Valvetrain geometry
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Valvetrain geometry

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    Senior Member lbhsbz's Avatar
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    Default Valvetrain geometry

    In my quest to sort out my rocker geometry, I've discovered two things. My cam has been reground and is only a .650 lift instead of .720 like the cam card says, and my valve stems are different heights. If I lay a straight edge across the exhausts on one head, I've can slide a .040" feeler gauge between the straight edge and the #3 valve while all the others are at zero.

    Consequently, it would appear as if the push rod that works on
    The #3 is .100 short for the other 3 ex valves on that head. Is this considered an allowable variation or should I once again beat my machinist?

    Edit: Just checked the other side...There's about a .070" variation in stem height. LOL. Looks like the heads are coming back off. Dammit.
    Last edited by lbhsbz; 11-06-2010 at 03:11 PM.

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    Certified Wildman! Sanger Flatbottom's Avatar
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    Yep, valve stem height being equal and tip height for your retainers/rockers is CRITICAL to obtaining the proper geometry, and one of the most mis-understood parts of "blueprinting" an engine, essential to engine life. I have to hand it to you to catch this... many guys would just call it good and average the height between the highest & lowest, but when you are talking 6k to 8k rpm and all the high dollar parts below that could be affected, the difference is having a usable core or an anchor. Good catch, you just saved yourself big bucks and major downtime. Always trust your gut feeling as you have... good job!
    Everything electrical has smoke in it.... and it's not done till you let the smoke out!

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    Senior Member lbhsbz's Avatar
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    Got the heads back off....just for grins I cc'd em. One head is 120-121-120.5-121...looks OK for as cast chambers. The other head is 116-117-118-119. Fawk me....he even screwed up the resurfacing.

    Compression ratio is anywhere from 9.9:1 to 10.4:1 depending on which cylinder you measure....LOL
    Last edited by lbhsbz; 11-06-2010 at 03:40 PM.

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    sounds like you need to find a new machinist-at least you can check your
    own stuff! think of all the other peoples stuff that took this guys word

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    Senior Member lbhsbz's Avatar
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    Yup, he's already been fired. I actually spoke with him today...he said not to worry about the valve stem lengths....just set the pushrod so that at zero lash with the valve closed the roller tip is in the center of the valve stem. What a tool.

    Don't take machine shop recommendations from people without making them show you THEIR measuring equipment....

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    Usually when the heights are off that much the valves are sunk into the head. Have these heads had seats installed? The installed height of the springs will tell a lot. If they had seats and they didn't grind them back to the proper installed spring height then you have more problems.
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    Bostick Racing Engines six-oh-nine's Avatar
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    Quote Originally Posted by lbhsbz View Post
    In my quest to sort out my rocker geometry, I've discovered two things. My cam has been reground and is only a .650 lift instead of .720 like the cam card says, and my valve stems are different heights. If I lay a straight edge across the exhausts on one head, I've can slide a .040" feeler gauge between the straight edge and the #3 valve while all the others are at zero.

    Consequently, it would appear as if the push rod that works on
    The #3 is .100 short for the other 3 ex valves on that head. Is this considered an allowable variation or should I once again beat my machinist?

    Edit: Just checked the other side...There's about a .070" variation in stem height. LOL. Looks like the heads are coming back off. Dammit.
    What you have here is why I actually bought my own equipment and started doing my own machine work. For the most part I have found that many of your "engine builder machinists" are neither... or at least half-assed at one, and less than that on the other. For 3/4 of the folks out there that do not know nothing about nothing, then what they don't know will be just fine for them. (Ignorance being bliss?) For folks that actually pay attention to what they bring home and start to build, most of the time they find that the folks that are supposedly "experts" or at least "professionals" are less than qualified to the job right, or just don't care enough to do beyond, "eh, close enough." The last time I had someone else do a valve job for me; it was by a well known local machine shop and was recommended by several folks, who was well known for building engines and doing machine work for quite a few roundy-round guys at Cajon Speedway. When I brought the heads (and block... which is another rant of its own!) home to assemble what I found pissed me off so much I drove back and went over each and every issue I had with his "quality work". 3cc different between heads, heads sufaced crooked, valve stem heights, though within "spec", were anywhere from the high side to the low side of said "spec" and a few stems "blued" from having the piss ground out of them, bronze guides reamed instead of honed, and loose for that matter, valves were not ground "because they are new and don't need to be ground", plus a couple of perhaps nitpicking details. His answer was, "Well if you think you can do better, then why don't you do it yourself?" Nice reply to being called out on chit work, huh?

