My screwed up Dart heads, and how I'm gonna fix em

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lbhsbz

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« on: November 08, 2010, 11:51:06 PM »
The problems are discovered here:

http://performanceboats.com/html/forums/showthread.php?t=77198

 

Maybe this thread will inspire people to measure up their stuff and check other peoples work. Heads in question are Dart pro 1 310cc. Came on a motor in a boat I bought. I just had the heads all done up at a local "performance" machine shop.

 

I have several problems:

 

1: Valve stem heights are all over the place requiring different length pushrods on different cylinders...which prompted me to pull the heads back off and then I discovered:

 

2: Chamber CC's on cylinder head #1 are 116-117-118-119, and cylinder head #2 is in the 121-122 range across the board.

 

now the quest to figure out why, then figure out how to fix it.

 

Head #1. The chamber volumes are indicative of a resurface job that took place on an angle...but there are no visual indicators that this occured. Dart says 0.005" per CC. 0.015" should be visable on that little rough cast area between the intake valve and the surface...but all looks well.

 

I know for a fact that the valves are screwed up....but I wanted to measure things to see if there was a sloping pattern that might lead to the chamber volumes I'm seeing. I also wanted to see if there was any surface worth trusting as a reference point from which to work from. I whipped up this little tool:


 



 

A couple pieces of scrap. The round piece has a releif for the valve guide and about 0.002 clearance over the valve itself. Doesn't give you any real numbers, but gives a good comparison between all the valves. It measures the distance between the valve stem tip and the spring seat.

 

I first picked 1 exhaust valve used it in every hole to get an idea of seat depth variation, or more realistically, varation in the distance between valve seat and spring seat. The 2 center cylinders were the same, one end was +.011 and the other end was +.006. Same test on the intakes revealed only a .004" variation. Shitty work, but not the cause of my problem.

 

Then I grabbed all of the valves and stuffed them into one chamber to compare the distance between the valve sealing point and the valve stems. Intakes had a 0.012" variation and exhausts had a .036" variation. Once again, shitty machine work.

 

I then wondered if all the spring seats from which I'd been referencing were in the same spots....but measuring between 2 angled surfaces is tough...so I whipped this up with a piece of stainless rodstock from the scrap bin and one of the valves...



 

When both ends of the rod hit the head surface, the valve stops moving.  It's repeatable in all the holes, so it's a good indicator of variations.

 

This gives me a measurement between the deck surface and the spring seat. I saw a .004" variation on the exhaust side and a 0.009" difference on the intake side, but with no real pattern.

 

I've still got to measure my total valve lengths, then scratch my head and put all these numbers together to hopefully come up with something meaningful that points me in a direction. I'm most likely gonna send these to Steelcomp to get done right, but I want to be able to know exactly what needs to be done before I hire someone to do 'em.

 

So far, I've found absolutely nothing on these heads that it halfway consistant.

 

More tomorrow....


lbhsbz

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« Reply #1 on: November 10, 2010, 11:07:57 PM »
Spent last night making a tool to compare the relationship between the ground sealing surface of the valve and the face of the valve. This is what I came up with:




I machined a 45 seat in the bottom half and reamed it to 0.001 over the valve stem size. It's got a shoulder that centers the top half for repeatablilty. It works remarkably well.

I found plenty of differences... +/- .010" measuring with this tool.

So, to determine the valve/seat height influence on my chamber volume (or c/r):

I add all of the tolerances together

Valve seat to spring seat (measured using only one valve on all ports)
Spring seat to head surface
Valve face to valve sealing surface.

While I found that some chambers were affected up to 2cc by the valve/seat depth, they don't really coincide with my chamber volume numbers from before. Which leaves me to the conclusion that the chambers are cast with about a +/- 2cc tolerance, all other things being equal.

Every measurement I make points to the deck surfaces being level, flat, and true on both heads.

