|04-11-2014, 06:33 PM||#1 (permalink)|
Join Date: Sep 2005
Rep Power: 24
iTrader Score: 9 reviews
Piston Stop tool (adjustable)
I've been working on a plateless H23A, which doesn't allow for the original timing method. One of the bolts also gets in the way of the timing window. Yeah, a timing "window" to line up marks on the flywheel - weird. This allows you to put timing marks on your crank pulley precisely, or check existing marks.
old NGK spark plug for your engine type (preferably copper)
3/8-16 threaded rod or bolt (aluminum can be found on ebay or decent hardware stores)
metal file (bench grinder helps)
I used an old NGK spark plug and 3/8" aluminum threaded rod so it won't dent the piston. You have to break the porcelain on both sides - be careful, broken porcelain is sharp enough to shatter glass windows just by pressing hard! Put it in a vice & cut/twist off the ground strap, hammer an awl into the gap, then finagle the electrode out. Turn it around & wack the top off with a hammer. Grind the metal around the porcelain so it can be pounded out with a thick pin punch.
Tap the hole to 3/8-16 threads & insert 3/8 threaded rod or a bolt - make sure you round the end that touches the piston. I had some aluminum rod left over from "pinning" my D16Z6 cylinders (an ancient, archaic practice!), it's nice since it reduces the chance of damaging your piston. I use a jamb nut on top to keep it from wiggling. It's also sized so a 5/8" spark plug socket holds it perfectly. I notched the top of the rod to make initial height setting easy:
Decide on where your timing pointer will be, then bolt on & bend a welding rod to nearly touch the pulley rim in that spot. Set the motor near TDC, screw in the TDC tool w/o jamb nut, and use a flatblade to advance the rod til it touches the piston. Remove the tool, tighten the jamb nut, turn the motor back a bit, reinstall the tool. Turn the motor in reverse SLOWLY til the piston locks, mark the pulley at the welding rod, then turn forward nearly a full revolution til it locks again (SLOW DOWN at 3/4 rotation), mark pulley again. Take pulley off, notch TDC (0 degrees) which is exactly in the middle of your 2 marks. If you're lazy, you can use an adjustable timing light to flash the TDC mark at 16 degrees. Otherwise do some math (diameter * 3.1416 / 360 * 16) to get the 16 degree mark, notch. Do the same math to get the 14 and 18 degree marks & fill the notch(es) with paint:
The rib for TDC is behind the 0 degree mark in this picture - it's easier to see with white paint added while using a timing light:
If you have a welder then you can just weld some steel rod to the end of the plug, but you'll probably end up marring your piston. You also can't get as precise, and it may even come out too short.
|04-12-2014, 09:41 AM||#2 (permalink)|
Join Date: Oct 2007
Location: Mission Raceway
Rep Power: 59
iTrader Score: 6 reviews
Once again, awesome write up man!
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