EKhatch

I have been asked by a few people on here if I could help them to understand why it is that 1st gen B16 LMA's may not be as good of a choice as newer GSR/ITR LMA's.

The main reason that the older LMA's are not as good for high lift cams is the fact that the circumference of the top of the LMA at the top were the rocker makes contact is smaller in diameter than their newer counterparts.

This presents a problem that I am going to describe with the aid of pictures that the higher the lift cam the more likely it is the the rocker is going to ride off the edge of the LMA were many problems can arise. The newer LMA's with the larger contact patch makes this event less likely to happen.

In these first few pictures you can see what I built to help explain what is happening inside of the engine. Granted the positioning is not 100% accurate this is good enough to get the point across. The main factors are that the rocker be hinged and is only allowed to move in a circular motion and the LMA is fastened so that it can only move up and down as is the case when both items are operating in their natural environment inside the head.













Next are a few pictures showing the contact between the LMA and rocker arm under essentially a "no lift" condition.

















The next series of pictures are a simulation of a the rocker pushing down on the LMA under a "lift" condition but nothing to extreme at this point.









Next we see high lift conditions and begin to understand the potential problem of the older style LMA's.









Now we see what has happened to some of us who were previously unaware of the potential of disaster. The rocker rides off the top of the LMA under high lift conditions.









Well that's about it. With a larger circumference area on top of the LMA this problem is not a guaranteed fix but it is certainly a big step in preventing this type of situation from ever happening.

All questions and comments welcome, thanks for looking.

Propulsion

props to you, very educational. So does the LMA move at all? or is it always stationary and just acts as a pivot point for the rocker?

EKhatch

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SilverCIVIC96 &raquo;</TD></TR><TR><TD CLASS="quote">props to you, very educational. So does the LMA move at all? or is it always stationary and just acts as a pivot point for the rocker?</TD></TR></TABLE>

The LMA moves up and down via an internal spring as the rocker pushes against it as the vtec lobe pushes on the pad of the rocker.

The LMA pictured is not moving as it would inside of the head. The whole thing is set up to move for demonstration purposes via a longer spring inside the black tube. The Spring inside of the LMA is too stiff to work with for this purpose of taking pictures but the results are more or less the same.

Propulsion

So what exactly is the purpose of the LMA?

Dan GSR

pretends to be a valve, and spring that isn't really there

Dan GSR

EKhatch awesome work
picture is worth a thousand words


can you do one with the newer style LMA ?

743power

Awesome pictorial.

EKhatch rocks.

EKhatch

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dan GSR &raquo;</TD></TR><TR><TD CLASS="quote">EKhatch awesome work
picture is worth a thousand words


can you do one with the newer style LMA ?</TD></TR></TABLE>

I could probably do that. I would just have to pull one out of my head that I have lying around. If I do I will make some marks so that you can see the difference between the two in the jig I made.

EKhatch

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by x743x &raquo;</TD></TR><TR><TD CLASS="quote">Awesome pictorial.

EKhatch rocks.</TD></TR></TABLE>

Haha, thanks bud.

Over the next couple of days I will try and get some more critical measurements and test out a modded ITR LMA for comparison.

2dark2bslow

Awesome tech and what a coincidence, i was wondering just today how exactly a LMA works.

so which LMA should we run with aftermaket cams to prevent rocker run-off as illustrated?

EKhatch

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2dark2bslow &raquo;</TD></TR><TR><TD CLASS="quote">so which LMA should we run with aftermaket cams to prevent rocker run-off as illustrated?</TD></TR></TABLE>

It just depends. I would run the newer GSR/ITR ones at anything at or over 12mm of lift. I have seen JUN 3's run on 1st gen B16's (like the ones pictured) without any problems and those cams are 12mm of lift if I am not mistaken but hey, better safe then sorry.

DEVIOUS_EG*

nice write up EKhatch.....

riceball777

wow nice write up
mad props to you
very educational

EMO-anthony

Nice work EKhatch! Very informative!

EKhatch

Thanks for the kind words guys.

I think I am going to expand upon this project and test an ITR LMA that has been modified by RLZ against this stock B16 one. I will try and get some numbered increments up on the display I made so it is easier to tell how much difference there is between the two.

Here are the two that will be tested next.

teg92

(same post from another thread)...

So I spoke with a guy from Comp Cams who actually has the 12.4mm lift cams in his 93 JDM B16A with original LMA's. He has been running them for over a year without any problems other than slightly louder valvetrain "clicking".
So either that extreme case scenario of the rocker coming off the LMA requires a lot more lift than 12.4mm, or i just don't know...

