Dry Valve Lash

[jls]

This must be an obscure area because googling it didn't bring up anything in
usenet. Be that as it may the O-300 we are presently doing a top on has
more than .110" dry valve clearance under the rocker toe on several of the
valves. That reading is the clearance between the rocker arm toe and the
top of the valve stem when the hydraulic lifter has been completely
collapsed.

However, the hydraulic units are Superior's, and so are the cylinders. So
I'm wondering if we are going to have to go to longer pushrods, since the
Continental Overhaul Manual calls for limits of .030" to .110" dry valve
clearance. Anybody here got any ideas? What I'm hoping (probably in
futility) is that the limits are greater with Superior hydraulic units. If
not we'll have to go to the next oversize set of pushrods and our budget is
already busted all to hell. TIA and bless you.

[Orval Fairbairn]

In article >,
" jls" > wrote:

> This must be an obscure area because googling it didn't bring up anything in
> usenet. Be that as it may the O-300 we are presently doing a top on has
> more than .110" dry valve clearance under the rocker toe on several of the
> valves. That reading is the clearance between the rocker arm toe and the
> top of the valve stem when the hydraulic lifter has been completely
> collapsed.
>
> However, the hydraulic units are Superior's, and so are the cylinders. So
> I'm wondering if we are going to have to go to longer pushrods, since the
> Continental Overhaul Manual calls for limits of .030" to .110" dry valve
> clearance. Anybody here got any ideas? What I'm hoping (probably in
> futility) is that the limits are greater with Superior hydraulic units. If
> not we'll have to go to the next oversize set of pushrods and our budget is
> already busted all to hell. TIA and bless you.
>
>
>

Nope -- the dry valve limits affect valve opening and wear. It sounds as
if you need longer pushrods.

[dave]

If you have access to a lathe, the pushrods can be made. I made a few on
my E225.
One thing to remember is that the rocker arms typically are not 50/50,
so getting a 0.020 longer pushrod does not change the clearance by
0.020, it may be more.
If you measure all the clearances, quite often you can mix and match to
get in spec with all pushrods.

Dave




Orval Fairbairn wrote:
> In article >,
> " jls" > wrote:
>
>
>>This must be an obscure area because googling it didn't bring up anything in
>>usenet. Be that as it may the O-300 we are presently doing a top on has
>>more than .110" dry valve clearance under the rocker toe on several of the
>>valves. That reading is the clearance between the rocker arm toe and the
>>top of the valve stem when the hydraulic lifter has been completely
>>collapsed.
>>
>>However, the hydraulic units are Superior's, and so are the cylinders. So
>>I'm wondering if we are going to have to go to longer pushrods, since the
>>Continental Overhaul Manual calls for limits of .030" to .110" dry valve
>>clearance. Anybody here got any ideas? What I'm hoping (probably in
>>futility) is that the limits are greater with Superior hydraulic units. If
>>not we'll have to go to the next oversize set of pushrods and our budget is
>>already busted all to hell. TIA and bless you.
>>
>>
>>
>
>
> Nope -- the dry valve limits affect valve opening and wear. It sounds as
> if you need longer pushrods.

[Paul Anton]

> not we'll have to go to the next oversize set of pushrods and our budget
is
> already busted all to hell. TIA and bless you.
>
>
>
They aren't all that expensive. Try Fresno Airparts.

Cheers:

Paul
NC2273H

[jls]

"dave" > wrote in message
news:BhJbc.67700$K91.157113@attbi_s02...
> If you have access to a lathe, the pushrods can be made. I made a few on
> my E225.
> One thing to remember is that the rocker arms typically are not 50/50,
> so getting a 0.020 longer pushrod does not change the clearance by
> 0.020, it may be more.
> If you measure all the clearances, quite often you can mix and match to
> get in spec with all pushrods.
>
> Dave

I think you're right, Dave and thanks. There's .080" to play with because
the dry valve lash limits are not less than .030" nor more than .110".
I'll measure each arm of the rocker from the fulcrum and see what kind of
ratio we get there and play around with the lash a little. There are just
four which are out of limits, i. e., more than .110". And the next size
pushrod is .030" overlength. Four of those should do it.
>
>
>
>
> Orval Fairbairn wrote:
> > In article >,
> > " jls" > wrote:
> >
> >
> >>This must be an obscure area because googling it didn't bring up
anything in
> >>usenet. Be that as it may the O-300 we are presently doing a top on has
> >>more than .110" dry valve clearance under the rocker toe on several of
the
> >>valves. That reading is the clearance between the rocker arm toe and
the
> >>top of the valve stem when the hydraulic lifter has been completely
> >>collapsed.
> >>
> >>However, the hydraulic units are Superior's, and so are the cylinders.
So
> >>I'm wondering if we are going to have to go to longer pushrods, since
the
> >>Continental Overhaul Manual calls for limits of .030" to .110" dry valve
> >>clearance. Anybody here got any ideas? What I'm hoping (probably in
> >>futility) is that the limits are greater with Superior hydraulic units.
If
> >>not we'll have to go to the next oversize set of pushrods and our budget
is
> >>already busted all to hell. TIA and bless you.
> >>
> >>
> >>
> >
> >
> > Nope -- the dry valve limits affect valve opening and wear. It sounds as
> > if you need longer pushrods.
>

[jls]

"Paul Anton" > wrote in message
...
> > not we'll have to go to the next oversize set of pushrods and our budget
> is
> > already busted all to hell. TIA and bless you.
> >
> >
> >
> They aren't all that expensive. Try Fresno Airparts.
>
> Cheers:
>
> Paul
> NC2273H

Thanks, Paul, and you're right. Fresno has them for $22.50 as opposed to
$85 apiece from another source.

[Orval Fairbairn]

In article >,
" jls" > wrote:

> "Paul Anton" > wrote in message
> ...
> > > not we'll have to go to the next oversize set of pushrods and our budget
> > is
> > > already busted all to hell. TIA and bless you.
> > >
> > >
> > >
> > They aren't all that expensive. Try Fresno Airparts.
> >
> > Cheers:
> >
> > Paul
> > NC2273H
>
> Thanks, Paul, and you're right. Fresno has them for $22.50 as opposed to
> $85 apiece from another source.
>
>

Have you tried El Reno Aviation? I believe that the O-290 uses the same
pushrods as the O-435. Both engines use the same pistons, cylinders,
rods, valve train.