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Witness marks on valve stem is not clean... Thoughts ?

18K views 80 replies 13 participants last post by  awsomeears 
#1 ·
Ive done this before on my old set of heads and it turned out perfect, but this go around its not as clean straight line.

All NEW Parts List I'm working with :

Profiler 176 series SBC
Scorpion 1.5 roller rockers
5/16 8.150 length smith brothers push rods
Solid Flat tappet
Cam 570/.590 http://www.summitracing.com/parts/cca-12-517-5

Last week I used the adjustable push-rod checker and came up with 8.150 and had a really nice witness mark and placed my order, that was on a set of Crane 1.5 Golds.

Now I ordered a new set of pushrods and decided to buy a New set of Scorpion 1.5 as I just wanted New everything.

Could the geomotry from my crane golds and scorpions even tho they are stated 1.5 be different ?


My process was exhaust open - Adjust zero lash intake
Intake almost closed - Adjust Exhaust zero lash



This picture shows both intake and exhaust, I did a total of 10 revolutions and I would think it would be enough ?



 
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#3 ·
Yes there can be slight differences in rockers. This is why pushrods are one of, if not THE last things to get for your engine. Get out your adjustable pushrod length checker and set it so that the witness mark is as close to center as you can get it. This should also give you the narrowest mark. You will probably have to get new pushrods if staying with the scorpion rockers. Also the one on the left doesn't look to be tracking evenly. Could a slightly off valve tip or rocker stud not quite true. Hope this helped.
 
#4 ·
set it so that the witness mark is as close to center as you can get it. This should also give you the narrowest mark.
If the centered pattern gives the narrowest mark then he should buy a lottery ticket- while it is possible for that to happen (and it is supposed to) it almost is never the same length for the centered and the narrowest pattern. Go with the one that produces the narrowest pattern.

And yes your rocker arms are likely slightly different, I'm not sure why you bought the rockers after the p-rods.

Your wear pattern on the right doesn't look too terrible to be honest though, i've seen a lot worse. The one on the left does look odd that only half showed a witness mark but I'd clean the tip and try again before I'd rush to conclusions.
 
#5 ·
The one on the left looks like the rocker was not sitting straight, or the end of the valve stem is not flat. I'd try it again making sure the rocker is situated correctly, and see what pattern it shows. Could be an issue with the guide plate pushing it to one side.
 
#6 ·
Yes different rockers may require changes in the push rod length as different brands do have dimensional variations in the realtionship of lines drawn between the push rod cup, trunion, and the tip. The ratio only describes the distance between the trunion and the tip divided by the distance between the trunion and the push rod cup.

The partial contact pattern is typical of rockers with a roller trunion as they are not able to roll side to side as does a ball trunion. So if the stud and the valve are not in the same 3D alignment the contact patch on the stem will be off to one side or the other. A similar thing happens on the push rod side but we tend not to check this contact so it goes unknown and un-noticed. The valve train runs just fine inspite of these inaccuracies.

In operation the valves rotate slowly as a result of the spring wind causing a rotational motion as the spring is compressed and released. So even without the valve rotators that Chevy is so fond of this rotation occurs, so eventually the stem tip wear surface will spread across the entire tip.

Bogie
 
#7 ·
One thing that jumps out to me is the pushrod length. 8.150 just seems pretty long to me for a SBC. Considering stock is 7.800 and even though those heads run a longer +.100 valves an extra .350 just doesn't add up. The cam you list isn't a small base circle either. Not questioning your numbers but it raises my eyebrows a bit.
 
#8 ·
I'm guilty of buying new rockers after the fact I checked in with my old rockers.

After work I'm going to remove the guide plates and check it again with my adjustable pushrod and start over...

I also thought 8.150 was long. My old edelbrock heads with a .480 cam used stock length
 
#12 ·
Thanks for all the help...

Profiler uses such Cheap JUNK guide plates, there not even exactly flat and on all of them near the corners theres extra metal, I was able to flip them over but I still don't trust them.

So what I did is I grabbed a washer to take place of my guide plate thickness, re-measured at they started to all turn out much better.

I'm finding 8.200 ( 8 revolutions on adjustable push rod ) is much cleaner, and that 9 revolutions 8.25 Length is slightly thinner but is getting away from the center a decent amount towards the exhaust port.

I called Profiler for Stud torque recommendations ( before I even started to work on the motor tonight ) and then breifly discussed my odd results. While talking with him he said

" Yea those guide plates are pretty chincey "

Well ya wouldn't say :evil::evil::evil:

I'm calling them tomorrow and letting them know this is bull ****, not only that my 1st set of heads had TWO spark plug threads garffed up.

I went with Profiler as there smaller a smaller company and also simply to not follow the heard of AFR or Edelbrock and now I'm questioning why I did so.

I'll update this as we go

Any recommendations on Quality guide plates ?

