I was provided both mag and AL (non push-pull)heads, by Henry. The mag heads were (being polite) very difficult, would not hold temp
evenly. The mag case mk 100 was also nearly impossible to race consistently for the same reason. There were some people who did use
them effectively, but if you looked closely at their models, they had excellent air-handling and cooling systems. Most people then did not
understand the fine details of cooling. building a good/excellent model before modern molded bodies was truly an art form.
I still have those early heads and a couple of the gold mk100 cases. although much of the gold treatment has corroded away...mag!
Mag engine parts turned out not to be a really good idea.
Sincerely,
Jed Kusik