Next step is align the spring seats by either shimming or milling, then perform a proper valve job with all new valves. Once the valve/seat variables are taken out of the equation, re-measure the chamber volumes, match all the chambers, then resurface based on the new chamber sizes to get to 115cc.

After making all the tooling, I've probably got all of 45 minutes into measuring this stuff.

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« Reply #2 on: November 11, 2010, 06:16:50 AM »
i have a valve and seat grinder if you want to try your luck

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« Reply #3 on: November 11, 2010, 09:13:10 AM »
i have a valve and seat grinder if you want to try your luck

I'll call you tonight.


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« Reply #4 on: December 22, 2010, 02:15:55 PM »
I've been busy selling everything I can find that I don't need to gather up funds to buy tooling.  

I have acquired an old Kwik Way valve face grinder from the 30s, and converted the original chuck to an ER-32 collet chuck which is concentric within .0002" and repeatable....good enough for me.  I had to put a new cord on it as the fabric insulation was coming off of the old one.  

I've also picked up a Sioux seat grinding setup....I really wanted to go single edge carbide, but couldn't afford it.  I picked up some carbide pilots in 0.0002 incriments so I can hopefully keep concentricity in check when I grind the seats.  It's gonna be tough keeping all my heights consistant, but not impossible with some care.

After measuring up the guides with my bore gauge...they're gonna be way tight with valves that aren't worn out, so I bought a sunnen valve guide hone


I've spent some time on the phone with Dart, and they can't give me the information I need...which is frustratiing.  They  said that the heads should be able to be cut .100 without getting into the intake seats....and that the stock chambers are 122cc.  Based on what I see on their website, it says 0.005" per cc, and minimum chamber volume is 108.  That means the max you can cut is .070", not .100"

None of this makes sense, because I've got about .030 left before I hit the seats, yet my chambers are still around 120cc.  

Of course, they could supply absolutely no information as to reference points and dimensions I could use to determine exactly how much had been machined off of the heads, nor could they give me any info as to how to how to determine where my seats are in relation to where they are in new head from Dart....so I guess I'll have to put new seats in one chamber and take it from there....

I'd really rather know what I have to do before I do it, but I guess that isn't gonna happen.  

Pics to come this weekend.

Oh, I'm building a flow bench too...so I can find the best seat profile and seat height....at least that's my theory behind it.

I'm starting to realize why a $250 valve job gets you what it does.

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« Reply #5 on: December 22, 2010, 06:00:30 PM »
yup.... $250.  U always get whatcha pay for :thumbdown:
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« Reply #6 on: December 22, 2010, 06:13:29 PM »
Just to add to your work.... Now you know how many hours are involved in a proper valve Job  :thumbup:  VERY MANY!

There are many other factors involved here as well .
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« Reply #7 on: December 22, 2010, 08:45:55 PM »
wow, i'm just shakin my head. a shame.
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« Reply #8 on: December 22, 2010, 09:27:16 PM »
well. I will do my best to help :thumbup:
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« Reply #9 on: December 23, 2010, 11:43:02 AM »
Maybe this thread will inspire people to measure up their stuff and check other peoples work. Heads in question are Dart pro 1 310cc. Came on a motor in a boat I bought. I just had the heads all done up at a local "performance" machine shop.

I have several problems:

1: Valve stem heights are all over the place requiring different length pushrods on different cylinders...which prompted me to pull the heads back off and then I discovered:

2: Chamber CC's on cylinder head #1 are 116-117-118-119, and cylinder head #2 is in the 121-122 range across the board.

Head #1. The chamber volumes are indicative of a resurface job that took place on an angle...but there are no visual indicators that this occured. Dart says 0.005" per CC. 0.015" should be visable on that little rough cast area between the intake valve and the surface...but all looks well.

