What are the Log heads problems and Solutions

[66shelby]

I have never seen or found a thread that deals specifically with the multitudes of shortcomings of the log head. Nor has anyone addressed ways to overcome those same issues.

There are bits and pieces scattered all over the Forum, but not a single dedicated thread. I would like to know what if anything can be done to improve the basic design as it is.

I understand that the best solution is most likely Classic Inlines new aluminum head. I can't justify the cost right now.

What I am most curious about are basic elements. We all know the head is considered a restriction. Is it the size or ID of the passage? Too many abrupt changes of the pathway? Etc., etc.

Another aspect is the ingenuity of all who have gone before. Tri Power's, Two barrell's, Turbo and Superchargers. I have seen photo's of milled logs, shaved logs, fuel injected logs.


Let that spirit live on. Please share your observations and experiences so we may all benefit.

 

[wallaka]

What I am most curious about are basic elements. We all know the head is considered a restriction. Is it the size or ID of the passage? Too many abrupt changes of the pathway? Etc., etc.

I'm thinking that all of the above is a valid answer. Poor flow, worse fuel distribution, and right angle turns add up to a bad intake tract.

 

[ludwig]

Another aspect is the ingenuity of all who have gone before. Tri Power's, Two barrell's, Turbo and Superchargers. I have seen photo's of milled logs, shaved logs, fuel injected logs.

And these would be all the solutions, varied only by the solver's performance intention, desire and skills.

 

[BIGREDRASA]

Another aspect is the ingenuity of all who have gone before. Tri Power's, Two barrell's, Turbo and Superchargers. I have seen photo's of milled logs, shaved logs, fuel injected logs.

And these would be all the solutions, varied only by the solver's performance intention, desire and skills.

Except for the Dilythium Crystals.

 

[jamyers]

Main problem is that the carb is in the middle, and the 90-degree bends - add it up and the end cylinders run lean and the middle cylinders run rich.

Somewhere around here there's a posting by (iirc) Xecute where he discusses the log head and makes the statement that the Clifford Tri-power is the only real fix for the loghead limitations.

 

[66shelby]

Ludwig you see my intentions,and Wallaka you get the point.

When you march to the different drummer you have to blaze some trails.

I have seen some really good ideas here and you guys have proven these things can be made to work. That being said, let's dig out some dilithium.....

We all know the later model heads have the largest (stock) valves and hardened seats. The latest models have the largest diameter tunnel. I have questions about distribution. We all know there are advantages to be had by jumping to a direct mount 2 barrel, but it seems to me that the 3 single approach would have advantages.

I saw one thread concerning Extrude honing, and IIRC no one felt it was worth the expense. Considering the bite it would pay to go CI Al.

Where does all this go when your under boost? Will made a 250 run 10's with a log. My built 302 won't do that!!!! :shockin:

If you got to go stock, start with the late model head.

Anybody got any new twists or thoughts?

 

[Anonymous]

Look through my website for loghead info.

I've done just about everything you can to one

http://www.geocities.com/mustang_man_1966/index.html

Later,

Doug

 

[JackFish]

Is this a log head? With an adapter plate? Or an argie variation?

 

[ludwig]

You might check the posts from 2004 to early 2005 if they still exist. (There was a massive data loss about a year later and many months of posts were lost.) At that time there was wave of log head modding going on. They tend to go in waves. For a while there will be a bunch of turbo ideas; then come the 2V and 4V carb variants; then you get the 3 in 1 stuff. Every guy has a new wrinkle or a new theory.

In 2004 there were a couple guys who simply sawed the log off completely using a Skilsaw and a metal wheel. Their intentions were to either make a home-fab FI, individual intake throats for side-draft Webers, or do some kind of collector FI box grafted onto the stubs of the intake. I still ponder this. Hot Rod mag had an article showing some guy who make up a stainless collector box and used 6 Stromberg style throttle bodies and modern fuel management. He mounted this on a single plane intake manifold with two giant carb throats. It looked real old school but had the scat of an EFI system. I have been thinking about this for a couple years now. Might be fun. Mount those 3 Stromberg horns on a collector box. There's a look no other sixer has.

There was one guy here who did a 2 in 1 with 2 2V Holleys, two custom mounting plates and a block-off for the original carb hole. Fewer carbs to tune and more throats than the 3 in 1.

If you haven't already, check out the poop on all the log heads from the Falcon Performance Handbook. If you have, then you know nearly as much as most of the guys here. You might even get to touch the hem of the garment of Will or Mike or Jack Collins, the FSF gods. The log head is both the fun and the frustration. You can fight back with a couple bricks of billet stock for carb mounts or a whole milling shop for a radical re-design. All depends on your imagination and your skill. Mine is real humble in both areas.

Edit in: There was one guy who sawed the top of the whole log head off with the intention of milling a long and narrow plate of billet stock, securing it with U-bolts like the Offenhauser, and then mounting the carbs of choice on the flat surface.

 

[drag-200stang]

I don't favor sawing off the log. It may have had a benefit with the early heads. Hundreds have been sawed off. Few have ever been finished and none are any faster.

I believe a homemade or modified Offenhauser tripower that uses a full bore instead of the small 1" restrictive hole provides the best carburated performance.

With this set up using the same size carburator I was able to disconnect carbs 2 at a time and 1 at a time and see how the car performed. Three performed best, not 1, not 2 and it was quite clear. I don't know if this test will work for the guys that have the choked down Offenhauser or smaller outside carbs. With the full bore set up the closest carb to the cylinder sucking gets a stronger signal meaning better throttle response.

