Tech tip, TDC stop tool.
Thread Starter
Melting Slicks
Joined: Dec 2004
Posts: 2,137
Likes: 5
From: Howard PA
Tech tip, TDC stop tool.
Pretty down home, I made it in a pinch. I can't remember if I posted this before. So anyway I'm posting this because we've had several discussions lately about finding TDC with a degree wheel and the heads are on.
Beat the snot out of an old spark plug emptying it of the ceramic. I ground the ceramic flush at both ends then stuck it in a 5/8 socket. Put the drive end down on my vise, most vises have a nice flat for beating stuff on a hard surface. Took a punch and started whacking away at the ceramic. Do whatever works for you, a hammer drill with a masonry bit might work.
Thread the empty spark plug for a 3" long bolt, thread pitch doesn't really matter. I used whatever I had wasting space in my bolt bucket. Grind the head of the bolt round so as not to nick your piston. I chucked the bolt up in my drill and ran it against the grinding wheel, run the drill at high speed and shape it into a ball or close to it. I took off the first couple threads below the head also. You can go crazy with polishing the ball you make if you'd like, but I think if you get it somewhat round and don't force your piston into it real hard it's OK a bit rough.
Tighten the nut down to the spark plug so it doesn't rotate or move on you. After that the picture is pretty self explanatory.
Beat the snot out of an old spark plug emptying it of the ceramic. I ground the ceramic flush at both ends then stuck it in a 5/8 socket. Put the drive end down on my vise, most vises have a nice flat for beating stuff on a hard surface. Took a punch and started whacking away at the ceramic. Do whatever works for you, a hammer drill with a masonry bit might work.
Thread the empty spark plug for a 3" long bolt, thread pitch doesn't really matter. I used whatever I had wasting space in my bolt bucket. Grind the head of the bolt round so as not to nick your piston. I chucked the bolt up in my drill and ran it against the grinding wheel, run the drill at high speed and shape it into a ball or close to it. I took off the first couple threads below the head also. You can go crazy with polishing the ball you make if you'd like, but I think if you get it somewhat round and don't force your piston into it real hard it's OK a bit rough.
Tighten the nut down to the spark plug so it doesn't rotate or move on you. After that the picture is pretty self explanatory.
Last edited by ALLT4; Jul 19, 2006 at 07:05 PM.
Pro
Joined: Jul 2005
Posts: 741
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From: Athens, GA
Originally Posted by MikeC4
very cool indeed. how do you know if you are on compression or exhaust stroke?
1. Remove the distributor cap, and note the position of the rotor.
2. Remove the valve cover, and note the position of the valves.
Steven
Pro
Joined: Sep 2003
Posts: 670
Likes: 1
From: charlotte nc
Originally Posted by MikeC4
very cool indeed. how do you know if you are on compression or exhaust stroke?
Racer
Joined: May 2006
Posts: 286
Likes: 0
From: Alpine California
ALLT4,
I'm not ragging on you here, but it seem's like an awful lot of work for a tool you can get from Summit for $7.88 http://store.summitracing.com/partde...5&autoview=sku. You don't wan't to hit the tool very hard with a piston because the damn bolt will bend also, ask me how I know!
I'm not ragging on you here, but it seem's like an awful lot of work for a tool you can get from Summit for $7.88 http://store.summitracing.com/partde...5&autoview=sku. You don't wan't to hit the tool very hard with a piston because the damn bolt will bend also, ask me how I know!
Pro
Joined: Apr 2005
Posts: 590
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From: Boynton Beach, FL
Very clever solution but I'm still confused as to how it actually works. When building engines I've always found TDC with heads off using a dial indicator on the piston and a degree wheel on the crank. At TDC you can move several degree off TDC and have very little movement of the indicator. I don't remember the exact numbers but I think it was in the .010" range.
Maybe I'm dense or just don't get it but I just can't exactly see how your device allows you to find TDC with out having an existing reference. please elaborate for the thick headed out here.
Larry
Maybe I'm dense or just don't get it but I just can't exactly see how your device allows you to find TDC with out having an existing reference. please elaborate for the thick headed out here.
Larry
Last edited by Vetracr; Jul 20, 2006 at 04:28 PM.
