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Stevedak
Dodge Dakota
JOIN HERE
6/11/2006
19:46:10
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 Subject: valve height adjust
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Message:
I'm working on my heads, lapped the valves. I installed the intake valves with new springs, the installed height was in spec (1.667). I installed the exhaust valves and found the height was way too high, it was 1.670 but should be 1.43 to 1.515. I know I can add shims but the thickest shim is 0.060. It seems unusual to have to add 3 shims. Am I missing something about the exhaust valve installation or should I add 3 shims to obtain the correct valve height.
All exhaust valves have the same height.
Any help or suggestions would be appreciated.
1992 Dakota, 3.9 L V6
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Scott C
Dodge Dakota
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6/11/2006
20:17:09
| RE: valve height adjust
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Message:
all the valves might have the same height on them all but what about the grind on the seat or the valve....
Scott C
Royal Auto
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J and J Auto
GenII
6/11/2006
21:30:00
| RE: valve height adjust
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Message:
The valve height is the same intake and exh
I have seen streached valves to high but never
a short valve, the only way it could be short
is if the end was ground or something in the
seat
You have to be mesuring wrong
Think about it all the base circles on the cam
are the same, cam off set .270 all the same
rockers all the same, push rods and lifters all
the same, so valve height is all the same
1.667 to 1.670 is only .003 diff nothing wrong
with that when you laped you probable removed
.003 some from seat some from valve its fine
Larry
J&J Auto
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Obio3
Dodge Dakota
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6/11/2006
21:38:58
| RE: valve height adjust
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Message:
The right height is important in these engines. The shims is your way to correct this. when new all the valves was the same as was the seats. on all new items, they should grind to the proper height provided the machinest is well experanced. when you laped them if things were as they usually are it took more or less on each valve.The exhaust valves take much more of a beating then intakes do. This makes more or less shims needed on each valve.Lapped valves will not flow as well as properly ground valves nor will they last as long. You may lose a tiny bit of power.
As you may know, there was a time most all engines were rebuilt with lapped valves. Shops made extra bucks lapping valves as opposed to either buying a valve grinding machine or sending out to a machine shop. I built my own presision valve grinding machine and used valve seat stones.All valve jobs got a 3 angle grind.
So many problems .... So little time
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stevedak
Dodge Dakota
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6/11/2006
22:46:10
| RE: valve height adjust
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Message:
Larry, I don't think my measurements are wrong, my problem may be what height I think they should be at. I measured from the base of the head to the bottom edge of the valve spring keeper. There isn't much difference between the height of the intake and exhaust valves. But my book (Hayes) says the intake should be 1.625-1.687, and my intakes are within this range. The book also says the exhaust should be 1.435-1.515 but my exhaust valves are much taller, more like the intake. It makes sense that the intake and exhaust be the same...is the book wrong?? Does the exhaust valve require more seat pressure??
Thanks for the help guys
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stevedak
Dodge Dakota
JOIN HERE
6/12/2006
10:20:14
| RE: valve height adjust
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Message:
Larry...I read your reply a second time. Looks like you answered my question already. you said intake and exhaust height should be the same. That means that I'm good as-is.
thanks again...
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J and J Auto
GenII
6/20/2006
00:11:58
| RE: valve height adjust
IP: Logged
Message:
the height is the same exh int
the lifter preload with the stock rockers is
around .050 .060 a small variance here will not
effect anything .015 .020 would work fine not
to worrie
As the other guy said here if you have a valve
job done they should have been mesured and be
within at least .010 of each other or hes right
the guy is sloppy
3 angle or 5 angle works good lapping will not
make your valves go bad this is what is done
when the valves are not bad enough for a grind
and you can see were they are ridding on the
seat to be sure you have enough margin on both
sides should be almost in the center of valve
most guys these days don't lap they just use dye
slam them into the seat and see were they are
hitting if it hits to close to either top or
bottom not enough margine they will burn and
leak sooner than they should again a sloppy
job was done on the seat or valve with the angle
being slightly off this can happen while dressing
you wheel or stones for the seats a good man will
see this right away and correct the prob so you
get a good job that will last a long long time
without burning or leaking
Larry
J&J Auto
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J and J Auto
GenII
6/20/2006
00:27:15
| RE: valve height adjust
IP: Logged
Message:
I should have also said here be sure if you have
a valve job done or a crank ground it a shop that
you know has a good reputation for quility work
The same guy has been doing all our crank work
for over 30 years I had a few cranks ground by
auto parts stores and when I speced them out
and checked with plasti guage they were at max
clearance like .003 when they should have been
at .0005
How in the world can a motor run good oil presure
and withstand the force when its put togather so
sloppy when I seen that I blew a gasket they
got an ear full and I also let everyone and there
brother know what a crap job they did
I had to take it to Dave wait 2 weeks get it
ground again to .020 under to get my 1/2
thousandts rod and main clearance I wanted I
would not put a motor togather like that I would
not even buy any parts from them after that and
to this day have never been to there store
I was hot to say the least
something like that is just terible but it happens
so be sure you use a quility machine shop to get
these things done
Larry
J&J Auto
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