:thumbup:



when you check the marks are you using a solid lifter, or a hydraulic lifter that has somehow been made solid?
Yes solid lifter @ Zero lash then rotate a bunch of times...
 
#10 ·
This is what I think about the one on the left, the black packman looking stem top.

The reason only part of it is contacting / wiping, is because it is wobbling. You do not have the lock nut on the square base(circled in red) of the fulcrum piece. The square is what is held up against the rocker nut. You are probably on the round part and not stable.

This is a total guess. It could be.

Picture.
 

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#14 · (Edited)
I've always liked Milodon guideplates, the raised versions. Erson and Isky make good flat style, Isky makes an adjustable spacing version for perfect tip alignment.

Dart also uses a pretty cheap guideplate, and studs are cheap looking too,..... it just doesn't inspire confidence when you see this in a new set of heads though, does it??!!. :(

Seems like nobody completely does a quality job anymore in the $1100 or under arena. Last I saw personally was ProTopline/ProAction, before they sold out to RHS.

I had hoped Profiler wouldn't let their quality fall off from their initial offerings....
 
#15 ·
Yea its been a big headache really, and what sucks is that I wasn't focused on the $$$ just a good product. You get what you pay for and I'm feeling shorted here. I will ask them to ship me a set of guide plates and see what they say...

I'm worried that if I get another NON adjustable set that they won't line up.

Whats the difference between the raised and flat, clearly they look different but ?

Summit has milodon but only the 10750 model and I don't see adjustables.
http://www.summitracing.com/parts/mil-10750/overview/
 
#16 ·
No difference really, just puts the position the plate contacts the pushrod closer to the rocker arm socket....probably makes no real difference.

I once had a set of SBC pushrods that were .060" wall moly, with a 1.25" long hardened pressed-in tip, the seam between unhardened tube and tip was right where it would rub on a flat guideplate...that type of pushrod seems to have fallen by the wayside, been a few years since I saw a set anywhere.

Milodon probably doesn't have an adjustable, I've only used the Isky myself in the adjustables.
 
#17 ·
I'll go back to my earlier post. 8.200 is really long. I have to believe something isn't right. That's .400 longer than stock. Make sure the bottom of the rocker isn't hitting the base of the stud. I've built some pretty exotic small blocks and I've never had to use anything near that long.
 
#22 ·
I usually run cast iron factory heads, with a good set of valves, and some work done to them. I did put Edelbrock Performer oval ports on my 464 BBC, but only because I got them so cheap I couldn't pass the deal up! I really do like them, but maybe I got lucky and got a good set. I haven't heard any quality complaints on Edelbrock myself. Only thing I've ever heard was some people said they didn't flow as well as some of the more expensive heads.
 
#25 ·
I usually run reworked stock stuff as well, to me the challenge of getting stock stuff to perform well is half the fun. No it's not as good as a $2500 set of aftermarket heads, but who would have though you can take a mostly stock long block and add 75% more power? I'm a fiddler and a tinkerer, I don't have to win races.
 
#23 · (Edited)
500 is nice budget for a head pair. My vortecs were $179. The total after beehive setup was well under that.

My vortecs still have not cracked, any time now right?

Iron, is a good material for heads. It works and there are plenty of castings around.

Those auction heads many like a 7.90 or +.100 pushrod . You got a 400 and said something about deck, with new rockers, so fine a 8.2 if it fits. Ap , addressed the lifter plungers possible sinking, so it is a checking lifter.
 
#27 ·
. Comp raised guideplates are dirt cheap and work well... I'm surprised Profiler would attempt to use anything lesser... I like the raised guideplates because I like to hold the pushrods as high up as possible for more stability...

. If the heads use wider than stock valve spacing, will definitely need custom or adjustable guideplates... I just break the inexpensive Comp raised guideplates in half and weld them back together with the exact pushrod spacing I need for a perfect fit over the valve stems...
 
#28 ·
I'm at a Total Loss for whats going on :rolleyes:

Picked up a set of adjustable comp cam guide plates, set everything up to zero lash, several revolutions and my witness marks are the same.

I will post a bunch of pictures and see what you guys can pick apart.

engineczar the last TWO pictures are for you to decide what could my issue be based on why my push rods are super long :thumbup:

Thank you !!!



^ clearly can see its wearing on the right side



^ Did it again, full lift and you can see the light :nono:






^ Zero lash with 8.125 before I started roating




^ closest is exhaust and that is a stock 7.800 length, other is 8.125



^ just showing when both lobes are not in any lift a STOCK 7.800 how short it truly is, I just pressed my finger down to seat the push rod in the cup.
 
#34 ·
I'm at a Total Loss for whats going on :rolleyes:



^ just showing when both lobes are not in any lift a STOCK 7.800 how short it truly is, I just pressed my finger down to seat the push rod in the cup.
In this photo, is the bottom of the rocker hitting hex of stud, preventing rocker from sitting fully down, or is the relief cut in the rocker for spring clearance not big enough for the rocker to clear the spring retainer and it's hitting there??

