Relieving 8BA Block

[1934calkid]

Should a block for a street car be relieved 286 ci

[19Fordy]

The first sentence in the Relieving the Block section Ron Halloran's book NOSTALGIA-Rebuilding and Modifying the Flathead V8 (Page 39) says:"Relieving the block is usually reserved for racing engines." He then goes on the explain."The reason an engine needs relieving is to produce power at high RPM's and that's not where a street engine spends much of its time." Also, read all of this:
http://www.flatheadv8.org/rumblest/intro.htm and
http://www.jalopyjournal.com/forum/t...eading.770895/

Here's a couple of good articles:
http://www.hotrod.com/how-to/engine/...lathead-myths/
and
http://www.jalopyjournal.com/forum/t...inions.420484/

[Bored&Stroked]

It all depends on your complete setup, how you plan to use the engine and what RPM range you want to run at.

Typically, relieving a block will not help lower-end torque or horsepower, will probably hurt it as you lower compression a bit. If you desire peak horsepower and plan to regularly ran it over 4,000 RPM, then it can help flow. Also, relieving by itself will probably not help a bit - so unless you do a full competition style port job and install bigger valves, probably isn't worth it.

What combination of parts in the engine (cam, intake, carbs, ignition, heads, compression ratio), what trans, what gear ratio and what are you looking at as far as usage and engine behavior.

Also, you might consider more of a 'step relief' or semi-relief, where you blend/smooth the valve pocket cuts into the transfer area to help the flow, but not hurt compression too much.

Best of luck - if you need more info, PM me.

Dale

Attached are some pictures of various reliefs I've done (full, stepped, semi) - mostly Ford, but also Flathead Cadillac:

Relief1 copy.jpg

DeckAtAngle.jpg

59L-Porting-Guides-Relief-80.jpg

ReliefWithRadiusBoreEdge copy.jpg

[40 Deluxe]

Air flows the best in a straight line. Anytime you force air to change direction, flow is reduced. So you want these changes to be as gradual and as smooth as possible. Thus the major air flow is out of the port and up against the head surface and then down into the cylinder, kind oaf a gradual arc. Relatively little air flows directly along the deck surface into the cylinder. Of course, in a high RPM race engine, you're after every last bit of flow, so you trade compression for better cylinder filling.

[KiWinUS]

Relieving will also lower your compression . Personally I want the compression.

[George/Maine]

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you could ruin good engine if not racing you will always beat your shadow with the sun at your back.

[B-O-B]

So why did ford factory relieve the 59AB in their truck engines?

[Ol' Ron]

Since I wrote that book, I've learned that relieving the block is basicaly a waste of time and money, for any aplication. Air flow is controlled by the combustion chamber shape. Relieving the block is just a cure for a bad chamber design.

[rotorwrench]

Truck engines were relieved to lower compression and reduce hot spot areas that could cause the dreaded ping or detonation under heavy loads.

[Capt Kirk]

George, with the sun at your back, your shadow will always win and in my 35 I'm thinking my shadow might lap me a couple times!

[Bored&Stroked]

We'll never solve the question of 'to relieve or not to relieve' - there are more opinions than bung-holes in the flathead world (which makes it fun - you get to pick your fortune teller and make up your own mind).

One thing I do believe is that in higher RPM engines having a relief has to improve flow - or Harley would not have done it for 15 years in their racing KR flatheads. In my opinion there is no flathead engine that had more development and dyno time than Harley and their racing KR's. I've had numerous sets of cylinders and heads and my neighbor built a lot of their race bikes. All were relieved - some 'stepped' - as the heads were stepped and in their larger roller cams, they ran dual profile cams. Nobody has achieved their horsepower per cubic inch - naturally aspirated and on gas. With that said - these were highly developed versions of the old 45 CI Harley flathead - our flatheads have nowhere near the optimized port sizes/designs and flow these guys had.

