Newbies: Flathead guide of death, read & heed

"God help me, I've almost got the balls to put mine back together..."
Stay away from all this theoretical whining and speculation...focus...it's 1952...there's just you, an 11/16th wrench, and some iron and oil...screwitalltogether and hit the starter ****on. If you need any mechanical advice, run down to the library and check out "The G****s of Wrath."

 

I'm bringing my block down to Pro Motion in the morning to get line bored and seeing all this it will be interesting to see what I can get out of it.....it has a few Flatdog porting tricks in there as well, DJ helped me a lot with design along the way so I'm hoping for some decent results.

 

Getlemen:

A rose is a rose....

A flathead is 8 Briggs & Strattons cast together as one. Love them for what they are and do as many tricks as you can, but there is only so many tricks you can do that poor old lump before you are treading into the nether world of OHV.

1950's tech. in a 2008 world. Now that is truly anti-establishment! Got to love it!

That being said, I also think JWL and guys who have flogged these lumps on dynos after a series of tweeks and mods. and redo's and changes. It seems like the more they dig into these things, the more digging we need to do to find out why.

Maybe milder cams, less carbs., adding computer controls, and other modern world wizardry will give you that extra 10 or 20 hp out of the motor. But seriously, does it really matter when you are driving a flathead on the street? C'mon, does it really?

I'd much rather be down 20 hp then hang an unsightly TPI unit on a flathead. Good grief!

Unless you are chasing the blackline on the salt were every extra H.P. may help you achieve that record, I personally don't think it worth it.

Build them in your garage with the help of your friends and various others who are willing to p*** the torch along. Enjoy them for what they are and take notes on what you would change on the next build up.

But what do I know. I've got a bare block waiting for a rebuild for two years now. Sure is going to be fun when it goes together this winter though.

 

banjo - i agree. although its fun, going over board with gimmicks and hip dood dads on a street car can get silly.

ernie - what are your thoughts about home made flow benchs? i dont know the difference between a pro setup and a backyard job put together with some blueprints off the net... id like to research my own flathead ideas and will be working from scratch, and of course on a budget.
do you have any suggestions?

started visiting this site... i havent read enough of the forum to pose the question, cant say i trust it as a reliable source, yet.
http://www.flowbenchtech.com/

i have been looking at these guys...
http://www.flowperformance.com/faq.html

neat article
http://www.ag.auburn.edu/users/parmega/articles/flowbench2/

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Tim good point it gets nuts because it's so easy to get caught up in it.....I just got in from the barn from turning the tops of all of my guides to meet the port flush, as I'm on the lathe and measuring i'm thinking I hope this gives me that extra 1/10 of a hp, gotta love em.

 

I finally jumped into this post after watching it for a few days now. I have had the pleasure to have spent a few hours via e mail and in person with the master JWL. If you have not had a chance to read his book, and are contemplating a flathead build, do so immediately. I was present at one of the dyno pulls recorded in his book, see pages 79, 80.

Yes, it was my first build and I thought I was doing it right, boy was I wrong. I can't say that I'm not happy with my build up, but after spending time with John and seeing how I could have done things differently. I could have spent a lot less money, or have spent it in other areas and gotten a lot more performance from my engine.

So here are a few things I can say from experience for a street flathead... yep just one build...

Flathead intake and valve ports can only flow so much air, even in a mild ported engine with enlarged valves (more than most "street engines" get) you aren't getting any additional flow above ~.300 lift, or with big duration. So where is this going... leave the big cams to the salt flat guys. Your killing your low end torque and you can't rev your engine high enough or p*** enough air to utilize the cam.

"But they sure sound good though..."

Increase your compression ratio... this will directly add to your tourqe and subsequently your HP. This will probably be the most noticable "seat of the pants" improvement. Bore, stroke, heads or a combination of all three, try to keep it under 9.0 for regular gas.

These are the two big things I would have done different, If I had know better, I should have increased my displacement to at least 276, maybe even 284 to off set the low end torque loss. And had more porting and increased my intake valves to help my top end breathing. But then I think I would have needed more carburation as my Holley 390 seemed to lay down above 3800 rpm. Live and learn...

