OldIHC

Posted: **Mon Mar 05, 2018 12:42 pm**

thought I'd post this for anyone having timing issues. I learned this long ago and it recently helped me with a "pinging" problem on my BD240 with turbo. told some of the young guys in my car club and they looked at me like I was a genius. hahahaha! can't take credit for it though

I'm sure a lot of you know this, but maybe it will help someone that doesn't.

if this is posted somewhere else, sorry for double posting.

so I made a piston stop tool from an old spark plug. its rounded on the tip as to NOT damage the piston. you can buy one just about anywhere. https://www.summitracing.com/search/par ... ston-stops

I had to make a pointer, so I mounted a piece of wire on the frame under the front of the engine and bent it to point at the harmonic balancer.

brought #1 piston up to about TDC.

screwed the tool into the spark plug hole and turned the bolt in the tool into the cylinder till it touched the piston. (if the tool won't touch the piston, back it out and get the piston a little closer to TDC.) lock the nut down.

mark the balancer where the wire is pointing.

SLOWLY rotate the crankshaft BACKWARDS till the piston goes down, then back up to touch the piston. we go slowly so as not damage the piston as it comes back to the tool.

make another mark on the balancer.

REMOVE the tool.

measure the distance of the marks, split it in half and make another mark.

rotate the crankshaft in the direction of rotation till your pointer is lined up with your center mark.

there is TDC the inexpensive way. as you see, the rivet on my flywheel is way off TDC.

Posted: **Mon Mar 05, 2018 7:05 pm**

I have had very good success with a modified compression tester. I attached the screw-in part of the tester to a manometer . I rotated the crankshaft clock-wise then counter clock-wise a few degrees and watched the liquid rise and fall in the manometer. There is a point on the TDC compression stroke where the manometer fluid will stop moving up or down. This mid-point is the true TDC. Pictures later. Maybe.
If a person does not have a manometer, a section of clear hose in a loop and some liquid in the loop will act like a manometer. If you are in Canada, Princess auto has clear hose. An aquarium store will have clear hose.

https://youtu.be/Ys80A6fL0_4

Posted: **Mon Mar 05, 2018 10:21 pm**

Both postings are very helpful for me, thank you. I am trying to learn (by doing) how to tune my SD220 and it has not occurred to me that the ball on the flywheel could be off. This could be a source of some of my tuning trouble, but chances are it's just my lack of experience. I will however take the time to verify TDC.

Posted: **Tue Mar 06, 2018 6:56 am**

My FIRST impulse is to comment that this is just basic engine tech.

But on reflection, I realize that a lot of the folks who are new to old IHC's are also new to old-school engine tech; so I'm glad to see someone pass this along.

Now...if carburetion and ignition were only this easy to teach...

Posted: **Tue Mar 06, 2018 10:36 am**

Nikki, that is a great method and one I've never considered but it makes perfect sense. I'll have to try it, I've always used the method first described.

Posted: **Mon Mar 12, 2018 9:44 pm**

It all sounds more complicated than it needs to be . . . for me anyway.

1. Finding the compression stroke.
If the valve cover is off, when you see #1 intake valve starting to close; i.e., the valve spring is being released, then you know that the piston is on the way up to TDC.

2. Through #1 spark plug hole I stand a long thin shanked screwdriver on the piston. Usually I need two hands to rotate the engine via the fan (one hand to put pressure on the belt by the water pump pulley for traction in the pulley) . . . so I tie a long string from the #6 end of the engine, around the screw driver and tie the string to something forward of #1 cylinder. The screwdriver just leans against the string.
What this does is keep your screw driver standing as straight up and down as possible so that the screwdriver doesn't bind in the plug hole as the piston comes up.

3. Once that quick string set up is done it is a piece of cake to watch the screw driver rise up to TDC. When you're there you can easily find the point where the driver starts to fall again, so you back up to the point between rising and falling.

Been doing that for years.
You can pick your spot where it barely hits TDC or a hair beyond just before the screw driver starts going down.

Terry

Posted: **Mon Mar 12, 2018 10:31 pm**

https://youtu.be/0tJGk4ofc18

Posted: **Tue Mar 13, 2018 5:19 am**

unclejtl wrote:thought I'd post this for anyone having timing issues. I learned this long ago and it recently helped me with a "pinging" problem on my BD240 with turbo. told some of the young guys in my car club and they looked at me like I was a genius. hahahaha! can't take credit for it though I'm sure a lot of you know this, but maybe it will help someone that doesn't.

if this is posted somewhere else, sorry for double posting.

so I made a piston stop tool from an old spark plug. its rounded on the tip as to NOT damage the piston. you can buy one just about anywhere. https://www.summitracing.com/search/par ... ston-stops
IMG_1023b.jpg

I had to make a pointer, so I mounted a piece of wire on the frame under the front of the engine and bent it to point at the harmonic balancer.

brought #1 piston up to about TDC.

screwed the tool into the spark plug hole and turned the bolt in the tool into the cylinder till it touched the piston. (if the tool won't touch the piston, back it out and get the piston a little closer to TDC.) lock the nut down.

mark the balancer where the wire is pointing.

SLOWLY rotate the crankshaft BACKWARDS till the piston goes down, then back up to touch the piston. we go slowly so as not damage the piston as it comes back to the tool.

make another mark on the balancer.
IMG_1024b.jpg

REMOVE the tool.

measure the distance of the marks, split it in half and make another mark.

rotate the crankshaft in the direction of rotation till your pointer is lined up with your center mark.

there is TDC the inexpensive way. as you see, the rivet on my flywheel is way off TDC.
IMG_1026b.jpg

Looked through this thread again saw your remarked flywheel pic for the first time. The river looks to be about 4* advanced. Isn’t that the timing spec for a BD240? Thus with a static timing light placing the pointer on the ball would give you the proper base timing. Not trying to confuse things, just an observation based on my interpretation of the service manual.

Posted: **Tue Mar 13, 2018 5:46 pm**

well the only manual I have is the cts 11. 2nd picture is the page I use. if you read #3 about TDC, it says "with the timing mark on the pointer". that seamed to me to be TDC and my 4 degrees was from the plate on the distributer. heard that here.

the 1st picture is from kevin this last week and it shows better picture of the flywheel rivet and marks. I got it this last Saturday. Thanks Kevin!

I don't know everything and don't claim to, just thought there may be somebody here that didn't know how to find true TDC, whatever method. with parts being swapped by previous owners, you never know what you have if it's not 100% original. I learned this in the late 70's working on vw's. some pulleys had a notch at TDC, some at 7.5 degrees, some at 10 degrees and 7.5 degrees.

Posted: **Tue Mar 13, 2018 6:13 pm**

Ah crap, it appears I scanned in the wrong 2nd picture. I’ll fix it in the morning.

OldIHC

finding true top dead center

finding true top dead center

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