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Number 1 Distributer Cylinder Position
#1375936 Fri Sep 04 2020 05:43 PM
Joined: May 2007
Posts: 287
H
Huck Offline OP
Shop Shark
I am trying to determine the correct number 1 cylinder position in the distributer of my newly rebuilt '54 235. Rotating the engine, and lining up the bb with the pointer the distributer rotor points to either about 1 o'clock or 7 o'clock and I am not sure which is correct. Thanks in advance for any help.
Mike

Re: Number 1 Distributer Cylinder Position
Huck #1375944 Fri Sep 04 2020 07:02 PM
Joined: Sep 2001
Posts: 30,450
ace skiver
Take all the spark plugs out.
(the engine rotates more easily with the spark plugs out)

Place a cork in the #1 cylinder spark plug hole.

Rotate the engine by hand (maybe by rotating the fan belt).

The cork pops out on the firing/compression stroke.

There are more technical ways to determine "the correct number 1 cylinder position".

Also: "Most old school mechanics would just use the finger method. Place one finger over over the end of the hose [that you have inserted into the #1 stpark plug hole], then rotate the crankshaft (clockwise is best but not essential)." (finding TDC [dannysengineportal.com]


Tim
1954Advance-Design.com [1954advance-design.com]
1954 3106 Carryall Suburban [stovebolt.com] - part of the family for 49 years
1954 3104 5-window pickup w/Hydra-Matic [1954advance-design.com] - part of the family for 15 years
- If you have to stomp on your foot-pedal starter, either you, or your starter, or your engine, has a problem.
- The 216 and early 235 engines are not "splash oilers" - this is a splash oiler. [chevy.oldcarmanualproject.com]
Re: Number 1 Distributer Cylinder Position
Huck #1375962 Fri Sep 04 2020 09:52 PM
Joined: May 2007
Posts: 287
H
Huck Offline OP
Shop Shark
Thanks again Tim!

Re: Number 1 Distributer Cylinder Position
Huck #1376025 Sat Sep 05 2020 05:30 PM
Joined: Oct 2019
Posts: 95
W
Shop Shark
Mr. tclederman, Greenhorn question for you if you don't mind: I have seen that you are an advocate of using vacuum pressure to set optimal ignition timing. That method makes the best sense to me also (greenhorn mind you), because it takes into consideration all the variables of the particular engine.

So my question is: after you determine TDC on No. 1 using your cork method, would you then hook up the vacuum gauge and set the ignition timing?

Thank you

Re: Number 1 Distributer Cylinder Position
Huck #1376027 Sat Sep 05 2020 05:50 PM
Joined: May 2005
Posts: 7,472
B
General Purpose
Just to be sure, you find TDC on the compression stroke. That is why the "cork" pops out. The other TDC is an exhaust stroke, no compression. I use a Kleenex stuffed in medium tight. There are other methods of observing valves if you want to take valve cover off.
My opinion on timing is that a timing light is sufficient.


Watch out for careful drivers!!!
I'm away on an ego trip. Will be back on Feb 30.
I'm not an Auto Mechanic, but I play one on TV.
I charge $0.02 for every opinion and I take Paypal.
Plan B is always better than plan A, by definition.


Re: Number 1 Distributer Cylinder Position
Huck #1376045 Sat Sep 05 2020 08:33 PM
Joined: Oct 2019
Posts: 95
W
Shop Shark
For the benefit of this greenhorn, if you had the valve cover off, what would you look for?

Thank you

Re: Number 1 Distributer Cylinder Position
Huck #1376054 Sat Sep 05 2020 10:10 PM
Joined: May 2005
Posts: 7,472
B
General Purpose
Both valves closed on #1 when BB on pointer. Turn dizzy CW until points close, then back until they just start to open. This is a "static" method.

The cork/Kleenex is with no helper.

With a helper: Just put your thumb over #1 plug hole while cranking, feel pressure and that's about #1 TDC. Turn dizzy so rotor points at #1 tower.

All these methods are just to get motor started, to begin fine tuning with a light and rotating dizzy. With the light, adjust dizzy til pointer is right on ball. Ball is already set at proper BTDC location. (proper advance)


Watch out for careful drivers!!!
I'm away on an ego trip. Will be back on Feb 30.
I'm not an Auto Mechanic, but I play one on TV.
I charge $0.02 for every opinion and I take Paypal.
Plan B is always better than plan A, by definition.


Re: Number 1 Distributer Cylinder Position
Huck #1376157 Sun Sep 06 2020 06:21 PM
Joined: Oct 2005
Posts: 2,994
"Hey! I sound like Darth Vader!!
I know a funny car driver that drove the WarEagle.

Re: Number 1 Distributer Cylinder Position
Huck #1376179 Sun Sep 06 2020 09:31 PM
Joined: Jun 2011
Posts: 3,630
E
Shop Shark
I use a grass straw from the field to check for TDC. Won't hurt anything if gets broken off, price is right, too.

Ed


'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
Re: Number 1 Distributer Cylinder Position
Huck #1376443 Wed Sep 09 2020 01:02 AM
Joined: Feb 2004
Posts: 21,018
H
Boltergeist
Setting timing with a vacuum gauge is about as accurate as sticking your hand out the window into the slipstream to measure road speed instead of using the speedometer.

With the valve cover removed, watch the last valve in line back by the firewall (#6 exhaust). Turn the engine clockwise from the front until that spring is fully compressed, then continue turning until the spring relaxes. Just as it reaches the full-closed position, the next valve in line #6 intake) will start to open. At that point the #1 cylinder (NOT #6!) will be at the top of the compression stroke, ready for the spark plug to fire. This is an absolutely foolproof method of determining which cylinder needs to fire as the BB lines up with the pointer. The crankshaft on all 4-stroke engines turns twice in a 4-stroke cycle, so the timing mark will line up twice- - - -once on compression, and 360 degrees of crankshaft rotation later, at the top of the exhaust stroke. The spark plug needs to fire at the top of the compression stroke.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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