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Forum: C4 Fuel, Emission Control, and Exhaust Systems

Topic: Hedman Headers

Hedman Headers (1/3)
 3/3/20 8:11pm
RetiredNavyChief
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Phenix City, AL - USA

Vette(s):
1985 Chevrolet Corvette VIN: 1G1YY0789F5107057 photographs to follow.


Joined: 2/9/2020
Posts: 10

Hi everyone.  I rescued my first Corvette the other day.  It’s a 1985 hardtop that was resting on low tires in a small used-car lot.  The lot-owner and I made a deal with the understanding that it was not running and “missing stuff”.

I have ordered or purchased many of those missing parts, including a battery, cruise-control servo, hood-prop and gas-pistons, heater core, heater valve, and headlight switch.

I’ve got it running on 5 of 8 cylinders, and have new wires on the way.  Once running, I quickly discovered that it doesn’t sound stock.  I discovered that the engine is piped with what appear to be a period-set(1980s) of Hedman Headers.  

As far as I can tell the 350 is otherwise stock.  I have been rebuilding and tinkering with motors since the ‘70s, but never GM small blocks.  I’m wondering if I should be looking out for other mods?  “Back in the day” we would be swapping cams and carbs along with headers and exhaust.  I’ll get photos of the engine compartment when it stops raining!



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USN 1982-2007. 

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Re: Hedman Headers (2/3)
 3/10/20 1:58pm
396c4
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, - Canada

Vette(s):
96 Vette with extensive list of mods, many one-off and custom.


Joined: 12/7/2011
Posts: 215

Go for it! (most would not) That should be a tune-port. Restriction seems to be on the intake side and it makes torque but not power so there are some aftermarket intakes available to help it breath. I have a buddy who put a cam in it as well and helped a bunch.

The draw-back is the chip for programming. You have to pull it, send it out to be flashed then hope they guess well based on what you've told them you've done to program it.

good luck

Re: Hedman Headers (3/3)
 3/24/20 6:42pm
RetiredNavyChief
Standard Member
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Phenix City, AL - USA

Vette(s):
1985 Chevrolet Corvette VIN: 1G1YY0789F5107057 photographs to follow.


Joined: 2/9/2020
Posts: 10

I have a new question concerning my old Hedman headers.  What O2 sensors SHOULD be on my '85 C4?  I'm not seeing anything on the header, and will be putting the car up on blocks this weekend to see if there are any downstream.  Virtually every vacuum line was disconnected/capped off, so I'm slowly putting the entire emission system back together.  Those check valves are hard to find though. 

I figure if I can get the emissions system back to functional and O2 sensors installed then I might just have a decent running engine!  After that I need to figure out why it won't upshift.  P, R, N, and 1 work fine.  It stays in 1st no matter what forward gear selection I choose(1, 2, D, or OD).



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USN 1982-2007. 

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