Head Porting Question on D5AE Heads

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May 11, 2004 | 05:42 PM

278broncos

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Head Porting Question on D5AE Heads

I have almost completed porting the heads for my 400, but have a question about how much I can safely take out of the exhaust ports. I have removed the thermactor bumps, but I am not sure how much I can take off of the guide boss. I can barely fit my finger between the short turn and the guide boss - very tight in there. This is obviously the main restriction in the exhaust port and opening it up would really help the exhaust side flow, but if I go too far and hit a water passage, you guys might see me on the 6 o'clock news for not acting right!

Anybody have a junk D5AE head laying around that they could drill a hole through that boss and see what's in there? Has anybody removed too much material there and would therefore know how much can safely be removed?

Any help would be greatly appreciated.

Thanks, Chris

May 13, 2004 | 09:24 AM

beartracks

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From: Albuquerque

The later 400 heads had a raised floor in the exhaust passage. Not sure if it was to increase velocity or to increase water cooling in that area.

May 13, 2004 | 12:39 PM

Bill_Beyer

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From: PacNW

Based on other porting jobs I've seen virtually all of the exh valve boss can be safely removed. If you take a look at pics of the Hot Rod build you can see they removed the valve boss completely.

May 13, 2004 | 02:19 PM

idfergusson

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From: Regina,Saskatchewan

I am working on a set of D1 heads right now and the area around the guide is much different than the D5 heads.If you check near the bottom of the page on this link there is a cross section of the D5 head which shows the problem area and the thickness http://raceabilene.com/kelly/hotrod/newmotor2.html

May 13, 2004 | 03:09 PM

278broncos

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Great picture on the cross-section. Thanks a million. That is what I have been looking for. I think I will stop with what I have done.

I can't wait to drive this thing! I'm like a little kid with a new toy!