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Piston position with flywheel pinned
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=91632		 Page 1 of 1
Author:  TKB4 [ Wed Aug 19, 2020 10:06 am ]
Post subject:  Piston position with flywheel pinned
General question for someone else with experience with head off. When the Flywheel is pinned are the pistons all at mid position and tops all level to each other? I am pretty sure they are supposed to be but just want reassurance.

Thanks
Author:  Mountainman [ Wed Aug 19, 2020 11:07 am ]
Post subject:  Re: Piston position with flywheel pinned
I never pay attention to that, but pretty sure that is 90 degrees ATDC, (after top dead center), which is why you can spin the cams at that position without a valve hitting a piston.
Author:  03black [ Wed Aug 19, 2020 11:37 am ]
Post subject:  Re: Piston position with flywheel pinned
When I recently installed a "new" head on my build, I was cleaning the cylinder bores of dirt/debris and carbon build up at the top of the cylinder walls and noticed all the pistons were at the mid-point position. So I think your good. Just remember that its 90 degrees ATDC on the #1 piston not BTDC....I had to double check mine since the flywheel pin was not installed on my engine when I picked it up.
Author:  WWDiesel [ Wed Aug 19, 2020 12:04 pm ]
Post subject:  Re: Piston position with flywheel pinned
TKB4 wrote:
General question for someone else with experience with head off. When the Flywheel is pinned are the pistons all at mid position and tops all level to each other? I am pretty sure they are supposed to be but just want reassurance.Thanks

That is correct, with the flywheel "pinned" in the proper position, all 4 pistons will be at mid point of their travel.

Another check is to make sure the crankshaft pulley index mark is setting at 3:00 o'clock with the flywheel pinned and looking at the front of the pulley as shown in the drawing & picture below.

Image

Image
Author:  TKB4 [ Wed Aug 19, 2020 12:20 pm ]
Post subject:  Re: Piston position with flywheel pinned
Thanks for reply That was the problem. There was a bunch of dirt dauber mud on the crank pulley mark and I thought there was only one flywheel position that an allen key would go in further than the factory tool which I have but dont use since its such a PITA I knew there where other places the allen could go into but I didn't think it would go in as far. So I saw the pistons at mid height and thought it was correct and the key went in the flywheel completely but in actuality wass exactly 180 degrees out of desired time. When I just cleaned off the crank mark area it was on left side not the right or correct side.

So now back to work with progress!
Author:  geordi [ Wed Aug 19, 2020 5:45 pm ]
Post subject:  Re: Piston position with flywheel pinned
TKB4 wrote:
Thanks for reply That was the problem. There was a bunch of dirt dauber mud on the crank pulley mark and I thought there was only one flywheel position that an allen key would go in further than the factory tool which I have but dont use since its such a PITA I knew there where other places the allen could go into but I didn't think it would go in as far. So I saw the pistons at mid height and thought it was correct and the key went in the flywheel completely but in actuality wass exactly 180 degrees out of desired time. When I just cleaned off the crank mark area it was on left side not the right or correct side.

So now back to work with progress!


Glad you got it sorted. You discovered the biggest complaint I have with the factory process - that the flywheel is full of giant holes! Many false positives from that.
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