Edelbrock 340 heads with factory HP exhaust manifolds

[340challconvert]

A66 and 34O Challenger owners- Using Edelbrock 340 heads with factory HP exhaust manifolds
Writing to help others who may have an issue with factory exhaust manifolds and using Edelbrock aluminum heads;
Installed an NOS exhaust heat shield on the driver's side head studs, then installed the factory hp 1970 exhaust manifold. Finally started the newly rebuilt 340 and had a bad exhaust leak! Manifold is intact, in good condition with mating clean surface. Using new eddie aluminum heads specific for the hp340.
It  looked like the exhaust manifold wasn't squeezing the bottom side of the gasket for some reason.
Thank you to MK for his thoughts. Based on his suggestion, I took a look at the bottom of the exhaust manifold to look for problems with the bottom of the factory 340 gasket. After some further research (abodies) had a lot of information on small blocks with this issue; Edelbrock heads designed for the 340 have a larger flange on the bottom right side that does not allow the easy use of the factory hp left side manifold. It protrudes far out enough to interfere with the seating of the exhaust manifold. In fact edelbrock recommends the use of headers with their 60179 340 designed heads. (Now I find out)
I should have done additional research when I purchased the heads. There is a solution though; to use  a header flange and gasket on the one side with some very prudent filing of either the head flange or the exhaust manifold. Have to be careful if filing the new head due to the closeness of the water passageway in this part of the head.
(One last gripe; why would edelbrock design a head specific for the 340 and not allow the use of the factory manifold on one side?)

[mk]

Glad you figured it out !

[MoparLeo]

I think that Edelbock assumes that their typical aluminum cylinder head customer is looking for a bump in performance and no factory exhaust manifold will help when choking an aftermarket heads flow.
They are quieter but will not fool anyone that your engine is stock.