400 Aussi head question
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Trailering
Joined: May 2010
Posts: 19
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400 Aussi head question
Hello,
I bought a 79 Bronco w/400 & auto for parts. Originally I thought I'd take the axles for my 74 Bronco & sell/scrap the rest. I've been reading here & everywhere else I can find, and think I want to put the 400 & tranny into my 74. I had no idea of the potential for this engine. I think the 400 is a better (and way cooler) choice over my planned 5.8L EFI upgrade. The low end torque from the 400 is awesome. This is a long term plan, my 302 is running strong, knock on wood.
I want to build the 400 for low end torque, run on pump gas, and be reliable. I live at 7,700 ft (drive over 11,000 ft), and it frequently is -20 or colder during the winter. I drive this truck around day to day (very small town)and need it to run. I don't mind spending some money, but don't think I'm shooting for 500 ft/lbs. I've read the Aussi 2v closed chamber heads are great. I also read that the Aussie heads w/stock pistons will yield a 10.75 compression ratio, higher with the flat top Badger pistons. Is this too much? Should I stick with the stock heads? Would milling the stock heads & adding flat top pistons be better?
At work someone mentioned the 400 was "externally balanced", where most engines are internally balanced. Can someone explain the difference? I haven't taken the 79 Bronco apart, so I haven't "seen" it.
Any other info/links are appreciated. This is only my first question of this long process. I need to choose intake/carb or f.i./head & valves, etc/cam/etc/etc.
Thanks
Chad
I bought a 79 Bronco w/400 & auto for parts. Originally I thought I'd take the axles for my 74 Bronco & sell/scrap the rest. I've been reading here & everywhere else I can find, and think I want to put the 400 & tranny into my 74. I had no idea of the potential for this engine. I think the 400 is a better (and way cooler) choice over my planned 5.8L EFI upgrade. The low end torque from the 400 is awesome. This is a long term plan, my 302 is running strong, knock on wood.
I want to build the 400 for low end torque, run on pump gas, and be reliable. I live at 7,700 ft (drive over 11,000 ft), and it frequently is -20 or colder during the winter. I drive this truck around day to day (very small town)and need it to run. I don't mind spending some money, but don't think I'm shooting for 500 ft/lbs. I've read the Aussi 2v closed chamber heads are great. I also read that the Aussie heads w/stock pistons will yield a 10.75 compression ratio, higher with the flat top Badger pistons. Is this too much? Should I stick with the stock heads? Would milling the stock heads & adding flat top pistons be better?
At work someone mentioned the 400 was "externally balanced", where most engines are internally balanced. Can someone explain the difference? I haven't taken the 79 Bronco apart, so I haven't "seen" it.
Any other info/links are appreciated. This is only my first question of this long process. I need to choose intake/carb or f.i./head & valves, etc/cam/etc/etc.
Thanks
Chad
Senior User
Joined: Feb 2009
Posts: 308
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From: Southern NM
Visit the TMI (Tim Meyer Inc.)website.Look around on that and see some of his projects.Give him a call and tell him what you are wanting out of your engine.Great guy and very sharp on these 335 series engines.
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Joined: Dec 2002
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From: chicago burbs
an external balance has an offset weight added to the harmonic damper and/or the flywheel/flexplate that is needed to balance the crank. w/o the weights the crank is not balanced, where an internal balanced engine's crank will spin balanced without the damper and flywheel/flex installed
external balance is common these days, when most engines were much bigger and heavier they were internally balanced. some modern engines are probably internally balanced but it's not an issue in your application. when you start turning a Cleveland 6000 rpm and up, and a lot, like in a racing application the internal balance becomes desirable but still not necessary until it becomes an issue. a 400 with it's larger and heavier crank would reach that threshold at a lower rpm but hopefully it wouldn't be using a stock crank either. at higher rpm's the added balance weight on the damper can cause the crank to flex, then it gets ugly
from the Hot Rod Technical Library
".... Perhaps one of the outstanding features of the new powerplants is their durability at sustained speeds. Much of this was achieved through Ford's new approach to counterbalancing which, in turn, was brought about by the need for a compact configuration in the case of the Fairlane V8. Only 70 percent of the total unbalanced couple is balanced by means of crankshaft counterweights within the crankcase. The remaining 30 percent of the unbalanced couple has been provided by two external counterweights-one located in front of the timing sprocket and the other incorporated in a segment of the flywheel. This arrangement gives the engines their outstanding smoothness."
