Thread:

More trainee valve train questions

Installing bigger roller cam..Iron head 427 When i got this motor it had bad intake guides....really really bad.

Exhaust are fine...both heads are worn the same....I eyeballed the mid lift angle when i first got it and it looked plenty close and this is what i have right now with new cam.
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mid lift

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The roller runs on the outside edge of the tip....It is what it is....
The intakes run a little closer to center.
Mid lift angle looks fine to me.
Trying to avoid any more guide issues....
Anybody want to hazard a guess what would cause guides to wear that much and do it pretty evenly...and not have an issue with the exhaust guides at all. The intake valves themselves are still good..stems were smooth and not worn....
Harlan Sharp rockers pushrods are 9.350/8.380, no excess wear from guidplates.
thanx
mike

The roller "sweep" pattern on the valve should be no more than .060" wide. How wide is your sweep path now?

Originally Posted by SoldHondaBoughtHondo

Installing bigger roller cam..Iron head 427 When i got this motor it had bad intake guides....really really bad.

Exhaust are fine...both heads are worn the same....I eyeballed the mid lift angle when i first got it and it looked plenty close and this is what i have right now with new cam.
closed

mid lift

Open

The roller runs on the outside edge of the tip....It is what it is....
The intakes run a little closer to center.
Mid lift angle looks fine to me.
Trying to avoid any more guide issues....
Anybody want to hazard a guess what would cause guides to wear that much and do it pretty evenly...and not have an issue with the exhaust guides at all. The intake valves themselves are still good..stems were smooth and not worn....
Harlan Sharp rockers pushrods are 9.350/8.380, no excess wear from guidplates.
thanx
mike

Your in the ballpark because you are certainly going from over arc to under arc in those pics and doesnt appear to be moving much across the stem, but to be exact you will need to setup a dial indicator and get to exact midlift and then use a square to get in there. Or a piece of key stock to lay across the retainer to line up with the trunion & roller as some have suggested. Not sure about the major intake wear maybe some of the experts will chime in. Would also help if the pic was of the intake valve instead of the exh.

Originally Posted by Hass828

Your in the ballpark because you are certainly going from over arc to under arc in those pics and doesnt appear to be moving much across the stem, but to be exact you will need to setup a dial indicator and get to exact midlift and then use a square to get in there. Or a piece of key stock to lay across the retainer to line up with the trunion & roller as some have suggested. Not sure about the major intake wear maybe some of the experts will chime in. Would also help if the pic was of the intake valve instead of the exh.

I set the intake up last night..took pics but my camera doesn't like
garage light. Intake looks a little better than the exhaust. The roller has a pattern plenty close to the .060 that was posted, runs on the outside half of the tip...about 5/8 of the way across...the 90* deal is very close and a line across the top of the retainer is as close to parallel to trunnion/tip roller as things get.....
I'm guessing the valve springs were sacked...machine shop hadn't
checked them yet but i do remember when i lined them up and put a straight edge on them to check free height that the tops on several weren't very square...and the shims were btf. I have a guaranteed good used ones on the way....only have 500 miles on them....down baja

Those look like '65-'66 396/427 heads. Errr, can it be that the absurdly loose valve guide clearance is due to somebody installing aftermarket 11/32" valves into the OEM 3/8" guides? If that's the case and the engine ran for any period of time, the guides would certainly be shot by now and need replacing....whereas they could have been k-lined down to 11/32" during the head work and run without issue. But that's not the fault of the location of the roller tip.

The roller tip not being centered on the vavle--in and of itself--is not a reason for super-accelerated guide wear and has nothing to do with valve train geometryy per se. The whole reason for putting a roller on the tip of the valve is to provide a second pivot point so that the downward forces from the rocker arm remain in line with the valve as the rocker arm moves through it's radial sweep, which reduces side loading. It is not to reduce friction as many mistakenly assume (the trunnion bearings are for reducing valve train friction).

So having a roller tip positioned outside of dead-center of the valve stem is inconsequential in most cases. (But other valve train loads can accelerate guide wear.) In 2010 we re-built a drag racing engine which came to us built by another shop. Inside this engine, the installed height of the valve springs were 0.300" taller than usually seen on the canted valve heads and this put the stem tip closer toward the rocker ams which thereby put the roller tip on the outer-most edge of the valve stem. I immediately evaluated valve train geometry prior to teardown and found it to be flawlessly perfect. Was there guide wear? Nope, zero, zip, zilch, nada. We touched up the seats and ground the valves but the guides needed nothing. Before being brought to us, that 557 cubic inch engine ran 7 years with 7600 rpm shift points with that roller tip on the edge of that stem. Now I'm not encouraging this type of build for the masses, I am only illustrating how proper valve train setup can make for minimal vavle train issues, etc.


LO

p.s. On your rocker arm geometry pictures, you are looking at only one side of the rocker arm. The other side does not look as good, and while most rocker arm brands will differ that particular setup looks about as good as you can get with that brand of rocker arm on that head.

