MinorForum

Morris Minor Chat

best fuel for a 948 Minor

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

373737 Gold Member Michael Rand
Sharon, CT, USA   USA
I am asking the assembled Minor aficionados as to what is the preferred gas for a 948 powered car ?
I am assuming leaded.
I am assuming ethanol-free.
Are these assumptions accurate ?
I have access to leaded race gas but thigh octane, like 110 or 112.
I have access to ethanol free 100 octane fuel.
I have access obviously to 93 octane but NOT ethanol free.
I have had negative experiences with ethanol gas and prefer to steer clear.
Given the year, it is a 1961 with a 948 motor, I am thinking any leaded ethanol free gas of 93 octane would be good ?

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
emjay Jim English
Marietta, PA, USA   USA
There is no need at all for extra octane. I run just fine on 87 octane, unleaded, with up to 10% ethanol. If you don't plan to drive much finding pure gas may be a good idea. The only issue is using left over low vapor pressure winter fuel on a hot day. Vapor lock before the pump will cause the pump to go crazy and may stall.

373737 Gold Member Michael Rand
Sharon, CT, USA   USA
Jim, thank you very much.
I did not mean to imply I was interested I using those high octane leaded, merely I had easy access to them.
I was just curious if unleaded with ethanol had created problems for any Morris owners.
It would seem the leaded fuels would be "good" for the motor and valves etc.....

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
John in Eugene Avatar
John in Eugene Gold Member John Quilter
Eugene, Oregon, USA   USA
Very sound advise. I run my two Minors with stock 948cc engines on 87 octane with 10% ethanol with no problems. Tried the no ethanol 92 octane for one tank and noted no difference at all.
Why spend an extra $1 per gallon for nothing?

John F. Quilter
Eugene, Oregon USA



In reply to # 26158 by emjay There is no need at all for extra octane. I run just fine on 87 octane, unleaded, with up to 10% ethanol. If you don't plan to drive much finding pure gas may be a good idea. The only issue is using left over low vapor pressure winter fuel on a hot day. Vapor lock before the pump will cause the pump to go crazy and may stall.

66jalopy Avatar
66jalopy Silver Member Phillip Jolliffe
Lake City, FL, USA   USA
Some old fuel lines may be adversely affected by ethanol but most have already been changed in regular maintenance. Biggest problem with ethanol gas is it going bad much faster than non ethanol. If you use the car regularly it should not be a problem. I can get 89 octane boat gas here, I like it better and my car does run better with it but I have a high compression 1275.

w3526602 John Williams
Burton Latimer, Kettering, Northamptonshire, UK   GBR
Hi,

Increasing the compression ratio speeds up the burn-rate, can cause pinking. Increasing the fuel octane rating slows the burn-rate, allowing the extra power from the high compression, but without the pinking.

Cars have been run on "liberated" aviation spirit (120 octane?) resulting in burnt valves. My theory is that the fuel was burning so slowly that it was still burning when the exhaust vales opened.

Can anybody translate the above into correct technical language?

The general advice in UK, is to run your engine on pump petrol until the valves die, then convert the head to lead-free. This is cheaper than paying for posh 4-star petrol, or adding additives. I have not yet heard of anybody having to convert their heads. It's a different matter if you are have major engine work done, where you can share the cost of lead-free valve with the other overheads.

I understand that modern fuels can affect fuel pipes and seals, etc, on older cars. I don't know any more than that.

My mate had a 1920's 'bull-nose' Morris, which suffered badly from vapour lock on hot days. His solution was to add a little paraffin to the petrol tank. I believe that a small amount of paraffin can be considered an additive, and does not offend Her Majesty's Revenue Men. It might be sensible to ask them.

John (602)

66jalopy Avatar
66jalopy Silver Member Phillip Jolliffe
Lake City, FL, USA   USA
My dad had a Fordson tractor in England. It had two tanks, one petrol and a larger paraffin. You would start the engine on petrol and when warm switch to paraffin for the rest of the day, turning engine off by closing due valve to empty the carburetor. It was magneto, no battery so hand start only.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
emjay Jim English
Marietta, PA, USA   USA
I think we call paraffin kerosene on this side of the Pond and it was also common to have flex fuel farm vehicles back in the day. Octane isn't so much as slowing the burning but increasing the pressure at which it might ignite. Since the incoming charge already has the fuel in it (at least until recently), it's very important to only have the explosion happen with the spark plug, It it happens before, you'll get a ping. The combustion engineers talk about flame propagation and all that, but it all happens so fast, it surely must be all burnt before the piston gets to the bottom of the stroke. The best thing to do for fuel lock (short of clothes pegs) is to make sure you have summer formulated fuel. The fuel companies may start backing off on doctoring the fuel in the summer to raise the vaporization pressure since most cars now have high pressure fuel injection with the pump in the tank.

