Creosote removal in screw holes?

[whoppr]

I have a VC encore 2550 and had the manifold off at the end of last year. I am trying to re-install it and there is buildup and creosote in the screw holes I need to use.

I figured PB Blaster might be good to spray on but any other ideas?

Thanks

 

[DAKSY]

The best way to clean ANY internal thread is with the proper sized tap.
Most of the VC fasteners were 1/4-20UN threads. Grab a 1/4-20 tap, hold
it alongside your fastener & compare the threads...