 

[66shelby]

Way back in Oct. '05 Linc's put this idea up. There was little response as the thread took a turn.

This would seem to be similar to the Offy setup, just not as direct. I have been trying to sort in my head (pun intended) what the flow and distribution would be like. I have seen references to "Scientific design of Intake and exhaust systems". If any of you scientist types want to shoot this down or comment it would be informative. Would the vacuum signal be all messed up? Would the plenum area under the butterflies be an advantage or not?

The most obvious shortcoming is one barrel feeding 2 cylinders in close proximity, and the other feeding 4 cyl's at a distance. It would seem to me this would be an issue under NA conditions, but not so much under boost.

I am seriously considering this mod. I have already fabbed a header from weld ells and I am convinced I could fab this setup as well. Unless you guys can crap all over this I am going to do it.

Has anyone tried something like this, or can you see any apparent flaws beyond what I question. This will be a turbo application, 99% street driven, and a daily driver.

 

[jamyers]

Is this a log head? With an adapter plate? Or an argie variation?

Pretty sure that's a bolt-on intake. Looks like a bolthead right under that radiator hose, and a curved end of the intake.

 

[66shelby]

Its an Aussie setup.



http://www.classicinlines.com/gallery/f ... 08_jpg.jpg

 

[xctasy]

Is this a log head? With an adapter plate? Or an argie variation?

It is in fact Argentinas wicked 221 SP engine, with non standard triple Webers. The car is a left hooker, American spec Todo Falcon SP

The word from all dyno simulation runs that have compared a 1 or 2-bbl to a Three 2-BBL set up is is that six chokes feeding to one log head would yield a 25% gain in power with no other alterantions, and would improve brake specific fuel consumption. No adaptor exists for a 3 times 2-bbl set up yet. The closest option is the Offy or Clifford 3 by 1-bbl, which yields very good improvements with a small budget.

Thinking further, you start with the Offy or Clifford 3 by 1 -bbl adaptor, then you could get three Stovebolt adaptors, and then mate three 350 or 500 cfm Holley 2-bbl carbs, and get a similar result with a slight loss of fuel economy. Or three 38DGAS 2-bbl Webers. Both are simultanoues opening carbs which would flow quite well with three 1.3 to 1.5" or perhaps 1.75" holes, but it would be harder to package under the hood, and you'd have to track down the right kind of flat top, early round body or later log adaptor, and it'd be hard work.

The real issue gain is in indivudal peak cfm flow to ach barrel. Flow efficency goes up a low vlave lifts, and the overall paek cfm improves. Fluid dynamics show that a sucession of combined inflection points (bends) hurt flow efficiency, and that shows as a drop in cfm on a flow bench. When Jack Collions and Bill at Indy do dyno runs, the computer always shows that the log or 1-bbl intake is a restriction. In my analysis, its only a problem when one 1 or 2-bbl carb is feeding six cylinders. When each one of three carbs has a better, equal shot at the cylinders, it yields solid gold power. The flow bench numbers skyroket, even though the ports haven't been touched.

If you go further and modify the later log heads for three direct mount 500 cfm Holley 2300 series carbs, you'd eclispe any other manifold, and get close to what the Classic Inlines head gives right out of the box with just one 2-bbl carb.

The issue is that you'd make a log head into a pulse tuned independent runner intake, and that is still the untlimate of any induction system, eclipsing port EFI for power.

 

[Does10s]

Will made a 250 run 10's with a log. My built 302 won't do that!!!! :shockin:

Well not quite!
The quickest pass with the log head in Kelly's Falcon was an 11.85@115.
Right after that pass we got the new aluminum head from Classic Inlines and then we dropped down to a best of 10.95@124.

I believe that the log head would've gone faster, but in our case, I don't think we would've ever got into the 10's with it.

Will

 

[Anonymous]

i'm building up a custom intake to run three one's or thre what ever just had planed on using 97's or 94's. using a lower efi intake with custom log to sit ontop. my question is it better for performance to have all three a direct link to trotell cabel so all open at the same time or have a progressive trotell that starts on the center carb and ends with all three at wot. ???

 

[60s Refugee]

Doug,

Looked at your site and time slips. Did you ever run the car with the stock engine to get a comparison of original vs modified results?
Also, did that header fit without modifying anything?

Harry

 

[69Falcon]

There's a photo around of an I6 with a draw-through M90 supercharger mounted on the driver's side feeding a single pipe bolted onto where the carb normally sits.



We know that the offy 3x1 setup is an improvement over stock.

Why not combine the ideas? Draw through the M90, then feed it into 3 holes in the log.

Or, if you want to get fancy, turbo/supercharge it going into an offy 3x1 setup except with fuel injected throttlebodies.

 

[jamyers]

Hmm... Seeing as the issue is poor flow to the ends, and as a tri-power setup fixes that...how about a tri-power setup, only with 3 EFI throttle bodies? You could then fab up an aluminum plenum to pressurize them from if you wanted to go turbo.

 

[66shelby]

I hoped to understand why if this was such a poor design, why did Ford produce it for almost 30 years?

We see the Argentine heads, and Aussie heads are wonderful to consider. Now we have the Classic Inlines head to buy. All are a great improvement over the stock log.

I guess I was hopefull that someone could shed some light on how to make the log work. It works fine for slightly better than half throttle, you just can't get it to really sing like it is. That is unless you modify the hell out of it.