The 'E' Type Forum

Hello all,

Will be starting the refurb of my series 2 soon.

Any adaptations I need to do for the car to run on unleaded?


thanks
Bill


Series 2.1969 2+2. US import.
Merc R107 300sl. 1989

As far as I know, none. The valve seats are already hardened

8:1 pistons?

Don't think it matters whether it's 8:1 or 9:1, valve seats the same. You might want to wait and check with others on here who know more than I, but i'm reasonably confident that's right.

You're right, Malcolm. All E Types run just fine on unleaded. The only problem with modern fuels that some have experienced is due to EtOH in some of the blends: water vapor absorption leading to tank rusting and eating away at rubber components in the fuel lines. I've been running E10 (10% ethanol) for ten years without any problems.

I was thinking about pinking due to generally lower octane ratings with unleaded.

64etype wrote: ↑

Tue Dec 04, 2018 7:23 pm

I was thinking about pinking due to generally lower octane ratings with unleaded.

Might be a problem if you have higher compression in your motor. I use 95 RON with no problems. My engines have around 160psi compression.

I had no end of trouble with a car with compression around 185/190psi and finally ended up fixing the problem by fitting a very thick head gasket and lowering the compression.

In general it is sensible to use 8:1 pistons if you rebuild, to compensate for skimming of the head and block.

As mentioned above the seats are already fine for ULP use.

64etype wrote: ↑

Tue Dec 04, 2018 4:02 pm

8:1 pistons?

What do the pistons (compression ratio) have to do with running on unleaded or not - octane level of the fuel yes but not whether it is unleaded or not.

Sorry saw this later

64etype wrote: ↑

Tue Dec 04, 2018 7:23 pm

I was thinking about pinking due to generally lower octane ratings with unleaded.

You just buy the unleaded fuel that has the octane rating to suit your engine. 98 Octane unleaded works fine in engines that required the old UK 5 Star.

cheers

garry

Even octane rating doesn't seem that sensitive. I'm on 9:1 pistons. I buy the highest Octane I can, normally 97, but often 99 (Shell or Tesco) However, touring the backwaters of France and Spain I often had to settle for 95 and it ran fine.

thank you loads everyone.

Rgds
Bill



Series 2. 2+2 1969 US import.
Merc R107 300SL