Originally Posted by LakesOnly

Those look like '65-'66 396/427 heads. Errr, can it be that the absurdly loose valve guide clearance is due to somebody installing aftermarket 11/32" valves into the OEM 3/8" guides? If that's the case and the engine ran for any period of time, the guides would certainly be shot by now and need replacing....whereas they could have been k-lined down to 11/32" during the head work and run without issue. But that's not the fault of the location of the roller tip.

The roller tip not being centered on the vavle--in and of itself--is not a reason for super-accelerated guide wear and has nothing to do with valve train geometryy per se. The whole reason for putting a roller on the tip of the valve is to provide a second pivot point so that the downward forces from the rocker arm remain in line with the valve as the rocker arm moves through it's radial sweep, which reduces side loading. It is not to reduce friction as many mistakenly assume (the trunnion bearings are for reducing valve train friction).

So having a roller tip positioned outside of dead-center of the valve stem is inconsequential in most cases. (But other valve train loads can accelerate guide wear.) In 2010 we re-built a drag racing engine which came to us built by another shop. Inside this engine, the installed height of the valve springs were 0.300" taller than usually seen on the canted valve heads and this put the stem tip closer toward the rocker ams which thereby put the roller tip on the outer-most edge of the valve stem. I immediately evaluated valve train geometry prior to teardown and found it to be flawlessly perfect. Was there guide wear? Nope, zero, zip, zilch, nada. We touched up the seats and ground the valves but the guides needed nothing. Before being brought to us, that 557 cubic inch engine ran 7 years with 7600 rpm shift points with that roller tip on the edge of that stem. Now I'm not encouraging this type of build for the masses, I am only illustrating how proper valve train setup can make for minimal vavle train issues, etc.


LO

p.s. On your rocker arm geometry pictures, you are looking at only one side of the rocker arm. The other side does not look as good, and while most rocker arm brands will differ that particular setup looks about as good as you can get with that brand of rocker arm on that head.

'Absurdly loose' lmao..The weird part is...it ran that way....never sneezed or missed...and it's not the reason i tore the motor down. Heads are 3964291...with a date of f 12 70...maybe 1st design LS 6 Intake valves are 2.24x.368x5.280.

I didn't think roller location on the valve tip was massively critical..i keep thinking stamped steel rockers slip sliding around....and the guides were not worn in an oval at all.
Aside from the roller running off the edge or running right on the edge all the time and not having enough area to distribute the pressure i wouldn't think it would cause a problem. As far as using push rod length to get the roller to run center it looks like it would take a 1" shorter push rod to get it on center and a cam
with .015 more lift to cover the lost lift.

If the roller tip is actually a pivot doesn't that mean if you check geometry using the mid-lift method the angle should run center through the trunnion to the outside edge of the roller.?

I didn't think of looking at both sides...and yep, they can't show the same angle. Rockers are Harlan Sharp..... I'm way new to all this, last time i worked on aftermarket roller stuff was about 1983. This isn't anything exotic...BBC iron head with an out of the box Isky .686 lift roller with instructions limited to where to grind the oil groove for early blocks and where to install the cam to get the advertized specs.

Thanx
mike

Wow that is rdiculously worn out for 3/8 stem valves.

Originally Posted by SoldHondaBoughtHondo

If the roller tip is actually a pivot doesn't that mean if you check geometry using the mid-lift method the angle should run center through the trunnion to the outside edge of the roller?

No, because the transition in motion from "inline" to "radial sweep" is occurrs at the roller axle.

The straight lines (trunnion axle-to-roller axle & roller axle-to-roller radius) will always be straight line forces with the hard, dynamic angle occurring between them at the roller axle as the valve train goes through its motion. They will never sweep in an arc as does the roller axle when the rocker arm goes through its radial motion.

LO

p.s.: That was a great question.

Originally Posted by LakesOnly

Wow that is rdiculously worn out for 3/8 stem valves.
No, because the transition in motion from "inline" to "radial sweep" is occurrs at the roller axle.

The straight lines (trunnion axle-to-roller axle & roller axle-to-roller radius) will always be straight line forces with the hard, dynamic angle occurring between them at the roller axle as the valve train goes through its motion. They will never sweep in an arc as does the roller axle when the rocker arm goes through its radial motion.

LO

p.s.: That was a great question.

As was your answer
As for absurdly loose valve guides worn in a reasonably round manner...nothing but a set of junk springs....most of the intakes were just plain crooked.....don't know how long it took to wear the guides that much but my local machine shop who fixed the guides on the other head put the same springs back on and while i don't have a way to precisely measure the hole, the spring end of the guide feels looser than the other end....and the shims have been rotating a bunch ....4 hours run time shows some wear.
Kinda odd...as much as the valves had to be flopping around and with 220 on the seat the valves and seats cleaned right up.
Actually kind of odd the motor would even run like that...never missed or backfired..although with earplugs the valve train always seemed noisy even for solids @ .030 and .024 didn't make a difference...no smoke either
thanx
mike

Originally Posted by SoldHondaBoughtHondo

...no smoke either

I'm not one of the super expert guys around here, but I'd have to say if your exhaust valves are flopping around like that and you're not smoking... perhaps the valve seals never passed enough oil to lubricate the valve in the first place, causing the wear altogether. What type of seals were on there?

My two cents worth anyway. Good luck!

-Seth-