DTI adapter / lathe project for someone?

[andyg0141]

Hi All,

I’m looking to get an adapter made to allow me to set the timing on the wee ones Comer kart engine which will essentially house a DTI (already got a decent one so trying to use it) in the cylinder head with a rod going down to determine where TDC is and go back 4mm ish from there. Does anyone know of an adapter that exists or fancy making one (aluminium would be fine) for some beer tokens? Awful drawing below with some comments:

• Main adapter
  • 20mm diameter (approx.) x 60mm long inc shoulder (+-1mm) – could be steel / alu / round / hex as long as approx. dia ok
  • Bottom section 10mm long (+-1mm) and threaded M14 x 1.25 (same as spark plug)
  • 6mm hole through entire 60mm length
  • 6mm hole enlarged to 8mm at top for 15mm depth (approx.) for DTI to sit in
  • 5mm hole through one “wall” of tube at bottom to allow engine to vent when turning
  • M5 thread tapped at top hole to allow grub screw to be used to hold DTI in place (top 5mm hole)
• DTI adapter / pin
  • 5mm alu / steel rod
  • 56mm overall (51mm main body) ideally with the end rounded for where it will contact the piston but flat would be fine if too complicated
  • End reduced in size for length of 5mm and M2.5 thread cut to screw in to DTI

Cheers,

Andy

 

[Pete.]

I screwed a red straw from a wd40 can in place of the tip and poked that down the plug hole when I timed the cams on my turbo engine.

 

[graffian]

I use a qtip with pencil marks- or a screwdriver with marks- to find the relevant piston position on my VB.
I got posh and made a screw in adapter. I could use a dial gauge with it, but I put marks every 50 thou on the moving bit and use the marks.
It works but no better than the qtip.





I have an adapter/gauge similar to what your after. It was made to time diesel pumps.

 

[Agroshield]

End reduced in size for length of 5mm and M2.5 thread cut to screw in to DTI

Given that you need to remove the OEM tip from the DTI to screw this into the DTI, why not put a female M2.5 in the other end and reattach the tip to contact the piston?

If you broke off the ceramic part of an old sparkplug (not _the_ old sparkplug of this forum) and drilled out the rest with a masonry drill, what would you be left with? It might be easier to 3D print something to mate that part with the DTI.

 

[Rrobson]

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Something like that will do you. Otherwise get a dti with a longer stroke, I’ve got one with a 4 or 5” travel.

I wouldn’t wast my time with the initial adaptor, just get a piece of scrap steel, affix it to the engine (bolt clamp etc) and stick the magnetic base of the dti to it assuming youve got one. Just need something to hold it steady nothing fancy

 

[500e]

Remember TDC on piston is not tdc on crank due to radial movement to get a true tdc you have to take a known measurement both sides of tdc with an degree wheel on crank and do a little sum then mark it, have seen marks up to 5deg out

 

[RichardM]

I used a stop fitted to the spark plug hole, stopped the piston BTDC and rotated both ways to set the degree wheel on the crank to set both cam timing and ignition timing.

 

[zeppelin builder]

made one out a old plug and a hilti fitting hacksaw round the swaged bit snap the fixed electrode off put plug in vice and welly tip with bfh "goggles a must " weld /braze / epoxy anything in and drill to suit your clock gage ! i put a bit of plastic airline pipe on the rod touching the piston , set up electronic ign on a yds7 with it best make it so you thread the adaptor into the head then push the gauge in , as you might not have room , you could also make an adjustable stop and set it for future
holes in the piston

 

[andyg0141]

Thanks all - plenty good ideas there so sure I will be able to cobble something up! Great shout on the 3D printer...it's not been used since the visor making of covid so would put it to good use