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I think you are barking up the wrong tree. The crank keyway does not change. The timing marks move on the tab and balancer. The crank key should be pointing up at the drivers side deck at #1 (and #6) TDC. Only the tab on the timing chain cover and the damper are moved for the motorhome chassis applications. They wil all look like this regardless of the application. Crank key pointing to drivers side block deck
If the timing line on the balancer moves, why then does there not seem to be different harmonic balancers listed for different 400 applications?
Some 400’s were used in cars, trucks and vans. I found only a common part # for all 400 balancer listings. Maybe that old listing info has just fallen a-stray.
I ordered a new Harmonic balancer for my 400. The timing mark on the balancer was in the exact same position as the mark on the original balancer in the van.
Either way I have timed my engine wrong based on where I thought the timing marks should be on an SBC engine. In a van application , that won’t work.
I lined up my timing chain and gears at this position, truly believing #1 was at TDC. I now realize my valve timing chain is out. I have to go back in there and address it. I set all my push rod clearances at this same incorrect timing mark. I will go back in and address all.
I don't think this is true. It's only possible to orient the cam and crank gears in single places (unless you're using an aftermarket crank gear with 3 possible settings). The cam dowel and crank key mean that it doesn't matter where the timing mark on the tab may end up, the dot on each gear has to be aligned with the other.
Maybe I'm unclear on what you're saying or I'm thinking about this wrong...
I don't think this is true. It's only possible to orient the cam and crank gears in single places (unless you're using an aftermarket crank gear with 3 possible settings). The cam dowel and crank key mean that it doesn't matter where the timing mark on the tab may end up, the dot on each gear has to be aligned with the other.
Maybe I'm unclear on what you're saying or I'm thinking about this wrong...
You may be right. I was thinking the timing gears may be out, despite having then lined up pin to pin. I am pretty sure my valves are incorrectly adjusted though.
I had the timing mark on the balancer pointed toward the 2 o'clock marker area when I set them. I am going old-school and will manually find TDC with a pin.
I'll mark it on my balancer and go from there. I'll readjust valves check for any possible bent push rods. If good fire it up again.
Where the Cam manufacturer locates its dowel pin AND where the timing set manufacturer of its Cam sprocket locates its dowel pin hole matters a great deal; where those're indexed matters most.
Where the Cam manufacturer locates its dowel pin AND where the timing set manufacturer of its Cam sprocket locates its dowel pin hole matters a great deal; where those're indexed matters most.
Exactly, but those are predetermined and not something that's adjustable in a standard timing chain installation.
You may be on to something.
But do NOT rely on the balancer to tell you where TRUE TDC is.
Do that with a piston stop.
Then make sure the timing chain is correct then.
Then figure out the balancer and timing tab location.
They can be anywhere, as long as they line up, at TRUE TDC.
Honestly we put that on the bottom on one race car, it was the best spot.
Maybe you are on to something.
