78 Spitfire CDI?

[bjt8008]

Hello. I have just rebuilt the engine in my 78 spitfire. I have set the timming with a timming light and the mark is dead on at 6000RPMS. The thing has no bottom or mid range power and i noticed when checking timming with the light the timming mark really varies with what rpm the engine is running ( like 10-18 degrees) Is this normal or is the cdi box going to heck. Funny thing is this is the reason i rebuit the engine i thought it was crank seals. Second question is where to buy a CDI box? Thanks in advance.

[Anjinc2]

change cdi had same prob fixed it right up