Printable Version of Topic
Click here to view this topic in its original format
914World.com _ 914World Garage _ Fuel Hose and linkage Routing for dual carbs
Posted by: Carlitos Way Dec 20 2005, 12:10 PM
Looking for dual carb fuel setups. Would love to see type/routing of fuel lines, how you ran them, how you set up your linkage, where you installed your fuel pump, filter and regulator (if any).
Thanks!
Posted by: Aaron Cox Dec 20 2005, 12:13 PM
fuel lines come up the right side... hit the regulator, then a tee. one line to right carb, other line to left carb.
fuel line runs across back bulkhead....
AA
EDIT: CB linkage. Facet pump up front.
tank - filter - pump - tunnel hardlines - rubber line to engine bay - filter 2 - cheapo regulator - tee - line to each carb
Posted by: Joe Ricard Dec 20 2005, 12:17 PM
Tank, prefilter, pump, fuel line through tunnel, can filter, Holley regulator with 2 outlets. one to each carb. Left carb get fuel line routed along back bulkhead.
Linkage is a modified tweaked for no slop CB style.
Posted by: brant Dec 20 2005, 12:32 PM
sorry If I sound like a broken record...
but I still believe in a return line for carbs.
cooler fuel is more hp, and less vapor lock.
Its important at altitude.....
anyways...
don't have a carbed 4 anylonger, but when I did:
-tank to pre-filter
-prefilter to pump
-pump to pressure line in tunnel.
-pressure line enters engine bay and a pressure guage (NOT MOUNTED ON MOTOR where it will vibrate/break!)
-pressure line to 1st carb (a T fitting on the rear of engine bay)
-pressure line continues to a second T fitting and 2nd carb
-Then pressure line goes into a regulator, which builds Back Pressure....
(the beauty of this set up is that you can use the cheapy facet regulator, because you have a decent guage telling you what your ACTUAL pressure is to the carbs)
-regulator then goes to the return line in the center tunnel and back to tank
brant
Posted by: maf914 Dec 20 2005, 12:35 PM
Ditto on the two fuel line setups as described above. It has worked for me for years.
Aaron,
What are you using as a bracket to hold your dual pole oil pressure sender? I like that placement. Thanks.
Posted by: Aaron Cox Dec 20 2005, 12:39 PM
| QUOTE (maf914 @ Dec 20 2005, 11:35 AM) |
| Ditto on the two fuel line setups as described above. It has worked for me for years. Aaron, What are you using as a bracket to hold your dual pole oil pressure sender? I like that placement. Thanks. |
a padded hose strap...without the padding.
remember..you must ground your external sender.... the clamp does a fabulous job at this.
BTW - carlos - there is a pic of the throttle cable bracket i made.... 2 bends...2 holes....
AA
Posted by: brant Dec 20 2005, 12:43 PM
This picture is the new car (old car was the carbed -4)
this one has the regulator first, instead of back pressure....
but same thing.
filter-pump
2 fuel lines.
in one carb and out to the other and then back to the front tank!
Attached thumbnail(s)
Posted by: Aaron Cox Dec 20 2005, 01:08 PM
also - a search for carb linkage yielded 3 pages of results...
here is some pics from a thread like this that i startyed when i was a carb newb...
lots of info URL=http://www.914world.com/bbs2/index.php?act=ST&f=2&t=7762&st=0&hl=]Here............[/URL]
Posted by: maf914 Dec 20 2005, 01:09 PM
| QUOTE (Aaron Cox @ Dec 20 2005, 10:39 AM) |
| a padded hose strap...without the padding. remember..you must ground your external sender.... the clamp does a fabulous job at this. |
Good idea. I'll check into pipe clamps at the local hardware sources. Thanks.
Posted by: Carlitos Way Dec 20 2005, 03:28 PM
Wow! Those are some really beautiful engine compartments. Would love to see more!
Posted by: tat2dphreak Dec 20 2005, 03:52 PM
| QUOTE (Joe Ricard @ Dec 20 2005, 01:17 PM) |
| Tank, prefilter, pump, fuel line through tunnel, can filter, Holley regulator with 2 outlets. one to each carb. Left carb get fuel line routed along back bulkhead. Linkage is a modified tweaked for no slop CB style. |
Posted by: Carlitos Way Dec 20 2005, 06:41 PM
What the heck is a pre-filter?
Posted by: Kargeek Dec 20 2005, 07:08 PM
The second photo in Aaron's post with the red carb filters is my car. I used a six cylinder fuel pump with the factory return line and routed the fuel hose to the first carb which had a tee fitting, then along the rear of the bulhead to the other carb. I made a mistake of running one of those dial pressure regulators between the fuel pump and the first carb...the factory fuel pump is internally regulated and the aftermarket regulator set at 3-4PSI starved the left hand carb. Always check fuel pressure with a gauge.
