#1
IP: 24.152.132.140
|
||||
|
||||
Finding TDC the easy way
A while back we had a tool concept for finding the compression stroke in a cylinder, critical when setting timing from scratch, without peering or inserting anything into the spark plug hole. Remember this?
Well it struck me as a pretty cool idea so I finally got around to making one and testing it out. I sacrificed an old spark plug by breaking off the porcelain, drilling out the electrode and grinding off the arm on the bottom, added a balloon to the top, threaded it into the #1 spark plug hole finger tight only and turned the engine over by hand. Once you know you're on the compression stroke you view the crankshaft roll pin for vertical alignment. Way cool.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#2
IP: 141.239.218.236
|
||||
|
||||
Neil-
IF you decide to mass produce... can we have a variety of color choices on the balloons?
__________________
-Jerry 'Lone Ranger' 1978 RANGER 30 |
#3
IP: 24.152.132.140
|
||||
|
||||
Yes, you may . . .
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
The Following 2 Users Say Thank You to ndutton For This Useful Post: | ||
Administrator (05-08-2020), sastanley (09-04-2018) |
#5
IP: 67.176.202.26
|
|||
|
|||
Very cool. Only thing I can add is that on this site you will either "learn" or get "entertained".
|
The Following User Says Thank You to Sam For This Useful Post: | ||
Administrator (05-08-2020) |
#6
IP: 76.66.159.112
|
||||
|
||||
Quote:
And that is why they call it enterlearnment! |
#7
IP: 70.186.110.20
|
||||
|
||||
You must also consider the oxygen permability of the rubber as to the accuracy of the device. More or less rubber thickness may distort the results.
:-) Yes I'm kidding.
__________________
Bill L. 1972 Ericson 27 Hull #61 Atomic 4 |
#8
IP: 108.24.164.223
|
|||
|
|||
TDC
If a Vee drive prevents a visual of TDC there is a notch in the Accessory Drive that tells TDC too-
|
#9
IP: 138.207.175.104
|
||||
|
||||
I hope that forum members will appreciate the engineering complexities at work with Neil's device.
All this stuff makes my head hurt, but kudos once again to Neil. Bill Last edited by Administrator; 05-09-2020 at 06:48 AM. |
The Following User Says Thank You to Administrator For This Useful Post: | ||
Surcouf (05-08-2020) |
#10
IP: 24.152.132.140
|
||||
|
||||
On your last two considerations:
4. There is zero atmospheric influence on the indicator short of being in a perfect vacuum. It reads only the pressure delta above ambient created by the moving piston in a closed cylinder. 5. Nitrogen permeability would be a 4X greater concern considering the chemical composition of air.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
The Following User Says Thank You to ndutton For This Useful Post: | ||
Administrator (05-08-2020) |
#11
IP: 165.225.38.121
|
||||
|
||||
for durability we would probably need to develop a balloon resistance test to Marvel Mistery Oil vapors too!
__________________
Surcouf A nostalgic PO - Previously "Almost There" - Catalina 27 (1979) |
#12
IP: 32.211.28.40
|
||||
|
||||
Since the air in the balloon has come thru the carb, it just might be flammable. Gives me all sorts of thoughts...
|
#13
IP: 99.30.185.198
|
|||
|
|||
Probably shouldn't go there
Al, Have you ever heard of an acetylene bomb?
Tom |
#14
IP: 155.186.124.219
|
|||
|
|||
Tom, my dad made acetylene balloons for parties. Only he knew which ones were which on the patio. Mom would get mad so he'd blow one up near her and the laughs would start.
I did some torch silver soldering for a while. we had coffee cans on the bench with water for keeping our "prods" clean of flux. If someone was bothering me I would fill a can upside-down and when they'd come back to annoy me I'd wave the torch past a hole. After the second time I moved the fluorescent lights a foot or so. Lots of can dents over my bench! Dave Neptune |
#15
IP: 99.30.185.198
|
|||
|
|||
Dave, I was pretty sure that you would have played with them.
Tom |
#16
IP: 155.186.124.219
|
|||
|
|||
Tom, I just could not resist .
