Flathead Combustion Chamber Cut-a-Way

This may not be of interest to those who know a lot about the Ford Flatheads but I learned I was dumber than I thought while doing this. I had a trashed Mercury block that was beyond help so decided to cut it up to do some measuring and see how it looks in a cut-a-way. One of the heads (8ba) I machined out the combustion chambers to use as a honing torque plate and the other head I cut up to use with the piece cut from the block. I saved all the useable components from the block (had a good 4” crank). The pictures have the caption below them to help explain what the picture shows.

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This is the chunk I cut from the block, I put a mark on my long nose die grinder 3” from the abrasive cut off disk and started cutting from inside the cylinders and the disk will go through the cylinder wall and the outside and inside casting for a sawzall blade to reach through to finish the cutting. If I cut another one it would be 4" down into the cylinders.



This head to be used as a honing plate.




This is the pieces after cleaning them up some on the milling machine. This also shows the exhaust port between the two center cylinders.
















We have been told and told others the cracks between the bolt holes and water jackets didn't hurt a flathead but if you look at the starting of the crack above and it continues into the bolt hole and down to end in the exhaust port you may get hot exhaust gases into your water from the crack. I suggest the repairing of the cracks from water jacket into the bolt holes between the center cylinders.




This shows how the cylinder walls varies in thickness, it also shows a pit and how thin the wall is at the pit. This engine has been bored .080" over.






I also used an eab head to compare against the 8ba. All the measurements were without a head gasket and the block had been decked so much that some of the valve seats had been machined down when decked. I used Manley SS valves when taking the measurements but they still give a reference between the two heads.




This how the piston fits into the 8ba combustion chamber. This doesn't show it very well but the piston relief in the head is about the same diameter as the cylinder.




This is the eab relief, you can see how much smaller it is than the cylinder bore.





This is the intake valve hitting the 8ba head and where it hits and how the valve angles into the pocket. The lift of the valve before hitting was .319" lift which I used to see what the difference to the eab. The lift for the eab was .367". That really surprised me because the eab is the higher compression head of the two. Later you will see why this is happening.




The exhaust valve hitting the 8ba head at lift of .313". The lift was .391" for the eab head.




This is the 8ba with the valve hitting the head. I could only get an 11/64" transfer punch between the valve and the head as the picrure shows.





The valve hitting the eab head and could only get a 3/32" transfer punch between the valve and head as shown, that is a difference of .078 ". the combustion chamber roof over the valve is tighter near the cylinder but gives more lift before hitting the head on the back of the valve on the eab head, but if the 8ba head was fly cut over the valve it would probably be close to the same as the eab.




Here I measured the transfer area between the two heads and the 8ba was .041" deeper than the eab head was. It would have been nice and a lot more accurate to have more heads to compare to get an average of the measurements. I do know I will now repair the center bolt holes and I will not get wild on boring them out after looking at the pits and core shift in the cylinder walls. This might help someone, it did me and if it helps only one that is enough for me.

Vergil


I forgot to post this picture so I will just post a link if you want to see it. It shows measuring the deep pocket by the piston relief. The 8ba is .030" deeper than the eab head and using the deepest pocket on the aeb head.

http://www.jalopyjournal.com/forum/picture.php?albumid=4136&pictureid=34984

 

Wow! thanks for posting, what a great deal !

 

very educational, thanks for taking the effort and time.

 

Fantastic. A great chance to see things that no one ever sees. Just like the cut-away engines at the auto shows.

 

Cool post.....looks a bit different in this perspective
Skot

 

Really nice job and great pictures.

 

Hey, Those are great pics and info. Thanks !

 

Really interesting stuff. Thanks for documenting your findings.

 

Great work as usual, Vergil! It's striking how little room there is in there for flow.

 

Very educational! This should be archived with Flatdog's post on the cutaway views for porting the flathead Ford!!

Flatman

 

that would make a realy cool coffee table now , great info !

 

Very well done. seeing is believing. nothing better than visual aids. Thanks for the great pics.

 

Man, You did alot of hard work! Thanks for a very cool post!!

 

It's easy to see why these engines are famous for running hot. Thanks for posting this stuff. That's alot of work just to see how it all works. Love it!!!

Kevin
Ooltewah Speed Shop

 

Awesome post man, a real eye opener to the ol flatty's breathing issues. Youcan see why blowers really wake up flatheads !!

Makes it real easy to see rather than have to mentally visualise what is happening in there !!

Rat

 

Wow, it is better to realize ho little you know when some one is proving the info. Normally I get the education after I broke some thing!

 

Thanks very much Vergil & AlbuqF-
It is skinny in there and reminds me of speedway advice stressing the importance of powerful spark ( e.g. twin point ? ) in these sidey's.

 

That's really interesting. Pretty cool to see it that way. I don't have any flathead experience.....yet.

 

Very cool. thanks for doing this.

 

Nice work, great education. Thanks.

 

thanks for taking the time to do that, it must have been a fair bit of work, but its worth it, especially to those that are new to flatheads, it might help them overcome their OHV tendencies.

 

Great post brother, as a Merc flathead owner I really appreciate the effort you've put in here. Fantastic insight into the flathead V8. Full marks for your commitment above and beyond!

Boner

 

Another thank you. Really informative. Well done.

 

What he said, although me thinks he was being politically correct.....lmao !!

Rat

 

Great post and very informative. Had to be a lot of work but worth it to us flathead lovers. You sir receive an A+ for this post.

Jim

 

Great info, thanks for taking the time to do all this.

 

Wow, Great post. Thanks for all the hard work. Here we are 75 years later and still learning about these engines.

 

awesome

 

Lots of work, but now you know how it looks inside! Thanks for sharing.

 

Thanks for takin' time for your fellow HAMBers. This good info don't jump on here by itself!!