Log Manifold modification

hotrodguy

Well-known member
I have the 69 250 , building a drag race only motor, turbo charged on E-85. On the intake I am mounting a rectangular log Holley E-85 carb with 3 down ports onto the existing integral log. Definately thinking of sectioning out a 1 1/2 inch piece between cylinders 2 and 3 and 4 and 5. This would give 3 isolated individual inlets of 2 cylinders each. Seal each of the sectioned ports and make sure the internal diameter of each tube is the same about 1 3/8th inch. Has anyone tried this and how well did it work? My engine builder says anyway to equalize the cylinders is good and this sure seems like it would . Thanks
 
You could cut the log off completely and feed all 6 intake ports equally with a custom intake, since your most of the way there with your idea, why not go the rest of the way. You can do a search on here and see how others have done this mod.
 
About a decade ago, this was a hot topic here. One fellow took a diamond saw and cut the entire log off of the head in a straight line. I'm thinking that would still be doable if you could attach a plenum box with a couple/three throttle bodies on top of the box. They did something like that to a big block V* in Hot Rod mag. It was just a big pan on top of the intake manifold and there were six Stromberg horns sticking up. Inside, it was just empty space for atomized fuel/air feeding all the cylinders equally.

The problem is connecting the plenum box to the intake stubs along the side of the head. Braze? TIG/MIG? Some kind of threaded bracket or something inside the box? That is the key.
 
Thanks , likely brazing, little weight or stress on the welds, just a little fabrication short inlet tubes and bite the bullet at get a Holley E85 carb. I have the existing log cleaned up pretty well, wall thickness is .220. I'm thinking this should work out well on a budget. Aluminum head is great but that really kicks things up a lot on cost, and car modification . Just looking for fun in Sportsman class.
 
I think there was a fellow here who did the plenum box on top of the log with the three intakes from an Offenhauser mounting bracket. It's one of the three-carb rigs you can get for the log head. In fact, that might be the search term: offenhauser.
 
didn't my neighbor from Hudson Valley area NY make one - powerband the right ford6 handle?
many pic posted here…
could be a different idea from this though, I'm not clear on your concept.
His (plenum) looked like a big box on there.
 
What , I believe, is different about what I am doing is that I am isolating the cylinders in to 1&2 , 3&4 , 5&6. The Offy did not isolate, just added carburetors. I am actually creating a new intake manifold out of the log.
 
Check Mustang Six (Jack Collins') pics. He has shots of that precise application. Along with individual motorcycle carbs on each cylinder. Just depends on how fiddly you want to get. Not his, but other people's ideas.

Not my dog in the fight, since I am far from doing anything like that, but it seems to me that you could slice the log between 2 & 3 and 4 &5, then weld or braze a divider plate in place. Since the Offy device has three carb mounting surfaces of the same size, you would achieve the desired result. The later 250 log is larger and not tapered, so you would get a similar intake profile at each location.

That would save you milling the whole thing up from zero. Just an idea. As the Russian nuclear engineer who fixed my kitchen range told me:
"Sympl is byest."
"Like an AK 47?"
"Exyactly."
 
ludwig, could you be more specific about those Mustang 6 pics, I searched and could not find anything. much thanks Randy
 
Not Jacks, but how about Rick's instead?
choppedhead.jpg

Log chopping revisited -- FordSix Forum -- RickWrench
 
... considered forced induction setup using the Tri-Port modified Offy setup with a suitable 2Bbl/4Bbl dumping into the swirl-reducing plenum and 3 ports to log as balancer. Currently running it N A with a 2300 Holley 500 with good results.



. . . .

.. another FI intake project uses adapter to log's intake from Buick draw-thru Turbo, runs good on test stand, needs wheels...

. .

have fun

b
 
Associated item , any one know why there is a 1/2 inch height difference between the log. End of log at number 6 is 1/2 inch higher than number 1? Thanks
 
hotrodguy":3cvrpl02 said:
Associated item , any one know why there is a 1/2 inch height difference between the log. End of log at number 6 is 1/2 inch higher than number 1? Thanks
The engine sits in the vehicle at an angle(front being higher than the rear), and the log is angled to compensate for that which also makes the carb sit level relative to the vehicle and not the engines angled orientation in the vehicle.
 
American 4 BBL knowhow is enough to make the dog turd head of the cattle herd.


If you'd aked me, for years I'd have sworn, based on the evidence, that Port on Port Independent Runner induction beats all.

In 90% of the cases, it does. But Shelby dual quad 4-bbl FE 427's and certain 240 Z's can beat a handfull of direct mount Webers or Motorbike carbs with good execution and design.



Port on port, Independent Runner carburation requires the biggest waste of space to get the intake venturis up to size of any carb system, and on a tight engine bay like a X shell Falcon, Mustang/Maverick/Granada body or any Fox platform, there just aint the space to fit one of those systems on without a lot of really hard, elite engineering work. American smarts alters the outcome of the carb crap shoot, though.


