Timing belt replacement/ Timing marks

[LowlifeB7]

Recently, my timing ripped at low speed and I’m in the process of replacing the components. I have the crank at TDC but I’m not sure how to safely move the exhaust cam into proper timing.

Do I have to remove the cam and place it correctly?

I used a bore scope and noticed minimal valve marks on the pistons so I want to see if it will run without a compression test.

I appreciate your time.

[Spike00513]

I mean, remove cam is more work and bolts to replace, but also not a lot if there's time

I'd hope there's a workaround
like get the crank to where pistons are in the middle leaving room overhead for valve opening and closing
set the cams where you want them, lock or hold them in position so valves are closed to prevent interference
I'd assume "TDC" for cams lined up to timing marks if present, or checking in other ways to verify valves are closed
including but not limited to $25 borescope + phone app

then rotating the crank where it needs to be, prior to putting the belt on

[Brillo]

Recently, my timing ripped at low speed and I’m in the process of replacing the components. I have the crank at TDC but I’m not sure how to safely move the exhaust cam into proper timing.

Do I have to remove the cam and place it correctly?

I used a bore scope and noticed minimal valve marks on the pistons so I want to see if it will run without a compression test.

I appreciate your time.

I suspect that you will have bent valves. Regardless, remove the valve cover. Visually note the position of the each cam lobe (exhaust and intake) on all the valves to see if any are becoming fully depressed or close to fully depressed. Using the exhaust cam belt pulley move the cams to relieve the full or almost full depressed condition in a direction to lessen the deflection without further deflection of the valve. Now move the crankshaft away from TDC about 20 degrees (no more) in the direction the engine runs. In this position you can now move the cams with impunity without fear of the valves contacting the pistons. In this position pistons in cylinders #1 and #4 will be just out of TDC. Normally, (with cams properly timed to the crank) one cylinder (#1 or #4) will have both valves completely closed (ignition/combustion stroke) and the other will be opening the intake valves (intake stroke) but not enough to hit the piston. (Pistons in #2 and #4 will be close to bottom dead center so no worries there.) Now move the cams to the TDC position, the two cut-outs facing each other - use the cam lock tool if you have access to one. Now move the crank slowly back to TDC using the crank pulley timing marks. Your cams are now in time with the crankshaft. Put the new timing belt on, pull the plugs, and check your compression. If you don't have compression even on one cylinder you're stuck removing the head and replacing those valves. Good luck.