Gas & Mixture Question

[asoupley]

Trying to get the car tuned... I have two questions:

1. What octane gas would I use w/lead substitute (original 1275 head)

2. Trying to get my carbs tuned... when adjusting the jets, after you turn the adjusting nuts two full turns, I have to turn an additional 15 or so to get the mixture rich enough. Is this normal? Mind you this is after I set the timing to 10 degrees @ 1000 rpms.

BTW: New plugs, wires, pertronix ignition, flamethrower coil...

Thanks
Tony

 

[Trevor Jessie]

Re: Gas & Mixture Question

If it is the original head, then it should be fine without lead additive. I've always run the highest grade octane I could afford. The car ran fine on all of it, though it ran better on premium.

I assume you mean 15 flats (15 turns and it would fall out). That sounds excessive. I'd check for air leaks around the carbs/manifold/head.

 

[asoupley]

Re: Gas & Mixture Question

Thanks Trevor, I'll check for air leaks. I remember someone posting a method of spraying carb cleaner, correct?

Why don't you need lead additive? I thought these were designed to need lead? Just curious

 

[Trevor Jessie]

Re: Gas & Mixture Question

If the head is original and has been run with leaded gas for years, then you should have little chance of valve seat recession. Save your money to rework the head and put in hardened seats when (and if) the time comes.

someone will be along shortly to disagree with me.

 

[jlaird]

Re: Gas & Mixture Question

Cause I am told you are not raceing. shrug.

Yup, air leaks for sure. Spray carb cleaner at all the gaskets and both sides of the throtle rod bearings. Not a lot just some, engine should pick up.

 

[asoupley]

Re: Gas & Mixture Question

I'll try that tonight... thanks guys!

 

[Trevor Jessie]

Re: Gas & Mixture Question

No, I meant disagree with me about the lead additive.

 

[DrEntropy]

Re: Gas & Mixture Question

Won't be me, Trev. I consider it all "snake-oil".

And further: agree on premium gas as well. It seems not to degrade as quickly as the other blends, and less chance of pinking.

That's two. /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif

 

[jlaird]

Re: Gas & Mixture Question

Man am I glad with gas prices my tank is only 6 gal.

 

[weewillie]

Re: Gas & Mixture Question

Man am I glad with gas prices my tank is only 6 gal.

almost $1.10/ litre here in King city this a.m. and that's Canadian too. What is it where you are Jack? Wonder what their excuse is this time for keeping it so high.

 

[dklawson]

I'll be the voice of dissent.

Some lead additives are "good" others may be snake oil, most contain phosphorous. My recommendations to you are second and third hand. The transverse A-series racers I know use Red Line additive (which isn't available in stores around here). Supposedly it's the best of the breed. One respected source who has looked into this and recommends it is Keith Calver who is a Mini guru in the U.K.

Trevor, I'm not trying to pick a fight but the lead deposits that once protected our valve seats will be LONG gone by now if the car has run at all. I think the last time I bought leaded gas was sometime in the 1980s. The deposits do not last forever.

As for premium vs. regular... the choice is really up to you. You can always retard the timing a bit if you hear pinging or knocking when running regular gas. Premium gas does not have any more power, however, because it burns more smoothly you can generally advance the timing which does give you more power. A surprising fact regarding regular vs. premium is that it's generally easier to start a car on regular than on premium. This is because the same composition that causes regular to burn "less smoothly" also makes it more volatile... and easy to ignite.

EDIT:
$1.10 / liter ? I'll stop complaining. That's about $3.80 U.S. /Gallon. I got lucky this a.m. and found the last station in the area that had gas at $3.05 for regular.

 

[Trevor Jessie]

Re: Gas & Mixture Question

Thanks Doug,
I always feel better when someone offers a differing opinion. (that way people won't blame me for leading them astray). I'm going from the advice of an old engine builder. He's been rebuilding engine since the mid sixties, and is still doing so today. He suggested that if a car was run on leaded fuel for the first 50,000 or so miles, that it would take another 75,000 or so before you might witness any significant problem running on unleaded (these number are educated guess on his part). The cost of lead additive could easily go towards a head rebuild that would be advisable at that point anyway.

My personal experience: I ran an original head for 30,000 miles on unleaded. the valves and the seats looked great when the head was stripped.

 

[jlaird]

Re: Gas & Mixture Question

$3.17 per gal yesterday.

 

[racingenglishcars]

Re: Gas & Mixture Question

$6.80 per US gal today

 

[dklawson]

Re: Gas & Mixture Question

When I rebuilt the Mini's engine it had probably been driven for about 15 years on leaded gas, followed by infrequent driving on unleaded for the next 20. The valves were very deeply recessed. I ended up buying a later 12G940 head (with inserts) to replace the original one as the AEG163 head didn't have enough meat between the ports to gamble on installing inserts. I wish that years ago they'd found a substitute for lead and the previous owners had used it.

That being said, for most engines you can run them fine without the lead additive until you're ready to rebuild the head anyway, at which time you (normally) can install hardened seats.

 

[asoupley]

Re: Gas & Mixture Question

It was definitely an air leak! Well, I guess it was not much of a "leak"... it was more like me forgetting to plug the vacuum port on the intake manifold. It's amazing how much air comes in through that little hole. After I plugged that, it purrs like a kitten! Brake master cylinder rebuild kit should be here tomorrow, possibly drivable by this weekend...

Thanks for the help!
Tony

 

[jlaird]

Re: Gas & Mixture Question

Arn't the fixes easy when you find em. hehe.

 

[DrEntropy]

Re: Gas & Mixture Question

Be sure to hone that cylinder and check it well.

 

[piman]

Re: Gas & Mixture Question

Hello Trevor,

lead memory and valve seat recession depends on how you drive the car. Thrash it (high revs) and the memory and valve seats will not last for long with unleaded petrol. How long, well that is difficult to say. Keep a regular check on the valve clearances will warn you of impending troubles.

Incidentally, with the dollar nearly half a pound sterling our fuel is about $2.00 a litre here.

Alec

 

[DrEntropy]

Re: Gas & Mixture Question

Cheer up Alec! With the dollar devaluating, you're getting cheaper fuel! /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif /bcforum/images/%%GRAEMLIN_URL%%/jester.gif


...yeah, right. /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif