Yes it is timing advance. You advance the timing a bunch when coasting and
the vacuum is high. No knocking and you get much better mileage. Is why
boats do not have the vacuum line on marine distributors.
Bill

"Bill" wrote in message
...
No it is for timing advance
"Calif Bill" wrote in message
...
You do not see vacuum hoses on most boats. IS for fuel savings when
coasting, which is not what a boat does.
Bill

"Bill" wrote in message
...
I would also check the timing advance. The weights in the distributor
may
be
frozen. I would also check the vacuum hose that runs to the
distributor.

Bill
"Scott Schaus" wrote in message
thlink.net...
Boat specs: 1967 SeaRay 190SRV with OMC 185 in/out drive. GM small
block
V8,
283 cid.

Laid-up for winter, working top-notch at end of last season.
Winterized
before storage.

Started right up after prepared for new season. When put in the
water
engine
started to have a miss. If distributor plug wire for cylinder number
7,
is
removed from distributor cap, miss seems to go away.

Put all new ignition parts in and acted the same way.

Have tried to run boat in water to get rid of possible carbon, but
boat
bogs
and backfires even when increasing speed very slowly. At low speeds
o.k.,
but when medium speeds are reached, backfiring starts.

Took off valave cover. No broken springs. Checked compression on all
cylinders and all had same psi of 90.

Mechanic suggested new gas.

Other mechanic at lake said low compression and take off both heads
and
have
hard seats installed.

Weird part is that boat ran fine at layup last fall. Inside all
winter
mand
profesionally laid up with new fluids and engine fogged out.

Any ideas what could be gong on.

Thanks,


S. Schaus