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Aug 19, 2013 | 10:26 PM

wooddyusa

Thread Starter

Senior User

Joined: Dec 2004

Posts: 469

Likes: 0

From: Bancroft, MI

TDC

Hey guys...I'm trying to find top dead center on my 390. I can't see a thing on the crank as far as degrees before TDC. Actually what I can see I can't make out....old eyes I guess.... How else can I know my engine is at TDC? I want to measure stroke to confirm this is a 390 before I buy any headers, intake or carb. Maybe I need to take a wire brush to the crank to see it better. Any ideas? Thanks

Aug 20, 2013 | 11:40 AM

Freightrain

Lead Driver

Joined: Jan 2003

Posts: 9,893

Likes: 12

From: Ohio

If you still have distributor in, pull cap and rotate engine over til the rotor points to the cap where #1 wire is attached. That is TDC of compression stroke. Pull #1 plug and with a light you should see the top of the piston. Using a long screwdriver, touch the top of the piston and rotate crank back and forth slightly. Stop when you feel it come up to the highest point.

Now get a piece of coat hanger and slide down the hole til it touches the piston. Keep the wire as straight as possible. Put a mark on the wire to a known reference spot on the head. Rotate engine 180* and stick coat hanger down til it touches top of piston(remember keep the wire straight down the hole as possible). Put a mark on the wire using the same reference point. Now using a tape, measure the distance between the marks on the coat hanger. It will be close enough to know if it's a 352, 360 or 390 crank.