    Three weeks later, bought a valve grinder, a surfacer, a few other tools to start out and was in the machine shop business.

    My recommendation as far as machinists go...
    1st. Visit the shop:
    See what they have going on, not so much as how pretty of a building and bitchen showroom. I've seen crap come out of a huge bitchen faclity, and excellent work come from a dude working out of his garage... what to look for is what kind of equipment and what sorts of projects are coming out of the joint, see how they take care of their stuff. You can a feeling for how much someone cares to do a nice job by how well they treat their own equipment. I mean you can't really expect a guy to care too much about your stuff if he doesn't care enough to take care of his own tooling. And chances are, though not always, that if a shop owner actually spends the dough to buy good equipment and has the right tools to do a proper job, then chances are better that he knows what he's doing. (Though this is not always the case, but in conjunction with the next two items, adds to the overall assumption of the work you'll get)
    2nd. Talk to the guy doing the work.
    You talk to the shop owner and he seems like a knowledgeable fellow and really has some good answers, great, if that is who is going to be working on your stuff. If it's a larger shop, you tend to have several people doing several jobs, and though Mr. Smith up front who owns the joint may be a knowledgeable chap, Hector out back doing cylinder heads may be "competent" at best. When I worked at another machine shop a few years back, it amazed me at how much crap had to be re-done before it left the shop due to "the guy in the back" trying to pass off half-assed "no-es mine" work.
    3rd. Word of mouth.
    If you ask around, chances are you'll get the word on whether or not the shop your checking out is worth a damn or not. I mean if you ask a bunch of penny pinching tightwads who have crap that runs like crap and are solely driven by the notion that cheaper is the best, if "Budget Economy Cheapest Machine Shop In The World Inc." is a good place to go, of course they'll say yes, because it suits their needs. But if you ask folks that you know to seek out quality and have stuff that runs good and are reliable where they take their stuff too, chances are "Budget Economy Cheapest Machine Shop In The World Inc." is not going to be on the top of the list. Just sayin'.

    Now granted, these three recommendations are just my opinion, and others may have a differing view, but it is of my opinion that if a shop can meet all three in a satisfactory manner, chances are you are going to get a decent shop and better chance of some quality work. But the last thing is, and perhaps should be considered the 4th and final must have, you need to have an understanding of what exactly you want and how you want things to be done. If you wish that all the valve heights be within +/- .002 of each other, let the machinist know. If you want .0055 piston to wall clearance, let him know. You cannot assume that what "your" tolerances are will be what "his" tolerances are... and CHECK EVERYTHING! Machinists are humans... anybody can make a mistake once in a while, it's what you do to remedy the situation, and how you insure that you do not make the same mistake twice is the difference between a shop you keep as "your machinist", and a place you shouldn't go back to.


    Btw... to answer your question... I tend to like to keep a variance of no more than .005 max between valve stem heights between heads... and I mean MAX. On old used up heads, sometimes this will have to do... new stuff... new parts... no excuse for not getting it nutted within a thou or two. Others may have a different opinion, but this is what I go with and have had good luck with.
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    Senior Member wizbang's Avatar
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    The guy you need is " steel comp'

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    Six-oh-nine.....your list of how to pick a shop is good...but for the one for checking out the shop. Most are probably like me and that is we know nothing of the machines in the shop. I don't one brand from aother or what each machine does. So what are we novice to do? I look for is how clean the place looks around the machines. If things are plied on them. I see if it looks like he cares for his machine as the precise tools they are.

