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!
Spring has sprung. Get out and shoot your Henry
My rainy day project......
- fortyshooter
- Ranch Foreman
- Posts: 6270
- Joined: Sat Dec 09, 2017 10:37 am
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My rainy day project......
- Attachments
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- little if any wear after 10,000 street miles in 1970-late 71 use. days of good oil.jpg (119.09 KiB) Viewed 285 times
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- Checking out an original 1970 426 Street Hemi cam for timing events. 10,000 miles on this cam.jpg (158.68 KiB) Viewed 285 times
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- 284 degrees duration at .006 factory check point and 228 duration at .050 tappet lift which most folks guessed at. .470 lift at valve.jpg (164 KiB) Viewed 285 times
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Re: My rainy day project......
Always wanted to know a machinist. Your stuff is cool.
0 x
Remember, it's not how many guns you have. It's how many bullets you have.
- fortyshooter
- Ranch Foreman
- Posts: 6270
- Joined: Sat Dec 09, 2017 10:37 am
- Location: Va.