Unleaded Fuel

[marnol74]

Hello all,

I am sure that this has been much debated in the past however, as a relatively new RSR member I am afraid that I can't find any reference to the subject of running on unleaded. My P3 is a 75 model.

The reason for asking is that I am undergoing some engine work at the minute and with unit removed I would like to consider the options for making it suitable for running on unleaded. I have two initial questions:
- Has anyone experienced burnt valves/valve seat recession on their engine?
- Are hardened valve seats and valves available?

I tempted to believe that the engine is so over engineered and of relatively small displacement for a six cylinder that there is sufficient material to disipate the heat away from the exhaust valve/seat and is therefore not a problem. Does anyone use an lead replacement additve? Is it also wise to use an octane booster?

Any comments, input and experience would be greatly appreciated.


My thanks in advance

Matthew

[P3Steve]

The whole idea of the engine design was to make an engine that would run on all types of fuel don’t forget that back in the forties the quality of fuel could be very indifferent especially in some of the far off colonies which were seen as major markets back then so I don’t think that an octane booster would be needed I do add the Castrol valve master though but would love to here from some of the others whether this is needed, as you say it’s a low revving fairly unstressed engine but other than that I’m not sure.

[marnol74]

Hi Steve,

Thanks for the info; how long/how many miles have you cover since running on unleaded with the Castrol additive? Had your engine been ran previously on leaded fuel? During the rebuid of my engine I am concious that there will be no remaining lead coating the valves and guides.

Thanks again

Matthew

[P3Steve]

I dont have much history of the car before I had it but Ive done about a thousand miles a year for the last ten years and all still seems in good order still. Ive even gone four or five fills and not used any additive but as I say its never pushed that hard (well ok I had a very spirited run on the A12 with a friend in his Stagg the other year which surprised my friend and a few other people in moderns as well) but I dont as a rule go above fifty five mph. I do have a full set of exhaust valves and a spare block just in case I need to do some work in the future.

[Dirkco]

Hello Steve,

The P3 block is quite strong and so is the head. I have a P3 6 light and have been running unleaded for years now and not had any issues. I decided when I restored the car after running it for a few years to up rate the diff to a later P5 so I could cruise on the US hi-ways at a respectable speeds. I would say that no special accommodations are needed for the P3 either in gas or additives. I don't plan to do anything different then I have been doing for the last 5 years I run premium unleaded.

Hope this helps

Dirk in the States

[P3Steve]

Hi Dirk
I have seen this said about the P3 block being strong enough as it is but was not knowlegeable enough to have claimed it my self. Thats a good idea about the diff as well and I beleive one of the other things one can do is change the gearbox for an overdrive P4 box as well though you lose the free wheel in the process. I've kept my car fairly standard in that respect as in my part of the UK (Norfolk) its quite rural with no major motorways (Freeways) nearby so the gearing is suited to the typical winding country roads we have here.
ps I found this on youtube the other day its a bit of home video someone took at a local car show and my P3 is the forth car in from the start after the blue Bently as the camera pans round. You might want to check out the P3 six light at 1-12 seconds into the video its a heavily customized one fitted with a Rover 3.5lt V8 like it or not the guy saved it from being scrapped, its very well done and to be honest although not to my taste it is rather good.

http://www.youtube.com/watch?v=UhFivPvqRPI

[marnol74]

Dirk, Steve,

Thanks for your comments; I think that I will follow in the same vane in that case.

Dirk; I'm interested in the P5 diff upgrade that you mentioned and have started a new topic to discuss it.


Thank again

Matthew

[Paul Gregory]

Hi everyone,
I agree with what seems to be the general view with regards running on Unleaded. I initially used some Castrol Valvemaster but generally don't know. I do about 1000 miles a year and have not become aware of any issues.
Regards
Paul