Newold1 wrote: ↑Sun Nov 11, 2018 6:11 pm
Polishing off hard chrome and rough metal on valve stems WON"T correct worn valve guides or correct stems to a point of getting back to good valve stem to guide clearances. Measure the stems carefully especially after removing material measure the guide and subtract to see if you are going to far out on good valve stem to guide clearance. If the stems are too far under their proper OD and the guides are ovaled, tapered or opened to far from their proper ID then my NON MICKEY MOUSE way of correcting the issues is to LOOSE the valves and REPLACE the goddamn guides.
If you don't own a couple of quality measuring tools like a small mic or some go-no go hole gauges and you are going to disassemble and build or rebuild good engines then damn it buy some!
This site sometimes starts sounding like a dirt floor machine and engine rebuild shop!
Sorry, but we are talking "SPEED HOME OF RACING" and high performance and racing engines here! Not your grand dads old 53 6 cylinder Chevy farm pickup out in the barn!
Sorry, just my reasonable REALISTIC professional opinion.
So who was giving unrealistic opinions? Who was suggesting to do whatever it is you're complaining about? Didn't see anything about used anything. So why are your panties in a bunch over this? Nobody recommended trying to bandaid anything. They didn't say used old guides and Jerry rig everything else to get it to work.
So why are you flipping out?
JC -
bigjoe1 wrote:By the way, I had a long talk with Harold(Brookshire) last year at the PRI show. We met at the airport and he told me everything he knew about everything.It was a nice visit. JOE SHERMAN RACING
Few more thoughts. I can see a need for increased oil retention in oil top end limited engines, so a crosshatch finish may work well as the seals may have a short life if even used. Still then a polished pitted surface would also retain oil better and possibly have no ill effect on seals. Would a lightly pitted surface be something you would consider on a new valve for mild street use?
Also DISCLAIMER if you choose to copy what I posted earlier and use rubber gloves on a moving part be sure the gloves don't fit loose or hang(maybe used thin gloves), used plenty of sauce and stop if it trys to grab the glove, use low speed or maybe not a machine that can kill or maim if it grabs you, do not wipe the part down while moving with a towel or something the machine can grab. Most on here wouldn't do this but for the random person who googles this, maybe just use your fingers or a trigger operated drill you can let go of.
Never, ever just drop in new valves. If you do, sooner or later you will get bitten. And I am just talking about the valve seat and its finish and trueness. Obviously I would assume guide condition and clearance would be correct for the application beforehand.
Regardless of who's valve they are I always check the stem and face for run out. Even the best quality valve available can have more stem or face run out then desired as well as a low time used valve may be fractured because they were installed a seat that was not concentric to the guide center.
It takes more time to QC every valve new or during a freshen up but if it is not done sooner or later there will be a come
back from lack of attention to the small details.
Stem taper is another issue that I see daily and it just drives me up the wall. The best quality valves can be as much as .0003 to .001 stem taper.
I recently did a bulk order for some valves of 2 specific sizes and after checking I found there was many valves unsuited to me requirements and when you are doing performance guide work this can really bite your ass hard.
It shows up fast.
And when honing guides and using from .0008 to .0012 intake clearance stem run out and taper show up right away when valves don't fit the guides at all and you need to open them up another .0005 or more just to get the stems to slide free;y in the guides. And the time it takes to get replacements is a waste of time and money just to get a job done when you get valves that are believed to be the best money can buy.
Regardless the stem taper and run out is checked 1st then the OAL or tip to valve face is checked and corrected as needed
then the valve is faced and runout held to less then .0005 or the valve is rejected.
I polish stems with 1200 wet/dry and solvent in the lathe to save time but there is many ways to spin a valve but watch out for laser inscribed brand names as well as roll stamped like milodon does that markings need to be removed if the valve is deemed OK to use as the markings will require the guides to be .002 to .004 larger to get the raised areas through
the guide. I have some heads in here now that the guides have a gouge in them where the engraved area was forced through making a trough for oil to flow straight down the guide.
Heads were here cause of oil consumption issue it did not have before the heads were freshened.
Don't know why you would 'polish' the stems of new valves that have been hard chromed. The chrome is a flash coating to reduce stem wear & polishing it with anything abrasive is just undoing the good work of the manufacturer.
Geoff2 wrote: ↑Mon Nov 12, 2018 3:44 am
Don't know why you would 'polish' the stems of new valves that have been hard chromed. The chrome is a flash coating to reduce stem wear & polishing it with anything abrasive is just undoing the good work of the manufacturer.
If you look close at a set of valves you will find small dings and otherwise rough areas on the stem that will prevent a valve from passing through a valve guide that has been honed to a specific size. When running .0008 to .001" intake stem clearance any imperfection in the stem will hang in up and not allow the stem to pass smoothly through the guide if at all.
Again the idea is perfection just like the keeper groove. It has small burrs from machining and this will keep a valve from going into the guide.
Today'a QC leaves alot to be desired and I am just doing the final steps needed to produce the best possible product. If that means a light polish on the stems then thats what has to be done to be perfect.
No different then washing the block or heads many times before assembly to be sure its clean as possible
Keith Morganstein wrote: ↑Sun Nov 11, 2018 9:27 am At minimum, I look at the stem finish. An easy way to polish the stem is to chuck the valve lightly in a cordless drill, then use crocus cloth (fine) to polish.
What bout maroon scotchbrite?
FullSizeRender.jpg
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Automotive Machining, cylinder head rebuilding, engine building. Can't seem to quit
On new valves & guides I use 100 grit and put a lite cross hatch pattern just to hold a little more oil during start up as it will disappear after a short amount of run time. On honed guides you don't need anything other than oil during assembly. This is what works for me; is necessary, probably not.
Keith Morganstein wrote: ↑Sun Nov 11, 2018 9:27 am At minimum, I look at the stem finish. An easy way to polish the stem is to chuck the valve lightly in a cordless drill, then use crocus cloth (fine) to polish.
What bout maroon scotchbrite?
FullSizeRender.jpg
Yup that's the stuff I got and tried, it cleaned up the scotch brite a tad. Mothers mag & alum did a better job and on the next valve skipped the crocus cloth for the same result.
Last edited by BOOT on Mon Nov 12, 2018 11:20 am, edited 1 time in total.
Geoff2 wrote: ↑Mon Nov 12, 2018 3:44 am
Don't know why you would 'polish' the stems of new valves that have been hard chromed. The chrome is a flash coating to reduce stem wear & polishing it with anything abrasive is just undoing the good work of the manufacturer.
This is why I didn't want to use anything too abrasive, while the red pad grit may be 600(what I read) it didn't seem as abrasive as 1000grit wet/dry. I also am waiting back on Manley to find out the chrome layer thickness.
