Tech Request: Flatty valve "Unshrouding"

Ok, I just don't get it...

In the past I've heard such comments as, "don't relieve the block but make sure you unshroud the valves." I have even read how this is done but I'm still lost.

So when I go pick up my heads from Navarro himself, he tells me to unshroud the valve and explains to me that due to the type of turbulance that's created in the chamber, it's important to open up the area behind the valve etc. I figure on a flathead, if Barney says it, it might just be a pretty good idea to try.

The problem is, when I get home and check his head and my block against a new head gasket, there isn't any room behind or around the valves to grind anything away.

So can someone tell us all how this might be accomplished and if it is indeed necessary on a street flathead?

 

Maybe something like this? leave the head full size at the gasket surface, but cut out the area that is around the valve when the valve is open.

Better check with someone who knows flatheads first!

 

This is like relieving--look through the wisdom of the ancients and read the current flathead books and you will find flat, positive, and expert statements saying A: There's no flow in that area no matter what you do, and any grinding back there just wastes compression...and B: grind the hell out of this area or your car's gonna be a stone. Hmmm. I forget which side I'm on this week...but I don't have a flow bench and I don't think the opinion of anyone without one is worth much on this. We need Flatdog, who is certainly one of the most successful flathead scholars on our part of the planet (3,000 pound coupe, genuinely streetable, that is just about to break into the 12's) and Ron Hollerhan (sp.???) who hangs out at the Fordbarn group and doesn't seem to know he belongs over here.
Ron has built and raced flatheads all his long life, has run them on a dyno, and has done lots of flow testing. He is a flathead GOD.
Me, my totally speculative opinion, I don't believe any air is trying to go that way--although I would speculate the exhaust side might differ...
I think the flow path is very strongly across the valve and out the cylinder side, and you can't turn it to flow all around because there isn't enough room in the pocket area. This is all hot air based on lots of reading/zero flow work.
Now, imagine if you COULD turn flathead flow 90 degrees in the pocket and get serious flow all the way around the curtain area...you'd need to turn the flow 90 degrees AGAIN to flow into the rest of the chamber instead of just crashing into the ceiling. The chamber would have to be huge and utterly different from anything familiar to us...and the flow changes would be revolutionary in their potential effects and in the new problems of a hopeless exhaust path.
This and relieving are the two great grey areas and great controversies shaping our times...at least over here on Flat Earth.
I think most flathead experimental work (not counting wildly reshaped engines like Flatfire) concentrates on the ceiling of the transfer area where the flow from the piston side of the valve wants to go.
I would love to see current chambers by Flatdog and Ron.
And we need to send out missionaries and diplomats to get Ron on this board.

P.S. edit with additional comment...Ron's technique of unshrouding is avery simple matter of massaging the shape of the little bowl area Ford cast around the valves, which bowls follow my hypotheticl idea of what the air is doing in that neighborhood. Ron's book provides a very simple method of doing most of the grinding necessary by just dropping in a stone cut to his specs on your seat grinder. And Ron's book would probably be my choice for a desert island--one book scenario.

 

Bruce, as usual, is right on the money. There are a lot of rumors, myths, & half-truths out there. In addition to the two flathead-gurus he mentioned, I'll add that Joe Abbin has done extensive flow bench work. Joe's latest data is leading him more towards work directly over the intake valve (in the head) than relieving...

Having said that, there are a lot of variables to consider.

I say, slap a blower on it & overcome whatever is in the way!

 

Bruce,

I've talked to Ron in depth about coming over here as well as other things. If I know Ron, he'd say "leave it alone, it's only going on the street!" Ron ain't coning over here. He doesn't have much time for the computer these days and he has had some run-ins with some prominant members here. (Stubborn old dogs fighting over the same bone! )

I tend to think that it doesn't do much but lower compression on a street flatty but I'd like to hear some science and maybe change my mind enough to fuck with my expensive old engine.

 

If you were going to buy just one book on flatheads, 49-53 specifically, what would you buy? Thanks!

 

BELLM,

One book just isn't enough. They all have pertanent info.

