stefanb

M42 engine swap / 46 liter gas tank, compatibility

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hi All

 

I've got a m42 engine swap scheduled with Jake B of classic daily, in September. Before that, I'm trying to remedy the gas vapor fumes, and swap out my gas tank for a new one. The 1968 model takes a 46 liter fuel tank

 

Two questions –

 

- Has anyone done the m42 swap, in a older car with a 46 liter tank? Is the tank deep enough to fit the e30 fuel pump? I've secured a (1991 318i engine and trans)

- If the 46 liter tank doesn't work, can a 68 roundie take on the newer 51 liter tank? And I'm assuming the 51 liter tank works fine, with the m42 swap?

 

many thanks... I'm new, but trying to learn up.

The forum has been great

 

Stefan

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Stefan, the pump doesn't reach the bottom of the tank in my '72 and I never extended the bracket. If anything, the pump might sit closer to the bottom of your lower volume tank. I'd bet it'll fit fine.

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thanks for the info, Skip.

 

Would you happen to know if the earlier 1968 model, can update to a 51 liter, from the old 46 liter tank?

I'm hoping to do that as well... that way clearance is guaranteed.

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Yes you can. You may run into different bolt locations but no big deal to adapt

 

Edit as long as the fuel necks are same 

 

 

 

 

Edited by BLUNT

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The fuel necks are different.  However, the earlier boot will fit over the later tank-

you're miles ahead if you make a 'cap' that fits over the end of the later tank so that

it retains the gas station filler and then vents the air back out separately...

 

t

 

Edited by TobyB

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thanks Toby.

 

I noticed that as well. My early neck is much longer, than the one I bought off Rogers tii.

I did a buy an adapted nozzle that another FAQ member sold...since  these California pumps are really hard to fill up at. Hopefully this should avoid future spillage.

 

You're mentioning something different though. 

If you know of any links that explains how to make that "cap"... I'd love to read up on it.

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It's just a cap that fits over the end of the tank inlet that sticks up into the boot.

I put the nozzle hole low, to angle the nozzle down into the tank.  It was 'wedge- on'

tight, since I didn't trust it to work....

 

t

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thanks Toby. If you're able to send over a pic of what that modified cap looks like, it be much appreciated. Do you happen to know any of the part numbers used to make it?

 

Attached is a photo of my current tank and neck. I'm tempted to just order the 46 liter tank and leave it be - but with enough research maybe I can pull the 51 liter off.

It's the safe bet for fitting the e30 fuel pump.

 

This one thread has been quite interesting...

 

 

68_Gas Tank.JPG

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Sorry, it's a fabricated thing-

about an inch of exhaust pipe, cut and welded to a tight fit over the extended neck

of the tank, with a disc of metal welded to the face of it.  A 1" hole drilled in the disc, with

something like a 1/4" vent hole at the top.

I'll add a bit of Paint art when I get time at work.

 

t

 

<edit- that's it, below.  It spit some gas out sometimes, but it was a lot better than before.  It was so hard to 

get to after installation that I never tried to make it fancier...>

filler cap.jpg

Edited by TobyB
added pic

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