Projects Flathead Porting: The Need For Speed

After doing years of research on here and the ford barn, as well as books I have available, I have decided to start down the path of trying it all out.

The plan: take a port mold of the short and long ports. I will then make a mold so I can cast ports with two part plastic. I am building a make shift flow bench. From there, I will be documenting my findings and what modifications were made.

First up will be porting with what is available in a stock block and various valve sizes.

We will see where this project leads me. I will be posting here as I progress. If anyone has anything they want tried out, I will do my best to accommodate. Guides are on the way as well as the plastic and silicone.

 

Wow! It’s so crazy it just might work!!

 

Thank you, with good blocks being harder to find, I rather get some good data in something disposable. Plus the added benefit of being light and I can work on it on a bench as opposed to an engine stand. Once I get a port I like, I will replicate it on a block.

 

thread watched,, im all in
miss you dad
fabricator john

 

Need for speed…..Pro Charger……

 

I think piston design has a lot to do with flowing one. I played with a 12 hp kohler in the garden tractor pulling stuff for bit. I felt the piston needed to be sticking way out of the block and more room above the valves.

 

Will follow along with interest

 

I tentatively agree on this. I am really looking forward to watching where the air wants to go in the port and how it comes out without a valve in it. Then watch it with a valve in at different lift values. I have a little smoke machine for finding vacuum leaks, I’m going to set it up so the flow bench sucks vapor through the port so I have a visual of dead zones and low flow spots.

Seeing how it all reacts and where it wants to go is going to be interesting. Once I get a good port, I’m moving onto chamber design next.

 

Alright, port mold for cylinder 2 is done. What a pain to get out, but now that I know this silicone can handle some pretty hard yanks and some prying, I will get it out faster on some of the other ones for comparisons.

 

Interesting, mapping out the internal air passages on a flathead. Good watch.

 

Staying clear of the water jackets seems like the hard part. Do you have a junk block to cut up and measure the wall thicknesses?

 

Looks like the king pin boss on the end of an axle .... uhmmm... interesting..


...

 

With a flathead, I assume the design of the head itself will play an especially large part in getting good flow in and out of the combustion chamber?

 

Corey: Here's a porting thread worth reading.
Flathead Porting for Dummies...? | The H.A.M.B.

 

Flow bench is built and I am going to be getting some numbers this weekend using a calibration plate. I am using Vizard’s example in his porting book.

I am still deciding how I want to cast plastic ports. I have soft non sulfur plasticine clay and have been contemplating building up the port mold to match Bored & Stroked’s findings from his post when he cut a block up and made measurements. I can then cast silicone around that as a mold, remove the silicone port and clay, then reinsert the silicone port plug. Plastic would then be poured into that and then removed. Wall thicknesses should be a good approximation of what’s in the block.

I made a mold to cast plastic guides so I can experiment with guide shapes. I have been studying a lot of high performance intake ports in overhead valve engines and have some ideas to try.

I will update here when I have pictures and numbers to share.

 

A good idea, but not fool proof unfortunately. Core shift when the block was cast means the metal thickness will vary from block to block, and all those years of rusting adds more uncertainty. But absolutely, it's a very good idea to find out how much metal you have to work with around the port, and the bigger ports you want, the more important it gets.

I believe there are ultrasonic devices for measuring metal thickness. Could be a suitable tool for this job, if they can get inside the ports.

 

^ ^ ^ What he said. They use sonic testers in the pits for chassis certs. Maybe someone is outta the game now and has one. I have one, paid 100 bucks. It tells metal thickness to the .001. Small probe, fairly easy to get into a port, you blob some proprietary ointment on the metal and hit it. Runs on some AA batteries.

 

I have one of the cheap Amazon ones, was a couple hundred bucks. Only has one probe and it’s flat. I may find some spots in the port where it will get a reading.

 

Soooooo coreythompsonhm,
A great book to help you on your quest is "Tex Smiths The Complete FORD Flathead V8 Engine Manual"
My copy was given to me by my good friend, writer, author, Hot-Rod Guru, neighbor Ken Gross for reading on one of my many trips to Bonneville for Speed week. Ken Kloth is featured starting on page 150. He still owns the XF/PRO record (for Flathead s only class production cars) he set in wait 4 it................. 1991 at over 144-mph.
Kenny made his own Flow bench by cutting up broken Flatties and testing the port flow. I spent some time in his work shop at the 2014 B'ville Speed Week "rain-out". What an amazing Flat-Head guy

 

The mystery of the Ford flathead ports how to get more flow or is it actually really needed. My experimenting has been more in the area of all out performance with testing over a number of miles. During our years of developing a combination that not only survives but also performs one of things learned has been high compression may not be needed.

