feadam (5/19/2010)
do these heads have the manifold heat passage in themThe heads are cast as being heat passage capable but unless ordered otherwise, they will be blocked internally. If wanting a working heat passage then when ordering the heads, just let John know that you’d like that passage opened up and made functional.Seems to be a lot of discussion around the heat passages. Heat passages are not necessary except in colder weather and specifically during warmup to prevent carb icing. Most driving situations do not require the heat passage and the lack thereof can actually prevent some percolation and carburetor heat issues that are the result of the heat passage. Many of the new Edelbrock heads come without the heat passage and most air gap styles of intakes also do not have heat passages. All racing heads come without heat passage provisions as the exhaust flow numbers are more easily controlled by not having an additional hole in the exhaust port. For Texas weather, heat passages are typically blocked so not having them in the heads or intakes simply eliminates having to block them off.