Detonation in my 59AB engine

[Pete]

Originally Posted by 40 Deluxe

Don't forget, if you're cruising the drive-ins you need to pay road tax on that alcohol!

Yea, that's why any more, you can only get av gas at the local airport by pumpimg it directly into an airplane.

I have always wondered, if you have an antique wood fired steam car, how do they figure the tax on the wood?

[qmdv]

Originally Posted by Brian

The distributor you get third gen to modify will fix your detonation...using the '68' advance curve is a far better solution than either retarding the whole distributor, or cranking down the vacuum brake...

Why do they call it "68 advance curve"? Dist sent off yesterday

[qmdv]

[QUOTE=Pete;2205963]Yea, that's why any more, you can only get av gas at the local airport by pumpimg it directly into an airplane.

At my airport anybody can drive up with car or boat and fill up. The upside of very rural Idaho

[Pete]

[QUOTE=qmdv;2206096]

Originally Posted by Pete

Yea, that's why any more, you can only get av gas at the local airport by pumpimg it directly into an airplane.

At my airport anybody can drive up with car or boat and fill up. The upside of very rural Idaho

I look forward to Greater Idaho.

[qmdv]

[QUOTE=Pete;2206098]

Originally Posted by qmdv

I look forward to Greater Idaho.

No you want lesser Idaho

[Brian]

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Why do they call it "68 advance curve"?

In post#7 I put up a chart, a bit hard to read, sorry, that shows the advance details of various distributor versions. The '68' refers to 1936 model Fords. The consensus of majority of people on here, is that the 11A advance is most desireable on account of it having more advance. My finding is that with a high compression engine, such as yours, this particular advance comes on too fast, and too soon, leading to the detonation you're experiencing. Using this setup, sure, you can retard the whole distributor, so you don't get to the 24 degrees, but the whole kaboodle is retarded, and the engine will be 'flat' at lower revs. Using the 68 advance, you'll end up with less total advance, but a more favourable curve throughout the rev range. When you get your distributor back from Michael, please post your results...I'm sure you'll be happy.

[Brian]

Read this thread, very informative;
https://www.fordbarn.com/forum/showt...=advance+curve

[qmdv]

So I sent in an extra well worn crab dist to Third Gen Automotive. Got it back with the style "68" weights. Installed yesterday and just got back for a test drive today. Only complaint is that 40 degrees out. So here is the deal. Stock crab dist had severe detonation with 87 octane non ethanol. No detonation with 100LL av gas. Some detonation with 91 non ethanol. Slight detonation with the 91 and the advance brake turned in 5 full turns. I could have lived with that if I had to.

Drum role please, With Third Gen modified crab dist, Zero detonation with 91 octane non ethanol gas. So I need to burn up some of that and test it with some 87 and 89 octane. I am quite pleased

[Phil Gillespie]

Originally Posted by qmdv

So I sent in an extra well worn crab dist to Third Gen Automotive. Got it back with the style "68" weights. Installed yesterday and just got back for a test drive today. Only complaint is that 40 degrees out. So here is the deal. Stock crab dist had severe detonation with 87 octane non ethanol. No detonation with 100LL av gas. Some detonation with 91 non ethanol. Slight detonation with the 91 and the advance brake turned in 5 full turns. I could have lived with that if I had to.

Drum role please, With Third Gen modified crab dist, Zero detonation with 91 octane non ethanol gas. So I need to burn up some of that and test it with some 87 and 89 octane. I am quite pleased

Sounds like a good result and hopefully its all now in the past.
All the best.
Phil NZ

[Mart]

Congrats, I'm glad Michael was able to get you a combo that works.

[qmdv]

Originally Posted by Mart

Congrats, I'm glad Michael was able to get you a combo that works.

They were great. I was treated like I was their best customer.

[qmdv]

Lots of rain equals poor roadster weather but I did do more testing. Drained out the 91 non ethanol gas and put in some 87 non eth. There is no detectable detonation even when really getting it to it. I am not sure why changing the advance had such a big effect. Car runs great.
Now just waiting for roadster weather.

[35fordtn]

I am glad this resolved your issue and thank you for letting us tackle it