0123 Mike D
Biddulp, Staffs, UK   GBR
In reply to # 26424 by w3526602 Hi,

Increasing the compression ratio speeds up the burn-rate, can cause pinking. Increasing the fuel octane rating slows the burn-rate, allowing the extra power from the high compression, but without the pinking.

Cars have been run on "liberated" Stolen aviation spirit (120 octane?) resulting in burnt valves. My theory is that the fuel was burning so slowly that it was still burning when the exhaust vales opened.

Can anybody translate the above into correct technical language? The other technical stuff seems fairly clear smiling smiley

Apart from that, Isn't
pre-ignition, or, more properly
detonation the problem
with higher octane petrol.

Detonation causes higher temps
and exhaust valve/seat erosion.

A friend, with considerable experience
at running 45s on avgas says he had
no problems from using it


The general advice in UK, is to run your engine on pump petrol until the valves die, then convert the head to lead-free. This is cheaper than paying for posh 4-star petrol, or adding additives. I have not yet heard of anybody having to convert their heads. It's a different matter if you are have major engine work done, where you can share the cost of lead-free valve with the other overheads.

I understand that modern fuels can affect fuel pipes and seals, etc, on older cars. I don't know any more than that.

My mate had a 1920's 'bull-nose' Morris, which suffered badly from vapour lock on hot days. His solution was to add a little paraffin to the petrol tank. I believe that a small amount of paraffin can be considered an additive, and does not offend Her Majesty's Revenue Men. It might be sensible to ask them.

John (602)

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
John in Eugene Avatar
John in Eugene Gold Member John Quilter
Eugene, Oregon, USA   USA
The general advice in UK, is to run your engine on pump petrol until the valves die, then convert the head to lead-free. This is cheaper than paying for posh 4-star petrol, or adding additives. I have not yet heard of anybody having to convert their heads. It's a different matter if you are have major engine work done, where you can share the cost of lead-free valve with the other overheads.

I understand that modern fuels can affect fuel pipes and seals, etc, on older cars. I don't know any more than that.


I think the above is sound advise. I have been running 5 vintage British cars, two Minors with 948cc engines, one Austin 1300 (1275cc) one MGTD and one 1965 Jaguar 3.8S on unleaded USA gasoline for over 40 years and suffered no valve issues. Furthermore, I have not had any fuel hose or fuel pump issues with the 10% ethanol gasoline.

John F. Quilter
Eugene, Oregon USA

0123 Mike D
Biddulp, Staffs, UK   GBR
In reply to # 26440 by John in Eugene The general advice in UK, is to run your engine on pump petrol until the valves die, then convert the head to lead-free. This is cheaper than paying for posh 4-star petrol, or adding additives. I have not yet heard of anybody having to convert their heads. It's a different matter if you are have major engine work done, where you can share the cost of lead-free valve with the other overheads.

I understand that modern fuels can affect fuel pipes and seals, etc, on older cars. I don't know any more than that.


I think the above is sound advise. I have been running 5 vintage British cars, two Minors with 948cc engines, one Austin 1300 (1275cc) one MGTD and one 1965 Jaguar 3.8S on unleaded USA gasoline for over 40 years and suffered no valve issues. Furthermore, I have not had any fuel hose or fuel pump issues with the 10% ethanol gasoline.

John F. Quilter
Eugene, Oregon USA

Would you kindly define "Valves die" please John?

w3526602 John Williams
Burton Latimer, Kettering, Northamptonshire, UK   GBR
<<< The combustion engineers talk about flame propagation and all that, but it all happens so fast, >>>

Hi,

To put that in context, at 6000rpm, your engine is turning 100 times per second. (A UK domestic light bulb flashes 50 times per second.) I think that means each spark plug is sparking 50 times a second ... virtually a continuous spark.

Take a few seconds to ponder on the forces required to accelerate a piston from stationary at BDC to an average speed of ... doh ... I have a figure of 2200 ft per minute, can anybody correct me? ... and back to rest at TDC (about 3 inches).

Lead was added to petrol to increase the octane rating. we can compensate for reduced octane rating by retarding the ignition (but I never do) or lowering the compression ratio (Volvo suggested fitting two head gaskets). I don't bother doing that either.

