover (rollers?)

[BlownMGB-V8]

https://youtu.be/o5is9BsH5OU

[mgb260]

Video explains it well. Have any pics. Did you fit a valve cover? Did you have to modify the guide plates? You do want oil through the pushrods so your lifters have to have the feed holes. Set screw to plug shaft oiling hole.

[BlownMGB-V8]

By all rights you also have to look at the pushrod side in the same way. Draw your line and see if it is square to the pushrod at mid-lift. If it is, job done. If it is not you then need to decide which way to split the difference.

Jim

[mgb260]

That video  is good for rocker geometry at mid lift.  I've always just made sure the line is the same level as the valve retainer. Never looked at the pushrod angle. Then check actual pushrod length with valve closed and lifter on base circle low point of cam.

[MGBV8]

I don't see how that is possible.  The pushrod & valve stem are at intersecting angles.  When the rocker centerline is at 90 degrees to the valve stem, how can the pushrod also be at 90 degrees at the same time?

[BlownMGB-V8]

The pushrod is at a different angle than the valve as you said, but the line for the roller tip is also at an angle to the line for the pushrod socket. So it is possible for both to be at right angles to the trunion. I don't know that it is, and there is some variance of course but it should be close? I'll be taking a look but it depends on engine and head geometry plus valve angles. Should be interesting to see how close it is. Seems like most inline engines have a  pretty vertical pushrod and both pushrods and valves being vertical isn't uncommon so it might be a mistake to switch rockers between the two. This could be where Max and I were having a bit of a communication breakdown during Happy Hour.

Jim

[mgb260]

Guys, I've been thinking about it, and pushrod angle is irrelevant. That angle changes with the rockers movement. The main thing is at half lift the rocker is level with the retainer so the rocker is in the middle of the arc like the diagram I posted early in this thread. That way the wipe on the valve stem is minimized. With the shaft rockers you do the same thing by shimming or milling the rocker stands.

[mgb260]

Also, initial rocker geometry and pushrod length are two separate things. Pushrod length is set after the rocker geometry when the cam is on the base circle low point and the valve is shut.

[Roverbeam]

If the rockers have geometry that is compatible with the head, within a couple degrees, then measuring the pushrod lengths after establishing the valve-to-rocker geometry will also give proper pushrod-to-rocker geometry.

Rover and Buick heads have about a 7 degree valve angle, and the pushrods lean inward/toward engine center, from the cylinder bore centerline by about a degree or two, for an included angle from valve-to-pushrod of about 6-9 degrees.

The rockers need an angle between the three pivot points that is similar to this, from the center of the pushrod's spherical tip, to the trunion center, to the valve tip roller's center.

[BlownMGB-V8]

OK I think I got this. First shot below is on the lobe with the valve closed.



Next off the lobe



Next the rocker square to the valve



And a shot of the alignment jig I made.



So, after a bit of mucking about I realized that as long as the reference line remains square to the valve the stud threads can indeed be used as a measurement device so with .550' lift (.544" actual) the midpoint is 5-1/2 turns down from photo 3 which is off the lobe. Squaring up the data line and measuring the movement of the rocker required to meet the pushrod resulted in a measurement of .075" short on the pushrod from the midpoint. Pushrods come in .050" increments so that should be acceptable. Ideally I'd order longer pushrods but there is another consideration.

What was it Max said? His 1/3 to 1/2 figure? Was it that he liked that shifted to the long or the short side? IIRC his reasoning was that he wanted a gentler approach to initial opening?

Well no matter, what a slightly shorter pushrod does is pull down the pushrod end of the rocker, bringing that data line closer to being square with the pushrod. That's got to be better in terms of rocker arm geometry. I think it'll be fine.

What do you guys think?

Jim

Also on the TA heads the valve angle is 13 degrees.

[Roverbeam]

"on the lobe with valve closed"? Do you mean on the base circle?

The method in the video you posted does all the alignment with no pushrod, and with the valve closed.

Then, by counting turns, the whole rocker is translated downward 1/2 lift so that the alignment you did with the valve high is now the alignment at 1/2 lift.

Are your valves perpendicular to the valve cover surface? -is that what your alignment shims are resting on? Maybe it just the foreshortening of the pic? Is that sheet of aluminum pinched under the nose, on the valve stem?

Your rockers clearly have more angle than that between your pushrods and valves. I'm good at figuring out the geometries, but I don't have the experience to judge if that's within an acceptable range. Typical bellcrank theory has both pivot legs perpendicular to the direction of the inputs. The fact that valves are constrained to only sliding in/out, while the pushrods can articulate with the arc may have effects that I'm not aware of?

Just for reference, since it's on the shelf and easy to take a pic, here's the angle on a TA rocker for 215/300/340/Rover heads:


And while getting that pic, I measured the 300 head I have - they are 10 degree valves (I had pulled a dimension off a drawing earlier, rather than walk trough the snow to get to the real thing).

[MGBV8]

What was it Max said? His 1/3 to 1/2 figure? Was it that he liked that shifted to the long or the short side? IIRC his reasoning was that he wanted a gentler approach to initial opening?

He wanted the rocker 2/3 of the way down because of the stiffer spring pressure as the spring is compressed.  Less wear due to not fighting the spring as much.

I don't see how that reasoning jives with the mid-lift geometry at all.

[BlownMGB-V8]

Well, it's a SBC rocker, apparently they had a 23 degree valve angle. so we're looking at a 6 degree difference. There might be a better choice for the TA heads but maybe not a cheaper one. One option might be to replace the cups with longer ones, maybe even an adjustable one. That would allow adjusting the rocker angle to match the pushrod-to-valve stem angle but might complicate things with the pushrod oiling.

The top photo was as described, look at the dimple in the pushrod.

