misshydro

we will be ordering parts from dave..he also sells on ebay too..

NailHead

Some may have noticed the heavy duty gaskets for these motors at Dave's
Discount Motors. The first one I tried was the exhaust gasket fd227:

http://www.davesmotors.com/s.nl?c=88...=&search=fd227

This gasket never sticks to either surface and just keeps on going. Even
after high heat events it just ignores them. I don't know where it rates
on heat transfer - I'm guessing better than copper and not as good as fiber?

DDM also has cylinder gaskets (ca336) and case gasket (dd253) with a
similar description.

http://www.davesmotors.com/s.nl/c.88...t.A/id.7581/.f

http://www.davesmotors.com/s.nl?c=88...=&search=dd253

Both are described as being 0.020 in. thick. I've measured both and I'm
reading the cylinder ca336 at 0.022 in. and the case dd253 at 0.020 in.

I'm guessing that the reason DDM is only offering these HD gaskets in a single
thickness is because it's intended to be a better quality replacement for the
OEM fiber.

Trying to squish it to the max is not important to me. If I can get a
good seal and and a more stable support from DDM's HD than that will be
be an upgrade for me.

__________________________________________________ ____________________

I just took a closer look at the F273 4-Bolt and realized that a tiny corner
of the cylinder gasket is exposed in front of the carb. Moving the free edge
up and down with a pick convinced me that the OEM is fiber - same material
which NAPA keeps in stock - comes in a variety of thicknesses. I found my
miniature micrometer and I'm reasonably certain the thickness is approx.
0.020 in.

I don't consider the fiber cylinder gasket to be an optimal material. If
it gets soaked in enough premix, exposed to enough heat cycles and repeatedly
crushed from cylinder screws being torqued, it will thin out. Great if there
is room to jack up the compression but not so good if things start to touch.

Also examined an R273 2-Bolt and it's cylinder gasket is not fiber (not the
same as F273). The R273 has a laminated material that is white on both sides
and has some other layer (appears to be a metal mesh) sandwiched in between
the white outer layers. Whatever this material is, I'm not familiar with it.
Was able to measure the R273 cylinder gasket with a micrometer and it reads
approx. 0.020 in. also.

rat now

My Feedback: (4)

Upon reassembly, I noticed that one of the bolts bottoms out in the block before it snugs up againt the cylinder ear. It appears to be about 1/4 inch too long. Both bolts are the same length. This explains alot...cylinder was never fully bolted down. Didnt notice when I took it apart. The bolt in question is near the carb side.

danielplace

A good squish gauge is very helpful in setting the squish accurately.

hendocap

Good investment to get one of Daniels tools ! If the cylinder wasn't getting tight then , when it does it will bring it even closer to the piston. Alot of guys put washers on top of those 2 bolt engines because they have a tendency to break off when ingesting water, thats why the new CY engines and RCMK & Zenoah all have 4 bolts. JMO