Well I could go on for days and plagerize John, but then you wouldn't need to buy his book...

Later Flathead Lovers...

 

I don't think there's any important difference when it comes to flow benches. If you take it for what it is and use it as a relative comparison, that's all that really matters.

In other words, you're comparing changes in airflow due to mods you've made. It honestly doesn't matter how accurate your numbers are with respect to the actual observed flow, what you care about is how does this latest mod compare to the last mod or baseline.

Go for it & keep us posted!!

I have no suggestions other than to say that it's more important to be repeatable rather than accurate for things like this...

 

Bruce, I think you're right. The area under the curve is what you want/need - the quicker that goes up & the flatter it stays, the stronger the flatty pulls and does seem to out-produce what the raw HP numbers would imply.

It's still about airflow though...milder cams will get that rise quicker, but will it be as high and as flat? That's the trick - perhaps it will be!!

One of the most important parts of JWL's book is the part where he explains dynos and correction factors. Much like I mention above about flow benches, it's more important to be repeatable, than accurate because no two dynos will produce the same numbers. They're a comparative tool, not necessarily an absolute. That said, I think if folks are using the correct factors (simple correction for sea level & standard day only), they should be within a small percentage of each other...

Hear! Hear!

Mine has only been sitting for a year and a half now...

 

I actually went ahead and started a thread on flow bench plans, inspired by plan9's post. I posted the pics of that article he linked to:
http://www.jalopyjournal.com/forum/showthread.php?t=309410

Didn't mean to step on anybody's toes...

~Jason

 

My 1/2 a flathead makes 30 hp at the wheels. More power to come in the spring.
nice job on the post
Bill

 

That totally made my day.

~Jason

 

Curious choice of word "hang", as if you could OK I made that last bit about 20hp up, it made 12hp over a 465 Holley 187@4700. I'm curious what you might consider so unsightly about it apart from the injectors, fuel rails and wiring.

While your projects lie there lame and you're torch light bench racing that car is an everyday driver and gets the odd comp fling.

 

I appreciate the ingenuity, but it's a simple matter of personal aesthetics.

And I've got two flatheads in drivers. Just the big engine hasn't been built yet...

 

I'm too dumb to multi-quote so here goes:

Sixcarb (Joe): Don't get me wrong. 2 H.P. there, three somewhere else, it all adds up to a decent number in the end. I did the same thing with my guides so we are thinking alike. No sense porting if you got a big 'ol guide in the way.

Ehduhya: Funny you picked up on the word hang for I used it on purpose. Understandibly, it is not hanging off the engine literally. I do appreciate the fact you worked through all the difficulties to adapt TPI to Henry's old lump. Seems like it is working pretty good for you as well.

But to me, a flathead should be something that the average guy can go into their garage put together, fiddle with the carbs., adjust the timing, etc. See where I'm going with this? I believe a motor should have period correct equipment. Yes, things like Hilborn F.I. were available, but used strickly for racing.

We can do all sorts of neat things to the inside of these motors in order to take advantage of modern technology and materials, but the outside shouldn't tip your hat to this.

This is not to take anyway from anyone taking flatheads to the next level using all sorts of modern tricks. Many guys, both alive and no longer with us, kept pushing the mods of flatheads to new heights.

Some guys are doing some really awesome stuff, it's just not for me.

Two Strombergs and a 12V generator start to press the limits of my IQ. I'm just a simple kid who enjoys the sounds of well built flathead done my way.

 

Banjo, I posted that pic in response to Jack's comment about there being nothing new making more power, not a recommendation for newbies. It's apparent from your blackline comment you don't get what TPI offers over carbs in terms of real world performance and economy, there's good reason why most every contemporary engine uses it.
Electronic management is the biggest thing to happen to the internal combustion engine since dot, the reason Hilborne injection wasn't used on the street is because it only works well if you're flinging the throttle wide open.
It's my brother's motor not mine and I'm not sure what you think is adapted, the manifold is fabricated for the application to the degree of the thin wall aluminium runners because no tube the desired size was available. Putting the injectors in the block where they have the best shot at the valve is something else again so you get rolleyes.
He loves this old Ford he's been driving for 36 years and simply wanted to make it better and was up to the challenge, I think traditionally this was called hot rodding. I don't see any difference between your at***ude and that of a purist restorer who doesn't believe in anything but OEM no matter how inadequate. if those rodders of yore put form before function they wouldn't have done much go fast stuff but I guess there was a lot of posturing for the herd then too.

