Shoud I relieve my block
 

The answer is: absolutely not!!!! The internet as posted several articles on relieving the flathead block. I did allot of this in the early days, untill I went racing, and discovered the fact that very few builders did this. In a conversation with a builder of a few good winning engines , stated there was no real information of the benefits of relieving the block and it was time consuming and a pain in the ass to install the pistons, PLUS no prof that it increased power or economy,
Gramps

Re: Shoud I relieve my block
 

I would never do it based on the lower CR. Some folks get a big kick out of a relieved block. I had a relieved block and sold it. I was glad to see it go. I agree with you Ron.

Re: Shoud I relieve my block
 

It's a relief not to relieve.

Re: Shoud I relieve my block
 

.

I must admit that I would never go to the expense in time or money of relieving a block. But with that being said, I've still gotta ask WHY did those Frenchmen go to the trouble on those beautiful French flatheads (one of which I just sold the last couple of days), as well as the relatively few that Henry Ford produced for buses and other industrial equipment?

Coop

https://th.bing.com/th/id/R.a9cae9d1...pid=ImgRaw&r=0

Re: Shoud I relieve my block
 

Some claim if the exhaust is left alone and the intake relieved a bit, good things might happen.


https://www.fordbarn.com/forum/attac...1&d=1701468985

Re: Shoud I relieve my block
 

I would not bother on a mild street engine but I can get well over 1 hp per cubic inch naturally aspirated on gas in a race engine.
The relief is as deep and wide as the block material will permit. The pistons are flat.

Re: Shoud I relieve my block
 

Is the head flat as well,Pete? Good compression.

Re: Shoud I relieve my block
 

Like Pete wrote for a mild street engine there's no need. However if your interested in getting some more power and economy taking the time to do it correctly is worth the effort. We know Ford did do it on engine's going into Ford trucks makes you wonder why. And as Coop points out the French flathead blocks all had the relief's. Plus as an added point of interest the one flathead design that produced a LOT of power and I would expect economy if needed was the Harley Davidson KR headed flatheads with a relief and that was in the 1960's era.
Like Pete wrote 1 HP per cubic inch out of a Ford flathead is easily possible its being done everyday.

The slight amount of compression reduction caused due to the block being relived in a flathead is actually a good thing considering the poor quality of the gas we have today. High compression and to much timing is a killer for a Flathead unless your burning a good quality high octane gas if your are than your good to go.
Ronnieroadster

Re: Shoud I relieve my block
 

I have a 99A block sitting under a tarp that is factory relieved.

GB

Re: Shoud I relieve my block
 

The head is flat also. The transfer area in the head is adjusted for compression ratio.

I can get 14 to 1 compression ratio for running alcohol.

Re: Shoud I relieve my block
 

I've run some flow test on cumbustion chamber design, and as airflow speeds increas so does the turbulence caused by chamber irregularities. overt 4500 RPN The turblance increase dreamily and the valve bowl is the worst. One reason the torque drops after 4500 rpm. John and I talked about it when he as buildinng his Bvill engine and he came uo with the new guides which helped this area. Photos in his book. I'll post some computer flow graphs, but can't be sure of their accuracy
Gramps

Re: Shoud I relieve my block
 

I’m no expert however I do have bunch of old literature from early days of Harley Davidson on their development of the side valves. All their successful racing engines had a relief area.
Hopping up Ford Flatties seem to follow suit. Ron you have real knowledge of real testing.
Good enough for me.

Re: Shoud I relieve my block
 

I have original Harley KR jugs and heads - they were relieved and also had a very different head design. They ran mostly flat-top pistons until later in the 60's when they tried a dome top. The dome top engines didn't make any more HP than the flat-topped piston designs. Of course, these were purpose built racing engines and ran way past 6000 RPM all the time. Flow was everything to their design, with huge ports, big valves, etc.. We only wish our Ford flatheads had anywhere near the type of ports and head-bolt layouts of the Harleys.

When I designed our FlatCAD chambers, heads and pistons (flathead Cadillac Bonneville engine) - we used as much of the 'KR' design as possible - including the custom mods that Jerry Branch made for his modified KR's.

