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Rebuilding the top end

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Old Apr 18, 2009 | 12:18 PM
  #1  
83Firebird420's Avatar
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From: Vancouver, B.C.
Car: 87 GTA 120,000k, 90 CRX Si
Engine: 5.7 TPI, 1.6L 16 valve SOHC
Transmission: 700r4, 5spd std
Axle/Gears: 3.73
Rebuilding the top end

so i am about to start a tear down, on my L98, of the top end all the way down to the headgaskets.

ill be sending the heads out to replace the valve seals. and machine it.

is there anything anyone would recomend me doing for the stock internals? such as springs or new rockers? i wont be doing the cam anytime soon so i dunno if doing that work would be worth it.

ive got some hooker 2055-1 and new fuel injectors going in.
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Old Apr 19, 2009 | 08:37 AM
  #2  
Viprklr's Avatar
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From: N. Illinois
Car: 92 GTA/ 00 TA
Engine: 383/350
Transmission: 700R4/T-56
Re: Rebuilding the top end

Aside from cleaning out the intake system you could replace the rockers with 1.6 to give you a little more oompf.
Porting of the intake if you so desire.
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Old Apr 20, 2009 | 01:03 AM
  #3  
83Firebird420's Avatar
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From: Vancouver, B.C.
Car: 87 GTA 120,000k, 90 CRX Si
Engine: 5.7 TPI, 1.6L 16 valve SOHC
Transmission: 700r4, 5spd std
Axle/Gears: 3.73
Re: Rebuilding the top end

ok cool thanks.

also i was under the impression that L98 heads were aluminum....i think mine are cast iron. very heavy and magnets stick to them.
is there any way i can identify them?
the marking on the engine block says:GM5.7 LG or L6

also the old headgaskets i pulled out were metal.

the vin on the hood matches all other vins on the car, the hood engine decal indicates its a 5.7 and the rpo sheet indicates its a L98. so mabey they arnt suposed to be aluminum heads?

Last edited by 83Firebird420; Apr 20, 2009 at 01:07 AM.
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Old Apr 20, 2009 | 01:11 AM
  #4  
88iroc52387's Avatar
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Re: Rebuilding the top end

corvettes had the aluminium head.... check the numbers 083 is iron head. unless they've been replaced they are iron.
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Old Apr 20, 2009 | 01:16 AM
  #5  
83Firebird420's Avatar
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From: Vancouver, B.C.
Car: 87 GTA 120,000k, 90 CRX Si
Engine: 5.7 TPI, 1.6L 16 valve SOHC
Transmission: 700r4, 5spd std
Axle/Gears: 3.73
Re: Rebuilding the top end

yea they have like a 7 digit number ending in 083.

is it worth buying new aluminum heads on a moter that will remain near stock? or are these heads worht keeping? i dont plan on doing much else to the motor ie cam/crank/pisons
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Old Apr 20, 2009 | 03:16 AM
  #6  
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Car: 87 GTA
Engine: 350
Transmission: Auto
Axle/Gears: 3.27
Re: Rebuilding the top end

Originally Posted by 83Firebird420
yea they have like a 7 digit number ending in 083.

is it worth buying new aluminum heads on a moter that will remain near stock? or are these heads worht keeping? i dont plan on doing much else to the motor ie cam/crank/pisons
Id like to know myself
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Old Apr 20, 2009 | 10:09 AM
  #7  
83Firebird420's Avatar
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From: Vancouver, B.C.
Car: 87 GTA 120,000k, 90 CRX Si
Engine: 5.7 TPI, 1.6L 16 valve SOHC
Transmission: 700r4, 5spd std
Axle/Gears: 3.73
Re: Rebuilding the top end

well after doing some research, decent heads arnt cheap so i think ill just stick with some 1.6 rockers.

oh yeah, anyone know if these motors came with metal head gaskets ffrom the factory? or has someone already been in my motor?
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Old Apr 20, 2009 | 10:26 AM
  #8  
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From: NJ/PA
Car: Yes
Engine: Many
Transmission: Quite a few
Re: Rebuilding the top end

yep, metal shim gaskets are factory. Iron heads are factory L98 for F-body. With just a standard rebuild like you are doing, either 1.6 rockers, or new cam will be a nice upgrade, and above all, if you can afford it or have the time, porting the heads, intake, plenum will also add some power. I would say the 1.6 rockers will have only a slight increase, compared to better flowing heads. Try and replace the head gaskets with the thinnest composite ones you can find. I never had any luck with replacing the metal shim gaskets unless both the block and heads are trued up (tend to leak a tiny bit of coolant)
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Old Apr 20, 2009 | 10:35 AM
  #9  
83Firebird420's Avatar
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From: Vancouver, B.C.
Car: 87 GTA 120,000k, 90 CRX Si
Engine: 5.7 TPI, 1.6L 16 valve SOHC
Transmission: 700r4, 5spd std
Axle/Gears: 3.73
Re: Rebuilding the top end

thanks for the response. i thought about replacing the cam but im just not too sure i want to do that at this point(someone convince me its a good idea to do it now lol). i would like new heads but i cant justify spending 1400 on them right now. and ill probably port the intake my self.
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Old Apr 20, 2009 | 12:18 PM
  #10  
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From: NJ/PA
Car: Yes
Engine: Many
Transmission: Quite a few
Re: Rebuilding the top end

well, you might be able to get your heads at least mildly ported, and little bowl work, for a few hundred, which would be worth it...
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Old Apr 20, 2009 | 03:49 PM
  #11  
83Firebird420's Avatar
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Joined: Dec 2002
Posts: 725
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From: Vancouver, B.C.
Car: 87 GTA 120,000k, 90 CRX Si
Engine: 5.7 TPI, 1.6L 16 valve SOHC
Transmission: 700r4, 5spd std
Axle/Gears: 3.73
Re: Rebuilding the top end

awsome thanks for the help and input! im about to take them to parts store to get em taken care of.
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