Posted by: Carlitos Way Dec 20 2005, 09:27 PM
That's a beautiful car/setup. Thanks for sharing!!!
Posted by: Carlitos Way Dec 20 2005, 09:28 PM
I love the throttle cable mounting bracket. Did you make that? That's awesome!
Posted by: campbellcj Dec 20 2005, 09:48 PM
Here's my setup. Sorry it's not very clean..."it's a track car"
Attached image(s)
Posted by: URY914 Dec 20 2005, 10:13 PM
Here is a shot of the engine that I'm going to put in my car. You can see the linkage there in the middle of the shot. I drilled it out to save some weight. I don't know if this will help you or not.
BTW, these are the two guys that helped me steal it.
Paul 
Attached image(s)
Posted by: Aaron Cox Dec 20 2005, 10:17 PM
| QUOTE (URY914 @ Dec 20 2005, 09:13 PM) |
| Here is a shot of the engine that I'm going to put in my car. You can see the linkage there in the middle of the shot. I drilled it out to save some weight. I don't know if this will help you or not. BTW, these are the two guys that helped me steal it. Paul |
my flat 16 is being shoe-horned as we speek.
suck my extra 4 cylinders paul
Attached thumbnail(s)
Posted by: URY914 Dec 20 2005, 10:19 PM
Here is a picture of my -16. MUCH better....
Attached image(s)
Posted by: Aaron Cox Dec 20 2005, 10:20 PM
| QUOTE (URY914 @ Dec 20 2005, 09:19 PM) |
| Here is a picture of my -16. MUCH better.... |
copy cat
Posted by: maf914 Dec 21 2005, 08:06 AM
Wow, I can't believe the flat 12 in Paul's pic is cantilever mounted to a standard Porsche engine stand! 
Posted by: rhodyguy Dec 21 2005, 09:45 AM
best linkage on the market in my book. expensive? a little. worth it? i haven't touched my carbs in a year and 1/2. disregard the bungee cord.
k
Attached image(s)
Posted by: jr91472 Dec 21 2005, 10:07 AM
Thanks for starting this thread. I am in the same process right now.
Question to all: is there any advantage to which way the carbs face? Specifically, having cross-bar closest to the cockpit vs closest to the trunk? I've seen picture of both installs.
hope this isn't a hijack
Posted by: rhodyguy Dec 21 2005, 10:10 AM
forgot to add mine is a triad. i never understood putting the bar on with the works on the rear.
k
Posted by: Carlitos Way Dec 21 2005, 10:18 AM
I really dig this linkage:
Attached image(s)
Posted by: rhodyguy Dec 21 2005, 10:29 AM
look are where the drop links are positioned in that picture (under the rear lid? ). you have to stand on your head to dial the carbs in. what keeps the bar centered? a couple of springs?
k
Posted by: Aaron Cox Dec 21 2005, 10:53 AM
| QUOTE (rhodyguy @ Dec 21 2005, 09:29 AM) |
| look are where the drop links are positioned in that picture (under the rear lid? ). you have to stand on your head to dial the carbs in. what keeps the bar centered? a couple of springs? k |
ive had mine on the rear before... PITA like kevin said.
Kev - the CB setup is self centering. it has springs in each end....
Posted by: Kargeek Dec 21 2005, 11:37 AM
Having the arms to the rear is no big deal... you set it up properly once and that's it. More time is spent adjusting fuel mixture and synchronizing both carbs... then adjust your drop links to fit with the throttle arms horizontal without any side to side preloading of your final carb set up.
It also makes for neatly routing the stock length throttle cable.
Yes, the arms are centered with springs in each end of the bar.
The only issue with arms to the rear is if you have a tall mount linkage - it may interfere with the trunk torsion bars- mine are gone as I’m using 944 rear hatch shocks.
DH
Attached image(s)
Posted by: Carlitos Way Dec 21 2005, 12:11 PM
| QUOTE (Kargeek @ Dec 21 2005, 09:37 AM) |
| Having the arms to the rear is no big deal... you set it up properly once and that's it. More time is spent adjusting fuel mixture and synchronizing both carbs... then adjust your drop links to fit with the throttle arms horizontal without any side to side preloading of your final carb set up. It also makes for neatly routing the stock length throttle cable. Yes, the arms are centered with springs in each end of the bar. The only issue with arms to the rear is if you have a tall mount linkage - it may interfere with the trunk torsion bars- mine are gone as I’m using 944 rear hatch shocks. DH |
Where did you get that mounting bracket for the throttle cable? That is AWESOME!!!
