Dean,
So here is how I remember it. I have used this method since 1972.
Best of all done with the engine out so you can actually see the geometry
well.
First of all this method takes in to account everything that you may have
changed on your engine including different cam, lifters, deck heights,
copper head gaskets, valve stem caps and stroked or not.
Deck height must already be set properly and matched on both sides of the
engine.
First of all lay a straight bar or ruler across the valve stems. If they
are not all the same, them send them back to be fixed.
Do not assume that just because one side of the engine gets one
measurement that the other side will be exactly the same...don't ask how I
know this.<grin>
Install your rocker arms without shims under them. Pick a valve(usually
#2 exhaust for me.
Adjust the valve adjustment screws so that you are in about the middle of
it's travel or less(look at some old factory rocker arms if you need to so
you can get an idea of where the factory started.
Rotate the engine until you have half lift from the cam on #2 exhaust(oh,
BTW, if you have a cam with different lift on exhaust and intake then you
get to do a lot more measuring).
Insert your adjustable push rod and start adjusting it until the rocker
arm is pushing the valve down half way. Unless you have a long travel
dial gauge this is going to be mostly by eyeball.
Rotate the egine now so that valve is now fully pushing down the valve
stem at max lift for that valve.
Make sure that the valve spring is not binding and has the proper
clearance between the valve spring coils(60 thousandths or better?)
If the clearance looks good, then rotate the engine though the entire lift
sequence for that valve several times and decide whether it looks right.
Oh, and you might as well add a piec of clay to the top of the lifter
adjusting screw andthen install you rocker cover and then rotate thru the
sequence again....so you know the adjusting screws are not going to hit
the inside of your rocker cover.
If that looks good, then you have your correct pushrod length. Now do the
same thing with your locked adjustable pushrod on the #4 exhaust checking
for too much clearance at no lift or too much valve spring binding at full
cam lift. If it is binding or too loose, then you will have two sets of
pushrod lengths to make.
Be aware that you are using the same type of adjustable pushrod similar to
what you will actually install in the engine. All pushrod ends are not
made the same.
Cheers, dave
On Tue, 26 May 2015, Dean Johnson wrote:
I read the How to hot rod instructions and couldn't make sense of them
'Adjust the push rod so that it fits...' Not helpful and I don't have any idea
what centerlines they're talking about and what
does it mean for two lines to 'coincide'? Not at all helpful.
Still looking for instructions with visuals.
On May 25, 2015 9:29 PM, "Dave C. Bolen" <dbo...@shockwaverider.com> wrote:
Guys,
Your good old copy of "How to hot rod vw's" has excellent instructions on
this.
Although...if you have stock rocker arms and stock pushrods they really
should be close. Oh, stroked engine?
Cheers, dave
On Mon, 25 May 2015, Daniel Moy wrote:
When I did mine I made an adjustable push rod out of a stock rod.
Basically cut one in half, trim down
then cut some threads
and insert threaded rod with two locking nuts.
Install the head torqued to spec. Do not install the push rods or
push rod tubes.
Install your adjustable push rod and your rockers with some spacers
to account for the swivel feet and
lash caps (these are a
good idea as the provide a larger surface area for the swivel
feet), check the geometry, there should
be no binding when
cycling the engine. If there is binding make the push rod shorter.
Check the adjusted rod in a few locations particularly the other
side of the engine.
If all is well then you now have a properly sized push rod, now you
need to make eight solid push rods.
I purchased mine from
gene berg back in the day. Chrome moly, cut them to length and
pushed in the ends.
It's been a while but I believe those are the steps.
On May 25, 2015, at 8:39 PM, Dean Johnson
<dean.john...@rochester.edu> wrote:
I re-read the info from the machine shop. He thinks the
original engine builder, Strictly Foreign,
didn't set up the
push rod length at all and that I need to do this. That makes
sense as they are way off. So who
has a good
description of measuring proper pushrod length?
BTW. RISMachine did the head work.
On May 26, 2015 4:13 AM, "Dean Johnson"
<dean.john...@rochester.edu> wrote:
No, stock rockers.
On May 25, 2015 5:32 PM, "Daniel Moy"
<sole...@gmail.com> wrote:
Hi Dean,
Did you have ratio rocker arms, if so did you size the push rods?
Dan
On May 25, 2015, at 5:21 PM, Dean Johnson
<dean.john...@rochester.edu> wrote:
I am finally installing my rebuilt heads into my 1915 cc
engine. I have the heads on, put in the
push rods and am test fitting the rocker arms to check
geometry.I put the shims that had been
installed under the shafts originally and there is not nearly
enough room for the swivel foot
adjusters. Even screwed all the way out, they nearly touch
the stems. If I use a thicker shim I am
afraid I won't have enough threads for the rocker arm nuts. (
can I back the studs out?) will
standard adjusters give me more adjustment? Where is the best
graphical description of adjusting
the geometry? I don't have a dial indicator so if there is
another way to do it, that'd be great.
Dean
'71 Super Beetle
http://deangj.tumblr.com
--
Dean G. Johnson, PhD
Postdoctoral Fellow
Biomedical Engineering
McGrath Lab
University of Rochester
Robert B. Goergen Hall Rm. 316
Box 270168
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dean.john...@rochester.edu
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