Re: [FWDLK] 331 hemi timing questions

[David Homstad <dhomstad@xxxxxxxxxxx>]

Chuck,

I'm not even sure what your problem is. The only symptom I heard is the
engine cranks slow when the battery is 3 years old. This sounds more like a
starter/battery/ground connection problem. Not uncommon with a 6 volt
system.

If you want to find TDC in an engine, the only accurate way to measure it is
with the # 1 piston location. You need a positive mechanical stop for the
piston just below the top of its travel, and mark the angle on the harmonic
balancer. Do this as the crank turns both directions. The middle of these
marks is TDC. This is easiest to do during engine assembly. These may be the
marks painted on the balancer by the builder. The painted line may be TDC,
or it may be 6 deg BTDC to assist in timing. Instead of guessing, why not
just ask him what they mean? You also need to know how many degrees the
timing divisions are: 2, 4, 5 degrees?

Using the method described by John may not yield accurate TDC results.
Depending on the cam profile characteristics and timing chain slack, it
might be off by + or minus 20 degrees.

If the timing is too advanced, it may make the engine crank slow. The
pistons are trying to compress the fuel charge and when it ignites too
early, the expanding gases work against the starter.

Remember, the timing light mark always advances to increased BTDC as the
engine rpm increases. Assuming the painted line is TDC, as the engine rpm is
increased from an idle, the timing should move away from TDC. If your timing
is set very retarded on the ATDC side, the mark will advance to TDC and
cross into the BTDC range as rpm increases.


Dave Homstad
56 Dodge D500

-----Original Message-----
From: Forward Look Mopar Discussion List
[mailto:L-FORWARDLOOK@xxxxxxxxxxxxx]On Behalf Of John McCann
Sent: Saturday, July 05, 2008 9:38 PM
To: L-FORWARDLOOK@xxxxxxxxxxxxx
Subject: Re: [FWDLK] 331 hemi timing questions

    I'm not sure I would assume the marks are at the ten degree mark, he
might have made the mark at the proper timing position. The lower mark seems
to be the advance mark since the light shows the centrifugal advance or
vacuum advance moving the timing down, try setting the timing on the lower
mark and see how that works out. Can you see the original marks on the
damper? One way to check to see if the TDC mark is correct is to pull the
valve cover over number one cylinder and turn the engine by hand until the
exhaust valve is closing and the intake valve is opening and rock the engine
back and forth until it is in the middle of the opening and closing, look at
the damper to see the location of the marks or make a mark because that is
top dead center, although it is not on the firing stroke, if you check your
rotor it should be 180 degrees from number one. Check your timing with the
vacuum advance hose off and plugged, a golf tee works great. I hope this is
clear to you, if not email me and I'll try to clarify.
John

----- Original Message -----
From: "Charles Deyoe Jr." <deyoe101@xxxxxxxxxxx>
To: <L-FORWARDLOOK@xxxxxxxxxxxxx>
Sent: Saturday, July 05, 2008 6:01 PM
Subject: [FWDLK] 331 hemi timing questions


>I just installed the new pretronix ignitor on my 55 new yorker with  the
>331 hemi.   I adjusted the timing but have a question that I can  not find
>the answer too.
>
> I adjusted the timing as per the service book at 6 Deg BTDC and on the
> harmonic balancer there is a line painted on it from the rebuilder  about
> two years ago and a dot on each side I am guessing is 10 deg  before and
> after .
>
> My question is when I shine the timing light to time the car the  timing
> is between the line and the lower dot on the balancer{ as  close to 6 as I
> can get}  is this location before or after TDC ?  as  the car runs and I
> just test drove it 45 miles { went for a ice cream  run }  and the only
> think I found is when I I went to start the car it  was very slow to even
> turn over at first.  I have found this happens  if I do not change the
> battery every three years and the new battery I  ordered came in a little
> small and I told them I need the larger size  to fit properly.
>
> Should I readjust the timing to read above the line when I look down  with
> the timing light ?  and I also noticed when i was adjusting it  today that
> when I gave the car a little gas the timing went past the  lower dot and
> returned to about 6 deg when I let off as I know this  what should happen
>
> I have not tried any other test so If any one has advise let me know.
> thanks again.
>
> Chuck Deyoe
> 1955 new yorker
>
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