Running on

[barnett468 418]

15 minutes ago, bigmal said:

Yep, understand that. More about setting the carby up correctly to start with. Thanks

The timing curve will affect the amount of fuel it uses, so it should be done as well.

[danno 128]

great discussion,  if I read this enough I might finally learn something. 

[bigmal 225]

Have been doing a bit of trouble shooting and chatting to a friend who builds hi perf engines. I have gone back to 98 petrol from 95 and it does not appear to run on, but as it doesn't do it every time it's not conclusive. It can't be the electric fans providing current while running down as the relay isolates the circuit.

A box was put on the engine that calculates compression ratio and it is not the 10:1 that the engine guy calculated, it's 9.1:1. The good thing is my issues are not related to compression ratio.

When the plug was pulled the engine guy asked why it fitted these triple electrode fancy plugs. They were on it when I got the car and as they looked expensive I didn't change them. They also have some carbon build up. This may be the cause of the run on. When he put it on the dyno the engine was breaking down around 4500 rpm. May be dizzy issues or maybe the plugs. New plugs going in on the weekend.  Would be great if that is all it is.

Main jets are a little on the lean side so also changing those.

As the electric fans are not adequately cooling I have put the flex fan back on.

Will report back after plugs and jets. Hopefully with good news.

[barnett468 418]

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[bigmal 225]

So, an update. New plugs and main jets and back to 98 fuel. No longer pinging and running on is gone. Dyno showed an extra 4 hp (202) which is not a lot but it is up to 9 higher at lower RPM. There is a noticeable increase in acceleration, so I'm pretty happy. While not conclusive, it looks like the running on was the old plugs.

I'm not across power outputs and what is normal. Is 202hp reasonable for a 351C 2V, 9.1:1, iron manifolds, 600 Holley and mild cam? 

[barnett468 418]

11 hours ago, bigmal said:

So, an update. New plugs and main jets and back to 98 fuel. No longer pinging and running on is gone. Dyno showed an extra 4 hp (202) which is not a lot but it is up to 9 higher at lower RPM. There is a noticeable increase in acceleration, so I'm pretty happy. While not conclusive, it looks like the running on was the old plugs.

I'm not across power outputs and what is normal. Is 202hp reasonable for a 351C 2V, 9.1:1, iron manifolds, 600 Holley and mild cam? 

Since it started running on when all you did was switch to lower octane,  the lower octane was causing it to run on, which is why I suggested you simply switch back to the previous gas you were using.

Old plugs will not cause an engine to run on. Also, when trying to determine the cause of a problem, only one item should be changed at a time.