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Carbed fuel system from scratch...


JMortensen

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I'm ready to buy parts to plumb my fuel system. I have a cell which has -8AN fittings for the fuel out and the vent, and Mikunis that have 5/16" hose barbs. Need to figure out what to use to connect them. I've already contacted Wolf Creek Racing to see if Todd has any AN banjos.

 

I'm not really set on anything, I could go AN all the way to the front and I think that would be my preference because they seem to seal better than your typical hose barb and rubber hose setup. If it's going to cost $500 though, I could just as easily get a -8 to hose barb connector and do it the old fashioned way.

 

Eventually this car will get an LSx, and at that point it would be better if the car would be fairly easy to convert to FI, which I would plan to do with a surge tank. I think what this means is that I need a fairly large fuel line from the back to the front, and then maybe a distribution block with smaller outlets to the carbs. Maybe???

 

I ran dead-headed before and that never caused a problem, so I suppose that would be the plan this time as well. Eventually I will need a return line for the cell when the surge tank goes in. I'm wondering how to do this. Is it as simple as drilling a hole in the fill plate and installing a bulkhead fitting?

 

Other stuff I need advice on is:

Fuel pump - was thinking Carter

fuel filter(s)

hard line

soft lines - braided SS or ???

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Why would someone use this AN to tube adapter fitting http://store.summitracing.com/partdetail.asp?part=EAR-165108ERL

 

instead of this aluminum tube nut coupler?

http://www.speedwaymotors.com/p/972,83_Aluminum-Tube-Nut-Couplers.html

 

It seems that they do the same thing (attach a hard line to a male AN fitting). Am I missing something?

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I just went through, diagrammed the fuel system and all the fittings necessary. Turns out to plumb the thing with regular hose barbs and rubber hose it will cost about $250. For all AN fittings it will be more like $490.

 

Is there a good reason I should pay double for the AN fittings?

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Wow Jon, 5 posts in a row ;)

 

It took some effort before I got my fuel system where I like it but now there's zero fuel feed issues at high rpms, here's what I have:

 

8AN supply AND return lines, all braided hose - I beleive the only type allowed by SCCA if passing through the cabin including hard lines. The fuel cells come with a traditional AN bulkhead, I doubt you'd have any issues adding a return to it as you describe. Personally I'd avoid the Summit "kit" and buy the fittings and hose separately.

 

Holley bypass regulator, 4.5 to 9 psi, the fuel pump runs MUCH quieter with the return and I suspect less stress and longer pump life as well.

 

Carter comp pump, IIRC around 100 gph - it's still quite loud with the bypass but has worked flawlessly!

 

Aeromotive fuel filter installed pre-pump, the style with about the same dimensions as a smaller oil filter

 

A friend machined a simple distribution block for the carbs, it literally took about 1/2 hour to drill and pipe tap solid AL stock on a lathe and mill. Metric to flare adapters for the carbs were used with 6AN lines to the block.

 

The AN hardware can really break the bank, I beleive I have over $600 just in the fuel sytem alone. I liked the idea of running the lines through the car to protect them during any off road excursions - there's been a few - and in that case it's pretty much a commitment to AN thoughout.

 

I suppose with autocrossing the vulnerabilty is not a concern, aside from rolling it, and being on a tight budget you'd probably be better off keeping everything external from the cabin going with the 'ole rubber and flared hard lines wherever possible.

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I suppose with autocrossing the vulnerabilty is not a concern, aside from rolling it, and being on a tight budget you'd probably be better off keeping everything external from the cabin going with the 'ole rubber and flared hard lines wherever possible.

Yeah, I agree and I finally ordered up all the rubber and hard lines and hose barbs necessary. I'm going to run my hard lines way up in the top of the trans tunnel for safety. I will be dead heading this one, but this is a temporary install and hopefully within a few years it will be pulled for the FI V8 fuel system, at which point I'll probably go with the AN fittings and all the rest. I picked the regular Carter pump, a Holley regulator, a Summit and a Fram fuel filter, all the fittings and hoses and all that for a bit over $200. I also got all the fittings, hoses, SS lines, NPT to AN adapters etc for the brakes for about $50 more. So I've got some major plumbing to do here shortly. Next is electrical. That's going to be a nightmare.

