Going dead at 80 mph

[Tommyt]

It looks like a lot of us (med included) appreciate your sharing the info reK the fuel evaporative canister having caused some of your problems. Moreover, it looks like ethanol and/or water in the fuel was also involved. The ethanol tends to absorb water, so it could have been a combination of factors involving the ethanol fuel.

In our area the only non-ethanol gasoline we have has a mere 90 octane. It leaves me having to run our vintage pony car engines at 6 degrees BTDC, instead of moving the timing to 12 degrees, where they begin to liven up. I prefer to run a little on the detuned side with non-ethanol fuel as opposed to running higher octane with ethanol. I haved seen, and heard, too much about the adverse impact of ethanol on these older engines and fuel systems.

I haven’t ran ethanol in this car. I’m quite content with 90 octane. We have 93 if I want to drive 15 miles but 90 is 5 minutes down the road. For a H code engine it does really good. I don’t know how black charcoal makes white junk but it do.

 

[Tommyt]

I haven’t ran ethanol in this car. I’m quite content with 90 octane. We have 93 if I want to drive 15 miles but 90 is 5 minutes down the road. For a H code engine it does really good. I don’t know how black charcoal makes white junk but it do.

Perhaps the water came from the canister. The charcoal was wet and mushy and the car set outside for the three years I tried to buy it.

 

[mrgmhale]

Just curious, but I run non-ethanol 91 oct. gas on an engine with 9.8:1 compression, timing at 14 degrees initial with 20 degrees crank (10L slot) with zero spark knock even if at times I do have to run with ethanol gas. I did have considerable knock issues before with an earlier 11:1 rebuild, with 6 to 8 degrees initial timing with 30 degrees on the crank (15L slot). The cam is a Melling MTF 2, so just a mild cam. IF and I do mean IF, I could get 94 non ethanol still, I might have been ok with the 11:1 motor. Other issues meant I could take the opportunity to install 13cc dish top pistons and be able to run 91 fuel.
What I'm getting at is, if I can run with similar octane, ethanol or not, why do you feel it necessary to drop your initial timing to only 6 degrees? To be fair, my factory Autolite distributor has been changed by welding and recutting the original 15L slot to a 10L plus I use 1 heavy spring and 1 Mr.Gasket 925D set to give the timing all in around 2800 rpm. It pulls like a train.
Don't get me wrong, I'm not being critical of your choice, just trying to understand more for my own furtherment of knowledge.

In our case, out 1969 Shelby GT500, with its 428CJ engine) will ping if I go any further advanced than 6 degrees BTDC. It has an original 87,000 miles on it and the engine, and its compression is still quite good as the prior owners (and me) have obviously made certain the oil is always fresh. I have decided to not try to use any octane boost additives and just live with the factory setting. My days of chasing every possible bit or power from an engine, and racing around all over town are far behind me. My focus now is on reliability and comfort.

That you are able to run with more than the factory timing setting is a good thing. There are factors other than just an engine's compression ratio that will cause an engine to ping under certain circumstances. One of the factors is a harmonic balancer, with its timing marks, may have slipped and is no longer showing correct timing information. Thus, it is possible I "think" I am running at 6 degrees BTDC, but am actually running more advanced than I realize. I have not tried to "power time" the engine, yet. your question is causing me to think that perhaps I ought to do it, wooner than later. Just because...

 

[Stanglover]

In our case, out 1969 Shelby GT500, with its 428CJ engine) will ping if I go any further advanced than 6 degrees BTDC. It has an original 87,000 miles on it and the engine, and its compression is still quite good as the prior owners (and me) have obviously made certain the oil is always fresh. I have decided to not try to use any octane boost additives and just live with the factory setting. My days of chasing every possible bit or power from an engine, and racing around all over town are far behind me. My focus now is on reliability and comfort.

That you are able to run with more than the factory timing setting is a good thing. There are factors other than just an engine's compression ratio that will cause an engine to ping under certain circumstances. One of the factors is a harmonic balancer, with its timing marks, may have slipped and is no longer showing correct timing information. Thus, it is possible I "think" I am running at 6 degrees BTDC, but am actually running more advanced than I realize. I have not tried to "power time" the engine, yet. your question is causing me to think that perhaps I ought to do it, wooner than later. Just because...