I know for a fact that the valves are screwed up....but I wanted to measure things to see if there was a sloping pattern that might lead to the chamber volumes I'm seeing. I also wanted to see if there was any surface worth trusting as a reference point from which to work from. I whipped up this little tool:
 
I first picked 1 exhaust valve used it in every hole to get an idea of seat depth variation, or more realistically, varation in the distance between valve seat and spring seat. The 2 center cylinders were the same, one end was +.011 and the other end was +.006. Same test on the intakes revealed only a .004" variation. Shitty work, but not the cause of my problem.

Then I grabbed all of the valves and stuffed them into one chamber to compare the distance between the valve sealing point and the valve stems. Intakes had a 0.012" variation and exhausts had a .036" variation. Once again, shitty machine work.  

I then wondered if all the spring seats from which I'd been referencing were in the same spots....but measuring between 2 angled surfaces is tough...so I whipped this up with a piece of stainless rodstock from the scrap bin and one of the valves...

When both ends of the rod hit the head surface, the valve stops moving.  It's repeatable in all the holes, so it's a good indicator of variations.

This gives me a measurement between the deck surface and the spring seat. I saw a .004" variation on the exhaust side and a 0.009" difference on the intake side, but with no real pattern.

I've still got to measure my total valve lengths, then scratch my head and put all these numbers together to hopefully come up with something meaningful that points me in a direction. I'm most likely gonna send these to Steelcomp to get done right, but I want to be able to know exactly what needs to be done before I hire someone to do 'em.

So far, I've found absolutely nothing on these heads that it halfway consistant.

Honestly, I'm confused by your accusations.   How is this the machine shop's fault???? You paid $250, which to me sounds like a standard dealio valve-and-seat grind.  And then you complain about 0.004" stem height difference, calling it "all over the place" and "shitty work" for a $250 valve & seat grind?

Do you know the history of the heads prior to your aquisition of them and what the chamber volumes were beforehand?  Why are the differences in chamber volume the responsibility of the machine shop?  Did you ask for--and pay them--to cc your heads and match the chamber volumes? And how are chamber volumes instantly indicative of "shitty work" when you even note that there are not indications that anyting like this occurred?  Do you understand casting pattern and mold setup and how chamber volumes--even within a given cylinder head--can vary so much as perhaps 7-8 cc's as cast? That wouldn't be the machine shops fault, would it?   Did you really expect to get a racing, "swiss watch" valve & seat grind and cc'd heads for a measely 250 bones?   If we did such for a customer, the cost for chamber volume matching and a valve job to the specs that you are insisting upon might be closer to $1000 than it would be to $250.

Honestly, I not coming on here to toss a stick in your spokes; I do feel a reality check is in order.  I am honestly perplexed at 1) how you can be so infuriated by the workmanship relative to what you paid (it sounds about right to me, and there's nothing wrong with that), and, 2) that you would be blasting it all over the internet instead of objectively evaluating what you have and how to move forward so as to bring the heads to the specs that are to your liking.

Probably the best thing you did is purchase your own cylinder head equirpment so that you may machine your heads to the tolerances that you desire.  By the way, I think that you're going to be suprised at the labor involved to meet your strict guidelines and also surpised at the loose "tolerances" of the performance parts (as delivered) that you check out, such as the chamber volume variation that you noted.  If the performance parts suppliers took the time to set all their tolerances to less than "0.004" or cc their head's chamber volumes to all have chambers within less than, say 0.4 cc, the workmanship of those heads out-of-the-box would be better than 80% of the consumers would need and also have workmanship executed that would dictate they price themsleves out of 80% of the consumer market as a result.

LO
« Last Edit: December 23, 2010, 12:16:36 PM by LakesOnly »

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« Reply #10 on: December 23, 2010, 11:45:58 AM »
yup.... $250.  U always get whatcha pay for :thumbdown:
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« Reply #11 on: December 23, 2010, 05:19:38 PM »
Honestly, I'm confused by your accusations.   How is this the machine shop's fault???? You paid $250, which to me sounds like a standard dealio valve-and-seat grind.  And then you complain about 0.004" stem height difference, calling it "all over the place" and "shitty work" for a $250 valve & seat grind?