Branch (and my neighbor 'Snuffy Smith') made some of the highest HP KR's of the day. I learned a LOT from Snuffy! Snuffy built a KR for use at Daytona for a rich guy back in the early 90's - was making about 60 HP on a 45 cube KR on gas. The guys running the dyno were really surprised about the HP he was able to achieve on the good ole' KR sidevalve motor.

Re: Shoud I relieve my block
 

Here is a picture of a KR head - for flat top pistons - the piston popped up about 3/16" of an inch into the chamber. This was very important for flow:

Attachment 531322

Here is a picture of the Navarro Hi-Flo head - which used some of the KR type design (stepped relief):

Attachment 531323

Here is a Tony Baron "Pop-UP" head - using a very tall pop-up piston design:

Attachment 531325


Here is a picture of the 3D CAD Model for the FlatCAD chambers:

Attachment 531324

Here is the actual FlatCAD Head Chamber:

Attachment 531328

Re: Shoud I relieve my block
 

Well I guess I'm wrong. I'd like to see a flathead that makes one HP per cubic inch flathead on gas. I nolonger have the eqipment I used for my testing, so I can't comment on these reselts with any acury. I agree with the HD engine design as we looked at it back then. The Grancore heads were similar with a pop up piston. someone out there has them, Ford factory relieved blocks didn't last long and were designed to limit detention. I was told. But they never included it in the late engines or the 337. The French were just copying it.
Everybody has an excuse for their actions and beliefs , I stand corrected.
Gramps

Re: Shoud I relieve my block
 

RR>>1 HP per cubic inch out of a Ford flathead is>>done everyday.>>


O'R>>Well I guess I'm wrong. I'd like to see a flathead that makes one HP per cubic inch flathead on gas. >>>



Maybe not Ol'Ron.. Prolly only done every other day. :D

Re: Shoud I relieve my block
 

For those that keep saying they would like to see a flathead Ford race engine that makes over 1 hp per cubic inch naturally aspirated on gas, I would like to tell you how simple that is.
First off, you will see the engine and car but you will not see inside the engine. These engines are seldom torn down at the track unless it is for record certification and unless you are a VERY good friend of the owner, you are not going to see much.
To see one of these engines, you must first find out what cars they run in by looking up records set at the various tracks they run at. This is easily done by looking up land speed racing tracks in the USA. There are several beside Bonneville.
When you find where they are running you contact the car owner and find when he is going to run, Then you go watch.
These engines have been around since the 50's so they are really nothing new.

Re: Shoud I relieve my block
 

Actually, you were not wrong - it is all about the application and usage of the engine. Relieving a Ford Flathead does nothing of value before about 4000 - 4500 RPM . . . actually it hurts low end power as it reduced compression (with everything else the same). Also, relieving is just one small piece of the overall puzzle - you have the ports to worry about (they take serious amounts of work), you have the cam to worry about, you have the valves, the chambers in the heads, etc.. As Pete noted - when all the things are specifically designed to work together (for racing) - then relieving is part of the "combo" that was typically used.

Also, typically these naturally aspirated engines were fuel injected - which surely adds horsepower over the typical Stromberg setup. And truth be told, the classical Hilborn flathead injector is too small for max HP. Guys like Don Ferguson Sr. cast their own injectors way back in the 80's - with big port/butterfly sizes more like a SBC injector (to get the flow they needed).

Then, one can start talking about oil-control, dry-sumps, crank scrapers, vacuum pumps, low-tension rings, straight-cut cam gears, etc.. A lot can go into one of these engines - and it is not for those "on the cheap". :D

Re: Shoud I relieve my block
 

Oh, so it's the old : "I could tell ya', but then I'd have to kill ya'".:D

Re: Shoud I relieve my block
 

I have the same understanding as Ron, the factory relief was an effort to limit detonation by lowering compression in truck engines, not an effort to improve power. Note that this method of lowering compression preserves the quench between the piston and head and doesn't suffer from the misery that was the 1970s attempts at the same thing by using dished pistons.