Here are two pictures for you to ponder - two different styles of reliefs:

01p-1965-krtt-head-barrel-2.jpg

user3389_pic8514_1309048160.jpg

[Ol' Ron]

Grancor made some heads with Harley combustion chambers?? Had a set that had a pop up design for a 3 3/4 stroke piston on a 4' crank. Heads are now in a junk yard in Yuba city Ca. With the rest of my engine.

[Bored&Stroked]

Originally Posted by Ol' Ron

Grancor made some heads with Harley combustion chambers?? Had a set that had a pop up design for a 3 3/4 stroke piston on a 4' crank. Heads are now in a junk yard in Yuba city Ca. With the rest of my engine.

The Navarro 'Hi-Dome' heads are a half-copy of the Harley KR design (in the valve area) - but not down in the combustion chamber area (or the pistons). I talked to Barney at length about doing the whole KR design back in the 80's - but he only wanted to make a certain amount of changes to his regular core boxes - so he made it about 1/2 way there.

On the Flathead Cadillac blown/injected engine that we built for Bonneville (the 'FlatCad'), I adapted the KR design to our head designs (we made them out of billet aluminum) as well as our pistons. My neighbor and I talked at length about whether to go pop-up with a flat-top or domed chamber. He said that Harley came out with a domed pop-up very late in the development, but that it really didn't run any better than the flat-tops (as a matter of fact a bit slower and everybody panicked) - so I went with flat-tops in my 3D CAD designs. Was a lot easier to machine the heads/pistons with a flattop and get the exact quench I wanted.

We've made 650 HP on alky on the engine dyno - our challenge is keeping the head gaskets in it - as the decks are 'thin', just like our Fords.

Here are some pictures:

Head1_ChambersHandPolished.jpg

Chamber_HandPolishedAndORinged.jpg

PistonPopUp.1.jpg

EngineBlowerDriveMockup101.jpg

[Bluebell]

The reason why Ford relieved blocks was because many ford trucks during WWII developed cracks from the valve seat to the bore. This was supposedly because the vacuum boosters caused the mixture to lean out which in turn caused over heating. Relieving the block was the cure.
That's how I remember reading it. I hope that helps.

[JWL]

The false impression that relieving is good for competition engines because they operate at higher RPM will probably never die. Why? Because visual observations of Flathead flow paths seem to indicate a relief would be an improvement. Only after following the science with back-to-back flow bench and dyno tests can the facts be revealed.

The concept of using "seat-of-the-pants" as a point of reference or to collet data does not bode well for uncovering the facts. The fastest and quickest racing runs I have ever made actually felt the SLOWEST. I think this is because things happen very smoothly during the better runs. Those "hairy" runs with jolting wheel stands and power-drift crabbing at the top end are very impressive, but slow. Often there are those who make reference to speed records as proof of the value of relieving. But, since there are equally, or even more, magnificent records established with non-relieved Flatheads and since there is no way to determine how fast the sited record setter could have gone with no block relief, this is hardly a method which will determine validity.

I have no data on systems operating with air pressure beyond atmospheric.

[Ol' Ron]

Grancor combustion chamber

[Ronnieroadster]

Originally Posted by JWL

The false impression that relieving is good for competition engines because they operate at higher RPM will probably never die. Why? Because visual observations of Flathead flow paths seem to indicate a relief would be an improvement. Only after following the science with back-to-back flow bench and dyno tests can the facts be revealed.

The concept of using "seat-of-the-pants" as a point of reference or to collet data does not bode well for uncovering the facts. The fastest and quickest racing runs I have ever made actually felt the SLOWEST. I think this is because things happen very smoothly during the better runs. Those "hairy" runs with jolting wheel stands and power-drift crabbing at the top end are very impressive, but slow. Often there are those who make reference to speed records as proof of the value of relieving. But, since there are equally, or even more, magnificent records established with non-relieved Flatheads and since there is no way to determine how fast the sited record setter could have gone with no block relief, this is hardly a method which will determine validity.

