Lead to Unleaded conversion advice needed

Hi, I would like a picture of your 1985 Passat for one of the Passat groups that I help run on Yahoo please. I need some clean pictures of the early Passats. ;-)

I believe we call your 1985 Passat a Quantum here in the USA and the engines here seem to run fine on unleaded fuel since the late 1970's.

thanks, dave (> What do I have to do to convert my 1985 Passat to unleaded now that LRP is

Wow, that's a question I've not seen in a Long Time.

Most manufacturers started using suitable exhaust valves in the mid to late 1970's as leaded fuels were phased out. There is a *very* small chance that any modification will be needed, but if one is, this is probably it.

Even if research shows you that this engine should have different (e.g., sodium-filled) exhaust valves, there is little to no advantage to pulling the head in advance to do the work. It would cost about the same whether they are changed preemptively or after they start to burn (reduced mileage and power should alert you *more* than early enough to avoid being stranded, and the seats usually clean up OK--and if they don't they are not that much more expensive to replace).

Also, as I said, the chances that a mid-80's engine will need anything at all are very small. This is more a problem for engines a decade or more older than yours.

WELL you could join the passat groups and submit pictures there. We would definitely want you in the groups. ;-)

Or send them to my address. vwdoc1 (at) hotmail (dot) com

thanks, dave (> Hi Dave. Interesting links. Thanks. I've owned my Passat from new and have

Many thanks JRE. That's good advice. Obviously you know what you are talking about. If that's so it sounds like I'm off the hook - hooray. I've written to VW giving them details of the car and asking about the need for conversion. Just one more thing JRE. When this business about changing to lead free started we were advised to advance the ignition timing and simply fill up with unleaded. I did and as a result the car lost power developed flat spots and started pinking. I assumed this was because of the fuel and switched back to leaded/LRP and reset the timing. If you are right were the problems caused only by change in ignition timing then? Many thanks.

RD

JRE wrote:

OK Dave next time I clean and polish the beast I'll either send you the pics or join the group and put them up there. It wont be next week or even this year but I will do it. I've saved your email. Thanks for your help.

RD

While it is possible it may need new valves and seats, it is not likely. Unless VW was making two versions of their engines at the time, yours came unleaded ready.

In the event it did not, it could burn the valves and then you would have to replace them, which is what you would have to do to update it.

Yep by the mid 1980s, the difference between a leaded-fuel European car and an unleaded-fuel US car is pretty much the presence or absence of a catalytic converter (leaded fuel fouls a cat). Engines are substantially the same.

The valve issue is really an issue for cars made for leaded fuel when unleaded wasn't even in the picture at all (early 1970s and earlier).

FWIW: my 1986 Jetta, designed for leaded gas (MZ engine, no cat, large filler neck) runs just fine on unleaded and has no issues, exhaust valves or otherwise.

A bit of experimentation showed that it runs better on mid- grade (power, knocking) rather than regular. So mid-grade unleaded it is. Stock ignition timing: if it ain't broke, don't fix it.

Laura Halliday VE7LDH "Non sequitur. Your ACKS are Grid: CN89mg uncoordinated." ICBM: 49 16.05 N 122 56.92 W - Nomad the Network Engineer

On Dec 10, 4:08 pm, "ukdodger via CarKB.com" wrote about my Jetta and its performance on mid-grade unleaded:

Yup.

I had some knocking on unleaded regular. On mid-grade, everything is fine, with noticeably more power. No knocking, no other issues.

I also looked at the numbers, the octane rating of leaded regular, circa 1987, and unleaded regular, now. At least here in Canada, unleaded regular has a lower octane rating than the leaded regular of Ye Olden Tymes.

Laura Halliday VE7LDH "Non sequitur. Your ACKS are Grid: CN89mg uncoordinated." ICBM: 49 16.05 N 122 56.92 W - Nomad the Network Engineer