[heater63]

So I am stumped, over the winter I built a 77 TA 400. Not much of a build,

-6X heads
-30 over
-Crank 10/10
-Cast Pistons
-Street strip comp cam (should be able to find card but don't think it would matter)
-HEI distributor
-Comp push rods......

Started up fine broke in fine runs good. Finally have some time to drive it so I put a timing light on the engine. I couldn't get it to idle with any less than 25* advance. I verified it with another timing light.

I switch distributors and same issue.

I took off the timing chain cover and marks on gears are at 12 and 6, no excessive slack in chain and slack is on the passenger side of the motor..

I did use a chain cover off a 69 400.

i used a bump stop to find TDC and with that at 0 on the cover it still ran at 25* advance.

I took it out and it performs well, not hot, and no rattle under load which makes me think it isn't really running at 25* initial.

Is it possible the timing marks are positioned differently on the older chain cover?

Thanks in advance for any ideas
Heath