Edelbrock Cylinder Head Quality

I have 2 sets of these about 10 years apart in age, both had guide problems, both sets had some tight ones, one set had 4 very tight ones and 2 very loose ones to the point it was smoking. I would have to say that given the born date of these two sets they are notorious for guide problems. My solution, sent them to Hughes and had them port them new guides, valves, resurface them and machine them for roller cam pushrod clearance and they have been awesome ever since. Now this is not something I would have thought I would have to do with a pricey set of new heads but that's what it took to make them work as advertised. Another issue that I found, not major but there is some core shift noticeable on the intake ports, easily rectified when porting but its there.