Ford flathead V8 chamber design is an interesting subject, and most of the top racing engine builders will not share what their development looks like. Kudos to Bored&Stroked for doing that.
I stumbled on another flathead Ford racing chamber design earlier this year while wandering around the Model T regions of the world wide web. Apparently one of the Kloth combustion chambers from the race motor in the celebrated 1950 Mercury sedan got used as the design for a new Model T high compression head. Link to the web page here: http://hcgarage.net/T-Head.htm
Picture of the combustion chamber, note the larger portion of the chamber is on the intake side:
https://fordbarn.com/forum/attachmen...0&d=1701569629

Re: Shoud I relieve my block
 

Here's one of them Ford flathead speed secrets learned some time ago a built not relived Ford flathead will rev to 5 grand. To get another thousand RPM a relief will get you there. And to get even more pay attention to what Dale wrote above.
Ronnieroadster

Re: Shoud I relieve my block
 

Well, actually, I have seen on both this and the HAMB forums, a few years ago, pictures of several of the top fuel drag engines with the heads off.
In the old days I saw the Bean Bandits engine with the heads off several times.
Also several other record setters of the day.
The info is out there if people really want to get it.

The thing is, most people can not tell what they are looking at even if they have a caliper and can measure things. Modifying a certain area by even .010 can lose you 5 hp. Few people can discern .010 with the naked eye.

Re: Shoud I relieve my block
 

With the Gas allowed at Bvill I can't see that running ON14: 1 CR I know John looked at allot of chambers, His displacement was alittle over 300 not sure what and the Cr around 12 :1 I know what the power was, ans it was nowhere near 1 per cubic inch. Just what kind of gas do you run on 14:1Cr???? Or is that a secret also/???
Gramps

Re: Shoud I relieve my block
 

I don't think that any of my modern engines have run at Bonneville.
They are circle track engines for vintage racing.

Most run alcohol but I do know that a couple run 118 race gas because of rules.
It works fine.
I ran the old discontinued 115/145 av gas in the 50's and it worked fine also.
Gas is usually down in hp about 10% from alcohol.

Re: Shoud I relieve my block
 

if you want a fast car buy a corvet. the more you do to a flathead the worst it runs if you want a smooth cool running eng leave it stock

Re: Shoud I relieve my block
 

RR>>Here's one of them Ford flathead speed secrets learned some time ago a built not relived Ford flathead will rev to 5 grand. To get another thousand RPM a relief will get you there.>>>


Interesting. I'd hafta guess that the Hudson racing cognoscenti had a few secrets like this as well.

Re: Shoud I relieve my block
 

Ron at Bonneville VP racing fuels brand is the gas available.
Anyone running for a gas record must use the VP gas. Example of the octane grades available C-16 has an octane rating of 116 for compression ratios up to 17.1.
The actual altitude at Bonneville is just over 4000 feet for a flathead that has a hard time breathing at sea level this of course is a big issue. I've read for every 1000 feet of altitude an engine can see a reduction in power of 15 percent.
When other factors are added in the density altitude gets even worse early morning at Bonneville the density altitude is just under 6000 feet. That's why the backup runs for a record at Bonneville are held early morning so our engine's have the the best air possible.

Here's one example and some details from the fastest run to date we made with our stock block Ford flathead
{Note stock block means we use the three exhaust ports on each side of the block as designed we do not add any other exhaust port}

Our flathead is 292 cubes we burn C-16 VP gas the car weight is well over 3000 pounds.
The density altitude just after 2 PM in the afternoon was over 7000 feet the Ford flathead engine turning 6100 RPM ran 219.8 MPH . To get a speed this fast burning gasoline takes horsepower lots of it we always run a block relief to help the combination to survive. Hopefully this information will help others in the future who may one day decide to try and do this crazy stuff some of us are doing. :)
Ronnieroadster

Re: Shoud I relieve my block
 

Well I'm sure there's a few flathead blocks around that would easily put some agent orange corvet to shame in a side by side run :D
Ronnieroadster

Re: Shoud I relieve my block
 

I don't know, but the Beach Boys seemed to think it made a difference. ;-)