See http://bringatrailer.com/2012/09/29/bat ... -race-car/

1971_Datsun_240Z_SCCA_Race_Car_For_Sale_Engine_resize.jpg


Induction is an unconventional but highly effective 390 cfm Holley 4150HP carb on a Bob Sharp style custom intake manifold. These manifolds were sold by Bob Sharp back in the early 70’s, and this is an improved reproduction. The Holley carb outperformed the 45 DCOE Webers on the car originally, and the seller says he was as astonished as anyone by this.

See https://www.youtube.com/watch?time_cont ... mUAw6CD1yU


And the answer is to keep the log, and do something like that 1971 Datsun 240Z SCCA Race Car. It has 45 DCOE beating 4bbl Holley carburation...


I studied real hard Ak Millers Horseing around with the Mustang Six. And then looked at what actually happened with the outcome of all that talk from Hot Rods 1967 articles. Ak continued to share the in line six gospel to all who would listen, with Jay Storer and many others catching the gist of it. What most weren't awre of was that the 1969 Mustang 200 and 250 was supposed to get an optional Aussie 2V head with a Fuel Injection unit that Ford Dearborn had been testing for years, which is why Ak could say some of his 1967 carb swaps made a 200 six fell like it was fuel injected.

http://www.classicinlines.com/HA7.asp

I was also very interested to find out what the small carburetors would do for horsepower in the lower rpm ranges, so we took a reading at 2800 rpm and netted 75 hp at the rear wheels. At 3800 rpm we had l05 hp, and we reached the top of the ladder at 4800 rpm, with 125 hp. This proved to us that our idea on the soundness of this type carburetion was right. When you jump on the throttle with the little bears, it is just like having fuel injection. It feels like all the horsepower unloads at once.

The gains in accleration were from a 120 hp gross rated Califonia spec 85 flywheel 0- 60 mph 12.5 sec, 19 seond 1/4 mile drag time car to a 125 flwheel hp 10.2 and 17.2 sec 1/4 mile car with just the head, exhaust, carb and cam change. Then an extra 25 rear wheel hp from the carb made it a true 158 hp car, able to do 8.5sec 0-60's and 16.6 second 1/4 miles, still with a 3 speed. The Jag carbs made it only sligtly slower, at 16.9 seconds for the 1320 dash.


At the 145 to 158 hp level with just 260 degrees of low lift cam and the open C7 DE closed chamber 52 to 54 nominal emissions head (it was planed down to 44 cc), Ak was right to where Nissan/Datsun was in the development 240Z engine...


AKART1.jpg
AKART2.jpg

AKART3.jpg
AKART4.jpg


The development from 1960 was little 156 cube engines Hilborn Fuel injection and the first Stropp Bros and Holman Moody tripower 1-bbls that have set in motion 55 years of Offenhauser bolt on adaptors which can make 180 bhp on a 200 and up to 220 or so on a 250. Hydrofoil racers like Clay Smith had looked into port on port injection with Stu Hilborn Hydofoils develped by Johnson Prop and Paul Sawyer. It was nothing to have those little four bearing pip-squeeks turn to 8600 rpm, and make 240 bhp. These days, a triple carbed 170 like Paul Knotts 1962 XK Falcon with saw off log can make 280 hp with 45 DCOE's.

But Ak Miller style, it went in public steps like this


Bigger 1-bbl 240 carb-->125 flywheel bhp
Twin HS6's-->145 flywheel bhp
Twin S&C carbs-->150 flywheel bhp
Four Keheins-->158 flywheel bhp
The MAVI GT Offenhauser 200 and 250 with a bewildering array of carb options--->125 to 220 flywheel hp depending on cam and pistons
Then Impco LPG and Turbo 250--->A Bye Bye little Buddy/Crosely Beater at---> 205 flywheel bhp
Triple Weber 45DCOE's on sawn off Argie style 200--->well over the 205 flywheel hp level
Bosch K Jetronic on sawn off Argie style 200--->well over the 205 flywheel hp level

When forced with California Air Resources Board Clean Air Rules, unlike others, Ak saw the 50000 mile durability requirments on the wall, and automatically ended up with making 2 and 4-bbl carb Holley or Autolite/ Motorcraft adaptors and draw through turbos if his customers didn't want his Impco or OHG propane carbs. The Pangra was first, then a whole bunch of AME kitset 200 and 250 turbo 4-bbl engines which produced better results.

So effectively, Ak Miller side shifted one step back

from the Aussie heads that used Six GSX 600 carbs,
the triple 45DCOE Weber and single throttle body Mercededs Benz Bosch Fuel injection set ups he also testing between 1967 and 1970,

and instead went back to 4-bbl Holley and turbo set ups that didn't have the space limitations of the 158 bhp four Kehien small log 3.3, or the 145 bhp twin HS6 1-3/4" set up.

The Offy tripower and 2-bbl Holley or Autolite/Motorcraft direct mount made some real power from every dollar. The probelm was fitting it all in.

In Australia and Argentina, the advent of the tall deck 250 and 221 in line sixes made all sorts of problems, they slanted the engine to fit it into 4 X 4's and early VA3000 Tri Power Falcons.

VA3000%20Falcon.jpg



But it was the Datsun guys who copied those methods the Aussies and Argies used to sort that out.

Reversed%20Datsun240z%20with%204bblintake.jpg
 
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