dibbons
Well-Known Member
I ordered a TDC tool on Amazon and hope the spark plug angle on a Mopar small block is not too extreme that the tool is not accurate. Thank you.
Will Spring-Loaded TDC Locator Tool Work on a Mopar Small Block?
- Thread starter dibbons
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Never seen THAT before. I've always used the solid type. They work well.
Sure highest up will do it!
More accurate would be a picton stop style with a degree wheel.
Alan J Odze
AJ
In over 50 years I never seen or used any tool inside a cylinder to find TDC.
Take out the number 1 plug and spin the engine and look at the timing mark to 0.
No need to insert anything into the cylinder.
Take out the number 1 plug and spin the engine and look at the timing mark to 0.
No need to insert anything into the cylinder.
dibbons
Well-Known Member
Not really an option when the timing mark on the balancer is in the wrong place.
So you've never degreed a cam then.
Demonstrator
Active Member
Correct. Only in a perfect world.
A piston stop accurately finds Top Dead Center. Turn it against the stop in one direction. write that number down, Turn it back in the other direction against the stop. Half way between those two points is an accurate Top Dead Center.
No guessing and can be done heads on or off. Once you find it using this method you can set your degree wheel to zero to degree the cam or check your timing mark on your Damper.
No guessing and can be done heads on or off. Once you find it using this method you can set your degree wheel to zero to degree the cam or check your timing mark on your Damper.
The short answer is yes, it works. It's up to you to decide when the plunger isn't moving at TDC, so I'd say it's accurate to within one or two degrees.
(Pro tip: if you put a small balloon over the end of the tool, you'll know when you're on the compression stroke.)
(Pro tip: if you put a small balloon over the end of the tool, you'll know when you're on the compression stroke.)
Ive used the exact same one. Works perfectly and has graduations on the one end.
When turning the crank and the piston reaches the top. You can turn it several degrees before it starts going down. So how would you know where the center of that is without using the piston stop method? You would be guessing.
I guess adjust it so the spring goes solid when the piston comes up against it?
Alan J Odze
AJ
I have worked on NYC cabs and police vehicles during the 1970’s and 1980’s. Most were MOPARS 440 400 360318’s and some 225’s. At every 100k timing chains were replaced. When the chains snapped or the plastic cam gears fell apart we had to replace push rods send the heads out and sometimes the cam and lifters replaced. I worked on thousands of these MOPARS and always used the timing marks and lined harmonic balancer. No never used these tools. I never had an issue with this procedure. 54 years later still working on MOPARS. I never saw these tools to find TDC.
I wasn't throwing off on you. I was just asking a question. Sounds like you had a cool career. I worked as a line mechanic mostly in dealerships from the very early 80s up until I was hurt on a job several years ago. I saw computers, EFI and front wheel drive come into vogue. You worked more in the era I wish I had.
Most stock engines do great without a degree wheel on the cam, but performance stuff is better optimized using a cam degree kit. Piston stop, dial indicator.....I use two with a degree wheel, of course. It allows you to install the camshaft in a much more precise place than just "dot to dot".
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Alan J Odze
AJ
I just went to Ford around the early 80’s in a busy dealer early 80’s. I too saw the electronic ignition come out in 72 I think Ford went over to Electronic Ignition 1974 GM 73. Before points condenser rotor
. I saw the first FWD with Ford in the Fiesta than Escort. Geez I pulled out trannies on FWD cars without engine supports I didn’t even know about it. Nobody said we needed them haha how times had changed. This was way before OBD1. Where we had to really figure things out or use that huge Sun diagnose machine..nobody knew how to use. So yeah stock engines is my experience. I still used the TDC and 0 on the harmonic balance lol.
I didn’t take any offense I was just relaying my experience.
Times sure have changed from working on 60’s 70’s and early 80’s
. I guess OBD1 and 2 sure helped.Hope you are ok with your injuries. I got out in 82 became a cop. I lost my patience with these new cars and the technology was just exploding back in the 80’s through today. It was fun working on these 60’s through 70’s cars. I still have a 66 Coronet 383/4 and a 73 340 H 4 speed.
Nice talking to you.
I'm as good as I'll get. Thanks. I cannot agree that either of the OBD systems made things "better". All we kept hearing was everything would be "standardized". That was the biggest crock ever, because they all have their own versions. I think marrying the computer to automobiles was the worst decision ever.I just went to Ford around the early 80’s in a busy dealer early 80’s. I too saw the electronic ignition come out in 72 I think Ford went over to Electronic Ignition 1974 GM 73. Before points condenser rotor
So yeah stock engines is my experience. I still used the TDC and 0 on the harmonic balance lol.
I didn’t take any offense I was just relaying my experience.
Times sure have changed from working on 60’s 70’s and early 80’s
Hope you are ok with your injuries. I got out in 82 became a cop. I lost my patience with these new cars and the technology was just exploding back in the 80’s through today. It was fun working on these 60’s through 70’s cars. I still have a 66 Coronet 383/4 and a 73 340 H 4 speed.
Nice talking to you.
dibbons
Well-Known Member
My definition of "high tech" is an apparatus that functions WITHOUT a computer chip.
I can do it faster with a dial indicator and I don’t turn the engine backwards.
I only use a positive stop when the head is on.
Yes you can find the top of piston travel when the piston comes to the top using the center of the piston for degreeing the Cam. But not Top DEAD CENTER. Unless you already know the roll over of the crank. Piston at the top rotating counter clock wise is not Top Dead center. Top dead center is the midway point between when it reaches the top and when it starts going down. That is roll over, and the only way to get back to TDC is turn it backwards.
Is TDC needed to degree a cam ? No, but that is the accurate top dead center. Sometimes there could be 4 degrees of roll over . I do not use a piston stop method to degree a cam. But use a dial indicator on the center of the piston, So piston rock doesn't come into play.
So yes you can find the top of the stroke with a dial indicator faster . But don't say you found top dead center without turning it backwards.
Is TDC needed to degree a cam ? No, but that is the accurate top dead center. Sometimes there could be 4 degrees of roll over . I do not use a piston stop method to degree a cam. But use a dial indicator on the center of the piston, So piston rock doesn't come into play.
So yes you can find the top of the stroke with a dial indicator faster . But don't say you found top dead center without turning it backwards.
lol. I know exact TDC without a stop. And I don’t need to turn the crank backwards.
I degree a cam and NEVER turn the crank backwards.
You already are reading the degree wheel and dial indicators (I use two), so to me having to read graduations on a piston stop to make sure you're in the right place is an extra, unneeded step and might even lead to more mistakes.
I think what he is doing is measuring before tdc at a point before the crank gets to the piston dwell area. Mark the balancer or degree wheel at that point noting the dial indicator reading. Then continue to rotate in the direction of rotation through piston dwell past tdc and back down to the previous dial indicator reading. Mark the balancer or degree wheel again. Measure half way between your marks and that will be tdc. Another way to skin a cat.
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