Dave Neptune |
#17
IP: 137.103.82.227
|
||||
|
||||
Quote:
|
#18
IP: 32.211.28.40
|
||||
|
||||
Well, this has been an amusing thread!
Just what I needed during this isolation. Spring trip to NOLA cancelled, instead we got to visit Loch Down. I hear that even Nessie is now in Loch Down. So, all this is just to keep from putting your thumb over the spark plug hole? No, the idea of acetylene balloons is new to me. Haven't tried one. Do they make your voice funny?? Another week or two of this and we can start a thread on vegetable guns. I've still got my potato cannon out in the shed - SpudZooka! I had the design for a radish pistol, but never made one. |
#19
IP: 24.152.132.140
|
||||
|
||||
One thing I noticed with the balloon indicator - - you can turn the engine very slowly by hand and still get a good indication. Oh yeah, you can turn the engine with TWO hands.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#20
IP: 166.170.14.22
|
||||
|
||||
Atomic 4 compression
Good Neil
Very interesting post a learning experience, thank you. Question: So once the balloon has expanded you are/may be at Top Dead Center with the #1 piston, what I want to confirm is are you on the compression stroke? I just replace all the valves on my atomic 4 and I have little to zero compression. Before I did this job I had (70, 80, 70,60) so I am trying to find out if since I have re-adjusted the valves on the compression stroke which I am having a difficult time trying to figure out, that I have or have not set the valves on the compression stroke. When I first set the valves I use a pencil in the #1 sparkplug hole to find (top dead center) TDC but didn't know if I were on the compression stroke. |
#21
IP: 100.40.58.241
|
|||
|
|||
Hello Theodore.
Here are Don Moyer's instructions for finding TDC, from one of his FAQ documents. Jack "The TDC position of the No. 1 cylinder is most easily found by holding a finger over the spark plug hole in the first cylinder, while manually turning the flywheel counterclockwise. As soon as compression is felt, stop turning and look at the position of the roll pin in front of the crankshaft. Continue turning until the roll pin is perfectly vertical. The piston will then be at TDC." |
#22
IP: 165.225.38.121
|
||||
|
||||
__________________
Surcouf A nostalgic PO - Previously "Almost There" - Catalina 27 (1979) |
#23
IP: 155.186.124.219
|
|||
|
|||
Theodore, first welcome to the MMI Afourian forum.
Note that if the valves a to tight from your adjustment position of the crank & cam the valves may not be seating and thus no compression. Finding TDC without the valves seating for compression can still be done. It is a bit more "engaging" but doable by watching the valves through the side plate. Dave Neptune |
#24
IP: 24.152.132.140
|
||||
|
||||
Quote:
If you have zero compression on all 4 cylinders, the balloon tool is worthless.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#25
IP: 166.137.8.27
|
||||
|
||||
Atomic 4 compression
Hello jcwright,
Unfortunately I can't do both at the same time but I will see if I can incorporate a friend to assist me with doing this procedure. I email back forth with Don Moyer in finding the TDC, by putting a pencil in the #1 sparkplug and watch the pencil rise to confirmed TDC, then set the valves to spec. Which I did but not knowing if I am on the compression stroke or not. I am going to contact Don again after I check the compression once again since I got the engine timed. I thought that maybe I tried to adjust the distributer while I have the engine in forward gear and get RPM up and I might get some compression because I have zero rise RPM when in forward gear when I put the throttle full open, which why I think my compression or valves may not be correct, unless I have a whole different issue. Thanks for your advice. Ted Gladden Last edited by Theodore; 05-14-2020 at 12:47 AM. Reason: add more info |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Finding TDC (top dead center) | jpian0923 | Drawings and Schematics | 4 | 09-18-2016 06:25 PM |
Easy distributor question | positron | Ignition System | 15 | 03-15-2012 05:29 PM |
Finding the waterline while inside the boat | ILikeRust | Exhaust System | 15 | 09-14-2011 01:30 PM |
If torqueing was easy , | Laker | General Interest | 14 | 01-27-2011 02:51 PM |
Finding TDC: how critical to be precise? | rigspelt | Overhaul | 4 | 12-15-2008 05:04 AM |