F-head high altitude head?

[51 CJ3]

How the octane rating is determined has changed over the years as well.

[gmwillys]

That is a very interesting chart Bmorgil.

[bmorgil]

It really does show the evolution of combustion technology. A GM "Gen V" L83 Engine has 11 to 1 compression and runs on 87 octane fuel with 32 degrees of ignition timing. That is just Wow!

[51 CJ3]

I think the computer controlled electronic fuel injection systems have more to do with the ability to run low octane fuel in high compression engines. “By guess and by golly” was all it took in the past to get an old carbureted engine to run good. Now it’s all very precise.

[bmorgil]

Yes the precision of the fuel delivery is important but, you still see the best "all out" horsepower from a carburetor. As old as that design is, on the dyno a well tuned carb has been proven over and over to make the maximum power. We have now seen the latest design heads make awesome power, with a carburetor and 11 to 1 compression on 87 octane. The emulsification of the fuel and air mixed well and far ahead of time is the key. The other tell tale of the efficiency in the combustion chamber design is the total timing required. As the combustion chamber efficiency increases the amount of total timing required for complete combustion decreases. This is also a huge help in preventing detonation. A Gen 1 GM small block would usually make the best power approaching and sometimes exceeding 40 degrees of total timing. A modern GM LS doesn't need any more than 30 with racing engines running around 34 on race gas. The newest design combustion chambers combined with the precise timing and fuel control of injected computer controlled engines, provide the unbelievable "best of both worlds" we now see from autos. Great power, smooth drive-ability in all conditions, fuel economy and low pollution. Now keep in mind, if it does start to detonate on a computer controlled engine, it will adapt. Power will be reduced. On a non computer controlled engine, you may want to back that 11 to 1 down a bit just in case!

[51 CJ3]

Thanks for the extra info. I remember when we started switching to electronic ignition and EFI. I didn’t want any part of it but 235,000 miles on my current truck, my EFI boat motor and even my last motorcycle has made me a believer in the newer tech. I turn the key and it starts ready to drive. It’s bad when it screws up because no one knows how to troubleshoot what the computer doesn’t tell them in plain english. Fortunately, the issues show up a lot less often while needing a lot less maintenance to get there. Who would have thought 100,000 miles would be the normal spark plug change interval 40 years ago? I still get to do old school maintenance on flat fenders, lawnmowers, old 2-stroke boat motors, airplanes and the like.

[56willys]

This could solve all the problems with the 134! https://www.facebook.com/marketplace...lace_pdp_share Definetely looks tempting, maybe its a good thing i dont have 2 grand to spend right now. One could do some really neat stuff with this head though. It would be a fun thing to play with, and could have some crazy results.

I dont know, i think Ham's 48 needs an aluminum head!!

[gmwillys]

7,500 rpm on the bottom end would definitely make for an oil pan failure. '56, your welds look a lot better than the ones on that intake.

[56willys]

7,500 rpm on the bottom end would definitely make for an oil pan failure. '56, your welds look a lot better than the ones on that intake.

It is sketchy that's for sure. I can just smell the rods twisting already. But hey, it was a cool experiment. And I appreciate you complement on my welds!

[bmorgil]

I have to agree gm, at nowhere near 7,500 rpm we can expect to see many holes in the oil pan! Very clear what to do with that cylinder head. Leave it on Facebook. Note its " Never been run, Outlaw status". I think someone is trying to recoup some costs on a bad mistake. Lets think about 7,500 rpm on a motor that only has one cam bearing...