dial indicator no spark plug adaptor

[tsutter]

Hello:<br /><br />I have a dial indicator with a magnetic holder base (i.e. no spark plug adaptor). Can this indicator be used to determine TDC for timing a 1969 Merc 350 35hp or do I need a spark plug adaptor?<br /><br />Many thanks in advance.

 

[Ben Konopacky]

Re: dial indicator no spark plug adaptor

You would be better off using some sort of a DEPTH Guage to meas. TDC.. Dial Ind. would need a long (1-1/2")probe to reach the top of the piston,and not enough Steel/iron to hold the mag.

 

[Laddies]

Re: dial indicator no spark plug adaptor

tsutter, I don't know what you are trying to establish TDC for on that engine, but if you don't have any other way, just break a insulator out of a spark plug, screw it half way in the hole, with the engine close to TDC, stick a metal rod or bolt in the insulator hole till it touchs the pistion, mark the rod for depth, remove from the engine, weld the rod to the plug base, then by screwing the stop in till it touches the piston youmay rock the piston back and forth as you back the stop out, you will be able to feel TDC. A long reach plug works the best for the project--Bob

 

[tsutter]

Re: dial indicator no spark plug adaptor

Hey Ben <br /><br />What type of "depth" gauge are you talking about? Somebody mentioned to me using a pencil with an eraser or a screwdriver. Anything else that would work?<br /><br />Bob - you must have replied the same time I did so I'm modifying this post. The seloc manual states for the 350 2-cyl to use a dial indicator to determine TDC. However, I've heard of others using other things (12footer mentions a screwdriver in an old post, etc...) I had the indicator in the tool box - old tool never used it. Oh yeah, I wondered about using a spark plug, but don't have access to a welder (per your idea). What do you do to check timing on this engine? I'm just trying to get as much info as possible. <br /><br />Thanks for the replies

 

[Moody Blue]

Re: dial indicator no spark plug adaptor

I'm confused by the whole TDC issue. Why is it suggested to use a dial indicator/depth gauge to determine TDC ? Can you not stick anything in the hole and turn the flywheel until the "probe" is pushed out to its maximum point ? Is this not TDC ? Why is it so technical ?

 

[robalofish]

Re: dial indicator no spark plug adaptor

Ok - now that you have TDC find .0462in off of that for the alignment of the timing pointer. This applies to some of the larger engines not sure if it applies to yours. I'm sure that the manual writers would want to use the most accurate method of measuring the TDC. This is why the dial indicator is the recommended tool.

 

[tsutter]

Re: dial indicator no spark plug adaptor

Thanks guys.

 

[rodbolt]

Re: dial indicator no spark plug adaptor

tsutter<br /> I use my mag base and indicator all the time. if you need to extend the needle use a piece of heat shrink tubing on it.

 

[Ben Konopacky]

Re: dial indicator no spark plug adaptor

like Robalo said its to locate the timing marks on the flywheel periphery if the timing lable is gone.<br />tsutter: i use a regular dial caliper w/id,od,& depth ,its a great tool for measuring as close as .0005 tol...