what heads?
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Posting Guru
Joined: Jun 2004
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From: Dracut, Massachusetts
what heads?
how do i know what heads i have? i just got a truck and the P.O. said the heads were not stock, but he doesnt know what they are, he didnt do the work, his friend did, who used to own the truck. he thinks they might be assie heads, how can i be sure? im going to rebuild the motor cuz its blowing oil out the breather cap, and i want to know what heads to use, as i have heads that have allready been machined, but they are just stock 77 truck heads. also what is the redline for a 400, im going to use the msd 6al ingnition box and i dont know what chip to use. is a 6000rpm chip ok? it comes with 3k 4k 6k and i think 7k. but dont quote me on that... thanks for the help guys!
Hotshot
Joined: Dec 2003
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From: iowa
Well if your gonna rebuild it, it will be easy if it has aussie heads they will be closed chamber, and the stock ones you have will be open chamber. so when you pull them off you will see a difference in the combustion chamber. If when you get them off they look the same then you know that they are and you can use your stock 77 heads.
As far as the MSD goes it should have a 3, 6, 7, 8k chips. just use the 6k chip. That is too high for the engine to be revved on a normal basis without some work but it shouldn't scatter the engine at that rpm, and the rev limiter is just to save the motor is something happens like while your under load you break a driveshaft (just an example here) and the motor freewinds under full throttle that will stop it from winding to the moon before you can get your foot off the throttle.
As far as the MSD goes it should have a 3, 6, 7, 8k chips. just use the 6k chip. That is too high for the engine to be revved on a normal basis without some work but it shouldn't scatter the engine at that rpm, and the rev limiter is just to save the motor is something happens like while your under load you break a driveshaft (just an example here) and the motor freewinds under full throttle that will stop it from winding to the moon before you can get your foot off the throttle.
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Posting Guru
Joined: Jun 2004
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From: Dracut, Massachusetts
are there any casting numbers on the aussie heads that will identify them? i dont understand what open/closed chamber means. is it shallow? or smaller, or what? thanks for the help so far!!
Junior User
Joined: Sep 2001
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Originally Posted by 77f2504by4
are there any casting numbers on the aussie heads that will identify them? i dont understand what open/closed chamber means. is it shallow? or smaller, or what? thanks for the help so far!!
Actually... check this site out http://www.geocities.com/provamo72/SLGoose_Heads_1.html -- has pics of closed chamber and possibly a way to tell without removing the heads.
Postmaster
Joined: Aug 2001
Posts: 4,270
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From: Delaware
Open chamber heads have circular combustion chambers, almost a dome. Closed chamber heads have more wedge shaped combustion chambers, with part of the chamber being flush with the rest of the head. It is the piston squeezing down on the flush area of the chamber that produces the quench effect.
If you take the heads off and are still not sure, just post a photo here.
If you take the heads off and are still not sure, just post a photo here.
Postmaster
Joined: Aug 2001
Posts: 4,270
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From: Delaware
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Thread Starter
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Posting Guru
Joined: Jun 2004
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From: Dracut, Massachusetts
thanks for the help! i think i understand now. unfortunatly it will be a while before i can find out, as im not ready to pull the motor!
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