Tom,
Thank You. Though its somewhat over my head, I
completely understand what I need to do. What are the
chances that Im that far off to begin with? I have
.030 over 2L flat tops and a mild street cam going in
the 1600 block. I assumed the pistons would lower my
compression but my head has been milled down to
minimum thickness. Also the engine that the head came
from has flat tops in it and ran great. It just has
this annoying BIG crack in the block. :(
Right now the parts are being "mocked up" for me at
the machine shop so I can see the clearances before
they torque it all down. They have been really
helpful and quick to point out possible issues rather
than just doing the job.
Im looking forward to the end result.
'Enjoying the Ride'
joshua milton
69 1600
91 Pathfinder
encino, ca
--- Thomas Walter <walter@omni.sps.mot.com> wrote:
> Joshua,
>
> It is a really good idea to check out the
> compression ratio
> while rebuilding the engine.
>
> I do not have a piston to deck height measurement
> for the 1600.
> Usually I set the piston to TDC, use a "ring" with a
> top cover,
> then fill the volume up with a pipette (I have a 50
> cc pipette
> for this reason).
>
> With the known volume of the "ring and hat", I
> calculate the
> difference in volume to know the offset.
>
> Then on to the cylinder head, same thing is
> measuring the
> volume.
>
> Do not overlook the 'displacement' of the head
> gasket.
> About 0.060" x area.
>
> Static C.R. = (Swept volume + displacement) /
> displacement.
>
> So if you measure 40 cc of displacement volume, on a
> 400 cc
> swept volume you have a compression ratio of 11:1 --
> really
> too high on pump gas. For 1600 engines sometimes it
> makes
> sense to drop in a 2000 piston (flat top).
>
> Using the 2000 cc piston, you'd get a total
> displacement of
> 50 cc. Compression ratio is ((400+50)/50) 9:1.
>
> The above numbers are GUESSES. Just to give you an
> idea of
> the calculation.
>
> WITH A 1600 ENGINE:
>
> When it comes time to reassemble, I'll get the cam
> set up
> to the correct installation.
>
> TEMPORARY install the head WITHOUT a head gasket.
> Just finger
> snug the head bolts down. Install the push rods and
> rockers.
>
> Rotate the engine by HAND... everything OK?
>
> If you can rotate the engine by hand, you'll be
> fine. Once
> the head gasket is installed, it has about a 0.060"
> clearance.
>
> WITH AN OLD HEAD GASKET: I'll repeat the above, but
> with some
> thin putty on the top of piston, and a old
> (previously compressed)
> head gasket installed. It is interesting to see the
> actual clearance
> from valves to piston.
>
> Hope this if of help.
>
> Cheers,
>
> Tom Walter '67 2000
> Austin, TX '68 2000
> '93 Dodge Dakota - 3phase 288V electric
> powered!
> '99 Nissan Maxima
> {Also a '63 Bluebird Sedan, and '71 510
> 4dr)
>
>
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