Author Topic: which heads are better  (Read 2568 times)

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Offline kc79ta

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Re: which heads are better
« Reply #15 on: April 14, 2011, 09:40:08 AM »
Sounds like alot of us think a like.  :)

Mongo...did you put in dished pistons or keep the flat tops? I thought the 6x-4 would put the comp. over the 9.5 mark for pump gas. I know in some parts 91 octane is the highest you can get. Just looking for more info. ,so I know where to look for more power if I feel I need it.  Sounds like stepping down hard on your gas pedal will be like hitting the afterburners in a F18....COOL 8)

Ya, I would start looking for another set of heads. Hopfully Mr. P will chime in and tell you the best way to go. You can find 6x heads all day long.
Keith

Offline Mr. P-Body

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Re: which heads are better
« Reply #16 on: April 14, 2011, 02:28:12 PM »

   6X, when properly done, is an excellent head.  the -4s are better left for 400s or 428s. The -8s have the correct chamber volume for the 455.

   For good power, the exhaust valve needs to be upgraded to 1.77". Jim hand's book has a good chapter on porting, and it's "aimed" at the 6X.

   4X is also very good, though it isn't "popular'. But really, once performance modifications are begun, all d-ports are pretty much the "same" except chamber volume and exhaust flanges. If all 6 boilt holes are "there", the head is "usable".

Jim

Offline y88rick

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Re: which heads are better
« Reply #17 on: April 14, 2011, 06:38:47 PM »
so 6x8's would be my best bet to grab?
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Offline Mongo

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Re: which heads are better
« Reply #18 on: April 14, 2011, 11:52:17 PM »
Pistons are flat tops. I need to double check the heads now. I thought they were 6X4's. Maybe they are 8's. gotta go look again.
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