Do you know the history of the heads prior to your aquisition of them and what the chamber volumes were beforehand?  Why are the differences in chamber volume the responsibility of the machine shop?  Did you ask for--and pay them--to cc your heads and match the chamber volumes? And how are chamber volumes instantly indicative of "shitty work" when you even note that there are not indications that anyting like this occurred?  Do you understand casting pattern and mold setup and how chamber volumes--even within a given cylinder head--can vary so much as perhaps 7-8 cc's as cast? That wouldn't be the machine shops fault, would it?   Did you really expect to get a racing, "swiss watch" valve & seat grind and cc'd heads for a measely 250 bones?   If we did such for a customer, the cost for chamber volume matching and a valve job to the specs that you are insisting upon might be closer to $1000 than it would be to $250.

Honestly, I not coming on here to toss a stick in your spokes; I do feel a reality check is in order.  I am honestly perplexed at 1) how you can be so infuriated by the workmanship relative to what you paid (it sounds about right to me, and there's nothing wrong with that), and, 2) that you would be blasting it all over the internet instead of objectively evaluating what you have and how to move forward so as to bring the heads to the specs that are to your liking.

Probably the best thing you did is purchase your own cylinder head equirpment so that you may machine your heads to the tolerances that you desire.  By the way, I think that you're going to be suprised at the labor involved to meet your strict guidelines and also surpised at the loose "tolerances" of the performance parts (as delivered) that you check out, such as the chamber volume variation that you noted.  If the performance parts suppliers took the time to set all their tolerances to less than "0.004" or cc their head's chamber volumes to all have chambers within less than, say 0.4 cc, the workmanship of those heads out-of-the-box would be better than 80% of the consumers would need and also have workmanship executed that would dictate they price themsleves out of 80% of the consumer market as a result.

LO

Hi Lakes...your points all have merit.  Let me further qualify my attitude toward this particular machine shop....

Short version:
It all started 3 years ago....

dropped off core block to "prep" for road race car.  Block was a "tight" .030" core with almost no wear.  I had special ordered .030" pistons to fit my Brodix X11 heads, and had confirmed that the block could be honed and would clean up at the right size for my pistons.  The guy never opened the box with the pistons and took my block .040.

He got me another core, which after getting it back the crank wouldn't turn becuase the rear cap was wacked.  He wanted to send it out to line hone/bore....AFTER he had done the deck/cylinder work.  BS.  main work comes first since everything else is referenced off of that.

I gave up and bought a used motor that I made work for the application

#2  Dropped off a 22RET motor with him to have the block prepped...even brought him the correct specs for it, since they're different than the N/A 22RE motor, and bought the pistons from him.  When I got it home, the piston, with no rings, wouldn't fall through the cleaned cylinder.  They left zero piston/cylinder clearance...so it went back, and was done about 0.0005 over the big end of the tolerance when I picked it up the next time.  I ran it because I had no other choice.

#3, 1st motor for the boat.  His core, I go to put it together and the crank won't turn....after he'd had it line honed.  someone before me, but after the line hone, had switched 2 of the caps AND misnumbered them.  After I figured that out, the thing went together and had about 3/4" of slop in the timing chain, with a .010 short chain.  Sumbitch.  Can't get a shorter chain....ran it.  It ate rear main bearings.  I shortened the driveline and put a new crank thinking that may have had something to do with it and it solved the trust surface problem, but after I sunk it (less than 1 hour on the new crank/bearings) the rear main was wiped out again.  Started measuring and discovered 0.0025 taper...clearance went from 0.004 to 0.0065 across the rear main.  Further inspection showed uneven hone marks, indicating that the cap was not seated when honed.  He wanted to line hone it again, even though the timing chain already had 3/4" slop in it.  Bullshit.  I gave him the block...use it for one of your other customer who don't measure anything.

