Fenton head - no more pinging

[Robin (UK)]

Guys,

I found a simple fix to the problem of the pinging I was getting since the Fenton head went onto my car...

High octane gas.

Changed to 97 RON from the standard 95. Pinging disappeared straight away.

Performance is better.

And even the MPG seems to be improved.

All good news.

Robin.

[Lou Earle]

Sometimes a slight timing adjustment will also help

Lou

[martybose]

My 230 is overbored a bit, has an Edmunds aluminum head and about 9 to 1 compression. My mechanic told me that I should always run high octane gas in it, as the old flatheads were sort of prone to detonation anyway.

Marty

[TodFitch]

My 230 is overbored a bit, has an Edmunds aluminum head and about 9 to 1 compression. My mechanic told me that I should always run high octane gas in it, as the old flatheads were sort of prone to detonation anyway.

Marty

I have never heard that "flatheads were sort of prone to detonation".

My understanding is that there is a direct correlation between compression ratio and octane requirements of an engine. With detonation sensors and computer control you can overcome some of it, but with our older non-computer carbureted engines you are limited in what you can do and still have power and drivability.

With your 9:1 compression ratio you will need around 96 octane gas. In my area that is premium. With my stock 1933 with its 5.5:1 compression ratio I can get by with somewhere between 72 and 81 octane.

See section 7.2 of the "Gasoline FAQ":

http://www.faqs.org/faqs/autos/gasoline-faq/part3/

Flatheads are prone to pumping losses (breathing problems) and, if I recall correctly, these are supposed to become significant with compression ratios above 8:1. Thus the focus on split intake and exhaust systems and, at least in the old days, with "porting and polishing" to assure that there is a smooth transition between the manifolds and the block.

[Guest jjmorrse]

I sometimes get the impression that people tend to think of the flathead ford when they talk of detonation problems, and lump all other flatheads in together with them. I personally do not think detonation is as much of a problem with the inlines. Of course, I do not run high compression either.

[claybill]

robin...very glad you have the head and its running well. i have another and will get it in my test engine soon.

bill aka claybill

[Robin (UK)]

Yesterday, I took the car to show a friend at his specialist classic car bodyshop.

He's a big fan of both British and American customs and classics and European sports cars and exotics (check his website at www.RomanceOfRust.co.uk and look at his custom Mercury and some of his other work).

He was amazed by the Plymouth - said it sounds like an early Bugatti, or an Allard.

I laughed, but he was serious.

He loved it.

The car has been transformed by the Fenton head and I'm having great fun driving it.

Thanks Bill.