At Speedweek last year after running our high milage stock block Ford flathead engine with a supercharged combination setting two fast records both over 200MPH burning gasoline we removed the blower and in its place bolted on a two deuce combination. We did this for two reasons first to give our new driver Carly Moody the opportunity to make her rookie runs. And second to see if our new driver and my experimental combination could run faster than the normally aspirated record of 140.735 that was in the record book since August of 2016.
Our engine measures 292 cubic inches being supercharged the compression ratio is very low so it survives at 6500 RPM at 12 pounds of boost for as long as five miles wide open. Upon removing the blower we installed a two deuce combination I built from scratch. For carbs I used the secondary Holley carbs used on many of the factory muscle cars of the sixty's running tri power intakes. Each Holley is 350 CFM so we had a total of 700 CFM flowing into a 292 cube ford flathead engine.

After Carly's 2 mile rookie run which she completed perfectly she was now able to run for three miles. At Bonneville the weather condition's effect what a normally aspirated engine will do. The weather condition's at Speedweek in 2025 were not the best temperatures were always over 100 degrees and the density altitude was well over 7000 feet in effect both were absolutely terrible. Here's the results Carly's combined speeds after two runs resulted in a new record at 158.767. That's over 18 MPH faster. The Ford flathead engine that held the record previously was a filled block that had all the ports coming out of the top of the deck this means an exhaust port per cylinder the engine was built by Jimmy Stevens.

Our stock block Ford flathead has the exhaust ports where Ford designed them to be as well as the intake also in their stock locations and a block filled with water. This combination performed extremely well in horrible condition's compared to a highly modified Ford flathead block. In my opinion and actual results seems to prove that possibly port flow is not the issue. Its possibly more related to compression.

Overall the best port design has been what the Harley race teams ran in the KR flathead researching that is the direction to go. However who knows 72 years after the Ford flathead production ended maybe you can come up with something that works well. Heck I know we did but it was only 71 years after the production ended.
Ronnieroadster

 

That is amazing really, especially under those conditions. Congrats on the record. Sometimes there’s no need to reinvent the wheel, huh?

 

Congrats on the records!
I measured cross section areas today. With some exceptions like how the short turn is not blended to the bowl and it being fairly restricted at the hump in front of the valve guide compared to the rest of the port, for a 1.5” valve the cross section area is averaging 73% (at least on this port).
I really don’t think I will be coming up with anything new, I think the chamber design in the head is the biggest issue. I have been looking at the Harley KR heads for awhile and have taken note of which companies are mimicking this design like Navarro with their Hi Flo heads. Most “trick” things I am looking at is how people have shaped their guides in overhead valve heads to help promote port biasing, and getting the air to want to flow away from a cylinder wall. I am curious if this could help in aiding flow out of the valve and into the chamber and bore.
I like small ports with high velocity, but in good balance.
One caveat, I will be eventually be building a lakester with an xf. Years away from now but I just wanted to clear about where this is all eventually heading.

 

That’s one book I don’t have, as well as JWL’s book. I have ordered Ron Halloran’s book.

Reading Abbin’s book and his flow testing, some things stand out to me. He likes Offenhauser heads, yet they were not the best flowing heads. The edelbrock heads he tested flowed better. I am curious to see how the mixture swirl into the bore differs between the the edelbrocks and the offenhausers. Navarro heads were untested at the time he wrote the book.

Now, following Vizard’s theories of the valve and seat being the greatest restriction in a port, and with the low lifts these valves see even on fairly radical Flathead cams, I would like to see how 30* valve seats help with breathing. Low lift being defined as 0.25 x diameter of valve, that would be 0.375” of lift as “low lift.” I think 30* seats would be a better choice than 45* seats since the valve would be open far longer in the low lift range.

 

there was a long article on here years ago on the HD45 flathead. What struck me was a tongue between the intake and exhaust valves that curved towards the intake to give a swirl to the mixture and add to the CR . Any books here you don't have?
http://www.roadrunnerengineering.com/BooksProductsServices.html

 

Thank you for reminding me, I do have that usb drive from Abbin! I will need to do some reading today.

I will search out that article. There was a member here, I don’t know if he is still active or not, but he was designing chambers and milling them out. He is also here in Federal Way according to his profile. I will dig through my saved files and find his name. He had posted a cad render of his chamber, very much like the KR, but enhanced and taken further.

 

Tex smiths and ol Ron's books are great.

There's a good video clip/story on flow with someone in brian darwas flathead ford dvd, a sweet sickness.

 

I think this was article but pics gone
https://www.jalopyjournal.com/forum/threads/600-hp-flathead-impossible.12269/page-2

 

Corey, are you thinking of Flat32 in Federal Way?
Wayno

 

Wayno,
you need to share a few pictures of your waaaayyy cool cast intake