Thanks for your interesting reply.
First, your Shelby GT500 is one awesome car. The 428 is a motor I have no knowledge of, so timing that motor is totally in your area of expertise.
As for the 351C, it's generally known that those motors seem to like much more initial timing than the factory set them at and we also know that was probably more to meet emissions demands than for performance. At least, that is my understanding.
As for my motor, at 87K original miles, it was getting tired and burning oil. I had it rebuilt at a local well known engine rebuilders. At that time, the builder decided to install a high volume oil pump and a Pertronix Ignitor III electronic module. The original factory distributor had been replaced with a Cardone reman at an earlier date, but was to factory spec for the 4V, i.e. 15L (30 degree) timing slot, factory spec springs. Initially, I had a world of issues with the timing. I'll not go into details, but the PIII's bad design was the issue. Pertronix replaced that with a PII and matching coil under warranty.
Timing continued to be an issue, but I was learning with the help of many great members here to understand it. I'll not go further into that right now, but jump ahead to the second rebuild. That was undoubtedly caused by the HV oil pump and again I'll not expand on that.
I did take the opportunity to remove the KB flat top pistons and install 13cc dish top. With zero deck, the static comp ratio is about 9.8:1 That alone dropped the pre-ignition knocking, but more needed to be done to run cleanly on Shell 91 non-ethanol gas. That's when I started to learn about the timing slots and spring choices. Knowing that the total mechanical timing needs to be a max of about 36 degrees and that many here say that 14-16 degrees of initial timing is the sweet spot, that means that the total crank degrees needs to be no more than 20 degrees. To achieve that, I stripped another distributor I had, welded the righthand side of the 15L slot and recut it to .410" which is a 10L slot dimension. With that done and tested, all I needed was to play with springs and tension to get the curve right. I ended up with a factory original heavy spring set to just loose and a Mr.Gasket 925D (I think!) set with slight tension. By the way, the harmonic balancer was new at the first rebuild. I have no reason to suspect that as an issue.
This combination has been working perfectly since 2016, so it will stay at that.
I hope that is not too boring to read through. By the way, if you happen to have a distributor with a 13L slot, installing a small piece of NYLON tubing over the post, will be a quick way to get you close to the 20 degrees you need.
EDIT: This information is in regards to a Motorcraft or Autolite factory distributor, and not an aftermarket type.

 

[mrgmhale]

Thanks for your interesting reply.
First, your Shelby GT500 is one awesome car. The 428 is a motor I have no knowledge of, so timing that motor is totally in your area of expertise.
As for the 351C, it's generally known that those motors seem to like much more initial timing than the factory set them at and we also know that was probably more to meet emissions demands than for performance. At least, that is my understanding.
As for my motor, at 87K original miles, it was getting tired and burning oil. I had it rebuilt at a local well known engine rebuilders. At that time, the builder decided to install a high volume oil pump and a Pertronix Ignitor III electronic module. The original factory distributor had been replaced with a Cardone reman at an earlier date, but was to factory spec for the 4V, i.e. 15L (30 degree) timing slot, factory spec springs. Initially, I had a world of issues with the timing. I'll not go into details, but the PIII's bad design was the issue. Pertronix replaced that with a PII and matching coil under warranty.
Timing continued to be an issue, but I was learning with the help of many great members here to understand it. I'll not go further into that right now, but jump ahead to the second rebuild. That was undoubtedly caused by the HV oil pump and again I'll not expand on that.
I did take the opportunity to remove the KB flat top pistons and install 13cc dish top. With zero deck, the static comp ratio is about 9.8:1 That alone dropped the pre-ignition knocking, but more needed to be done to run cleanly on Shell 91 non-ethanol gas. That's when I started to learn about the timing slots and spring choices. Knowing that the total mechanical timing needs to be a max of about 36 degrees and that many here say that 14-16 degrees of initial timing is the sweet spot, that means that the total crank degrees needs to be no more than 20 degrees. To achieve that, I stripped another distributor I had, welded the righthand side of the 15L slot and recut it to .410" which is a 10L slot dimension. With that done and tested, all I needed was to play with springs and tension to get the curve right. I ended up with a factory original heavy spring set to just loose and a Mr.Gasket 925D (I think!) set with slight tension. By the way, the harmonic balancer was new at the first rebuild. I have no reason to suspect that as an issue.
This combination has been working perfectly since 2016, so it will stay at that.
I hope that is not too boring to read through. By the way, if you happen to have a distributor with a 13L slot, installing a small piece of NYLON tubing over the post, will be a quick way to get you close to the 20 degrees you need.
EDIT: This information is in regards to a Motorcraft or Autolite factory distributor, and not an aftermarket type.

Excellent info. Thank you for taking the time to put that out onto the forum. I am going to stored what you wrote in case I or someone else eve3r needs info on this matter.

Gil

 

[Stanglover]

Excellent info. Thank you for taking the time to put that out onto the forum. I am going to stored what you wrote in case I or someone else eve3r needs info on this matter.

Gil

Thanks Gil.
Over time, there has been much written here on timing the 351C and there is some well documented material out there on the web also. I make no claim to be the originator for the information I provided. You can find much of the information I provided in an article written by Gerard Forgnone entitled "Timing tips for Ford (and other) distributors" at http://www.bob2000.com/dist.htm . I am not sure if this is still out there, but if not, I can scan and PM you that article. It likely is not appropriate to post/copy that article here.
Again, I must state that what I found to work for my motor, may not work for all. It may also depend on the cam and cam timing you chose.
The idea of welding and recutting a slot to match the 10L ( I did not have a a distributor with a 10L slot!) was actually given to me by a friend who built race car engines and also had a distributor machine. He has since passed away unfortunately.
My apologies to Tommyt if I've over stepped on his original post. Thing just happen that way sometimes.