Lead had another bonus ... it acted as a lubricant for the valve seats. This led to dire warnings about valve seat erosion ... which seems to have never happened. Just pour pump petrol into your tank, drive until it dies (which might be never) then have your head rebuilt for lead-free. You will save money in the long run.

John (602)

John in Eugene Avatar
John in Eugene Gold Member John Quilter
Eugene, Oregon, USA   USA
Thanks for these statistics. I marvel at how my engines stay together even at my more moderate engines speeds of less that 4500 RPM.

John F. Quilter
Eugene, Oregon USA

In reply to # 26446 by w3526602 <<< The combustion engineers talk about flame propagation and all that, but it all happens so fast, >>>

Hi,

To put that in context, at 6000rpm, your engine is turning 100 times per second. (A UK domestic light bulb flashes 50 times per second.) I think that means each spark plug is sparking 50 times a second ... virtually a continuous spark.

Take a few seconds to ponder on the forces required to accelerate a piston from stationary at BDC to an average speed of ... doh ... I have a figure of 2200 ft per minute, can anybody correct me? ... and back to rest at TDC (about 3 inches).

Lead was added to petrol to increase the octane rating. we can compensate for reduced octane rating by retarding the ignition (but I never do) or lowering the compression ratio (Volvo suggested fitting two head gaskets). I don't bother doing that either.

Lead had another bonus ... it acted as a lubricant for the valve seats. This led to dire warnings about valve seat erosion ... which seems to have never happened. Just pour pump petrol into your tank, drive until it dies (which might be never) then have your head rebuilt for lead-free. You will save money in the long run.

John (602)

0123 Mike D
Biddulp, Staffs, UK   GBR
Not for me thanks John :-(

I keep a check on mpg.
When I get a sudden drop
I sort it.

Same if it's reluctant to start.

Plugs, points, compression.



In reply to # 26446 by w3526602 <<< The combustion engineers talk about flame propagation and all that, but it all happens so fast, >>>

Hi,

To put that in context, at 6000rpm, your engine is turning 100 times per second. (A UK domestic light bulb flashes 50 times per second.) I think that means each spark plug is sparking 50 times a second ... virtually a continuous spark.

Take a few seconds to ponder on the forces required to accelerate a piston from stationary at BDC to an average speed of ... doh ... I have a figure of 2200 ft per minute, can anybody correct me? ... and back to rest at TDC (about 3 inches).

Lead was added to petrol to increase the octane rating. we can compensate for reduced octane rating by retarding the ignition (but I never do) or lowering the compression ratio (Volvo suggested fitting two head gaskets). I don't bother doing that either.

Lead had another bonus ... it acted as a lubricant for the valve seats. This led to dire warnings about valve seat erosion ... which seems to have never happened. Just pour pump petrol into your tank, drive until it dies (which might be never) then have your head rebuilt for lead-free. You will save money in the long run.

John (602)

0123 Mike D
Biddulp, Staffs, UK   GBR
All down to a bearing oil
pressure of thousands of PSI thumbs up
.
In reply to # 26448 by John in Eugene Thanks for these statistics. I marvel at how my engines stay together even at my more moderate engines speeds of less that 4500 RPM.

John F. Quilter
Eugene, Oregon USA

In reply to # 26446 by w3526602 <<< The combustion engineers talk about flame propagation and all that, but it all happens so fast, >>>

Hi,

To put that in context, at 6000rpm, your engine is turning 100 times per second. (A UK domestic light bulb flashes 50 times per second.) I think that means each spark plug is sparking 50 times a second ... virtually a continuous spark.

Take a few seconds to ponder on the forces required to accelerate a piston from stationary at BDC to an average speed of ... doh ... I have a figure of 2200 ft per minute, can anybody correct me? ... and back to rest at TDC (about 3 inches).

Lead was added to petrol to increase the octane rating. we can compensate for reduced octane rating by retarding the ignition (but I never do) or lowering the compression ratio (Volvo suggested fitting two head gaskets). I don't bother doing that either.

Lead had another bonus ... it acted as a lubricant for the valve seats. This led to dire warnings about valve seat erosion ... which seems to have never happened. Just pour pump petrol into your tank, drive until it dies (which might be never) then have your head rebuilt for lead-free. You will save money in the long run.

John (602)

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions

Members Sign In   or   Create an Account

Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster





Join The Club

Sign in to ask questions, share photos, and access all website features

Your Cars

1972 Morris Marina

Text Size

Larger Smaller
Reset Save

Sponsor Links