Agree with Chuck, 7.900" to 7.950" should be about correct, depending on what cam base circle is (reduced or not for stroker clearance?), maybe 8.000" at the absolute most.
 
#29 ·
. There's nothing you can practically do about that and it won't hurt anything... roller trunnion lifters just do that since they can't rock side to side like ball pivot ones do... just so it's centered over the valve stem like you have it...

. Actually, flat tappet lifters are designed to do the same thing, they just ride on one edge of the cam lobe which makes them spin slightly to even out wear and allow oil in between...
.
 
#30 ·
Maybe this will help, it is a video on exactly how to correctly do valvetrain geometry with a stud mounted rocker, and how to measure pushrod length.

Everyone interested in correctly doing this work should see this vid, some may already know the mid-lift method and it won't be anything new to them, but a lot of guys that think they know need to see this :

https://www.youtube.com/watch?v=o5is9BsH5OU&feature=em-upload_owner

Have you tried a different cylinder, to see if the unlevel contact is elsewhere, or just at that cylinder??
 
#32 ·
Some info posted on another board noted the off-kilter contact in the valve tip with AFRs bigger heads, the 210's and bigger, and IIRC Brodix, Dart, and RHS too were included...it is a result of the manufacturers slightly moving valve centerlines and stud locations, to allow pushrod clearance with a wider port and not having to force the head user to buy either shaft or offset stud mounted rocker arms and allow them to use common standard pattern roller rocker arms. It leaves the rockers aligned slightly pigeon-toed away from each other, not parallel, and so with the rocker locked into a plane of movement not entirely perpendicular with the valvestem because of how the roller trunnion in the rocker is located by the stud shank, you end up with a slightly off-level pattern on the valve tip.

Several of the pro builders there, along with AFR's tech man said it wasn't a problem and just run it., and the only way to completely eliminate it is with an offset pushrod cup shaft rocker set-up.

Trying to remember where I saw this discussion, seems like at SpeedTalk forum, but it might have been one of the YellowBullet Tech forums
 
#33 ·
Have you tried a 7.900" pushrod, thats what should be there...the trunion should be almost bottomed on the stud not way up on the thread like your photos show. Look at the excessive clearance between the retainer and rocker body...theres your sign.

7.900" is the recommended length BTW.

As for the offside pattern on the valve tip, a quick dress on the rocker stud pedestal with a file will correct that as will a light tap with a soft faced hammer to push it over as it might not be perfectly straight.

Hardly anything is ever perfect with castings especially if the studs were finished or tapped on a drill press or the heat treating warped the stud slightly...all very common issues in the real world particularly with aluminum.

Your overthinking this whole thing by trying to achieve some type of theoretical perfection...think practically.
 
#35 ·
The length of the pushrod is irrelevant! The pushrod length is based upson lifter height, rocker, and cylinder head design. It may want a 8.200..

The plates are NOT from Pro-Filer. The guide plates, studs, retainers, locks are all USA.. The valves are Eaton, and the springs are Erson.

This picture might sum it up. AFR vs Pro-Filer..

 
#36 ·
Chad, has Profiler raised everything on the head enough that the 8.200" long pushrod would be something considered in the "normal" range for this head?? Photo sure looks that way....+.200" valve also??

. I'm just going off previous experience with most other head brands and similar short block builds as to what would be a "normal" expected range for pushrod length....am I just not familiar with what Profiler has done with their casting?? Just trying to gather info here....know the mid-lift rocker set up well and know that pushrod length will be what it will be.....8.200" just "seems" real long for a stud mount on a non-raised runner 23° SBC head :confused:

Trying to observe scale and help over the 'Net via photo's can be a tricky devil.....
 
#39 · (Edited)
Chad thanks for the reply, I'm assuming you got my voicemail. I had to grind some of the original guide plates corners and just wanted to use something else to take any issues out of the equation. These comp adjustable are nice.

Thanks for the info, I figured I can't be the only one with long pushrods.

What about my valve tip markings not being clean straight line and flat on the valve stem ?

Thanks
 
#40 ·
I have been reading this thread and have kept my mouth shut as there are so many old school ideas floating around here.
Chad Knows his stuff with out a doubt.
Push rods are just a mechanical device to operate the rocker. You give the engine what it needs to make things work properly.
While it is always good to ask questions about these things if we are naive about things, some times you need to let common sense prevail.
Some time if any one has the opportunity, check multiple brands of rockers and see how much difference there can be between different brands.
Another big eye opener is set up a dial indicator on the Valve retainer with a check up spring and record max lift. Now install your race springs and check. You will be amazed at how much valve lift you can loose due to push rod flex. The amount of loss will be dictated by the amount spring tension.
It will show why the big change to huge push rods in race motors.
 
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