Low RPM
 

ok,

350 gm mercruiser.

I had a burnt valve. I took the head in to the machine shop and had it
replaced. I put it back together, did the timing ect. It is running a lot
better, but doesn't seem to have the full power. On the engine it says that
the max rpm should be 4400 - 4800. Although I only seem to be getting 4200
at the most. Also it seems a little slugish out of the hole. I checked the
compression on all clyinders and they are all very good. (160-170). I feel
as though it might have something to do with the timing. I read in a book
that the timing mark should hit in the same spot everytime. It's pretty
close but seems to very about 2-3 degrees each time. Might this be the
issue?

Any thoughts on what the problem might be here?

Cam setup timing?

In article ,
says...

ok,

350 gm mercruiser.

I had a burnt valve. I took the head in to the machine shop and had it
replaced. I put it back together, did the timing ect. It is running a lot
better, but doesn't seem to have the full power. On the engine it says that
the max rpm should be 4400 - 4800. Although I only seem to be getting 4200
at the most. Also it seems a little slugish out of the hole. I checked the
compression on all clyinders and they are all very good. (160-170). I feel
as though it might have something to do with the timing. I read in a book
that the timing mark should hit in the same spot everytime. It's pretty
close but seems to very about 2-3 degrees each time. Might this be the
issue?

Any thoughts on what the problem might be here?



So, I am guessing it did run better back before the burnt valve, and gave
you more power. If you had the head off, then you must have had to adjust
the valve lash. Back off until you hear the tick-tick-tick, and then tighten
slowly until the ticking stops, and adjust 1/4 to 1/2 turn more. Also, play
with the ignition timing. It may be just a bit late, advance it a bit and
'road test it'. Listen for the ping of detonation, in case you advance to
far. Also remember an over advanced motor will often not start when hot, it
will actually kick backwards and try to rip the starter right off the
engine. If you feel the engine doesn't make the power it used to, a bit of
tweaking is in order. Hope the new head is the same as the old head. You
did say you replaced the head? 67CC chamber vs. 73CC chamber? Port sizes
differant?

Same head. It does make a very light ticking sound, but that sound does not
increase with throttle. Would advancing the timing be to the right or left
of the line? also, would the adjustment of the rocker arms cause this
issue? And one last thing, I did put new plugs (gapped them) & wires in it
too.

"Gudmundur" wrote in message
...
In article ,
says...

ok,

350 gm mercruiser.

I had a burnt valve. I took the head in to the machine shop and had it
replaced. I put it back together, did the timing ect. It is running a
lot
better, but doesn't seem to have the full power. On the engine it says
that
the max rpm should be 4400 - 4800. Although I only seem to be getting
4200
at the most. Also it seems a little slugish out of the hole. I checked
the
compression on all clyinders and they are all very good. (160-170). I
feel
as though it might have something to do with the timing. I read in a book
that the timing mark should hit in the same spot everytime. It's pretty
close but seems to very about 2-3 degrees each time. Might this be the
issue?

Any thoughts on what the problem might be here?



So, I am guessing it did run better back before the burnt valve, and gave
you more power. If you had the head off, then you must have had to adjust
the valve lash. Back off until you hear the tick-tick-tick, and then
tighten
slowly until the ticking stops, and adjust 1/4 to 1/2 turn more. Also,
play
with the ignition timing. It may be just a bit late, advance it a bit and
'road test it'. Listen for the ping of detonation, in case you advance to
far. Also remember an over advanced motor will often not start when hot,
it
will actually kick backwards and try to rip the starter right off the
engine. If you feel the engine doesn't make the power it used to, a bit of
tweaking is in order. Hope the new head is the same as the old head. You
did say you replaced the head? 67CC chamber vs. 73CC chamber? Port sizes
differant?

You know I was thinking about it. When I did the timing there were 2 marks
on the flywheel, the org. factory mark and was that was scratched in. It
only seem to run ok when I used the scratched mark. But when I inserted the
distrutor, I used the factory mark to align to Top Dead Center. The 2 marks
are about a couple of inch's apart. Is this the problem? If so do I need to
reinsert the distributor at TDC (with the scratch mark), or can I just move
the timing a couple of inch's?



"Gudmundur" wrote in message
...
In article ,
says...

ok,

350 gm mercruiser.

I had a burnt valve. I took the head in to the machine shop and had it
replaced. I put it back together, did the timing ect. It is running a
lot
better, but doesn't seem to have the full power. On the engine it says
that
the max rpm should be 4400 - 4800. Although I only seem to be getting
4200
at the most. Also it seems a little slugish out of the hole. I checked
the
compression on all clyinders and they are all very good. (160-170). I
feel
as though it might have something to do with the timing. I read in a book
that the timing mark should hit in the same spot everytime. It's pretty
close but seems to very about 2-3 degrees each time. Might this be the
issue?

Any thoughts on what the problem might be here?



So, I am guessing it did run better back before the burnt valve, and gave
you more power. If you had the head off, then you must have had to adjust
the valve lash. Back off until you hear the tick-tick-tick, and then
tighten
slowly until the ticking stops, and adjust 1/4 to 1/2 turn more. Also,
play
with the ignition timing. It may be just a bit late, advance it a bit and
'road test it'. Listen for the ping of detonation, in case you advance to
far. Also remember an over advanced motor will often not start when hot,
it
will actually kick backwards and try to rip the starter right off the
engine. If you feel the engine doesn't make the power it used to, a bit of
tweaking is in order. Hope the new head is the same as the old head. You
did say you replaced the head? 67CC chamber vs. 73CC chamber? Port sizes
differant?