Posted by: Aaron Cox Dec 21 2005, 12:14 PM
| QUOTE (Carlitos Way @ Dec 21 2005, 11:11 AM) | ||
Where did you get that mounting bracket for the throttle cable? That is AWESOME!!! |
he made it.
looks like 18ga, a little dremel, and a set of vice grips to fold it, and a drill...
Posted by: Eddie Williams Dec 21 2005, 12:52 PM
I planed on using the Aeromotive A1000 Bypass regulator for my setup, any thoughts??
http://216.242.145.16/products/product.phtml?p=20
Posted by: Aaron Cox Dec 21 2005, 01:59 PM
| QUOTE (Eddie Williams @ Dec 21 2005, 11:52 AM) |
| I planed on using the Aeromotive A1000 Bypass regulator for my setup, any thoughts?? http://216.242.145.16/products/product.phtml?p=20 |
-10 feed????? thats the size of my front oil cooler lines....
way too big i think.
Posted by: jhadler Dec 21 2005, 02:32 PM
| QUOTE (Eddie Williams @ Dec 21 2005, 10:52 AM) |
| I planed on using the Aeromotive A1000 Bypass regulator for my setup, any thoughts?? http://216.242.145.16/products/product.phtml?p=20 |
An-10 feed?!?! Good grief, this is a 914 we're talking about, not a top fuel drag car...
Way overkill. You'll need one seriously hefty pump to deliver enough fuel at enough pressure if you use -10 lines...
-Josh2
Posted by: Kargeek Dec 21 2005, 04:34 PM
[/QUOTE]Where did you get that mounting bracket for the throttle cable? That is AWESOME!!!
Yes, I made it- 18 years ago. You can make one too. Some scrap metal, cardboard template (I'm big on templates) , hacksaw, drill, grinder and files. It got thrown into all of the parts that got cad plated.
Posted by: Eddie Williams Dec 21 2005, 05:03 PM
indeed, quite large
as my feed is -6 can I just use a -10 to -6 union adapter? and a -8 to -6 on the return? and then -6 to each weber?
Posted by: Aaron Cox Dec 21 2005, 05:04 PM
| QUOTE (Eddie Williams @ Dec 21 2005, 04:03 PM) |
| indeed, quite large as my feed is -6 can I just use a -10 to -6 union adapter? and a -8 to -6 on the return? and then -6 to each weber? |
or buy the right one to begin with and be money ahead.
mallory makes a great regulator WITH return
Posted by: Eddie Williams Dec 21 2005, 06:07 PM
| QUOTE (Aaron Cox @ Dec 21 2005, 05:04 PM) |
| or buy the right one to begin with and be money ahead. mallory makes a great regulator WITH return |
ok, smart a$$... All my research for a FP Regulator with bypass pointed to this... I'll check out the mallory, is it all -6??
Posted by: Eddie Williams Dec 21 2005, 08:15 PM
the Mallory has -8 lines so i'd stll have to buy fittings...
Posted by: Aaron Cox Dec 21 2005, 08:35 PM
| QUOTE (Eddie Williams @ Dec 21 2005, 07:15 PM) |
| the Mallory has -8 lines so i'd stll have to buy fittings... |
http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10002&storeId=10001&categoryId=14185&parentCategoryId=10323&langId=-1
use these fittings...
Posted by: Eddie Williams Dec 21 2005, 08:51 PM
How do I get -6 fuel line to screw onto that? 
Posted by: fin Dec 21 2005, 09:14 PM
Having emptied a fire extinguisher in the engine compartment of a 914 only to hear and see the fire re-ignite, I would recommend to err on the safe side of this issue.
Luckily, the guy that I thought was a jerk when he saw what was going on and sped off, redeemed himself by showing back up five minutes later with a shiny red truck with bright lights, noisy horns and 1500 gallons of water and a herd of friends in all sorts of vehicles.
I LOVE small town volunteer fire departments!
I don't think you can overdo fuel delivery in the engine compartment.
Good Luck,
Fin
Posted by: Aaron Cox Dec 21 2005, 09:41 PM
| QUOTE (Eddie Williams @ Dec 21 2005, 07:51 PM) |
| How do I get -6 fuel line to screw onto that? |
oh... adapters either way...
missed what you were asking.
ever thought about a rising rate regulator?
ie less PSI at idle.... more at 5k....
AA
Posted by: Eddie Williams Dec 21 2005, 09:48 PM
The Mallory and the Aeromotive both have vacume ports on them I understand this can be used to lower pressure at idle or increase pressure at boost. I assume at idle manifold pressure is negative in relation to ambient and at boost it is positive. Is this correct?
