CLASS RACER FORUM - View Single Post - 427-425hp w/GM 401 heads

Don Morris · 12-12-2012, 03:09 AM

I come from the land of Mopar where things seem a bit easier. That being said, I have to ask a few questions: How did NHRA wind up allowing the "401" aluminum head as a replacement head for the 427/425 iron head combo when it has a 1.845 exhaust valve? Didn't this combo originally come in only one version and that being a 1.725" valve in an iron head? There is also the question about how did NHRA arrive at the smaller chamber volume with the 401 head?

I would gladly stand corrected if any of my information is wrong. Inquiring minds would like to know.

12-12-2012, 03:09 AM	#3
Don Morris Junior Member Join Date: Dec 2009 Posts: 39 Likes: 5 Liked 69 Times in 9 Posts	Re: 427-425hp w/GM 401 heads I come from the land of Mopar where things seem a bit easier. That being said, I have to ask a few questions: How did NHRA wind up allowing the "401" aluminum head as a replacement head for the 427/425 iron head combo when it has a 1.845 exhaust valve? Didn't this combo originally come in only one version and that being a 1.725" valve in an iron head? There is also the question about how did NHRA arrive at the smaller chamber volume with the 401 head? I would gladly stand corrected if any of my information is wrong. Inquiring minds would like to know.