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Author Topic: Heads  (Read 8032 times)

Offline mikewb

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Heads
« on: March 03, 2008, 12:50:07 am »
anybody know what head this is? i found this number 8986889X or 3986339X
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Offline joesgarage71

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Re: Heads
« Reply #1 on: March 03, 2008, 07:11:37 am »
339X is a 1971 307/350 74 CC head
 couldn't find the 889X you must have read it wrong 3's 9's 8's look alike and sometime the casting gets sloppy. If they are near the same date there most likely from the same motor.
 Steve
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78' K-20 355/SM465/twin stick 205 6" on 36's
14 bolt FF/big bearing Dana 44 4.56 gears
92' GMC C-1500 454/4L80E/14 bolt

Offline mikewb

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Re: Heads
« Reply #2 on: March 03, 2008, 03:11:38 pm »
was trying to figure out what valves
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Offline red4wd

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Re: Heads
« Reply #3 on: March 03, 2008, 03:48:14 pm »
I saw them listed as 1.72 and 1.50
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Offline mikewb

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Re: Heads
« Reply #4 on: March 03, 2008, 04:53:37 pm »
is that a bad head to have?
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Offline Captkaos

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Re: Heads
« Reply #5 on: March 03, 2008, 05:42:23 pm »
What are using it for?
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Offline mikewb

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Re: Heads
« Reply #6 on: March 03, 2008, 06:27:17 pm »
there on my motor right now. 350
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Offline Captkaos

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Re: Heads
« Reply #7 on: March 04, 2008, 11:04:42 am »
I meant when you say are they bad in what reference are you asking?  If you are asking if they are a good performance head then the answer is no.  If you are asking if they are a good head in general, they would be a good low rpm head.
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Offline mikewb

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Re: Heads
« Reply #8 on: March 04, 2008, 02:29:39 pm »
i meant for performance
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Offline mikewb

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Re: Heads
« Reply #9 on: March 05, 2008, 07:20:32 pm »
should the numbers on both heads match or are they different?
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Offline Captkaos

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Re: Heads
« Reply #10 on: March 05, 2008, 10:15:23 pm »
The should[/b] be the same on both sides.
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Offline mikewb

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Re: Heads
« Reply #11 on: March 05, 2008, 10:18:35 pm »
I have these . left 3946813 right 3986339X
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Offline joesgarage71

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Re: Heads
« Reply #12 on: March 08, 2008, 11:02:04 am »
3946813= 69-79 350 truck. And you know the other one. The casting numbers should match but I have seen untouched motors that had different heads on them from the factory.
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78' K-20 355/SM465/twin stick 205 6" on 36's
14 bolt FF/big bearing Dana 44 4.56 gears
92' GMC C-1500 454/4L80E/14 bolt
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