The aluminum plate has a hole that allows it to sit on top of the retainer. I had to hold it in position while checking but maybe some sort of spring might fit between the plate and the rocker body to do that. I haven't tried it. A little tricky to hold in place while trying to take a photo, mainly because the small retainers don't have much of an area for the plate to sit on. But I think my results are pretty accurate.

I decided I would have to trim the guide plates for gasket clearance. In retrospect I think it would have been better to have just bought the TA guide plates. I still might do that.

If nobody sees a problem I think this is good enough.

Jim

[mgb260]

You guys are really over thinking this. Look at my diagram on page 1. You just want the rocker level with the retainer at mid lift so it is in the middle of the arc. No pushrod yet. No spring. Just mark the valve on top of the guide. Mark it .275 above the first mark. I use a piece of tape to hold the retainer and keepers on. Lower the valve to the .275 mark. Tape to hold the valve at that position. Rocker should be in same plane as the retainer. Mid lift setting is done. Then you use an adjustable pushrod with valve closed and taped up, lifter on the base circle of the cam to figure pushrod length. Those rockers look nice!

[mgb260]

Jim, Another rocker video:

https://www.youtube.com/watch?v=Sr4JbpO6034

[BlownMGB-V8]

I've decided to resell these rockers on ebay and order the TA rockers and guide plates. The cost is $135 higher (plus I'll lose a bit on the resell) but the rocker angle should be correct (I will check), but the single most important consideration is that these rockers do not hit in the center of the valve tips. They are offest to the outside. Now this might not be a real problem with a standard setup but because I'm running titanium valves I'm installing lash caps and as a remnant of the old application the valve tips have a small groove around the tip which theoretically could allow the lash cap to cock a bit if the roller is far enough off center. I don't think it is that far off and it would probably work, but at high speed with that stuff all bouncing across hell's half acre who can say? So I'm going to do the safe thing. It's not a huge price to pay compared to the rest of the investment in this engine.

Now, with that problem solved, it's back to the original topic of this thread and the use of the Procomp rockers on the Rover heads. The shafts I have do have a little wear, about .0015" so I'll be breaking down the other rocker shafts I have on hand to see if there's anything better at hand. Then I can decide if new shafts are justified.

Next I will be checking the rocker arm angle to get some idea of how far it deviates from stock.

Then I'll look at setting up to bore the rockers. More on that later.

Jim

[BlownMGB-V8]

It's possible to use the Procomp rockers if certain concessions are made.



The adjuster needs to be run out to about the limit of it's adjustability to match the rocker angle of the stock rocker.



It will be using a plain bore bearing with the rocker body as the bearing material.



And the biggest issue, the distance from the rocker shaft to the valve tip is a bit far. and puts the roller off center on the valve stem. Some of that can be corrected by moving the enlarged bore off center but it will still be past center. Maybe not enough to matter, I will probably go ahead and use them. But there may be better prospects out there.



For me, this is a refresh on a good engine. It will get new bearings and a different set of heads with the piston dish deepened to match, but it isn't a fresh build. If it was I think I'd be looking for some rockers that were a better match.

Jim

[mgb260]

Jim, On the push rod cup you could use longer pushrods.

[DiDueColpi]

The rover rockers are offset Jim. Can you accommodate that with some machining to the procomps?
Also moving the shaft bore around is going to change your ratio. It might be better to move the pedestals.

[BlownMGB-V8]

Yeah, I don't think moving the pedestals is going to work. You're right, the ratio total lift will take a hit, I'm not too worried about that. The procomps are also offset but not the same. I hope I can get them to line up good enough though.

On pushrod length, that adjuster position was the point at which the pushrod angle was about the same, so a length measurement with it in that position should give the closest geometry to the stock rocker. In that location the adjuster does move a little below the trunion centerline so it also has a very slight negative affect on the ratio. But again I think I can live with that. I am not that married to the current lift figures.

Jim

[gsjohnny]

been a long time for me.
don't know how much difference between 350 and other sbb rockers.
but i run 1.65 rollers. with the 350 casting for lack of room, i didn't want a bigger cam, i wanted more rocker ratio.
i bought some stud roller1.6 and 1.7 sb fords. i took one apart and reamed the hole to 350 size, only issue
with the ford vs sbb is shaft c/line to valve roller. the fords are about .050 longer. i could move the hole over,
but the 1.7 ratio would diminish. don't know how much. but its all doable.
i bought some 1.7 shaft rollers. this would require a new shaft with different o.d. spacers. still working on how to make it work.
one other idea, which i have lots of 350 heads, is to adapt ford 390-428 shaft rockers and stands. i can machine the stands
to whatever dimension that will work with the fords. looked at them, just have to buy them.

btw, those who try other parts to work, how much junk have you made and keep? i know i have a bunch of scrap. lol

[mgb260]

Johny, Welcome aboard!

[gsjohnny]

being a scatter brain doesn't help. look for something, i end going all over the world. lol
the 350 whines for me. i may have to expand my r&d to the little engines. got 3 340's, have to find a 300.

[BlownMGB-V8]

Only really two reasons to use a 300 over a 340. One is if you don't have room for the 340 (the MGB falls into this category) Two is if you want a better intake than the stock factory cast iron 340 4bbl intake and aren't willing to either use spacers on a 300 intake or to fabricate one. Other than that I don't really see an advantage and with the larger mains the 340 crank should be a little stronger. There is only 2lbs difference in the weight of the blocks. I modded an MGB to accept the 340 and fitting the 455 turned out to be almost exactly the same except for the exhaust. By contrast the (RB) MGB needs no body mods to fit the 300, making it the logical choice.

Jim

[MGBV8]

#3  If you want a smaller displacement V8.