    Even a well known shop with a good repose can screw you. I had this happen just resently. I just feel he didn't have time for me or I wasn't part of his click. I even dropped a name of a well known racer that used this shop extensively and recommended him to me. The shop had my parts for 3 months and didn't even start on them till I started to call. All I got for my $365 was "we checked your parts and theres nothing wrong" He supplied the bearings and set the clearances and said I'm good to go. Being a novice, I checked the clearances as best I could, thought they were good and put it together. Ran 30 minutes and chewed the bearings.

    Longer story short.......I went to a smaller less know shop that found my crank was bent. He set me up with a new crank, damper, bearings and set clearances. After 36 passes, it's still running.

    The best thing I learned fro this experience.....I can now measure clearances to the tenth like I need to. When I checked the second shops work, everything came out as he said.

    I now have a new shop.

    Tim

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    Senior Member lbhsbz's Avatar
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    I already talked to Foxwell, and I might send the heads up there. I have a problem though. In looking at the heads, nothing jumps out at me as a sign that these were machined on an angle. The only really accurate surface to reference off of is the surface in question. I get about a .008" variation measure between the gasket surface and the valve cover surface, but with as far out as these chambers are, I'm looking for a 0.020" variation (0.005 per cc)

    I was thinking of machining a pin to go in some headbolt holes and measuring how square the surface is to these pins, but I don't trust the headbolt holes. i suppose I could get some specs from dart on the valve angles and do something similar using the valve guides, then run an indicator up and down 'em and shim the head on a mill table to establish what Should be a level deck, then drag the indicator along the deck to see if it's out.

    I want to know how to determine if the chamber size issue is a function of crooked machine work or feature of varations in the rough cast chamber, or variations in the valve seat/face depth.

    If #1, we can machine the head straight to fix it.

    If #2, we can work the chambers to match them to the largest, then resurface down to my desired chamber size

    If #3, it just needs a proper valve job...maybe new seats and valves.

    If it's a combination of all 3, then my head will start to hurt.




    In response to the other posts here...

    609- I've been shopping for equipment but most that I can afford is junk....and I'd only have one job to do on it, because it would get done right the first time.

    I can't stand the "good enough" attitude. Sure, it has its place...but not in an engine. There's right and there's wrong.

    I've given the guy a lot of slack...

    The first engine he did for me was a SBC was supposed to go .030 over, he took it .040 after I'd bought pistons. He got another block and took it to .030, then when I torqued the crank down it wouldn't turn because the rear cap twisted. Ended up buying a used complete motor to throw in the car that turned out to have a .040 over block that was cracked....so I jambed over and grabbed the .040 block and got it done.

    While all this had been going on I bought yet another block and brought it over to speedomotive....purchased a new set of main and head studs from them, and told them to make sure the mains were torqued with the studs for every operation, along with very specific, almost idiot proof instructions on exactly what I wanted done and how I wanted it done. I'm the one with the money, do it my way. $1000 later I went to pick up the block...mains held on with the stock bolts and the studs still sealed in the package. I told 'em to get me another block and start over again since the mains, which every other operation is referenced off of, will now have to be re-honed...they said they could fix it. I told 'em to keep it and cancelled the credit card payment and walked out.

    I gave him another shot when I did the 22RET turbo motor in my crawler...I brought very specific instructions, along with OE spec sheets. I warned him that wall clearance was different for the turbo than for the N/A motor. When I got the block back....even without rings on the pistons, they would not drop to the bottom of the cylinders. So, back it went to be honed to the correct size.

    The motor he did for the white boat...when he gave it back to me...his line hone sub or someone had switched the 2 and 4 main cap and mis-labeled them after the line hone operation....so once again, the crank didn't turn. Once it was all together, even a 0.010 under chain was sloppy cuz they moved the crank too far up in the block, and the rear cap didn't fit tight in the block. I had just purchased a bore gauge and measured the mains at one spot...all looked good, so I said screw it and put it together because I was outta money at that point and I wanted to go to the river.

    After I sunk it, I tore it down to clean everything up and noticed that that rear main had 0.0025 taper from front to rear...I'd previously measured it at the rear. Crap, so this block is toast.

