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Fuel question.

wtaylor

Silver Level Sponsor
Last weekend I installed the Weber conversion kit from Alpine Innovations. I had about 3/4 of a tank of ethanol-free 87-octan. Today was the first day I had a chance to get it out on the road, and man can you tell the difference. It runs a lot smoother and has more get-up-and-go. It does seem to be a little more cold-natured. According to the gauge, it is running a lot cooler after warming up. I don't think I have the idle set quite right just yet and am having more spark knock than before.

Just wondering if those of you who have made this change before have recommendations on fuel before I work to get it filed on this tank.
 

hartmandm

Moderator
Diamond Level Sponsor
I think the fuel question has more to do with your ignition setup than your carburetor. What is your ignition setup (distributor, coil, plugs, timing advance, ...)? e.g. stock Lucas distributor with original timing advance weights, rebuilt stock distributor with modified timing advance weights, Pertronix, ... ?
 

wtaylor

Silver Level Sponsor
I think the fuel question has more to do with your ignition setup than your carburetor. What is your ignition setup (distributor, coil, plugs, timing advance, ...)? e.g. stock Lucas distributor with original timing advance weights, rebuilt stock distributor with modified timing advance weights, Pertronix, ... ?
I was asking because that was the only change made to the car. It is the stock distributor with an electronic conversion. I don't know which one, it is the way the car came to me and I can't see any marking on it. With the old carbs, it seemed to like the ethanol-free 87 the best. With the new carb it appears to be more cold-natured and more spark-knock. My mechanic said after I ran it for a couple of weeks he would stop by the house and check it over and make any needed adjustments. I am mainly just asking if others running this carb setup have found it likes one fuel over another.
 

husky drvr

Platinum Level Sponsor
I am mainly just asking if others running this carb setup have found it likes one fuel over another.

Keep in mind, the carb(s) haven't got a care in the world about what fuel is being metered. The engine, and how it's tuned decide what fuel is liked or disliked. The carb meters by throttle position and airflow. It's a full mechanical analog system without any way to adjust except by the way it's assembled and adjusted.

At this point, the AI kit is considered to be a known good system. The way your engine is described as now running show just how far from optimal your tuning and fuel have become.

If you can hear spark knock, that is a bad sign. Rootes recommended to use premium fuel with both alloy and iron H/C 1724 engines. I suspect you'll have to change fuel, retard your timing to end spark knock, and re-baseline your carb settings.

Hope this helps,

1716241128098.png
 

albeam

Donation Time
wtaylor,

you need to use the best octane rated fuel you can get. i do not know how it works in the US but in OZ i am running pump 98 octane and even though it is expensive the car goes much happier with it.

Albeam
 

Tim R

Silver Level Sponsor
In the U.K. I run the Alpine Innovations curved manifold and single Weber carb set up. I use 99 octane (currently with zero ethanol in it). The car is bored +0.060, Vizzard style head modification, standard pistons, a 3.7 Differential and overdrive. Since fitting this carburettor the car ticks over strongly at around 600rpm, accelerates like a train and will give me 400 miles to a fill up (up from around 280 miles). I just think that you have a timing issue. Get your mechanic to set the timing correctly and tune the carb to match and you will have a great set up.
Tim R
 

Acollin

Platinum Level Sponsor
What is better?
1) higher octane
2) non ethanol fuel
I ask because I think I can buy 92 non - ethanol or 98/99 octane.
 

Mike O'D

Gold Level Sponsor
The UK uses a different octane rating system. UK 95 is about 91 US. Our "premium" is 93, which I imagine is your 99.
Acollin - non ethanol is good for all of the reasons you can read about on the internet and would be good for the Alpine. I don't know where you are able to buy 98/99 in the US other than maybe special race gas.
 

husky drvr

Platinum Level Sponsor
What is better?

Best answer is "It depends."

It's a cost-benefit ratio thing, your goals, and your car's condition.

Generally in your Alpine, the least ethanol and highest octane would be the better choice. That choice might not be the best fit for your needs, usage, and car's condition.

This Kelly Blue Book article and the video can help answer your question.


 
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