Tex Smith's is pretty good for your run-of-the-mill building info and some history as well as Carb setup. If I could only have one, and wasn't panning on building a high-output flatty, that's where I'd start.

If I already had some knowledge of flatty's, I'd buy Joe Abbins book. It's very informative with lots of good data about performance build techniques and possible performance.

After you had both of those however, I'd find a copy of AV8's Flathead Porting article from right here on the HAMB and go to town on a block!

 

Thanks Kilroy! What is the name of Abbin's book & where can I get it? Think I can find Tex Smith's without any problem.

 

An excellent FREE flathead book, largely focused on practical street use and early Ford repair and interchange:
http://www.flatheadv8.org/rumblest/intro.htm

Go to the very bottom of that page for the book chapters. The technosource further up the page also has some good material.
Ron's excellent book is available from him over on Fordbarn--look for Ol'Ron.

 

Joe's Site...

Blown Flathead

 

I captured Mike Bishop's excelent article on porting flathead blocks and stuck it in a PDF file.

http://lonestar.texas.net/~mcdaniel/porting.pdf

It's 1.7 meg and an acrobat file, so, no whining. You've been warned.

 

Grim,

Was flatdog's stuff included in the Flathead tech article in the Tech-O-Matic?? Don't recall off the top of my head (& I'm lazy right now), but that's a great resource too - lots of awesome info in there!

There is no "one book" on flatheads - unfortunately.

 

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I say, slap a blower on it & overcome whatever is in the way!



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Done that. What's next?

 

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I captured Mike Bishop's excelent article on porting flathead blocks and stuck it in a PDF file.

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Thank you! modernbeat
Now I have the piece all in one place!

As small request (or suggestion) for us ole' farts that are "blind in one eye; and can't see very well out the other"; could you maybe number the pages?

Other than that; EXCELLENT!!

 

I don't think Mr. Navarro is talking about opening up the back of the head around the valve, but I may be wrong. I personally open it up there very mildly. I think Navarro is talking about removing the V shaped area between the valves. I have somewhere in my archives a drawing by Mr. Navarro about this exact thing. I can't locate it now, but I know I've posted it in the past either here or at one of the other forms. It's hard to get better tech information than from Barney himself.

 

I second Dave re Modernbeat. THANKS for that PDF

 

I have the Hop Up "book" and there is alot of articals from Mr. Navarro on the fundamentals of the flatty. Very good info.

 

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I don't think Mr. Navarro is talking about opening up the back of the head around the valve, but I may be wrong. I personally open it up there very mildly. I think Navarro is talking about removing the V shaped area between the valves. I have somewhere in my archives a drawing by Mr. Navarro about this exact thing. I can't locate it now, but I know I've posted it in the past either here or at one of the other forms. It's hard to get better tech information than from Barney himself.

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Flatdog, I just checked in my files. It was a drawing that Barney scribbled on a napkin. (think you posted it)

It does show reducing the "V" between the valves.

I would post it here, but my computer suffered a MAJOR meltdown last week and I just dug it out of my hardcopy book to look at it.

 

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I think Navarro is talking about removing the V shaped area between the valves.

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While I certainly am not qualified to question Mr. Navarro, I know that on the Harley Flathead racers (WR, KH, KR), they are adamant about NOT touching that triangular section & leaving it alone - of course, Harley's guides always just said "do this, don't do that" w/o any real explanation...

(I realize there are some minor differences such as valve tilt/cant, etc between the two)

 

Have you guys ever seen the insides of a Pierce- Arrow V12 or in its later use as a Seagrave fire truck engine? They are flatheads but the valves are at about 45 degrees to the cylinder. When the valve opens the intake port is aimed directly at the dome in the cyl head above the piston. IMO the Flathead Ford could benefit from this greatly. As it is now on the Ford V8, airflow is caused by pressure differential (obviously) as the piston travels down the bore. The fuel/air charge rushes in and wants to go up. Then it is influenced to make a 90 degree turn and go down the cylinder. I believe Mr.Navarro feels that relieving the valve pocket area in the head serves to enlarge the area where the intake charge "wants" to go. I tend to agree with him though I don't have a flow bench to back it up either.