H-T user NC-B17A said to me he "wore out" his b17a LMA's and replaced them with ITR LMAs which later self destructed (retaining clip came out of LMA....). So it seems to me that it is possible to run this kind of lift with tapered LMAs...

It would be great to be able to re-do Ekhatch's experiment a little more accurately... and it just came to me..

Teamcracka could maybe help us out with his 3d model....

https://honda-tech.com/zerothread?id=755759

i sent him a pm, maybe this will set it all straight!

teg92

Ok. just popped my valvecover off, used a dentist's mirror and rotated the crank and watched the middle rocker and LMA contact....

At max lift on a 12.4mm cam, the edge of the lip on the bottom of the rocker is flush with the OUTSIDE of the LMA. Meaning, there is still the full face of the pad in contact with the lip on the rocker.

So I have no idea what people are talking about, but there seems to be NO problem running 12.45mm lift on tapered style LMAs.

Seat pressure may be an issue, but I can only see insufficient seat pressure causing ticking or noise, not failure. And might I mention, the guy from comp cams also did mention his valvetrain is a little noiser... (probably lmas)...

EKhatch

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by teg92 &raquo;</TD></TR><TR><TD CLASS="quote">(same post from another thread)...

It would be great to be able to re-do Ekhatch's experiment a little more accurately... and it just came to me..

</TD></TR></TABLE>

Yes, this is something that only took me about 10 minutes to do. Accuracy was not a big consideration when I made this. It was just a model to help people understand how the LMA works and clear up some confusion.

I will work on a better model that I may be able to take more precise measurements on later but for now this was just to show a few people about what is going on inside the engine.

I do not know if this has any affect but I know not all cam manufactures use the same base circle dimensions and this may add to some of the confusion and problems people are having.

WuRKD b16

i have a first gen b16 with crower st 2 cams and my car makes ticking noises especially loud from 3k-4kRPM. What is the worst that could happen if i dont change my LMAS or should i definately change them? I was told it was my distributor making the noise but its not my dizzy.

TeamCracka

teg92 expressed interest in me creating 3d models with accurate dimensions and lift. If someone can temporarly donate (i'll send them back) whatever LMA's you need testing and a rocker arm, I'd be glad to.

EKhatch

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TeamCracka &raquo;</TD></TR><TR><TD CLASS="quote">teg92 expressed interest in me creating 3d models with accurate dimensions and lift. If someone can temporarly donate (i'll send them back) whatever LMA's you need testing and a rocker arm, I'd be glad to.</TD></TR></TABLE>

That would be cool. I have a stock 1st gen B16 LMA that you could borrow along with the rocker arm. I guess if you could only test one then this would be the one in question.

EKhatch

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WuRKD b16 &raquo;</TD></TR><TR><TD CLASS="quote">i have a first gen b16 with crower st 2 cams and my car makes ticking noises especially loud from 3k-4kRPM. What is the worst that could happen if i dont change my LMAS or should i definately change them? I was told it was my distributor making the noise but its not my dizzy.</TD></TR></TABLE>

The noise could be from the LMA's themselves. They can weaken over time and start to make noise. If you can take them out and press on them between your fingers there should be no play in them at all.

WuRKD b16

is it hard to remove the LMAs? How would i go about doin it

EKhatch

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WuRKD b16 &raquo;</TD></TR><TR><TD CLASS="quote">is it hard to remove the LMAs? How would i go about doin it</TD></TR></TABLE>

Only hard because you have to pull the rocker shafts and rocker assemblies to get them out. This can't usually be done with the engine in its mounts. You will most likely have to take the drivers side mounts off and jack up that side of the engine to get the shafts out. This entails pulling the cams so it is a fairly in depth ordeal.

onepoint6i

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EKhatch &raquo;</TD></TR><TR><TD CLASS="quote">

Only hard because you have to pull the rocker shafts and rocker assemblies to get them out. This can't usually be done with the engine in its mounts. You will most likely have to take the drivers side mounts off and jack up that side of the engine to get the shafts out. This entails pulling the cams so it is a fairly in depth ordeal. </TD></TR></TABLE>
I tried doing this in my EF with hasport mounts and it wouldn't work the shafts would hit the car itself , then again i have a front motor mount too.. i pulled them from the vtec solenoid side just have to pull the solenoid off...