french flathead stock valves and hot cam?

You never cease to amaze me.

 

Good port job for a mild engine. You are leaving a lot of flow on the table though.

 

So where do you think it could be improved?

 

As said, most French blocks needs a good porting job.
Very nice illustrations AV8, and a book is an good idea
Bored&stroked has also posted a really good thread here, that you should look into!
I would go for Isky 185g springs for your Potvin cam.
And find some new lifters. Several has reported that the French lifters has collapsed, and you don't want that!!

.................................
Taildragger&fenderless

 

It is hard to show without pics and I never take any of that stuff.
The intakes need to be "D" shaped to get maximum area for one thing.(sonic test as you go)
The area on the bottom of the port just ahead of the valve stem needs to be lower.
The area behind the valve stem needs to be filled.
Top of guide contoured to port. This usually requires making guides from scratch due to stock guides not being long enough. A plus of this is you don't have to copper plate the guides to get a press fit in the block. You just machine them with the fit.
5/16 stem dia. valves.

In the pics shown you could probably go at least 1/8 inch bigger all around on the exhaust ports and contouring the bottom of the port especially in the corners.
You can take the bottom end of the ports out to 2 inches.
You take the maximum out all the way through the ex. ports using sonic test to gauge as you go. Leave .080 wall.
The outside edge of the 4 corner ex. ports are moved out to leave only 3/32 of the flange.
This straightens the flow. Much more can be done here but it involves welding and machine work. The headers need to be "W" type with 2 1/16 ID. This leaves a ridge at the junction point which is a reversion dam.
Use a baffle in center ports. Make it from inconel. 1/4 thick at the top and tapers to 1/16 at the bottom. It extends down only as far as the center line of the adjacent valves.

There are more things that can be done to improve flow but these are the ones that can be done without welding and expensive machine work.
These mods were first done on 315 ci engines back in the mid 50's and dyno proved.
They made over 1 hp per cubic inch, naturally aspirated on alcohol.

 

Wow Pete, thanks for all the informations
Will do so on my next block

 

One more question,who sells a good sonic tester?

 

I will buy it as well. Just picked up one of the FF's from SF by way of So-Cal.
I would be interested in it to learn more, I have two old flatheads with possibilities to learn on.


Thanks,

James

 

No clue as to which is best. There are a lot of them on the market.
I haven't heard anything bad about any of them.

 

my little port job this weekend:
befor

after




I'm open for ideas and Critique,school me

 

and here my intakes before and after first grinding

in the darkroom






more later, have ordered long grinder and polisher

 

nice job...seems like mine....for the intake ports i have used a long grinder too..

 

Hi all,
A little off the subject but we all know that there has been many debates about whether a conventional relief job is beneficial these days so I'd like to ask for your opinions about this alternative "semi-relief" proposal.
I'm suggesting that the transition area above the valve seats be blended with flowing radius up to the deck surface and then grind a ~1/2" radius at the bore edge in the non gasketed or traditionally relieved area. This radius would need to wash out about 1/8" down the bore much like a conventional relief does to avoid the top ring. I know that the blending above the seat area is a given but I'm more interested in your opinions of the deck to bore radius. By removing the sharp ledge at the top of the bore the intake charge will have a smoother, less turbulent flow over the deck edge and into the cylinder. The reduced metal removal would also help gain a little compression normally lost when conventional relieving is done. The exhaust charge predominately takes the roof path so I believe it would not help or hinder that. I'd suggest that upper HP gains would be minimal but definately offer some mid range torque improvements.
We all know how intake flow improvements have progressed over the decades by providing larger "short turn radius" ports in modern OHV heads.
I'm looking forward to your thoughts and opinions whether negative or positive.
Thanks in advance, Graham.

 

Get in touch with Joe Abbin - he's one of the few who have actually done extensive flow testing.

He does find it beneficial to relieve in both the head immediately above the valves, as well as the full transfer area.

 

what type of camshaft do i need for a French Flathead, 59A- or 8BA-style?

 

8ba I believe.

 

Technically the top and front of a french engine are 8ba. You can run a 58ab set up using the right 59ab parts. Big thing is the front gears - 8ba are angled one way, 59ab another I believe ....

 

And the thrust direction is opposite too...

 

Yep - you are right big deuce .... forgot about that ....

 

For those of you who haven't kept your antennae up:
The book is now out and available...
http://www.verntardel.com/collectio...ild-and-modify-ford-flathead-v-8-engines-book
I've gotten mine. Pictures are huge and crystal clear, and there are more block cutaways showing the secret tunnels where the sun don't shine than I've seen anywhere else.
Anybody looking at this post needs it. The french flathead even has its own coverage.

 

yeah just got my copy.. great book as expected from Vern and Mike