Originally Posted by Z'Stein
I just read an older thread ("how to adjust engine timing"), which is very interesting. I have been "some-what modifying" these little engines for years, and after destroying many, I figured out how to make them scream. They even start and idle without stalling constantly. However, I never knew about the "timing adjustment" associated with them. So I have a few questions to all persons knowledgeable of engine timing; what is the stock timing of the OS TZ-18, and should the recommended 2mm cut be made on the opening or closing side of the crank. I have always simply trimmed metal off (knife edged) the closing side of the crank, but left the stock timing alone. Further, what is the best timing for a drag race only (TZ-18) engine, and how do you balance the crankshafts? Thanks
Stock TZ.18 timing is as follows:
Crankshaft open 38 degrees abdc
Crankshaft close 60 degrees atdc
Crankshaft total open 202 degrees
Transfers, and boost are open for 120 degrees. Open 115 atdc.
Exhaust open for 168 degrees. Open at 95 atdc.
I don't want to disclose my exact crank numbers for my modified TZ.18, but you should start by removing .75mm from opening, and closing.
You should also enlarge the bore of the crankshaft, and add a tungsten weight to the crank.
How I balance is something I will keep to myself. Sometimes crankshafts need weight removed from certain areas. Sometimes I need to add tungsten weights to certain areas. A lot of the time, I do both.