    I got him another one outta the new boat that needed to go .060 over, and even though I bought a set of MLS gaskets from him, he failed to properly measure deck height (said I was at zero and that's why he didn't deck it) and didn't think that the MLS gaskets wouldn't seal on the super coarse existing finish that was on the deck. I measured up deck height to be about 0.008 in the hole....and brought it to superior in orange to have them check it out. They took off exactly .008", that I verified upon reassembly, and said the block was twisted 0.006".

    It came out perfectly, they told me exactly what they did, how many passes they took at it, how much off each pass, and it all verified when I measured it up at home.

    The guy who has screwed everything up will not accept that any of these ****ups have been his fault....it's always that I'm too picky. Well, yeah. I'm too picky. I want my shit right. maybe it'll stay together for a few years that way.

    Every engine I assemble teaches me a lot more about it. Measure Measure Measure Measure Measure. Trust no one. Everything I measure on one that I failed to measure on the previous one, I find screwed up.

    After thinking back and looking at pictures of my old heads (gone now)..My old heads were probably in the 125-130 cc area, but the machine shop polished up the chambers so who knows what it really was, I doubt they were the same....I now realize that it put me around 9:1 c/r.

    I had just used the stupid moroso plastic thing to select pushrod length and didn't pay attention to valve stem height or weather I was getting full lift at the valve.

    I can't wait to get this motor together...with everything correct and the same on every cylinder...it'll probably make considerably more power. I guess I've never had a motor that was "right".

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    Quote Originally Posted by lbhsbz View Post

    I've given the guy a lot of slack...

    The first engine he did for me was a SBC was supposed to go .030 over, he took it .040 after I'd bought pistons.
    I would have been done with him here

    Quote Originally Posted by lbhsbz View Post
    I gave him another shot when I did the 22RET turbo motor in my crawler...I brought very specific instructions, along with OE spec sheets. I warned him that wall clearance was different for the turbo than for the N/A motor. When I got the block back....even without rings on the pistons, they would not drop to the bottom of the cylinders.
    If it was my bother in-law, and I really loved my sister and she begged, he would have been done here.



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    Quote Originally Posted by lbhsbz View Post
    I already talked to Foxwell, and I might send the heads up there. I have a problem though. In looking at the heads, nothing jumps out at me as a sign that these were machined on an angle. The only really accurate surface to reference off of is the surface in question. I get about a .008" variation measure between the gasket surface and the valve cover surface, but with as far out as these chambers are, I'm looking for a 0.020" variation (0.005 per cc)

    I was thinking of machining a pin to go in some headbolt holes and measuring how square the surface is to these pins, but I don't trust the headbolt holes. i suppose I could get some specs from dart on the valve angles and do something similar using the valve guides, then run an indicator up and down 'em and shim the head on a mill table to establish what Should be a level deck, then drag the indicator along the deck to see if it's out.

    I want to know how to determine if the chamber size issue is a function of crooked machine work or feature of varations in the rough cast chamber, or variations in the valve seat/face depth.

    If #1, we can machine the head straight to fix it.

    If #2, we can work the chambers to match them to the largest, then resurface down to my desired chamber size

    If #3, it just needs a proper valve job...maybe new seats and valves.

    If it's a combination of all 3, then my head will start to hurt.




    In response to the other posts here...

    609- I've been shopping for equipment but most that I can afford is junk....and I'd only have one job to do on it, because it would get done right the first time.

    I can't stand the "good enough" attitude. Sure, it has its place...but not in an engine. There's right and there's wrong.

    I've given the guy a lot of slack...

    The first engine he did for me was a SBC was supposed to go .030 over, he took it .040 after I'd bought pistons. He got another block and took it to .030, then when I torqued the crank down it wouldn't turn because the rear cap twisted. Ended up buying a used complete motor to throw in the car that turned out to have a .040 over block that was cracked....so I jambed over and grabbed the .040 block and got it done.