#4, After #3, brought him another block and told him to prep it.  Also, purchased MLS gaskets from him.  Block came back without being decked.  Deck looked like crap...no chance in hell of sealing against an MLS gasket.  Called him on it and he said "It was running before...it'll be fine" and "we didn't deck it becuase you were already .005 outta the hole".  I had asked him to set my Deck at zero.  I feel he should have called me and let me know we had a problem, but he didn't because we really didn't have a problem.  He didn't measure shit.  I went back out and measured deck clearance and I came up with 0.007 in the hole.  I brought it to another shop, sat their while they measured it up and their numbers agreed with mine, so I paid them to do it. 

#4A...the heads.  They were on a boat I bought so I don't know the history, but I brought them down and asked him to go through them.  If it needs seats, put seats...make them right.  I asked him to set the chamber volume at 115cc. 

He did the bare minimum rebuilder grade shit careless job.  I've spent $18K with him over the last 4 years or so....he knows the kind of work I'm looking for, but can't seem to give a shit. 

and trust me, I'm not bitching over 0.004.  I'm bitching over the fact that I can teeter-totter a straight edge 0.070 on the valve stems of the assembled head.  I'm bitching about the fact that one head has 2 of the exhaust seats .025" deaper than the other 2.  And most of all, I"m bitching at the fact that he told me "that's why you've got adjustable rockers...just order a few different length pushrods and put it together". 

Fawk That!

 We were buddies, so naturely, I'd always give him shit about his prices over a few beers when I'm down at the shop after hours....but I've always made him understand that I have no problem paying for a job done right....no matter the cost....as evident by the fact that this valve job will now probably cost me somewhere in the $3000 range.  Thats fine.  It'll be done right.  I asked for proper valve job done right the way I wanted it. He did a $250 valve job, which is the best he can do apparently.  That's my beef. 






« Last Edit: January 10, 2011, 01:56:26 PM by lbhsbz »

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« Reply #12 on: December 24, 2010, 06:10:08 AM »
Ahhh, so this is your "straw that broke the camel's back" incident.   I know that I myself can be a reeeeally hard guy to please in some situations where I feel the machining/workmanship is critical and where I specifically called out the specifications.  On many occassions in the distant past I've tried to work with some shops and I'd make very clear how important it was that my specs be met and that I didn't care how much it cost to have them met.....and I still end up rejecting the work instead of picking it up when it's supposed to be ready.  I'm not super picky in all cases, of course, it depends on the build and applicaton. But you begin to know which shops to use depending on the kind of work needed/relative to the build's needs. Today, we still outsource our crankshaft work, for example, and the needs of the build in question dictate to which crank shop I might send a crankshaft. There's a difference between "please turn the rod journals to 2.4888" @ 70*","  and, "grind it on the low side, thanks."  In some cases, the latter is perfectly acceptable (and priced accordingly), while in the more exotic builds the former example is the only way to go (and the price certainly reflects the effort of the detailed workmanship.)

Anyway, things that you are bringing in-house, such as valve and seat grinding and cylinder head setup, will give you the ultimate control of what you want out of your builds.  I suspect that you're going to like machining your own stuff.

LO

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« Reply #13 on: December 24, 2010, 05:48:21 PM »
This is over the top.....Bring a blueprint of the machine work you expect and you pay for it, then you will get whatcha looking for...thats what i did with Ralph/Brad...And all  customer that bring me there required tolerances..............
They tell me what they want and I give them that....Within a couple tenth's.

This is just over the top....WAY OVER!...I can go on forever her...but let it be said that I learned my trade in military work...and we were expected to hold tolerances tighter than you can imagine..Engine work is a walk in the park compared to that shit.

Too add to this you can spend countless hours when you have tolerances requested at
+/-.0002/10....or plus or minus 1/2 cc... Fat Azz wallet required here.