"nate" wrote in message
...
ok,

350 gm mercruiser.

I had a burnt valve. I took the head in to the machine shop and had it
replaced. I put it back together, did the timing ect. It is running a
lot better, but doesn't seem to have the full power. On the engine it
says that the max rpm should be 4400 - 4800. Although I only seem to be
getting 4200 at the most. Also it seems a little slugish out of the hole.
I checked the compression on all clyinders and they are all very good.
(160-170). I feel as though it might have something to do with the
timing. I read in a book that the timing mark should hit in the same spot
everytime. It's pretty close but seems to very about 2-3 degrees each
time. Might this be the issue?

Any thoughts on what the problem might be here?

You have had this running 44-4800 at some time? If it never ran that speed
than you need a smaller pitch prop.
If it did run at speed and all you changed was the head than timing may be
an issue. Advance it 2 degrees at a time till you hear knock. See if that
picks it up a bit.
You did follow the timing instructions and remove/plug correct hoses or
disconnect certain wires (you didn't mention the year so I don't know what
kind of ignition you have)

In article ,
says...

You know I was thinking about it. When I did the timing there were 2 marks
on the flywheel, the org. factory mark and was that was scratched in. It
only seem to run ok when I used the scratched mark. But when I inserted the
distrutor, I used the factory mark to align to Top Dead Center. The 2 marks
are about a couple of inch's apart. Is this the problem? If so do I need to
reinsert the distributor at TDC (with the scratch mark), or can I just move
the timing a couple of inch's?


I would leave the distributor alone for now, at least as far as pulling it
out goes. If you can get the desired timing without the advance can hitting
anything you will be o.k.

I hope I am correct about your motor here, Turning the distributor
counter-clockwise will advance the timing. I like a lot of advance, but
you have to quit when you hear pinging under acceleration when the engine
is hot, and you have cheap fuel in it. Also, I find with a lot of
advance the engine is hard to crank over when it's hot. The spark occurs
to early and almost stops the motor dead while cranking. If you have
that much advance, back it off a bit. I time by ear and by feel, and
not with a light. A light gets me in the ballpark only. Every engine seems
to have a personality, and some like a ton of advance, others don't, and
none seem to run at their peak using the factory setting.

As for the 'ticking', I was refering to the click-click-click of a
to loose rocker adjustment. I very very slowly adjust mine looser until
they very lightly start clicking, then very slowly adjust tighter about
1/3 turn past where they stop ticking. Never more than 1/2 turn.
Of course you do this one rocker at a time. If they are all clicking you
can't tell what's going on. I made a very special valve cover with eight
3/4 inch holes punched directly above the rocker studs. I can adjust my
valve train all day long, and never spill one drop of oil.

Hope all of this helps.

calhoun,

Sorry I left that out. That is a good point It's a 1997. Do I need to
disconnect anything when doing the timing?. The only 2 things I noticed
that were connected to the distributor was 2 wires. I know with both of
them unplugged it doesn't start.

"calhoun" wrote in message
.. .

"nate" wrote in message
...
ok,

350 gm mercruiser.

I had a burnt valve. I took the head in to the machine shop and had it
replaced. I put it back together, did the timing ect. It is running a
lot better, but doesn't seem to have the full power. On the engine it
says that the max rpm should be 4400 - 4800. Although I only seem to be
getting 4200 at the most. Also it seems a little slugish out of the
hole. I checked the compression on all clyinders and they are all very
good. (160-170). I feel as though it might have something to do with the
timing. I read in a book that the timing mark should hit in the same
spot everytime. It's pretty close but seems to very about 2-3 degrees
each time. Might this be the issue?

Any thoughts on what the problem might be here?

You have had this running 44-4800 at some time? If it never ran that speed
than you need a smaller pitch prop.
If it did run at speed and all you changed was the head than timing may be
an issue. Advance it 2 degrees at a time till you hear knock. See if that
picks it up a bit.
You did follow the timing instructions and remove/plug correct hoses or
disconnect certain wires (you didn't mention the year so I don't know what
kind of ignition you have)

In article ,
says...

calhoun,

Sorry I left that out. That is a good point It's a 1997. Do I need to
disconnect anything when doing the timing?. The only 2 things I noticed
that were connected to the distributor was 2 wires. I know with both of
them unplugged it doesn't start.

One wire should be the +12vdc 'run' wire, and one should be to the tach.

At the base of the distributor should be a vacuum advance hose, but
some distributors don't have a vacuum advance, only the internal
weighted mechanical advance.

Normally, you remove and plug the advance hose while setting the
timing. If you have vacuum advance, and you didn't remove the hose
when setting your timing, your timing is way off, very late indeed!

Marine distributors do not have vacuum advance. Is worthless on a boat
motor. If it has the electronic ignition with computer, there is a wire to
remove the computer induced timing.

"Gudmundur" wrote in message
...
In article ,
says...

calhoun,

Sorry I left that out. That is a good point It's a 1997. Do I need to
disconnect anything when doing the timing?. The only 2 things I noticed
that were connected to the distributor was 2 wires. I know with both of
them unplugged it doesn't start.

One wire should be the +12vdc 'run' wire, and one should be to the tach.

At the base of the distributor should be a vacuum advance hose, but
some distributors don't have a vacuum advance, only the internal
weighted mechanical advance.

Normally, you remove and plug the advance hose while setting the
timing. If you have vacuum advance, and you didn't remove the hose
when setting your timing, your timing is way off, very late indeed!