I have no data on systems operating with air pressure beyond atmospheric.

The Harley KR flathead using a releived block using atmospheirc air proved with data it is the best way to go on a flathead.

[JWL]

A relief on the Harley KR might have provided a flow or combustion improvement on the Harley KR. My testing has been confined to the Ford Flathead V8 where relieving is a waste of time, compression, and adds to the undesirable residuals in the unswept areas.

[rotorwrench]

The KR models were a modification of the basic WL cylinder design just like the old Army WLA "45" bike engines had. Since they are air cooled with separate piece design, it made them easy to work with or replicate. The aluminum heads crack easily due to the heat so a person has to stock a lot of parts if they run those old engines on the track. My 1948 WL 45 solo has surface cracks in the top area of the combustion chambers but it still runs OK if you don't let it idle too long. Then again, it's definitely not a KR model. The intake ports and exhaust ports are a lot different than a Ford flathead V8 so it is harder to get a good comparison between the two designs other than they are both flatheads or valve in block types.

[Ronnieroadster]

Looks like its best to throw away that die grinder all those wasted hours! I DONT THINK SO

[Dennis Jarrell]

Anyone seen the Evans heads? They have a raised roof between the piston and valve pockets. Looks like a better choice to relieving.

[cdan34]

This relieving the block has always been fascinating to me. I have done it on a few blocks in the past and I've heard the negative comments. Just with common sense thinking, you know there is pressure in the combustion chamber. Granted it is forced against the top of the head as the exhaust valve is open, and works it's way around the valve into the port. If you have a relief that pressure will also have an open path to under protruded valve directly into port which seems to me would reduce the pressure on the top of head. For the minimum compression loss you can always take some material of the head surface.
The French blocks are nice castings with more nickel for strength and a better exhaust path then Ford. All the ones I've seen are relieved.
I would like to see a dyno test between two naturally aspirated engines, one with relief and one with out. My money is on the relieved engine!

cdan34

[rotorwrench]

All of the SUMB French engines were army truck engines. Near all of the engines that were purposed for big trucks were relieved. Trucks always needed some help in keeping them from self destructing under hard use. Since gearing made up for the lack of horse power, they needed a change from the stock automobile design to improve long term work performance. Relieving was the fix that FoMoCo engineers settled on since the flathead is so limited with respect to what can be done to it that won't take more away from it's capability to function in order to effect a change. In later years they did more modifications to the heads. The 8RT heads are a good example of a low compression head but when pulling a full load in the old F6, it really made the difference between the roughness of detonation or running smoothly. It was all about warranty consideration and reliability to keep the customer coming back for a new truck every so often. The big F7 & F8 trucks were the first Fords to get the new 317 Lincoln Y-block in 1952 so that they could get away from the flatheads. Even the Lincoln 337 wasn't up to the task well enough for the big trucks so it was finally dropped for the OHV engines.

Relieving was such a mainstay for the old aftermarket aluminum heads with crow foot chambers(that are still available to this day), that it's been viewed by so many to be the performance way to go that it is doubtful that there will ever be an agreement between folks that are all for relieving and those that don't use large reliefs.

Barney Navaro was one of the guys that played with the bent 8 long after most folks were adjusting there rocker arms. He preferred a small relief that basically just made a smooth ramp from the valve seat edge to the edge of the cylinder wall. After all those years of both seat of the pants experimentation and using science to effect meaningful changes, this was what he settled on.

[panic]

Have a nice day.

[Ronnie]

2015 thread ???

[tubman]

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New guy, first post. Happens all the time.

Testing the waters, so to speak.

[panic]

Exactly the response I expected.

[cadillac512]

panic: Thanks for your post. Maybe some here don't realize how much you know about this stuff. Please continue!