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Racer
Joined: May 2006
Posts: 286
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From: Alpine California
Originally Posted by Vetracr
Very clever solution but I'm still confused as to how it actually works. When building engines I've always found TDC with heads off using a dial indicator on the piston and a degree wheel on the crank. At TDC you can move several degree off TDC and have very little movement of the indicator. I don't remember the exact numbers but I think it was in the .010" range.
Maybe I'm dense or just don't get it but I just can't exactly see how your device allows you to find TDC with out having an existing reference. please elaborate for the thick headed out here.
Larry
Maybe I'm dense or just don't get it but I just can't exactly see how your device allows you to find TDC with out having an existing reference. please elaborate for the thick headed out here.
Larry
It's just a piston stop for use with a degree wheel. You install it, turn the engine one way till it hits the stop, note degree wheel reading, turn the other way till stop, note degree wheel reading, add the two together, divide by two, and at that number of degrees to the number the stop hits at and that tells you top dead center on the degree wheel. Then you turn the engine to that point, reset the degree wheel to zero, and then degree your cam. Takes longer to explain it than it does to do it though.
Thread Starter
Melting Slicks
Joined: Dec 2004
Posts: 2,137
Likes: 5
From: Howard PA
Originally Posted by Blownfuel1
ALLT4,
I'm not ragging on you here, but it seem's like an awful lot of work for a tool you can get from Summit for $7.88 http://store.summitracing.com/partde...5&autoview=sku. You don't wan't to hit the tool very hard with a piston because the damn bolt will bend also, ask me how I know!
I'm not ragging on you here, but it seem's like an awful lot of work for a tool you can get from Summit for $7.88 http://store.summitracing.com/partde...5&autoview=sku. You don't wan't to hit the tool very hard with a piston because the damn bolt will bend also, ask me how I know!
I think I did say this is for finding it with the heads on, also it sounds like a lot of work but took only about 15 minutes. And what do you do when you can't find yours or lent it out? Stop your work, place an order and wait. Heck no, not this Cowboy.
Pro
Joined: Apr 2005
Posts: 590
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From: Boynton Beach, FL
Originally Posted by Blownfuel1
Larry,
It's just a piston stop for use with a degree wheel. You install it, turn the engine one way till it hits the stop, note degree wheel reading, turn the other way till stop, note degree wheel reading, add the two together, divide by two, and at that number of degrees to the number the stop hits at and that tells you top dead center on the degree wheel. Then you turn the engine to that point, reset the degree wheel to zero, and then degree your cam. Takes longer to explain it than it does to do it though.
It's just a piston stop for use with a degree wheel. You install it, turn the engine one way till it hits the stop, note degree wheel reading, turn the other way till stop, note degree wheel reading, add the two together, divide by two, and at that number of degrees to the number the stop hits at and that tells you top dead center on the degree wheel. Then you turn the engine to that point, reset the degree wheel to zero, and then degree your cam. Takes longer to explain it than it does to do it though.
Thanks. Makes perfect sense. Now all I have to do is to figure out how to get a degree wheel to mount on an LT-1 hub with the engine in the car.
Larry
Team Owner
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From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
Very cool indeed! It's always nice to be able to do something and manufature something yourself! Good job! It's also nice to save some money by doing something like this as well!
Thanks,matt
Thanks,matt
Thread Starter
Melting Slicks
Joined: Dec 2004
Posts: 2,137
Likes: 5
From: Howard PA
Originally Posted by Vetracr
Thanks. Makes perfect sense. Now all I have to do is to figure out how to get a degree wheel to mount on an LT-1 hub with the engine in the car.
Larry
Larry
Since the stock balancer is 7" or 7 1/2" it should be easy to line up. And with the magnets, turning it to TDC when you figure out what it should be would be a piece of cake.
A 14" inch degree wheel would be more accurate, but we all know that won't fit with the motor in the car.
Heck when find TDC, you could make a nice line on your balancer and leave the pointer on for future cam checking. You would'nt need to find TDC again.
Dam! Someone should pay me for these ideas.
Last edited by ALLT4; Jul 21, 2006 at 02:28 PM.