I do not intend to piss anyone off here....yet in the "Machining" industry there are blueprints & guide lines that
you follow...   be it whatever you are machining... With that being said ,  Ohhh...foggettaboutit..I'm out :thumbup: basically... plus/minus "Zero" tolerance is unheard of period.
« Last Edit: December 24, 2010, 06:04:00 PM by enginedoctor »
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« Reply #14 on: January 10, 2011, 10:20:01 PM »
A little bit of progress in the way of my tooling....I got rid of the 6 ball chuck in my valvegrinder as it would give about .004" of runout in the valve and fitted a modified  collet chuck setup, which is supposed to be within .0005" TIR.  I've been playing with the old valves and getting frustrated because I can't get better than .0015-.002" TIR on any of the valves.  I got my new valves in from dart, so I threw one of those in and saw .0003" at the stem.   SWEET!   I also checked the seat surface and saw .0005".  Pretty impressive for an outta-the-box new valve. 

Ok, why are all my old valves bent?  I wasn't happy with the seat Concentricity Gage I bought...very inconsistent...so I tried the bounce test.   Even the new valves didn't bounce in the existing seat....they feel to be about .006" or so off center after seeing how different valves react with the bounce test and then measuring the valves on v-blocks...maybe that, along with 300lbs of seat pressure bent 'em.  I blued one of the seats and ground it with a carbide tapered pilot and while results improved, I wasn't happy with the Concentricity results.   Seems all the available pilots out there (with a .385 top) taper about .002" over the whole tapered section, not .0002 like the guy who I ordered them from told me..so I returned them and bought some oversized pilots and had 4 of them reground to taper only .0003 over the 3" taper (will cover guide clearances from .0015 to .0025)....much better....I get about 3 good bounces when dropping the valve on the seat now, checked 4 times 90 degrees apart with .0015 guide clearance.   This isn't hard, just takes time.  While not perfect, it looks like I can get it a whole lot better than it was, and as good as available toolng will allow.  I'd like to get rid of the little bit of TIR in the New collet chuck....I can measure .0003"-.0004" in the taper....I'm going to see my tool grinder on thurs to see if he can correct it.
« Last Edit: January 10, 2011, 10:59:02 PM by lbhsbz »

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« Reply #15 on: January 10, 2011, 11:09:20 PM »
This is over the top

This is just over the top....WAY OVER!...

... plus/minus "Zero" tolerance is unheard of period.

Why is it over the top?  The only reason I'm spending so much time is because I've never done it before....this is all new to me.   I'm investing my time discovering all of the possibilities for errors so that I can establish methods to prevent them.  As far as tolerances go, I'm happy when the needle on my indicator stops moving, but I understand that's not gonna happen in a lot of cases.....doesn't mean you shouldn't try though.

lbhsbz

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« Reply #16 on: February 19, 2011, 05:22:46 PM »
Finally found the time to get some work done....

Cleaned everything up a bit and sat down to re-measure everything and make a spreadsheet with all my numbers so I know exactly what needs to happen to each seat....Found out that if I don't zero my guages between heads, I can find where my 4ccs went!... exhaust seats are cut .062-.085 deeper in one head than the other.......guess we're doing seats.

I got all of the seats out...welded old valves to the seats and knocked 'em out after it cooled. ... worked pretty good.

I've had some trouble getting consistant measurments of my valve guides...tried a couple different methods, all of which gave me different answers.  I got on ebay and picked up a better quality mitutoyo bore gauge and inside hole mic to see it that would be more consistant...and it is....which prompted me to dive in and figure out why my high dollar carbide pilot, that should be smaller than the hole, won't fit in the hole.  I measured both ends and they are correct....then I measured about 10 more places on it, and found a fat spot in the middle...about 0.0005" too fat,  The other 4 pilots that I had made have the same problem, which makes them worthless.  I'm gonna go see the grinder on monday and see what we can do about this. 

1975_Challenger_461

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« Reply #17 on: February 20, 2011, 08:29:19 AM »
Sounds like you should have gone somewhere else after the second attempt. That probably would have been better than wasting your time over and over again. ;)
"I'm a simple man....
I like lolie pops in my mouth and butter in my ass."

 


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