<VV> Damage discovered

[MarK Durham]

Bob, since all the pistons are galled in the same area, there must be a
heat problem where the pistons expanded too much and caused the galling on
the piston cylinder wall you see.  Or there is lack of proper lubrication
from a poor type of oil.

Did I hear you right in saying your compression was even at 185 PSI?
Please, others chime in if I am wrong, but that is 30-40 PSI to high for
even the highest compression corvair engines I am aware of.

I am running modified heads on my car and have to run plugs two heat ranges
cooler than a normal plug to keep the spark plugs from cracking and showing
signs of pre-ignition.  Pre-ignition only happens when temps are out of
normal range. To high of compression ratio causes extra heat but also puts
extra stress on the pistons, piston pins and bearings. It will also cause
harder slap, however, engines run for many miles with slap. I think the
slap happened because of a heat problem that galled the pistons.

 What do your spark plug electrodes and ceramic look like?
What plug are you using? What heat range is it?
What do the tops of the pistons look like?
What do the combustion chambers look like?
What jet size do you have in the carburetor's?
Which distributer were you using and what was the setting for timing?
What were cht temp and oil temp readings?
What type and weight of oil was being used?
Was additional ZDDP added to help with break in?

A few pictures would be helpful of parts mentioned above, as removed and
without cleaning.

Also, I am going out on a limb here, because I have no experience with
motor home motors, but I do have experience with high power output aircraft
engines with tight cowlings: but the cooling system for the corvair engine
is at best just effective enough to prevent overheating in moderate power
conditions. Turbo guys that keep their foot in it eat up more parts than
most engines do and the engines have a shorter life span.

You have added more cubic inches which means more heat produced the same
cooling system must dissipate, plus you put the engine in a motor home
where consistent higher torque means more heat is generated.

I assume you are running the engine with the lower shrouds off? Do you have
a deep oil pan for extra capacity and ribbed so it helps to dissipate heat
from the oil? Same for valve covers?

3.1 owners, please chime in here. What happened?

Regards

Mark Durham
Hauser, Idaho
62 Monza coupe Red/Red 4 speed


On Sat, May 3, 2014 at 5:17 PM, Bob Gilbert 1 via VirtualVairs <
virtualvairs at corvair.org> wrote:

> Hi,
>
> I just removed number 6 piston as it was the one with the deepest skirt
> scratched.
>
> The piston has been quite severely galled from the bottom of the oil ring
> to
> the bottom of the skirt. The scratches/galling is about ¼ inch wide.
>
> The scratches are on both the top and bottom of the piston, 180 degree
> apart
> and in line with the conrod
>
> The cylinder has damage in an equivalent are but it’s minor and I hope it
> can be honed out.
>
>
>
> It’s only cylinder but I think I will find something similar on the other
> cylinders which I’ll remove tomorrow.
>
>
>
> Now exactly what CAUSED the scratches is still a mystery…
>
>
>
> Bob
>
>  _______________________________________________
> This message was sent by the VirtualVairs mailing list, all copyrights are
> the property
> of the writer, please attribute properly. For help, mailto:
> vv-help at corvair.org
> This list sponsored by the Corvair Society of America,
> http://www.corvair.org/
> Post messages to: VirtualVairs at corvair.org
> Change your options:
> http://www.vv.corvair.org/mailman/options/virtualvairs
>  _______________________________________________
>