Author Topic: Removing Stock Factory Exhaust Manifolds for shorty headers?  (Read 309 times)

Offline Ed4all10

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Hello all. Sorry if this has been asked before, but I couldn’t find exactly  what I was looking for in the search.  :) I’m helping my nephew fix up his 86 k10 with a factory 305. Since he just got his license, budget is an issue. He wants to install a header back exhaust with shorty headers, so that when he saves up for a 350, he can keep the exhaust on the truck. I have 3 questions:

1. Any tricks on getting the stock exhaust manifolds off? I.e heat, penetrant, etc?

2. What to do with the air pump lines after removing the stock manifold? If memory serves, there are 2 on the pass side, and 1on the drivers. Where would be the best place to plug them, or cut them off? He already removed the belt that is driving the air pump I believe, so no air is flowing through them.

3. Would shortys even be worth it on a 305 with 85k miles on it? I have only ever dealt with long tubes on my 85, so I assume the fitment is still a chore.

Thank you very much!




« Last Edit: July 14, 2018, 09:25:21 PM by Ed4all10 »

Offline VileZambonie

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Re: Removing Stock Factory Exhaust Manifolds for shorty headers?
« Reply #1 on: July 15, 2018, 07:00:34 AM »
Penetrating oil is good. I would suggest take pics, unbolt everything and crate it up. Some people want the factory smog stuff so it has resale value or if you ever decide to sell the truck you can sell it with the original parts. Shorty's are fine and you will notice an improvement in performance over the stock manifolds but if it's going into the factory cat, single exhaust it won't be much....
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Offline 75gmck25

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Re: Removing Stock Factory Exhaust Manifolds for shorty headers?
« Reply #2 on: July 15, 2018, 07:04:45 AM »
I just replaced heads on my 350, so I had to remove the exhaust manifolds.  It all came apart well, but I made the mistake of using an impact wrench and 12 point socket, and it rounded off one of the stubborn bolt heads.   Just get a six point socket and make sure its fully on the bolt, and then use a breaker bar so have better feel of the tightness. 

When I reinstalled them I had to use a manifold spreader tool on one side to get all the bolts lined up.  The directions suggested installing the tool before you take the manifold off, since it may relieve pressure from misaligned holes.  The tool was about $15 (I think) at NAPA.

I've seen several articles that say shorties aren't worth the trouble when long tubes will fit.  However, I also know how restrictive those stock manifolds are.  It seems worthwhile from a power perspective if you can get them cheap enough, but I would seriously consider if its worth the labor.   I put exhaust work in the same labor category as digging holes in the yard.  Somebody needs to do it, but I prefer it to be someone other than me.

I don't have an air pump on my '75, but if you remove the exhaust manifolds it seems like the entire air system should also come off.  It just sucks in air and pushes it to the manifolds, so without stock manifolds there is no place for the air to go.

Bruce

Offline Ed4all10

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Re: Removing Stock Factory Exhaust Manifolds for shorty headers?
« Reply #3 on: July 15, 2018, 05:26:45 PM »
Thank you both! He got shorties for about 125 bucks off eBay, and they are already coated. He is going to run them to a thrush dual system with an X pipe. Thanks again!

Offline Patman

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Re: Removing Stock Factory Exhaust Manifolds for shorty headers?
« Reply #4 on: July 29, 2018, 03:14:49 PM »
How did you get that front bolt off on the passanger side? I cant get a socket to sit on it. Not enough side clearance for the socket to seat on the nut.

Assuming you still have all of the smog stuff on yours...
85 K10 350, 700R4, NP208, Quadrajet, Long Bed w/ 33’s
All stock except for the motor, used to be a 305.

Offline Ed4all10

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Re: Removing Stock Factory Exhaust Manifolds for shorty headers?
« Reply #5 on: August 09, 2018, 08:06:25 PM »
The front bolt on the manifold? I used a wrench.