Terry

[KiWinUS]

Panic please repost. That was great info. Obviously you have some special knowledge on the WR/KR. This forum has all types please don’t take any post personal as there are many readers & for everyone that may not be interested in your post there’s possibly many that are. Thanks so much for the opportunity to at least read it once but would love to read again & retain as much of your knowledge as possible.
Cheers
Tony

[tubman]

"panic" - I think you're reading this wrong. My post was to explain to "Ronnie" what was happening, not to criticize you.

I will however, suggest you develop a slightly thicker skin if you are going to post on internet message boards. There are some that are a lot worse than this one.

As to your post, I found it quite informative.

[Bored&Stroked]

Well . . . seems 'Panic' came and went. He might be the same guy that I've seen on other forums (in the past) - most likely the HAMB. Hopefully he has some good information to share, he'll repost it. If he some information about the Harley KR - would love to hear it as my neighbor built many of them for flat-track, Daytona, side-hacks, etc..

There is always more to ponder, learn about, debate, etc -- if one isn't willing to debate ones 'facts' that one posts . . . then it seems a waste to post them.

I didn't get to read the infamous post . . . maybe he'll rethink . . .

[tubman]

He deleted his post after several of us tried to explain what happened and invited him to stay and contribute. Probably not a greatr loss.

[Pete]

Engine:
305 ci. Naturally aspirated. Dry sump.
14.5 to 1 compression.
FLAT TOP 2 ring pistons.
307 hp @ 6300 on 118 race gas.
.200 deep relief.

[40 Deluxe]

Originally Posted by Pete

Engine:
305 ci. Naturally aspirated. Dry sump.
14.5 to 1 compression.
FLAT TOP 2 ring pistons.
307 hp @ 6300 on 118 race gas.
.200 deep relief.

Just curious: What might the horsepower be if the block were not relieved but instead the same amount of material were taken off the roof of the combustion chamber in the transfer area?

[Bored&Stroked]

Originally Posted by Pete

Engine:
305 ci. Naturally aspirated. Dry sump.
14.5 to 1 compression.
FLAT TOP 2 ring pistons.
307 hp @ 6300 on 118 race gas.
.200 deep relief.

Pete, you should know that nobody can make horsepower with a relief . . . you should not have tried. I'd fill that relief back in with JB Weld and get your compression up to 16:1 and run regular pump gas. This should give you 308 hp @ 8000 rpm. LOL

[Ol' Ron]

At 14 CR on a 307 ci engine, The combustion chamber would be so small, not much air would be in there

[JM 35 Sedan]

What does JWL say about recieving a Flathead block in his book? Did he run Dyno comparisons? What were the results?

Whoop's, just went back and saw his previous post. Never mind

[Pete]

Originally Posted by 40 Deluxe

Just curious: What might the horsepower be if the block were not relieved but instead the same amount of material were taken off the roof of the combustion chamber in the transfer area?

It did not work as well because of the longer path.

[Ol' Ron]

B&S, how come you didn't place the spark plug in the transfer area on the new heads.Just curious./ That
s really a long flame front??

[40 Deluxe]

Originally Posted by Pete

It did not work as well because of the longer path.

Thanks for the interesting reply! I didn't think of the longer path as being detrimental. I was focused on the loss of air flow due to the sharper turn from valve to cylinder, caused by the lower roof of the combustion chamber. Always more to think about!

[dumb person]

No.

And not just no, but hell no. (as a response to the first post, just fyi)

[Pete]

Originally Posted by dumb person

No.

And not just no, but hell no. (as a response to the first post, just fyi)

Everyone is entitled to his opinion and I respect that, no matter what it is, BUT,
I would like to know how many that say "no" have actually built a FAST street engine and tested it with and without a relief?
Remember, for a valid test, you CAN NOT run the 2 tests with the same heads.

The relieved block will win every time.