Ernie, making them bigger and increasing their known volumetric inefficiency seems odd, how much low end torque do you actually get and what are you trading?

 

You appear to be taking this personally. It's not meant that way at all.

As I said, I really appreciate the ingenuity that goes into adapting modern components in the interests of furthering our beloved flatheads. Would I do one with EFI and electronic engine management? Maybe - in certain applications. In my traditionally-inspired hot rod? Probably not. I'm not a traditional purist by any stretch either...

As for bigger and inefficient, that's all relative. Stock, you've actually got a good exhaust to intake ratio flow-wise. It's not a revving engine by any stretch and most are done by 5K - tops (yes, there are a few that run harder & higher, but few). If I can flow to increase the torque with displacement, super. There are well-proven combos out there too. By "big" I mean 284 - it's all relative. And 284 isn't "big" in flathead circles. I'm confident traditional mods will flow more than enough for 284 inches.

Besides, even if I just built it big and made no breathing mods, there would be a point where the breathing restricted the inches so much that it would make no more power than a stock sized engine, right? But if I've increased the total torque below the curve, I've still accomplished something useful.

All of this discussion is moot, however, as I intend to put a blower on it & eliminate most of the breathing issues artificially!

 

Yes!! Now you're understanding. I think? That's what they mean by unsightly.

 

Michelle, it's a play on unsightly, where do you see those?
Ernie it's the uninformed puritanism that bothers me. Given that a normally aspirated little engine runs out of puff below 5k how can the flow be considered good, I can't help but wonder just how much is gained and lost making them bigger.

 

Uninformed puritanism? YGBSM - I've conceded your efficiency point already.

I never said flow was good - I said it had a good ratio between exhaust and intake.

I also said I was going to make it scream in pain with a blower.

BTW, I'll bet I can pick up more than 20HP with port & chamber work...

 

Ernie, I was referring to Banjo's initial comments and not your blown motor, just some fictional larger normally aspirated larger motor.

-Andy

 

It seems Hotrod added a couple of their own myths when they wrote that article, not really convinced that it was worthy of the $6 price tag when it came out as there is certainly a lot better and more accurate info out there from people who aren't out to sell you their own product or a full page ad for that matter.......


"That's all I got to say about that" -Forest Gump



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Fair enough - some of the old timers like Navarro actually ran destroked engines due to breathing limitations, but I'm not sure how effective they were...

Well, not that I'm a purist by any stretch, but I can appreciate what they do and the effort they make to put together a truly period-correct car/engine combo. It may be slightly disingenuous to paint them as uninformed, and, on the contrary, the research of such an effort alone would be more education than many on here have of our roots. I do agree that there are elements of our hobby who are somewhat puritanical in the same vein as paint and chalk mark restorers are though...

But that's what makes all this fun - we all have our own interpretation of what we like!

 

Andy:


Take a deep breath, broter. The key words you are missing in my comments are "In my opinion".

Gold bless your brother and his craftiness for grafting the TPI to his flathead.

Bottomline, it is not for me, I don't think it looks the part on the flathead, and MY opinion will never change. So I run out of breath at 5K, really don't think my motor will be seeing that range with any regurality on the street.

Again, it's my thing. I would never look down upon your brother's ride or keep him out of the show for it appears his mechanical skill seems to be way above my own.

BTW: I am the farthest thing from a period correct Nazi. I like what I like and do things my way. You are more than welcome to do it your way. Don't let my post deter you.

It's not personal, just flatheads.

Tim

 

I'm sorry Andy (ehdubya). I was just trying to lighten the mood.