Spark but no Bang 💥

[RSTMatt]

Hi guys,

Been making some long over due progress on my 80 something 400.
I bought it years ago, was about 9 boxes of parts and a frame.
I’ve had the cylinder off and honed it, & new rings.
Cylinder head has been lapped and re-seated
All back together now, got spark from new coils but no bang, not even a cough or splutter when spraying in easy start
I can only imagine the timing is off
I’ve set the gap in the points, done the valve clearances but can’t get the timing to line up with the left and Right fire marks, it’s close-ish but I guess it needs to be bang on(?)
(Compression tested by a mechanic - 105left 125right)
Any ideas? It could well be something really obvious
I can get the left cylinder firing at the right time but if left is bang on then even with the right hand points to max adjustment it still fires too early.

 

[RSTMatt]

I think I might have the cam at 180 degrees out, hence no bang because the exhaust valve are opening when the spark is going leaving no compression
That said, I have the cams pointing down, nipple at 12oclock, engine at LT and it’s still running on the exhaust stroke - how??
Please help

 

[CaptChrome]

I think I might have the cam at 180 degrees out

Please help

Go back to square one and reset the cam chain and cam timing per the manual. Then before just throwing everything else together, manually rotate the engine over and verify the piston position and valve operations for each cylinder and make sure that they match what is supposed to happen on intake/compression/power/exhaust portions of the engine cycle and that the cam drive looks like the manual pictures when the timing mark on the flywheel is pointing to LT.

The picture of your points looks about right, so you need to re-time your cam.