Leak-down Test
Thread Starter
Instructor
Joined: May 2006
Posts: 135
Likes: 0
From: Hot Springs Village AR
Leak-down Test
Doing a leak-down test on my 71 350. With the crank timing alignment mark @ 0 degrees, number 1 & 6 cylinders would be @TDC. If I rotate the crank 90 degrees does this put #8 & 5 @TDC? Then another 90 degrees #4 & 7 etc?
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
i can never do it that way becasue i cant remember it.... my easy way to do this is to mark the distributor base at the bottom of each spark plug tower and then take the cap off and turn the motor so the rotor is pointing to the next mark and follow the firing order around the engine...
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
You need to do each cylinder in the firing order and rotate the crank 90 dgr each time.
Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
If you have a manual trans car, and no timing tape on the harmonic balancer, you can raise the rear wheels, and with the car in top gear, use the orientation of the u joints on the driveshaft to determine when you have moved the crank 90 degrees. If the plugs are out, it won't be too difficult to turn the engine by turning the rear wheels.
I know, it's a Bubba way, but it works in a pinch.
Laugh and enjoy a beer afterwards. Unless you found out by your leakdown that the engine needs work. Then you can cry.
I know, it's a Bubba way, but it works in a pinch.
Laugh and enjoy a beer afterwards. Unless you found out by your leakdown that the engine needs work. Then you can cry.
