Odd fire and even fire engines

[Dan6457]

Hi there,

Am I right in thinking that Delorean engines are Odd fire, and so is a volvo 760 engine but the only difference is the volvo dizzy has a difference advance curve?

I remember hearing from somone that the volvo was even fire which confused me, is this wrong?

Cheers, Dan

[jerzybondov]

There's some banter here about it (go to page 5 too). Can't say what's right or wrong as I don't know myself, but I'm sure some enlightenment is possible!

http://www.dmctalk.com/showthread.php?t ... ire&page=4

[NickT]

Delorean engine and early volvo b28e/f engine is even fire.
The original design was for a v8 but due to oil crisis at the time decided they would effectively lop off the front 2 pistons.
The odd fire is due to the fact that they retained the V at 90 degrees whereas a V6 should ideally have be 60 degrees.
Due to this the timing is not perfect between each sparking. Look at the top of the distributor cap and you will see the spark plug leads not equally spaced between each other. This engine will also give a slightly lumpiness to the running (although not too noticable)

The later engines were called even fire because to give a smoother running car, the crank was off set between each pair of opposing pistons so the spark timing would be equal. Looking at the distributor cap on an even fire engine, the output spark leags would be equally spaced out at 60 degrees. Bit of a bodge but it was a quick solution to reduce tooling/ re-design costs.

Hope this helps

NickT

[Dan6457]

Cheers Nick, thanks for confirming that.

[Tourettes Tony]

yeah, i would have just said, ones odd and ones even TT