 

EDIT--For what it's worth, I believe those banjos I linked to will fit on the Mikunis based on feedback I got elsewhere, and there are also 12 x 1.5mm AN adapters that fit right in and then you can use an 90* angle full flow adapter to attach if preferred.

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Why would someone use this AN to tube adapter fitting http://store.summitracing.com/partdetail.asp?part=EAR-165108ERL

 

instead of this aluminum tube nut coupler?

http://www.speedwaymotors.com/p/972,83_Aluminum-Tube-Nut-Couplers.html

 

It seems that they do the same thing (attach a hard line to a male AN fitting). Am I missing something?

 

 

You dont need to flare the ends of the tube with a compression fitting. 37 degree flaring tools are expensive for decent - good ones and cheap ones might make crappy flares ending up with leaks.

 

Jon, post pics of your process as I know of a few people here that are also on the same subject, including myself!

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EDIT--For what it's worth, I believe those banjos I linked to will fit on the Mikunis based on feedback I got elsewhere, and there are also 12 x 1.5mm AN adapters that fit right in and then you can use an 90* angle full flow adapter to attach if preferred.

 

I agree, the banjos will most likely work, I have the adapters and 90's. I'd personally avoid any inline banjos and keep each carb on it's own feed from a fuel block.

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I agree, the banjos will most likely work, I have the adapters and 90's. I'd personally avoid any inline banjos and keep each carb on it's own feed from a fuel block.

I guess the disadvantage to the banjos is that eventually the aluminum washers would wear out (depending on how many times you pull the fuel lines off the carbs), where the 90* fitting would last a heck of a lot longer. The upside of the banjo is less parts needed so less cost.

 

One other thing I might mention is that I was having a hard time finding "fuel distribution blocks" in anything other than 2 or 4 outlet versions, but I did later on find a 3 outlet block, but it was referred to as a manifold. Here's an example:

http://www.speedwaymotors.com/p/3258,164_Aluminum-Fuel-Manifold-Fitting.html?itemNo=an%20manifold

Spendy little sucker. after I saw that I was thinking about doing T's and one line instead of three separates. With the T's it would be fairly easy to disconnect the fuel lines with the manifolds, just like you do with the old fashioned rubber lines.

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Jmortensen,have you checked out a competent hydraulic hose & fitting shop? Any shop worth it's salt will have all kinds of AN fittings,but they know them as JIC fittings, plus metric and British adapters. You should be able to get a stainless braided teflon hose with machine crimped ends,not those aluminum screw together ones, they're not as pretty (not anodized) but plated steel& should hold up better, some even offer them in stainless for a price of course........ Just a suggestion.

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Jmortensen,have you checked out a competent hydraulic hose & fitting shop? Any shop worth it's salt will have all kinds of AN fittings,but they know them as JIC fittings, plus metric and British adapters. You should be able to get a stainless braided teflon hose with machine crimped ends,not those aluminum screw together ones, they're not as pretty (not anodized) but plated steel& should hold up better, some even offer them in stainless for a price of course........ Just a suggestion.

 

Yeah, we have a place like that here, a place called PECO, Plant equipment company. JIC fittings in steel are about 1/3 the cost in aluminum. The total weight savings in a car is probably about 1 to 1.5 lb. Not worth the cost difference for aluminum IMO. Buy your aeroquip hose on EBAY and save alot more $$$ IMO.

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It's amazing how a project can stretch out. Work, life responsibilities, and the next thing you know it's rusty. Scope creep is my problem. I've had an oil change turn into a complete freshening......and I'm a good bit closer to social security than Jon is.....

 

John

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