Little Deuce Coupe, you don't know what I've got
(You don't know what I've got)
Little Deuce Coupe, you don't know what I've got
Well, I'm not bragging, babe, so don't put me down (Deuce Coupe)
But I've got the fastest set of wheels in town (Deuce Coupe)
When something comes up to me, he don't even try (Deuce Coupe)
'Cause if it had a set of wings, man, I know she can fly
She's my little Deuce Coupe
You don't know what I've got
Little Deuce Coupe
You don't know what I've got
Just a little Deuce Coupe with a flathead mill (Deuce Coupe)
But she'll walk a Thunderbird like it's standing still (Deuce Coupe)
She's ported and relieved, and she's stroked and bored (Deuce Coupe)
She'll do a hundred and forty in the top end floored
She's my little Deuce Coupe
You don't know what I've got
(She's my little Deuce Coupe)
(You don't know what I've got)
She's got a competition clutch with four on the floor
And she purrs like a kitten 'til the lake pipes roar
And if that ain't enough to make you flip your lid
There's one more thing, I've got the pink slip, Daddy
And coming off the line when the light turns green (Deuce Coupe)
Well, she blows 'em outta the water like you've never seen (Deuce Coupe)
I get pushed out of shape, and it's hard to steer (Deuce Coupe)
When I get rubber in all four gears
She's my little Deuce Coupe
You don't know what I've got
(She's my little Deuce Coupe)
(You don't know what I've got)
She's my little Deuce Coupe
You don't know what I've got
(She's my little Deuce Coupe)
(You don't know what I've got)
She's my little Deuce Coupe
You don't know what I've got, what I've got

Re: Shoud I relieve my block
 

This whole thread was great reading on a cold rainy day......Thanks guys!!.......Mark

Re: Shoud I relieve my block
 

Dale, Thanks for a very balanced and informative discussion of the topic!.
John

Re: Shoud I relieve my block
 

You are right there. I learned a lot from Smokey.

Re: Shoud I relieve my block
 

This has been a good thread - based on a lot of the folks contributing who have many years of experience with these goofy engines (not only Ford, but many other variants).

Like anything else, there is no one "right" answer . . . the answer is the usual "well, it depends". :rolleyes::rolleyes::rolleyes:

Re: Shoud I relieve my block
 

I am not sure exactly how the rating system works on this forum, but if you have enjoyed this discussion I encourage you to rate this thread. The “Rate this thread” button is in the ribbon at the top of the thread. Normally I would rarely rate a thread, but there are special discussions that warrant a rating.

I have thoroughly enjoyed this discussion. Thanks to Ol Ron for kicking off this thread.

Re: Shoud I relieve my block
 

Well over 1400 people have looked at it so I guess you can take your pick RR , I appreciate your input, what you've done to improve the flathead in competition is impressive. What I learned from limited stock car racing has allot to do with my building knowledge. Right now I working on a street engine with Good performance, good economy, long life and under 3K$. That might be harder than running at Bivll.
Gramps

Re: Shoud I relieve my block
 

To add to this, I have three 99A's. Two are relieved and one is not. I'd assume the two that are were in trucks. One of the relieved and the non-relieved are both crack in the #3 intake valve seat.

Re: Shoud I relieve my block
 

Is this a decent summary of the information in this thread?


1 - Below 4500 rpm there is no benefit to a relief.

2 - For motors built for competition use a relief can help, but must be carefully designed. The rpm range of competition will heavily favor whether a relief is helpful or not.

3 - For all out high rpm use such as land speed racing a relief is necessary.

Re: Shoud I relieve my block
 

Thanks all for contributing to this thread.

Re: Shoud I relieve my block
 

Truck and industrial engines which see high load over extended periods of time will often have lower compression ratios. One way of doing this is to relieve the block. GM did this on the 348-409 Chevrolet truck and industrial engines. I'd suspect Ford did the same.

Re: Shoud I relieve my block
 

1 - "Below 4500 rpm there is no benefit to a relief."
Wrong.

2 - "For motors built for competition use a relief can help, but must be carefully
designed.
You will be in the "C" main without it and there is no design to it. You just
go bigger.

"The rpm range of competition will heavily favor whether a relief is helpful
or not".
It helps over the whole rpm range.

3 - "For all out high rpm use such as land speed racing a relief is necessary."
Right.