Fuel system priming tips for crate break in - Team Camaro Tech
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post #1 of 7 (permalink) Old Aug 6th, 09, 10:39 AM Thread Starter
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Brian
 
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Fuel system priming tips for crate break in

Hi, looking for some time tested tips on how to get a solid line of fuel/carb ready to go for break in.

Facts:
*Carb is a Holley Avenger 750, new out of the box.
*Have had fuel lines disconnected for months, surely have run dry.
*Fuel pump is my old OEM stock mechanical and installed, would like to know if there is a way to bench test that it's pumping. No reason to suspect it wouldn't but you never know.

I have never done a break in myself, but I understand that it's critical to get the motor to fire as quickly as possible after the oil priming process. What I am most concerned about is cranking too long just drawing gas from the tank.

1969 Camaro 383
2.02/1.63 & 234/244 Vortec
TH350 / 12 bolt 3.73
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post #2 of 7 (permalink) Old Aug 6th, 09, 10:59 AM
Steve
 
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Re: Fuel system priming tips for crate break in

To prime the system, I just disconnected the fuel line at the pump inlet, and used my Mityvac to draw the fuel up to that point. She fired up pretty quick. I have a Carter stock replacement mechanical pump. Probably wouldn't hurt to fill the fuel bowls either, but I didn't do that.

To test the pump...I suppose you could put hoses on the inlet and outlet, and compress the pump arm to see if it moves the fuel. Never tried this myself though. That pump arm has a rather strong spring behind it though, so eat yer Wheaties.

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post #3 of 7 (permalink) Old Aug 6th, 09, 11:04 AM Thread Starter
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Brian
 
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Re: Fuel system priming tips for crate break in

What is a Mityvac? I was thinking of some way to suction the fuel line from the tank, but didn't want to risk injesting gas into a shop vac or something and blowing myself up!

1969 Camaro 383
2.02/1.63 & 234/244 Vortec
TH350 / 12 bolt 3.73
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post #4 of 7 (permalink) Old Aug 6th, 09, 11:15 AM
Steve
 
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Re: Fuel system priming tips for crate break in

That's what a Mityvac does. It's just a small hand-operated vacuum/suction pump. No electricity needed. No arc, no spark, no fire.

http://www.mityvac.com/

There's other brands on the market too. I just mentioned this one because it's the one I've had for years.

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'77 Type LT - 86K, 350, ST-10, COX 3.55 12-bolt

Next up: ZZ3/TKO600

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post #5 of 7 (permalink) Old Aug 6th, 09, 12:02 PM
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Re: Fuel system priming tips for crate break in

Prime the CARB by filling the float bowl(s) through the vent opening. I use a squeeze-bulb deal; which worked great until the gasoline reacted with the rubber bulb and the rubber swelled up. A glass measuring cup would work OK too--they pour very nicely and you shouldn't have too much trouble getting the gasoline to pour into the vent stack of the carb. Or cheat--and use a small funnel.

Be sure that the fuel filter is clean (not restrictive.) Just a couple of days ago I had a Pontiac engine that would not prime the fuel pump when running on fuel I poured into the carb. I ran the engine several times; perhaps a total of a couple of minutes. I thought the pump went bad--but--I pulled the in-carb fuel filter (Quadrajet) and it was almost plugged. As soon as I got a clean filter in place and re-primed the carb--it started and ran and primed the fuel pump almost immediately.

The old plastic-bodied Mityvacs were terrible for fluid contamination of the vacuum piston and cylinder. Even a hint of brake fluid in the tool would totally ruin it. I would not use a mityvac--plastic or metal--to draw gasoline from the tank without using the brake bleeder canister thingie to positively prevent fuel from entering the mityvac. But then, I wouldn't vacuum the fuel forward--I'd put compressed air in the tank and push the fuel forward with pressure. Don't get carried away--it won't take much pressure to move the fuel. Even more likely--I'd just run the engine and let the fuel pump move the fuel.
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post #6 of 7 (permalink) Old Aug 6th, 09, 02:57 PM
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Russ
 
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Re: Fuel system priming tips for crate break in

Unless you have ultra tight clearances on the rings cranking the motor a few times will not hurt it. Prime the oil pump, static time the engine, pull the plugs out, crank over a few times, re-install plugs, prime the carb, and go at it. The most import part of breaking in a new engine is do not let it idle. I generally run them 2500-3000rpm for a solid 30 minutes and vary the rpm +/- 200rpm every 5 minutes or so. Use the idle screw and a external tach to set rpm. Once that is done then worry about your final dynamic timing and carb settings.

Russ (RJ)
The Garlic Capital, Gilroy,CA

(sold June 15,2014) 1968 RS convertible that is not quite stock

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post #7 of 7 (permalink) Old Aug 6th, 09, 08:39 PM
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Steiner
 
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Re: Fuel system priming tips for crate break in

I've always done it by using a clear fuel filter in the pump outlet line so I could see the fuel coming, then removing the line from the carb and sucking until fuel got to the filter.

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