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Mr Pimpdaddy
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49 Posts
Discussion Starter #1
Hello Modded Mustang's

New here in town ....

Last week my thermostat got stuck closed , causing my car to overheat & Blow a freeze-plug on the head . me and my brother ripped it apart and this is what we had done :

Resurfaced Heads ( Valve job )
New Water Pump
New Radiator
Head Gasket set
Oil-change
all new fluids

( new plugs / wires 2 weeks before )



After successfully Putting the car back together , The Car started Just fine
BUT is running SLUGGISH .....

( kinda like the car want's to die but does not )

Does Anybody have any ideas what this problem could be ?

( Im thinking vacuum leak ) or ( O2 censor )

Thanks in advance
 

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557 Posts
You may have a vacuum leak somewhere, I would rule that out first.
 

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Mr Pimpdaddy
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49 Posts
Discussion Starter #5
Yes i got a new Head Gasket set and torqued everything down correctly

I have 5-6 broken ( vacuum ) Hoses
and a bunch ( brittle/ old )

does anybody know where i can get a vacuum diagram ( besides under the hood ) Possibly Whole car ?

Thanks in Advance
 

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a.k.a. Racecougar
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4,775 Posts
I have 5-6 broken ( vacuum ) Hoses
and a bunch ( brittle/ old )
Well that would certainly cause a vacuum leak.

How much was removed from the deck surface of the heads? Did you reuse the stock length pushrods? Did you check lifter preload when you installed the pushrods/rockers?
 

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Mr Pimpdaddy
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49 Posts
Discussion Starter #7
Im not sure i took them to the local machine Shop , Everything was left on it

Everything was left Stock, How do i check the lifter pre-load ?
im going to re-check torque on heads and lifters on friday and do another oil change ( friday = 500 Miles )
 

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a.k.a. Racecougar
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4,775 Posts
Do you have a dial indicator or an adjustable pushrod length checker? You'll need one or the other to check lifter preload. Typically, decking the heads/block will require shorter pushrods. Depending on the amount of material removed, you could be hanging the valves slightly, which will significantly reduce performance.
 

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Do you have a dial indicator or an adjustable pushrod length checker? You'll need one or the other to check lifter preload. Typically, decking the heads/block will require shorter pushrods. Depending on the amount of material removed, you could be hanging the valves slightly, which will significantly reduce performance.
i think this is why felpro sells a copper spacer that goes on the HG. when i did my HGs the machine shop guys said you cant deck the 3.8 heads. i felt lucky mine had no warpage.
 

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Fee Fie Foe Fum
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1,724 Posts
i think this is why felpro sells a copper spacer that goes on the HG. when i did my HGs the machine shop guys said you cant deck the 3.8 heads. i felt lucky mine had no warpage.
You CAN deck 3.8 but w a non adjustable rocker decking the head is going to change the length of the pushrod you need for correct lash and preload...in a non adjustable setup the only way to control lash and preload is the length of the pushrod.

And the wrong length pushrod could for sure make your engine run "sluggish".....

Personally I'm terrified I am going to get this part wrong finishing my build engine..
 

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a.k.a. Racecougar
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4,775 Posts
After Debating I am Replacing all the vacuum lines & hoses and all 4 o2 Censors tomorrow so i will post with my end result
If the primary O2's have 80K+ miles on them, it wouldn't hurt to replace them. Don't waste your money on the secondary O2's unless they're generating a CEL. Either way, the O2's aren't the source of the problem here.
 

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Mr Pimpdaddy
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49 Posts
Discussion Starter #14
after replacing all 4 o2 Censers , and vacuum lines , the pony purrs like a kitten

With a small miss somewhere .... Check engine light came on so its probably going to tell me where the miss is coming from
 
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