Compression test question

I want to do a compression test on my 258 before I re-install it (I'm doing
a complete rebuild). The engine was advertised as being rebuilt about 10K
before I bought it (I've added maybe 3k), but then again the PO also said
the frame and body were in "good shape".... (did I mention I'm doing a
complete rebuild).

I've read a lot of threads about compression testing, but haven't read about
anybody doing them with the engine out of the vehicle. I plan to remove all
the plugs and crank it by hand. I hope to see results in the 120-150 psi
range without a lot of variance. The engine really does seem to run fine,
doesn't leak any oil, and doesn't seem to burn much/any oil. It does smoke,
but I think maybe my carb was never adjusted properly and maybe was just
running rich. I know I messed with the mixture when I was having issues on
the trail caused by a in-operable charcoal cannister. I had to set it
richer and richer to keep it running. Obviously I tried to adjust it back
when I fixed the cannister issue.

Anyway, I just think running the compression test will give me a better idea
if I should spend some $$ on a rebuild before I get this whole thinkg back
together. Advice?

http://www.georgiazclub.com/tips/ztech/comptest.htm
God Bless America, ßill O|||||||O
http://www.billhughes.com/

Kevin S wrote:
>
> I want to do a compression test on my 258 before I re-install it (I'm doing
> a complete rebuild). The engine was advertised as being rebuilt about 10K
> before I bought it (I've added maybe 3k), but then again the PO also said
> the frame and body were in "good shape".... (did I mention I'm doing a
> complete rebuild).
>
> I've read a lot of threads about compression testing, but haven't read about
> anybody doing them with the engine out of the vehicle. I plan to remove all
> the plugs and crank it by hand. I hope to see results in the 120-150 psi
> range without a lot of variance. The engine really does seem to run fine,
> doesn't leak any oil, and doesn't seem to burn much/any oil. It does smoke,
> but I think maybe my carb was never adjusted properly and maybe was just
> running rich. I know I messed with the mixture when I was having issues on
> the trail caused by a in-operable charcoal cannister. I had to set it
> richer and richer to keep it running. Obviously I tried to adjust it back
> when I fixed the cannister issue.
>
> Anyway, I just think running the compression test will give me a better idea
> if I should spend some $$ on a rebuild before I get this whole thinkg back
> together. Advice?

Good luck cranking it by hand? I guess if you have a breaker bar long
enough that will give you enough torque but then you need to turn it over
like three times.


How about a leak down test? That would certianly be easier with the engine
out.


Anybody else?

bill



"Kevin S" > wrote in message
...
> I want to do a compression test on my 258 before I re-install it (I'm
doing
> a complete rebuild). The engine was advertised as being rebuilt about 10K
> before I bought it (I've added maybe 3k), but then again the PO also said
> the frame and body were in "good shape".... (did I mention I'm doing a
> complete rebuild).
>
> I've read a lot of threads about compression testing, but haven't read
about
> anybody doing them with the engine out of the vehicle. I plan to remove
all
> the plugs and crank it by hand. I hope to see results in the 120-150 psi
> range without a lot of variance. The engine really does seem to run fine,
> doesn't leak any oil, and doesn't seem to burn much/any oil. It does
smoke,
> but I think maybe my carb was never adjusted properly and maybe was just
> running rich. I know I messed with the mixture when I was having issues
on
> the trail caused by a in-operable charcoal cannister. I had to set it
> richer and richer to keep it running. Obviously I tried to adjust it back
> when I fixed the cannister issue.
>
> Anyway, I just think running the compression test will give me a better
idea
> if I should spend some $$ on a rebuild before I get this whole thinkg back
> together. Advice?
>
>

William Oliveri did pass the time by typing:
> Good luck cranking it by hand? I guess if you have a breaker bar long
> enough that will give you enough torque but then you need to turn it over
> like three times.
>
>
> How about a leak down test? That would certianly be easier with the engine
> out.
>
>
> Anybody else?

You can turn it by hand but it is going to be a pain in the butt. You also
won't get good numbers as the engine will be cold and there won't be any oil
flowing to the rings yet.

Might get some numbers off it but I wouldn't expect much.

--
DougW