Posted by: Aaron Cox Dec 21 2005, 09:49 PM
| QUOTE (Eddie Williams @ Dec 21 2005, 08:48 PM) |
| The Mallory and the Aeromotive both have vacume ports on them I understand this can be used to lower pressure at idle or increase pressure at boost. I assume at idle manifold pressure is negative in relation to ambient and at boost it is positive. Is this correct? |
sounds right...but i dont know
Posted by: Eddie Williams Dec 21 2005, 10:07 PM
These are a few of the options.Have I left anything out?
Attached thumbnail(s)
Posted by: Aaron Cox Dec 21 2005, 10:14 PM
options C D and E are all good imo
Posted by: Eddie Williams Dec 21 2005, 10:32 PM
I forgot Brant's option.
Attached image(s)
Posted by: brant Dec 22 2005, 12:13 AM
I'm using option B on the new car.
only B and E have cold/fresh fuel flowing past the carbs.
that will promote the most hp.
It might be miniscule, but I believe in doing everything you can to have fate on your side!
brant
Posted by: yeahmag Dec 23 2005, 08:11 PM
I don't see how option B could ever work. There is no resistance for the pressure to build against if it flows straight back to the tank. The regulator would have to be after the carbs... Am I missing something?
-Aaron
Posted by: campbellcj Dec 23 2005, 08:25 PM
Maybe it doesn't really matter, but is it a good idea to run the fuel thru one carb and then into the other? Seems like you would get more even flow and pressure splitting the supply line before entering the carbs so each one gets an even supply. That's how mine is setup up. Then again I'm not presently using a return line (I think quite a lot of carbed cars don't, eh?)
Posted by: URY914 Dec 23 2005, 08:43 PM
| QUOTE (campbellcj @ Dec 23 2005, 06:25 PM) |
| Maybe it doesn't really matter, but is it a good idea to run the fuel thru one carb and then into the other? Seems like you would get more even flow and pressure splitting the supply line before entering the carbs so each one gets an even supply. That's how mine is setup up. Then again I'm not presently using a return line (I think quite a lot of carbed cars don't, eh?) |
I agree. My set up T's off of the regulator (one in/ two out) and go to the carbs with a seperate lines and no return. I don't like running to one carb and out to the other.
Does it matter?
Don't know.
Posted by: trekkor Dec 23 2005, 10:15 PM
I'm doing the one in, two out thing. No issues.
KT
Attached image(s)
Posted by: Aaron Cox Dec 23 2005, 10:16 PM
cept the hoseclamps 
Posted by: trekkor Dec 23 2005, 10:21 PM
zoiks
Posted by: Aaron Cox Dec 23 2005, 10:22 PM
| QUOTE (trekkor @ Dec 23 2005, 09:21 PM) |
| zoiks |
just pokin fun....
better than my "hacked up shit" welds
Posted by: brant Dec 23 2005, 10:25 PM
couple of things...
were not talking fuel injection here.
especially in the -6 with the PMO rails, all the fuel has to do is flow (downhill) into a bowl. The floats shut that off when they are full. No need to distribute it evenly.... just need to keep some in the bowl, and you'll know it if you can't keep that done. Even with 3lbs of fuel pressure there is still plenty of fuel to return to the tank after filling the bowls. (I've got Wideband sheets to show I'm not running my bowls dry.... maybe if it was a 3.6 I would (doubt it), but its pretty effective for me.
the -4 carb doesn't really have a convienient way to go from one to the next and that a part of the reason my plumbing was different when I ran a -4
by having the fuel flow past one carb, it assures circulation and cooler fuel.
having fuel sit above the motor where heat is radiating into it is not a good thing.
in fact as you'll notice in my picture on page 1, we bothered to heat rap our stainless lines every inch of their travel after exiting the firewall. (hot zone)
Modern fuels Suck even as low as at 100 degree's F
fuel injection pressures can mask this.... (and is the reason modern cars don't vapor lock.
but carbs and especially carbs at 5000 ft don't mask it as well. (altitude reduces cooling or air density you know) Most of the SCCA guys in colorado run cool cans on their fuel in the hot engine bays. Check out the mazda guys sometime if you don't believe me.
but heck..
you don't like it thats fine with me.
thats the beauty of free will.
brant
Posted by: Eddie Williams Dec 24 2005, 12:25 AM
Either way I think it's a good discussion. My $.02
Posted by: synthesisdv Dec 24 2005, 07:29 AM
here's my rig, the IDF's need 3lb or less so make sure you get the right low pressure regulator, mine is a return style mallory. The return keeps the fuel cool and prevents perculating when temps go way up.
Attached image(s)
Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)