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201fireman

SBC to BBC 489

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Ok, I made the swap.  Going from a 355 to a 489.  I realize there is a ton of work to do so I am going to pick one issue at a time and handle it.  First thing is the fuel system... I think I am going with a Mallory 110GPH fuel pump and a RobbMc pickup in my stock tank.  I have a few questions listed below that I am hoping you smart folks can help me with.  It is a forged 489 stroker (engine dyno came to 640HP).  I have a Holley Ultra HP 850 carb.

1. Am I correct on the -8AN size or will a -6AN work?  If the -8AN is right, the Mallory pump has 3/8" inlet and outlet. Does thins mess me up with the -8AN?

2. Any feedback on the RobbMc sending unit with a send and return line? Good choice? Bad?

3. From sending unit to filter (which one), out to pump, out to second filter (which one), up to regulator and out to carb.  Which filters and does this seem right the way it's laid out?

 

I will also have cooling system questions and a how the hell do I power the electric fuel and water pump and fans and all the other stuff with a 140 AMP alternator.  But we'll wait for all of that.

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IMG_0036.thumb.JPG.77fc2d473470443a5d200a05b427f214.JPGHi, hope this helps,

1. I have used the Mallory comp 140 on a few of my projects. Great, quiet pump!  I ran -8 line aka 1/2" line all the way from tank to carb. 

2. I have the RobbMc 1/2" sending unit in my 70 SS with a 496. It has the return line but is capped off because I am running a mechanical pump. 

3. Your fuel system layout is good. Get a good filter. I'm running a 10micron cleanable filter. Meaning I can disassemble the filter, clean the screen and reuse. I only use one filter, between the mechanical pump and the carb. (Zoom in on pic to see the filter.) 

The 850 carb is a good choice. I am running a Holley 950HP on my 496. These engines love fuel! I have 1/2 line from the RobbMc sending unit to the carb. No issues at all. I have hot lapped the car at the track 4x in a row and have had no issues. 

4x in a row, made a run, up the return road, right into the burnout box, made another... You get the idea. Lolol this was also at a test and tune. No waiting. 

Hope this has helped. 

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Thanks alot!  It does help.  I think the Comp 140 has 3/8" inlet and outlet so that would make sense with running -8AN all the way to the carb?  Would I need the Comp 140 or would the Comp 110 work?

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The comp 110 should be fine.  I would use -8 all the way to the carb. 

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This will get you from 3/8 NPT to -8AN. Also available in natural or blue.

https://www.summitracing.com/parts/sum-220846b

90deg if you need it:

https://www.summitracing.com/parts/aer-fbm5037

(I just bought a box full of fittings to start plumbing my fuel & trans lines, had some of this stuff saved in my summit wish list. Aeroquip, summit, fragola, ICT, vibrant, etc. Various prices, some better than others for the same type of fitting.)

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Ok perfect. So going from -8AN down to 3/8" through the pump and back up to -8AN isn't a big deal then I am assuming. Thanks guys!

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the 3/8" part is "pipe" sized. I'm at work now and can't measure it, but the ID of the -8AN fitting probably won't be much different than the ID of 3/8 pipe.

Edit: Quick search shows that the ID of a -8 AN fitting to be .39"

ID of sched 40, 3/8" pipe to be .495", sched 80 pipe to be .423" (this is the pipe itself, that would thread into your part, NOT the threaded fitting connection of your part). This all means, the ID of the -8AN fitting would still be smaller than the 3/8 pipe screwing into your Mallory pump. No problems as far as flow restriction (the -8AN would be the restriction in this case).

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Sounds good. I will go with 8AN with 3/8" fittings then. Thanks for the extra effort in explaining. I really appreciate it!

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Fairly quiet day at work today, glad to help! 12 hours in front of computer screens, as long as the lights stay on, it's all good.

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Just out of curiosity, if I were to add the RobMc sending unit, run -8AN lines to the front, and go with a mechanical pump, would it work just as good for 650HP? What would a good mechanical pump be for that set up?  Also, I have a Straub hydraulic roller cam so am I correct that I would need a special pump rod?

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I run a Holley mechanical pump on my 496. It's the biggest gph without having to use a regulator. It's fed from the tank using the RobbMc sending unit. I have a solid, old school cam in my 496 but using a roller you will need a "special" pump rod. There are a few brands out there . 

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Ok, I am assuming you got the one below.  No issues with it hitting the frame cross member? I had an issue with that with an Edelbrock one on this car once when I had the small block in it.

https://www.summitracing.com/parts/hly-12-454-11/overview/year/1972/make/chevrolet/model/monte-carlo

 

 

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I believe that is the one. No clearance  issues whatsoever. The Edelbrock has a larger main body. I have had issues with Edelbrock fitting the crossmember aslo. 

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Perfect. I just talked to Straub Technologies about the fuel pump pushrod and they have me on the right track there. Now I just need to find the right -8AN line and fittings to run. This seems a lot easier than messing with the electric if it isn't needed.

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IMG_0124.thumb.JPG.68df9b98ef6f5748095d60e9e0cd0a71.JPGDepends on the type of line you are using. Steel or cloth. I ran cloth style 1/2 line from the fitting on the  RobbMc sending unit all the way to the pump. Then from the pump to carb. 

I removed the front half of the original fuel line to run the 1/2 fuel line like the factory did. That the only somewhat difficult fitting to get. Zoom in on the pic I posted earlier, you may be able to see.

Found the above pic to show what I mean. Also, I believe it was necessary to "clock" the body of the pump to the desired position. 

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That looks like Summit Racing nylon braided hose (link below).  Does that seem right? If so, did the push to connect fittings work ok? In one of the reviews for that hose someone said it doesn't work with push to connect but the push to connect are listed in the "Suggested parts" tab under that hose. 

 

https://www.summitracing.com/parts/sum-240820b/overview/

 

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I believe that is the style hose. I did not use the push to connect fittings. I used the braided steel style fittings and have no issues whatsoever with them. I also used black fittings to try to make all invisible to the eye.  As you can see I went for more of a stock look to my engine. 

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Yea I am going with black also. I will have to dig around and look for the fittings you said you used if you said they worked well.  Thanks

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Most were summit fittings. I believe the one from the frame to the pump was not. Summit didn't have that type of turn. 

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Hey Todd, as you're staying carbureted, your actual fuel flow rate is fairly low. Unless you're running dual quads on a 8,000 RPM engine, even 3/8" lines will feed your float bowls more than adequately. I wouldn't worry about the internal sizing of a fitting that goes from -8 to -6 AN.

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Yea I figured around 60GPH.  I was wanting to make sure I found a fitting that was easy to use with the nylon braided hose when I am making the lengths that's all.  Sending stuff back sucks lol.  Thanks!

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