[Vics Stuff]

I relieved my block for street use. Used 11:1 Offenhauser heads. 3/4 old school cam , tri power set up and my truck runs well. Been on the road since 1985 and never any engine issues. Just did a lot of reading and felt that was the best thing for this engine.
Do not regret it.
Vic

[dumb person]

Originally Posted by Pete

Everyone is entitled to his opinion and I respect that, no matter what it is, BUT,
I would like to know how many that say "no" have actually built a FAST street engine and tested it with and without a relief?

You can't put ardun heads on them very easily.

[JWL]

So many experts and so many myths.

[marko39]

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I knew a old timer who raced stock cars in the 50s and asked if they ever relieved the blocks on the flatheads. He told me they tried it but never saw any improvement on the track. Fwiw.

[old Tom]

I talked with 2 flathead giants in my time. One was Stan Lamelino at Cordova Il In 1962 and John Bradley in 1998 I asked each of them if their blocks were relieved and they both replied Yes.
Roger Huntington in his book and Don Francisco in his articles both stated that relieving the flat head motor increased the horse power. We are talking full out racing engines not street cars. Could all of these Giants of the past be wrong or is it because they are not able to take advantage of the modern technology we now have. Maybe some food for thought. Although John Bradly was still racing in the late 90,s and early 2000. Thank You

[Pete]

The original question was:
“ Should a block for a street car be relieved 286 ci”.

This can NOT be answered accurately without more information.

Static “street” display in a museum?
Daily driver/commuter?
Occasional street driver to the drive-in, parades or car games?
Fast driver to run at weekend drags and driven to work on weekdays?
Built to flip for quick cash.
Budget concerns?
Stock OEM heads?
Modified heads?
Driver driving style and habits.
How much hp can you be satisfied with.

[JWL]

Since I was the crew chief for Stan Lomelino, up to the time he stopped racing, I feel qualified to respond---It is true in the early days we would spend countless hours porting and relieving our engine blocks. This had to change when we started using 100% nitro and the racing schedule expanded wildly to a minimum of 3 events weekly. Eventually we found that softening the eyebrows combined with "normal" porting worked best and gave us the most power. There are several reasons why that is true which I explained in my book.


As an aside, Ken Kloth, perhaps one of the more well known Flathead racers, learned to avoid relieving the Flathead block in order to get top performance.


The secret (if there are secrets) is in the port, valve pocket, and head. Not the block relief. Doing wet flow studies will help us understand that the area being "relieved" does not play a significant roll in the breathing potential of our Flathead engines.

[Ol' Ron]

I modified a junk aluminum head to determine the affect of the transfer area had on flow. I sterted with a 4 deg angle and went up to a 12 deg angle. After 8 degs no improvement in flow took place with the port valvr combination i had in the block. Although this did increase flow, it also reduced the CR drastically. I then got as piece of wood and made up a bunch of combustion chamber designs t find the one that flowed the best with the highest CRr This was a wedge chamber the same as the Chevy 348/409 style. I waanted to have Egge make a set oof blanks for me so I could machine the heads and pistons to match, but the cost was much too high. Later i discovered that this chamber had already been used in a Bonneville engine. This is probably the best design so far, untill some one comes uo with a better one.
When it comes to running a fast car I believe the normally aspirated ones require th highest degree of engineering. Stuffing an engine with fuel or a blower is a lazy way to make power. However, I repect those that do, because they have to hold them together.

[Pete]

Originally Posted by Ol' Ron

When it comes to running a fast car I believe the normally aspirated ones require the highest degree of engineering.

You are sure right about that.

[JWL]

Not sure what you mean when using the term "engineering"? There are many little problems to be overcome to get maximum performance from any set of components. Mistakes in component selection or status are more readily exposed with boosted or boosted and fueled engines. There is something to be said for the level of refinement in engines of the Pro-Stock or Competition Eliminator categories where a gain of 5HP on a 1200HP engine is considered a great achievement. But the amount of work. study, engineering, and problems is present in all the full competition classes.