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Ok, so my guy over at Dart started work on the heads last night (finally!!) and we think we found the problem. On the cylinders that were making contact, the valve seats weren't cut deep enough. From the lowest to the hightest on the exhaust, we found .050" variance on the exhaust and .025-.030 variance on the intake for valve height from the deck.   We're figuring that the valves have always been making contact since the motor was built two years ago but I may have a spring that's a bit week allowing them to interfere a bit more and bend. We'll check spring rates before reassembly. So he started with a 5 angle valve grind and set them all the same. Then tapered the tops of the seats a bit more. Continuing on, he did a bit of bowl work to continue unshrouding the valves. He's going to be working on these hopefully this week. He's guessing maybe around 10 more ponies from the work he's doing but we'll see.
I'll put holes in him!!
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Joined: May 2000
Posts: 21,197
I have no life
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I have no life
Joined: May 2000
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Didn't you get these heads from Kinger? 
Originally posted by Kinger:
Also as FYI on every set I have sold even low milieage units with less then 10k miles on them we have found numerous guides cracked/worn out of spec, and seats improperly seated!!
I think I'll take my chances. 
-'96 SE MTX 3L
-'98 SVT 1,173 of 6,535
-'05 Mazda 6s, loaded, g/f's ride
-Need a 96-00 manual on CD? PM or email me
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Joined: Aug 2001
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Originally posted by SvtTour98.5-3:
Ok, so my guy over at Dart started work on the heads last night (finally!!) and we think we found the problem.
On the cylinders that were making contact, the valve seats weren't cut deep enough. From the lowest to the hightest on the exhaust, we found .050" variance on the exhaust and .025-.030 variance on the intake for valve height from the deck. We're figuring that the valves have always been making contact since the motor was built two years ago but I may have a spring that's a bit week allowing them to interfere a bit more and bend. We'll check spring rates before reassembly.
So he started with a 5 angle valve grind and set them all the same. Then tapered the tops of the seats a bit more. Continuing on, he did a bit of bowl work to continue unshrouding the valves. He's going to be working on these hopefully this week.
He's guessing maybe around 10 more ponies from the work he's doing but we'll see.
Well, I don't think I'd be happy with the valve seats being cut so different, but I don't see that causing the contact.
You see, the installed height of the valve may change but the rocker assembly can not push the valve ANY close to the piston than the calculated amount of lift unless there is a problem with the pivot point being higher than it should, rocker arm ration has changed, or valve stem length has changed.
I also find it hard to believe that this cylinder had float and others did not.
The only other possibility is deck height, a problem that would move the whole valve train assembly closer to the pistons, or some portion of it if it wasn't even. Did you measure the deck height????
I suspect that the heads were decked by hand on a sanding belt and they may not be decked evenly. This would make one side of the head thinner than the other and the net result could be interference on one side of the head while not on the other side.
If the wedge-shaped effect was enough, there could be all four valves in the cylinder on the end touching and maybe only one or two in the middle cylinder touching and the head would still seal.
This may not be the case at all, but see if there is a pattern in the interference. Look and see if you can see more evidence of contact on one side of the head or if it is evenly disrtributed.
I just don't buy the argument on valve installed height problem causing it, at least not by itself.
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
See My Mods
'05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red
'06 Mazda5 Touring, 5spd,MTX, Black
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Originally posted by warmonger:
You see, the installed height of the valve may change but the rocker assembly can not push the valve ANY close to the piston than the calculated amount of lift unless there is a problem with the pivot point being higher than it should, rocker arm ration has changed, or valve stem length has changed.
I agree to a point. The problem comes in there of the lash adjusters. If the seat isn't cut deep enough, the installed height of the valve is lower into the cylinder. The lash adjuster will compensate for some of that by pumping up more, ending up with the cam still having the same lift on that valve (meaning....a .400 lift on a valve that's already .050 deep ends up with the valve in an effective cylinder position of .450, not .400 where it should be). The valve stems were measured and no discernable difference was found.
Originally posted by warmonger:
I also find it hard to believe that this cylinder had float and others did not.
I agree, but we'll check them anyway.
As far as deck height, with the head sitting on a flat inspection surface, we put a height gauge on the valve cover mounting surface. We saw maybe a .002 variance from end to end.
And yes, these heads were from Kinger. I had the 3L valves installed so they should have installed new exhaust seats and cut.....cut existing intake seats.
I'll put holes in him!!
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Okay, so did you actually measure the head thickness and compare against stock? Since you've already checked for a wedged shape and found that within .002 (close enough I'd think) then now you just check to see if it is a combination of deck height and valve installed height. BTW, your explanation of installed height causing the lash adjuster to pump up higher makes good sense. I'm comfortable with that answer.  It also fits my logic that it could have been an increase in the pivot point height..
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
See My Mods
'05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red
'06 Mazda5 Touring, 5spd,MTX, Black
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What about the added fact that decking the head or block will adjust the valve timing also as the timing is based on a set height from the cam centerline to the crank - if he took off anough and also adding in all the other anomalies it could explain how he was able to get the valves to touch the pistons.
2000 SVT Turbo 295hp/269ftlb@12psi
#1 for Bendix Brakes Kits!
Knuckles rebuilt w/new bearings $55
AUSSIE ENDLINKS $70
Gutted pre-cats $80/set
A lack of planning on your part does not constitute an emergency on mine!
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Originally posted by warmonger:
then now you just check to see if it is a combination of deck height and valve installed height.
I will, next time I'm over there, get height measurements. all I was primarily looking for was a wedge shape so I didn't write them down or anything.
Does anyone have a set of NEW heads (or used but not decked) or know off the top of their head what this height should be??
I'll put holes in him!!
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I have used 3L heads - what measurement do you need?
2000 SVT Turbo 295hp/269ftlb@12psi
#1 for Bendix Brakes Kits!
Knuckles rebuilt w/new bearings $55
AUSSIE ENDLINKS $70
Gutted pre-cats $80/set
A lack of planning on your part does not constitute an emergency on mine!
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CEG\'er
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I was looking for height measurements from the deck to the top of the valve cover mounting surface.
Are the 3L heads comparable to the 2.5's? I don't know as I've never seen them.
I'll put holes in him!!
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Not sure but I'll measure it tonight. Actually I MAY have some 2.5's i the trash still out back. I'll go check.
2000 SVT Turbo 295hp/269ftlb@12psi
#1 for Bendix Brakes Kits!
Knuckles rebuilt w/new bearings $55
AUSSIE ENDLINKS $70
Gutted pre-cats $80/set
A lack of planning on your part does not constitute an emergency on mine!
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