^^^^^^^^^^^^THIS^^^^^^^^^^^^^^^^^^ is EXACLY correct.

To the OP...pushrod length is not used to change geometry on shaft mounted rockers. There is a correct adjuster protrusion with either the ball adjusters or the cup adjusters. You set the adjuster where it SHOULD be and leave it alone.


For the sake of redundancy I’ll post it again. If you have ball adjusters and the oil hole in the back of the rocker is at the bottom of the threads (at one point evidently Crane got sick of telling people their pushrods were too short so the moved the oil feed hole to the adjuster lower on the rocker so if your hole is lower than the bottom of the threads, plug that hole and move it up) the ball of the adjuster should protrude .287 (9/32) inch plus .050, minus zero.

That’s where it goes. That’s the final dimension. That’s valves lashed, ready to run. If you have cup adjusters the correct setting is screw the adjuster all the way up until it bottoms out in the rocker and screw it down 1.5 turns and no more than 2.5 turns down. That’s where they stay.

Every time you change adjuster protrusion you change the geometry AND you can affect getting oil to the adjusters. So set the adjusters and make the pushrods the correct length.

It also sounds like you are concerned with centering the sweep pattern. Get the sweep as narrow as you can and as long as the roller isn’t running off the valve, your geometry is correct. Centering the pattern and making it wider is not the way it should be. Minimum sweep is what the goal is.


Edit: I forgot to mention that Hysteric is correct in adjuster protrusion does affect geometry. My point is is there is a correct protrusion and IMO you don’t alter that to correct geometry. Also, when the adjuster is lower in the rocker (more protrusion) you LOSE ratio. When someone says they lost .050 lift with a relatively small solid cam, the first thing I think of is the pushrods are too short.

I’ve never run that much rocker with that lobe family........ but the problems you’re experiencing don’t surprise me one bit when everything is taken into consideration.
Imo, it was way under sprung.

Personally, I can’t see myself using those lobes with 1.7 rockers for a basic bracket combo, but if someone asked what I thought for spring loads.......for say a 7300 upper rpm operating limit..... I’d be looking at 155-160 on the seat and 420-440 open(450-465lb/in spring).

The Isky 8005a is only 400lbs/in, so it would look like a new spring is in order, as I can the 150 seat pressure but only get to 390 open.

Question1, with the change in geometry my effective lift is down to .568, which if I calculate the ratio, I get an effective ratio of 1.56 (.568/.363), would that change your spring recommendation since it is not a true 1.7?

Question 2, if a spring change is in order, is there any advantage in looking at a beehive?

Thanks

If the net ratio ends up at only 1.56, then yes....... the spring load requirement would be lower.

Is the .568 number “net lift” with full spring load after lash?

For a 1.55-ish net ratio, you should be okay with springs that are 145-150-ish/380-400(at net full lift), and trying to keep the open height so it’s within .100 or so from coil bind.

The only personal experience I’ve had with beehives on the dyno are BBC marine applications, where they haven’t shown any magic to me thus far.
I’ve sold quite a few, but my own testing with them is pretty limited.

“In theory”, they should work in your application.

Going strictly off the specs, something like a Comp 929 set up at 1.870IH should do the trick(150 seat/390@.550 lift).

which lobe family are we talking about here? I don't see it mentioned anywhere.

Going from memory, I thought his cam had the same intake lobe family as what I ran in my 383...... the Comp XX Restricted.

Yes, I measured the .568 with everything mocked up, full springs, +.150 shaft spacer, and valve lash set at .020.

This is the one thing about the math on the spacer, the change in lift keeps you chasing your tail just wee bit.

I have looked at a set of the PSI-1511ML springs. They seem to be close to what I may need. If my math is right on them to get 150 on seat that would put me about .060 from coil bind, which I have read that some favor the beehive very close to coil bind (.020-.050).

On the 8005A, getting to 150 on the seat gets me to .065 from coil bind.

Cam card says 6329 on the lobe, both intake and exhaust - High RPM II Solid

I’m not sure how you come up with that(unless the springs have lost some load).
1.840IH should put you at 149 on the seat, springs coil bind at 1.160, for a total travel range of .680”.
.680”-.568”= .112”

Also, the rocker ratio would be calculated from the gross lift at zero lash.

Proof once again that one should never rely on memory!!

Okay....... so you’re not so far off then.
Those lobes should be fine with the 1.7......... still need adequate load though.

I’d have the current springs tested to make sure they haven’t lost too much.
If they’re still good, set them up at 150-155 on the seat....... and that will give you a little more closed/open load, along with putting them closer to c/b(which I would expect to be enough of a change to calm things down).

I’ve run a cam with that lobe family in a 446 with RPM heads on the dyno, using the single springs that came on the heads to 6500 and saw no signs of float to that point. That motor had HS 1.5 rockers (that measured 1.55).

Did you have a different cam in that motor at one point that had an XX intake lobe?

