My rainy day project......
Posted: Fri May 13, 2022 1:44 pm
I have this factory original 10,000 mile camshaft that came in my brother's 1970 Hemicuda and have always wanted to know what the duration was at
.050 tappet lift like most today's cams are compared at. .050 lift at the lifter was chosen by cam companies because times the rocker arm ratio would give about .100 valve lift where airflow begins at the valve.
So machined up a copy of a Chrysler .904 diameter lifter and a matching retainer block. Set it up in my lathe between centers and attached a degree wheel. Take degree readings off of wheel and the total of opening and closing points times 2 gives you the theoretical duration and timing degrees that you would see at the crankshaft. Actual might vary a bit due to timing chain flex and rocker arm ratio variances on the engine.
Just a cool little project I have wanted to do!
.050 tappet lift like most today's cams are compared at. .050 lift at the lifter was chosen by cam companies because times the rocker arm ratio would give about .100 valve lift where airflow begins at the valve.
So machined up a copy of a Chrysler .904 diameter lifter and a matching retainer block. Set it up in my lathe between centers and attached a degree wheel. Take degree readings off of wheel and the total of opening and closing points times 2 gives you the theoretical duration and timing degrees that you would see at the crankshaft. Actual might vary a bit due to timing chain flex and rocker arm ratio variances on the engine.
Just a cool little project I have wanted to do!
