Dial test indicator

[tim wood]

I need to get one of these ( I think) so as to accurately set TDC before I fit my ( superbly overhauled by CMES) cylinder head.
I’ve seen plenty on Amazon, eBay etc at about £20 including the gauge and magnetic mount which seems cheap . I guess I won’t use it often and don’t mind spending the cash but does anyone have experience of these low cost ones?

Thanks
Tim

[Mark Gordon]

I bought this one to adjust my woodworking tools. It's probably not accurate enough for high precision demands, but for adjusting a table saw, jointer, etc. it's more than adequate. Certainly accurate enough to find TDC on an auto engine.

[rfs1957]

viewtopic.php?f=3&t=5856&hilit=tdc

Waste of money if you're just looking for TDC,
this way is free, and it's highly accurate.

Either tape measure as shown, or degree disc.

[Fuel.inj]

From experience I’d look at a second hand one of either Mitutoyo, Starrett, M&W or Baty manufacture for smooth operation and precision. Plenty on flea bay etc.

[mgcjag]

Hi Tim..the cheap ones are OK as an indicator for your tdc as you dont have the head on and can measure straight on the piston tops..also suitable for front/rear wheel bearing.....were not talking high precision here...Steve

[Gfhug]

Follow Rory’s advice, even if it means waiting till you’ve got the head on. And if you do buy the dial gauge, try checking at the 90 degree position to cross check how accurately you’ve measured at actual TDC.

Geoff

[rfs1957]

Indeed, same approach with no head on, bolt a strap across the block, with a spacer of some sort, then approach it from both directions and divide by 2.

[tim wood]

Thanks guys, opposing views ……..

[abowie]

I have a number of dial gauges from different manufacturers.

The el cheapo units are surprisingly accurate and should be fine for what you want to do. The digital ones seem a little more robust and are easier to read.

I also have a couple of Mitutoyo gauges I use when it matters.

While the concept of buying used is attractive, you don't know what's been done to the gauge and dropping them, in particular, can damage them.

[mgcjag]

Hi Tim... just to add.....a lot of what's available are metric...so beware that you need to calculate to thou inch if measuring wheel bearings etc...Steve

[Fuel.inj]

I agree with you buying second hand, it’s a chance you take. Just buy carefully. Genuine good sellers, are they still in original box etc.

[tim wood]

As an update on this.
I bought a used dial gauge and stand from flea bay. And set it up on the front cylinder ( I know it’s number 6) but it makes no difference.
By gently turning the crank I found TDC fairly easily. Checked it a few times and feel reasonably confident I’m there. Pistons 1 & 6 are a few thou below block surface which I think is correct.
Next step of course was to take a look at the crank pointer, this is maybe a few degrees out. Not much but worth adjusting.

Good point from Steve about making sure the gauge was imperial measures, most of the new ones are metric. This will make the gauge more usable for run out on discs etc.

( by the way I kept my promise to keep out of the garage over Christmas- well apart from the odd moment or 2 checking all was ok !)

Tim

[mgcjag]

Hi Tim..you do realise that when checking tdc on the piston tops that as you turn the crank the piston rises up gets to the top and than stops.. as you continue turning the crank then starts to go down....at the crank pointer tdc is the mid position between when the piston stops and when it starts to move again.....watch the dial guage it's easy to see....Steve

[tim wood]

Thanks Steve,
I think I took note of this but you’ve made me think again, I’ll check tomorrow

Tim

[Gfhug]

Tim, as encouraged before, go for the mid point, 90 degree position and halve that as suggested above, please.
It will really help get you to the real TDC.

Geoff

[chrisfell]

" does anyone have experience of these low cost ones?"

The best low cost ones are second hand tools. There are several specialists who deal in second hand precision tools. Why buy a new piece of oriental junk when for the same price you can have a tool that has been used by a time served engineer from his apprentice days to his retirement? I learned this lesson first with micrometers. I won't repeat the error.

[tim wood]

For Chris, yes , agree good quality secondhand is better. The used one I bought came in a nice little wooden case. A while ago I bought a few taps and dies which I was pleased to see were of “ good British quality “

Anyway back to the TDC issue. I’ve been through it again using the dial gauge and am fairly confident it’s all good now. As a second check I used a depth gauge to measure the very small depth between piston edge to block. Both pistons sit at 98 thou. Thanks to all for the comments on using the alternative method- sorry to ignore your advice - hopefully I won’t regret it !

Fitting the head is delayed since I’ve condemned 2 head studs due to dodgy threads. I had checked these previously but when inserting into the block ( using the double nut method) its was clear that the treads were damaged.
I ran a die nut over them but still had tight spots so I’ve binned them.