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Old 01-26-2017, 04:16 PM   #1
TechBill
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Compression test with the carburetor removed?

Howdy folks!

I am in the process of getting the motor to run again on my truck, here the story on my truck

http://67-72chevytrucks.com/vboard/s...d.php?t=728539


Anyway, it haven't ran since 2008 and the carburetor is needing a serious rebuild so I plan to take the carburetor off however I am wondering if it will affect the compression result if I do the compression test without the carburetor?

Thank for inputs!
Bill
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Old 01-26-2017, 04:40 PM   #2
keystoneGerm
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Re: Compression test with the carburetor removed?

It's will be fine. Most of the time manuals have you open throttle anyway. Make sure you disconnect the fuel line to the pump so you aren't pumping gas everywhere.
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Old 01-26-2017, 05:14 PM   #3
TechBill
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Re: Compression test with the carburetor removed?

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Originally Posted by keystoneGerm View Post
It's will be fine. Most of the time manuals have you open throttle anyway. Make sure you disconnect the fuel line to the pump so you aren't pumping gas everywhere.
Thank you

I plan to disconnect the fuel line from the pump and attach it to a pimp which has e a drill attachment to try to pump all the 8 years old gas from the tank anyway. I am hoping to find away to empty the tank without having to remove it.
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Old 01-26-2017, 07:52 PM   #4
100%Chevy
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Re: Compression test with the carburetor removed?

I use a primer bulb like used on a boat tank.
You can put it in the filler neck or attach it to line at the pump.
Pretty easy!
Mike.
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Old 01-26-2017, 08:22 PM   #5
TechBill
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Re: Compression test with the carburetor removed?

I removed the carb. It doesn't look too good inside the intake so I am hopeful that where the water ended and it did not go into the head or the cylinders.

The smell of a 8 years old gas, I think it going reek in my garage for the next 100 years.
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Old 01-26-2017, 09:01 PM   #6
Dead Parrot
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Re: Compression test with the carburetor removed?

That looks like a spare parts carb. Inside the carb is probably just as bad.

Pull the plugs now. If all or some are rusty, you know you have rust in the cylinders. Drain the oil and inspect for water.

Agree on the bad gas smell. Sticks around for a long time since all the good stuff evaporated years ago.
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Old 01-26-2017, 10:25 PM   #7
TechBill
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Re: Compression test with the carburetor removed?

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Originally Posted by Dead Parrot View Post
That looks like a spare parts carb. Inside the carb is probably just as bad.

Pull the plugs now. If all or some are rusty, you know you have rust in the cylinders. Drain the oil and inspect for water.

Agree on the bad gas smell. Sticks around for a long time since all the good stuff evaporated years ago.
This will be my next goal which I probably will do on Monday since weather supposedly be nicer at around 55 degree sunny.

I plan to pull all plugs and inspect them then get a lubricate spray can and spray it in each cylinders and also change out the motor oil. After changing oil, I plan to rotate the engine using breaker bar to see if there any bind in it or not.

If I don't feel any bind then I will do compression test on each cylinders to determine if I need to break down the engine further to do overhaul or not.


As for intake and carburetor, I am building a Baking Soda blaster which I will use to blast the rust away on the intake and carburetor to see if it salvageable.

If the carburetor look salvageable and not pitted after blasting then I will rebuild it with a rebuild kit. I am trying to keep it close to stock as much possible.

I think only thing that won't be stock is the exhaust manifold which I might replace it with headers coated in ceramic .


Bill
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Old 01-26-2017, 10:35 PM   #8
franken
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Re: Compression test with the carburetor removed?

I bought a $10 borescope off the internet that connects to the phone so I can look into the plug holes on a Christmas present big block in the garage. Just a thought. I keep forgetting to play with it, or I'd have more info.
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Old 01-27-2017, 12:03 AM   #9
Dead Parrot
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Re: Compression test with the carburetor removed?

I would do the breaker bar attempt before adding in new oil. If the motor is rusted tight, you just wasted 5 qts + filter. You won't turn it enough to harm anything that isn't rusty or fast enough for the oil pump to do any good.

Spray the penetrating oil down the intake to lube/de-rust the valves before your breaker bar attempt.

Even if the carb isn't usable, save any small parts and linkage bits that are not rusty.
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Old 01-27-2017, 01:49 AM   #10
TechBill
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Re: Compression test with the carburetor removed?

Quote:
Originally Posted by Dead Parrot View Post
I would do the breaker bar attempt before adding in new oil. If the motor is rusted tight, you just wasted 5 qts + filter. You won't turn it enough to harm anything that isn't rusty or fast enough for the oil pump to do any good.

Spray the penetrating oil down the intake to lube/de-rust the valves before your breaker bar attempt.

Even if the carb isn't usable, save any small parts and linkage bits that are not rusty.
Just give it a good hearty WD40 spray in each cylinder then wait an hour and do the breaker bar turn?


I think carb might be salvageable and can be rebuild but will need to do soda blasting first to see. Here some picture of the carb
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Old 01-27-2017, 02:47 PM   #11
rgunlock
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Re: Compression test with the carburetor removed?

If that carb had gas left in it from when it last ran in 2008, be prepared that the inside may look much worse than the outside parts you are showing. I had one sit for about 6 years and the corrosion in the fuel bowl was so bad I had to dig the float out of it.
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Old 01-28-2017, 09:46 PM   #12
TechBill
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Re: Compression test with the carburetor removed?

I took the carb apart today and took some pictures of it in pieces and uploaded the photos to my project thread.

My C10 project thread can be found at

http://67-72chevytrucks.com/vboard/s...d.php?t=728768

Thank you
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