Good catch on the math.

I was comparing 1.825 (154.6 lbs) to 1.225, instead of 1.255. At the 1.825 that should put me at .095 to coil bind (check me).
Putting the lash back in puts the rocker ratio to 1.619, for whatever reason that makes me feel a little better.


We talked about the XX lobes but I think you did go away from the XX lobes because I was using a 1.6 rocker. I was planning to use the Cranes but I had better adjuster position with the CAT.
I have been very happy with it, I was tickled when it went 119 right off the trailer. I am still very happy with it, it just seems that its not very happy with me.

Machinist said he would have the spacers before the end of the week and I'll start shimming tonight. We have our first test and tune Sunday so hopefully I can have it back together by then and we can see if its happy.

Fast-Where do you shift yours?
I was actually following your dyno graph to try and get to a 4,000 fall back on the 1-2 shift.

After a bunch of shift point testing, I ended up shifting 1-2@6000, and the 2-3@6500.
That was using an 8” converter with 5400 flash stall. The 1-2 shift came really quick.

There wasn’t any real magic in the shift points with my combo, but the early 1-2 shift was a couple hun quicker than 6500...... even though it didn’t “feel” quick shifting it like that.
It “felt” awesome shifting at 7k, and the motor pulled up there effortlessly....... it just wasn’t as quick on the time slip.

With 5400 stall, that’s the lowest rpm point for the whole run after my foot hit the floor.

If the springs are still close to spec, I like the 1.825” IH plan.

And the hits keep on coming.

Pulled a couple valve springs this morning and the two I tested looked good 1.855 @ 135#. I then decided to go ahead and measure valve height and I got 1.975. I knew when I went to put the locks in they were going in easy as I usually have to wrestle with it just a bit to get the locks in. My original measurement was 1.8875 so nearly .100 of valve sink. So the good news looks like I found my problem. Can the heads be run like this or will the seats have to be recut? If I still with go with the 1.825 install height is .150 shim even a consideration or is it time to buy an aluminum head?

If you beat .100 out of the seats you’ve got other issues. Measure the OAL of the valve and see if it stretched some because .100 gain is a MILE.

I suggest you look everything over carefully.

I highly doubt the valve has moved .100”.

Did you have the valve lash shrink from whatever you set it at, to zero...... 4 or 5 times?

My guess is, there was a measurement error previously, which had the installed height set way too tall...... which is the root of the whole problem.

I question the 1.975 too though....... since it’s not always easy to get there with std length valves in 906 heads.

I’d pull the heads, inspect the guides and seats, and start over from scratch with the spring set up.

If you’re not using a height mic....... you should get one.

There was lash on the few I grabbed when I took the valve covers off before I saw the metal which started all this. I guess if the valve would have moved I would not have had any lash, right? How can tell if the retainer has moved? There is always a chance there was some error on setup but I do use a height mic. Just curious if there is a combo between pilot error and some retainer movement. I may stick a different retainer on it and see if the measurement is the same.

You’re saying the installed height changed about .100.
That’s about 5 times what the valve lash is....... so, we know it can’t be the valve tip height being raised that much, since the lash didn’t go to zero a bunch of times.

This leaves either a parts failure of some sort(keeper pull through, etc), or assembly/measurement errors when the heads were put together initially.

I would think if the retainers have moved up .100 on the valve stems, there would be evidence of retainer to rocker interference........since there is often less than .100” to spare.
It’s also unlikely(though not impossible) they would have all failed the same amount........ so you could look for a lack of uniformity in the relationship between the top of the valve and the top of the retainer.
If the retainer/lock/valve interfit was compromised enough to change the installed height even .010”, I wouldn’t reuse any of it.

As I said....... time to pull the heads, inspect everything, and start over on the spring set up.



Can you explain that a bit more? I’m trying to picture why you’d have to wrestle with the locks when there is no spring tension.

My height mic only compresses so far so the shorter the valve height the tougher it is to have enough room to get the locks in.

Must be you have a tall height mic.

The one I use for stock BBM heads goes from like 1.600-2.000.

Are you running single groove valves?

I think mine is the same 1.60-2.0 but it is aluminum so I am little more gentle with it when spinning it in. Yes the valves are single grove, stainless. Like I said when I get home this afternoon I have a set of steel 7* retainers I will measure with to see if I get anything different.

There are no industry standards the cam companies are trying to adhere to, so different brands of parts(retainers & locks) will often yield different installed heights.

I use a Comp 10* steel retainer with std height 10* locks as my normal reference point for height.

I’m working on some 906’s right now. They have oversized valves and will be used with a roller cam that will use springs installed at about 1.900.
For this type of build I always use a spring cup under the spring.

I check to see if any of the spring pads will need to be made deeper to facilitate the desired 1.900” IH.
The cups are .060” thick, so this particular one is just about perfect(no need to go deeper).

The next 3 pics show how non-standard this stuff can be.....