V6 Conversion with original tank.

[jfk]

Hi

I have a V6 conversion in my FC Sedan and my question relates to tank modifications.

Having read heaps of threads, everybody seems to install the Commodore tanks, but I already have a drop tank from when I ran my old 202 and have a new floor in my boot and I'm not keen to chop it up.

I plan to keep the original 0 -30 ohm sender and will see how it goes with an inline filter and fuel pump for the desired 48=55 psi.

I plan to fit new outlets for the fuel uptake and return lines.

What size lines are on the Commodore tanks ?

Has anybody done this before, or have any advice ?

Thanks

JK

[FC427]

5/16'' or 8mm bundy tube  for a standard V6  will be fine for both the supply and return lines ......FC427........

[hsv-001]

Ok , can probably help with this one . Five years ago I put a v6 in a 1948 Vauxhall with a standard FE-EK fuel tank .I was running a gutted series 1 wiring harness with everything I didn't need removed . Anyway a few problems surfaced ,the first being the fuel guage runs on less voltage[amps whatever] so to overcome this problem I just resized the commodore fuel tank sender unit mounting plate by cutting it down and redrilling the holes to the FC tank . By simply bending the wire on the sender I was able to make the float travel in the correct arc from bottom to top of the tank and the reading is very close to accurate . You may have to also add extra length to the wire because you have a drop tank . Just measure the depth of the tank and see if the sender wire travels in a large enough arc to make the  contacts at the bottom and top position of the float . Now someone on this forum a few days ago was showing how to graph a commodore fuel guage mechanism into a FC fuel guage . I kept a few commodore fuel gauges above my bench 5years ago for this reason .Doesn't look like that's very difficult anyway . Be alert for the airlock problem you may have if your tank isn't well baffled . I have overcome this with a very large fuel filter [500mm] positioned just behind the in line fuel pump [the commodore pump wont fit in the tank] . But its probably best if you email me and we can run through the rest of the change over and swap ideas . Cooling system , transmission , other gauges and wiring .Anyway I hope I can help .Cheers Haydn

[hsv-001]

Sorry about this but I was very tired last night .Having reread your post I realize you probably have a modified sender that works on your guage so ,no problem there but the point about the air lock if you have no baffles is valid . When doing these conversions we used the original fuel tank outlet on the original tank but as the early holden tanks had no vent pipe we would drill the filler pipe and the tank return pipe would go through a grommet. Like I said pm me or call [07]55477094. Haydn

[mcl1959]

My feeling is that most people use the commodore tank because it has the sender issues covered and an inbuilt fuel pump that is correct for the engine and so therefore eliminates a lot of modification and noisy external fuel pumps. Your thought on installing new supply and return line fittings are good. These should be as per the commodore tank with appropriate connections. 8mm is fine as suggested by FC427
Does your drop tank have a vent line fitted and have a non vent cap?  These are also needed.
I assume your sender already works in your drop tank so this should be fine.

Ken

[jfk]

Thanks for all that.

My sender is already adjusted to the drop tank and I have a breather etc. The tank was an approved mod for my QLD rego along with all the rest, but I will have to jump through all those hoops again shortly as I've replaced all the running gear and power train.

Haydn, I'll PM you to chat mods next week...... I'm on a boat at present, back to the garage and solid land next week.

Cheers

JK

[NES304]

My feeling is that most people use the commodore tank because it has the sender issues covered and an inbuilt fuel pump that is correct for the engine

Exactly. I used a VH Commodore fuel gauge with a complete VS Tank as it matches the ohms resistance to the VS pump (which runs both V6 and V8)

[hsv-001]

I may be wrong but if you were to use the commodore sender and pump in the commodore fuel tank then you also have to modify your guage because in the back of the instrument cluster there is a resistor to reduce the voltage . This was addressed a few days ago on this forum . As I said ,you already have a tank that will do the job and if your sender and guage are working and your drop tank has a vent pipe and is well baffled then its only a matter of a good electric pump . I think mine is from a VL and is wrapped in a sleeve of high density foam rubber [Clarke rubber I think] and cannot be heard when the car is running . It is mounted on the chassis just in front of the rear DS spring and I have a large filter behind the pump as the FC tank I am using obviously has no baffles . Because I have modified the filler neck to accomadate the non sealing Vauxhall cap do not need the vent pipe . You will need a fuel return line . Cheers Haydn 

[jfk]

Hi

Further to the above, I just wondered what experience anyone had had with rego in NSW.

I'm wondering if I can put a 2.5 litre surge tank in the line and then run the return lines etc to it ?

Just wondering if that will surfice for engineering and rego ?

Cheers

JK

[FCRB26]

Hi JK shouldnt be a problem run your return to your surge tank and have an overflow from the top of that back to your tank.

Most people that havent gone commodore are using a lift pump say black carter into a surge tank then into a bosch 044 ... engineers dont seem to comment to much on fuel systems. must be majority of it hard line no flexible.

[jfk]

Thanks.

JK

[hsv-001]

I just run a FC tank in my V6 Vauxhall with a return line back to a modified commodore sender .I cut the flange of the sender down to fit the FC hole and redrilled the bolt holes to suit but didn't fit the V6 pump . I put one in line in front of a very large Nissan fuel filter[as a surge tank] then sleeved the pump in high density foam like the kind used for roll cages just to quiet it because my Vauxhall is convertible . As I use the VS dash and wiring there is no fuel gauge problem or computer compatibility problem. In my second Vauxhall I have a custom tank with baffles and a commodore sender and pump [simple] . Cheers Haydn