Someday I'm gonna figure out a way to tilt those valves to 45 degrees or so with a rocker arm in the valley or sumthin' and thats when I think airflow on Flatties will improve dramatically.

 

"Someday I'm gonna figure out a way to tilt those valves to 45 degrees or so with a rocker arm in the valley or sumthin' and thats when I think airflow on Flatties will improve dramatically"
Dig through some early Special Interest Autos--they covered a V8 with a system like that once--think it was an Oaklan or Pontiac of some sort...or Viking?

 

Earn, I think we are talking about two difference area.I have studie KR stuff and it is a whole difference amimal.

 

Barney was talking about the turbulance created by the mixture being pushed up at the head and then tubling over itself like the slipstream of a jet. He said that not much flows over the top of the valve but that the back of the valve needs to be unshrouded.

I've talked to him twice about this and I got two different answers about what to do. But both sounded more detailed than grinding down the v between the valves.

I have a call into him so we'll see if he calls back.

So far, I like Mikes "relief" the best. Barney was adamant that you should not do a traditional relief. The mixture doesn't hug the inside edge of the cylinder as it comes up anyway. Releiving lowers compression and weakens the deck.

 

I'm loving this thread!

Here we are discussing "How To Improve" a fifty year old technology, and even the "experts" have different opinions!

You have to wonder if Henry had ANY idea of what would evolve from a design that was created 72 years ago!!??

It's not hard to see why the OHV "gang" think us flathead lovers are a, "Brick short of a Full load!"

BUT, hey, we are smitten!!
Keep the IDEAS and Opinions commin'!

 

One interesting thing about the 72 year old stuff--several of the experts are beginning to focus on original heads as the best for flow, implicitly rejecting all the post-Henry design work!
Don Francisco went this way back in 1956 in the big HRM flathead series, and now 286 Merc and Ol'Ron are respectively recommending 1953 and 1938 heads for many builds.The basic stock combustion chamber design on these dates back to 1936...I wonder what sort of work,testing, and thinking went into that transfer area back then??
I hope to get up to Vermont and get Ron to flow test my killer factory secret 81AS Denver heads someday soon--those were the head of choice for "stock" class flatheads once upon a time, but they were rare even then. They were Ford over-the-counter heads for high altitude or natural gas engines. The "S" in the prefix is for special...60 cc chamber.

 

Bear with me - I'm going to type out loud here...

The stock setup forces the intake charge to make almost an 'S' turn tilted off to one side. Inertia tells me that I want as straight a shot as I can get, so anything I can do to straighten out the 'S' should help. This means lots of short-side work & relief. This seems to work reasonbly well up to a point.

The challenge to me is that it doesn't seem like there's a lot of back to back testing - we tend to try to do bunches of stuff all at the same time & the most significant one from a flow perspective may well be increased compression & the potential negative affect on the chamber & transfer areas. This only clouds the issue & hence we have experts who know what works for them & their combination, but maybe it doesn't apply across the board? I dunno - I'm just rambling...

The last one I built (which has been about 8yrs ago now), I did a traditional relief, but I ported the short-side to within an inch of its life. I D-shaped the outer edge of the port & moved it enough that I had to have the intake base welded to build it up to match the port as well as make a custom gasket. I did use 1.6" valves on the intake side too. This was a 276" engine with, I think, a Max-1 & Edelbrock heads w/single 4bbl 390cfm & heavily ported exhaust. Sadly, this engine still sits on an engine stand, so I'm unable to report how well it works (or doesn't).

Maybe the answer is as simple as EAB heads with a blower!

 

I just got off the phone with the man hisself, and squirrel nailed it...

Mr. Navarro's talking about creating a gentle curve at the back of the head, like squirrel's picture.

Since I was going to clean up the casting over the valves a bit anyway, I might as well do that too.

 

I think this should be added to the flathead tech in the Tech-O-Matic!!

 

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It was a drawing that Barney scribbled on a napkin. (think you posted it)


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Digger sent me the pic & since he's having some 'puter issues, thought I'd post it for him.