    While all this had been going on I bought yet another block and brought it over to speedomotive....purchased a new set of main and head studs from them, and told them to make sure the mains were torqued with the studs for every operation, along with very specific, almost idiot proof instructions on exactly what I wanted done and how I wanted it done. I'm the one with the money, do it my way. $1000 later I went to pick up the block...mains held on with the stock bolts and the studs still sealed in the package. I told 'em to get me another block and start over again since the mains, which every other operation is referenced off of, will now have to be re-honed...they said they could fix it. I told 'em to keep it and cancelled the credit card payment and walked out.

    I gave him another shot when I did the 22RET turbo motor in my crawler...I brought very specific instructions, along with OE spec sheets. I warned him that wall clearance was different for the turbo than for the N/A motor. When I got the block back....even without rings on the pistons, they would not drop to the bottom of the cylinders. So, back it went to be honed to the correct size.

    The motor he did for the white boat...when he gave it back to me...his line hone sub or someone had switched the 2 and 4 main cap and mis-labeled them after the line hone operation....so once again, the crank didn't turn. Once it was all together, even a 0.010 under chain was sloppy cuz they moved the crank too far up in the block, and the rear cap didn't fit tight in the block. I had just purchased a bore gauge and measured the mains at one spot...all looked good, so I said screw it and put it together because I was outta money at that point and I wanted to go to the river.

    After I sunk it, I tore it down to clean everything up and noticed that that rear main had 0.0025 taper from front to rear...I'd previously measured it at the rear. Crap, so this block is toast.

    I got him another one outta the new boat that needed to go .060 over, and even though I bought a set of MLS gaskets from him, he failed to properly measure deck height (said I was at zero and that's why he didn't deck it) and didn't think that the MLS gaskets wouldn't seal on the super coarse existing finish that was on the deck. I measured up deck height to be about 0.008 in the hole....and brought it to superior in orange to have them check it out. They took off exactly .008", that I verified upon reassembly, and said the block was twisted 0.006".

    It came out perfectly, they told me exactly what they did, how many passes they took at it, how much off each pass, and it all verified when I measured it up at home.

    The guy who has screwed everything up will not accept that any of these ****ups have been his fault....it's always that I'm too picky. Well, yeah. I'm too picky. I want my shit right. maybe it'll stay together for a few years that way.

    Every engine I assemble teaches me a lot more about it. Measure Measure Measure Measure Measure. Trust no one. Everything I measure on one that I failed to measure on the previous one, I find screwed up.

    After thinking back and looking at pictures of my old heads (gone now)..My old heads were probably in the 125-130 cc area, but the machine shop polished up the chambers so who knows what it really was, I doubt they were the same....I now realize that it put me around 9:1 c/r.

    I had just used the stupid moroso plastic thing to select pushrod length and didn't pay attention to valve stem height or weather I was getting full lift at the valve.

    I can't wait to get this motor together...with everything correct and the same on every cylinder...it'll probably make considerably more power. I guess I've never had a motor that was "right".
    The chamber variations are probably a combnation of everything you mentioned. As-cast chambers being differene right from the get go isn't unusual, the heads being mis-machined, and then the valve depth differences all contribute. A 2.25 valve sunk .070" (which is hard to believe someone would do that and think it was acceptable) would add 4.5cc's. An ex. valve that deep would be almost 3.2cc's.

    As for the decks, you can measure form the head bolt washer pad to the deck and see what kinds of variations you come up with. That's usually a reasonably good indicator. From the deck side, use the tail end of your dial calipers against something flat on the washer pad.

    Put some pics of these heads up when you get a chance. Mainly of the valve job and chambers.
    Last edited by scott foxwell; 11-07-2010 at 01:52 PM.
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    Pictures won't really show much...if I can't see it with my eye, you won't see it in the pictures.

    I tore one head down, set all the exhaust valves on a straight edge with a white background and eyeballed the fillets. On looked real small compared to the one next to it...until I turned the valve 180°...then it was bigger than the one next to it. I think it's a slightly bent valve that was ground straight or the collet/chuck on the valve grinder didn't center the valve correctly.

    I'm making a collet to check concentricity and straightness of the valves right now.

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    Save yourself some time and $$$$ and let Steel do your heads .. You wont be sorry and they will be right

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