and
" ...The Challenger 221 and 260 have established themselves as a new concept in the V8 field. This concept is based on the assumption that it would be possible to build a V8 engine in this size category that would be competitive weightwise with an aluminum block of comparable displacement....
To accomplish this, Ford engineers employed the latest techniques in thin wall casting. Also, the extremely compact configuration of extreme rigidity, incorporating five main bearings, was necessary to achieve the desired margin of strength and to provide for a further power growth pattern. As an example of the engines compactness, the block is only 8.93 inches high, 16.36 inches wide, and 20.84 inches long. Crankshaft stiffness is such that the fourth harmonic occurs beyond the normal engine operation range. An advantage of the two added counterweights outside the engine is the fact that less mass at this polar separation accomplishes the desired results because the further the weights are from the center of rotation, the more effective they become."
external balance is common these days, when most engines were much bigger and heavier they were internally balanced. some modern engines are probably internally balanced but it's not an issue in your application. when you start turning a Cleveland 6000 rpm and up, and a lot, like in a racing application the internal balance becomes desirable but still not necessary until it becomes an issue. a 400 with it's larger and heavier crank would reach that threshold at a lower rpm but hopefully it wouldn't be using a stock crank either. at higher rpm's the added balance weight on the damper can cause the crank to flex, then it gets ugly
from the Hot Rod Technical Library
".... Perhaps one of the outstanding features of the new powerplants is their durability at sustained speeds. Much of this was achieved through Ford's new approach to counterbalancing which, in turn, was brought about by the need for a compact configuration in the case of the Fairlane V8. Only 70 percent of the total unbalanced couple is balanced by means of crankshaft counterweights within the crankcase. The remaining 30 percent of the unbalanced couple has been provided by two external counterweights-one located in front of the timing sprocket and the other incorporated in a segment of the flywheel. This arrangement gives the engines their outstanding smoothness."
and
" ...The Challenger 221 and 260 have established themselves as a new concept in the V8 field. This concept is based on the assumption that it would be possible to build a V8 engine in this size category that would be competitive weightwise with an aluminum block of comparable displacement....
To accomplish this, Ford engineers employed the latest techniques in thin wall casting. Also, the extremely compact configuration of extreme rigidity, incorporating five main bearings, was necessary to achieve the desired margin of strength and to provide for a further power growth pattern. As an example of the engines compactness, the block is only 8.93 inches high, 16.36 inches wide, and 20.84 inches long. Crankshaft stiffness is such that the fourth harmonic occurs beyond the normal engine operation range. An advantage of the two added counterweights outside the engine is the fact that less mass at this polar separation accomplishes the desired results because the further the weights are from the center of rotation, the more effective they become."
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From: Denver Metro Area, CO
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Hi Chad,
Just a quick reference to something I recently read that might be useful to you.
"High altitude reduces cylinder pressure, so if you only drive at high (above 4500') altitude, a 10:1 engine can often be substituted for a 9:1 compression engine"
United Engine & Machine Co. Incorporated
Good luck,
Vince
Just a quick reference to something I recently read that might be useful to you.
"High altitude reduces cylinder pressure, so if you only drive at high (above 4500') altitude, a 10:1 engine can often be substituted for a 9:1 compression engine"
United Engine & Machine Co. Incorporated
Good luck,
Vince
Thread Starter
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Trailering
Joined: May 2010
Posts: 19
Likes: 1
Great info, not too much knowledge about high altitude out there. It does allow us to run lower octane and advance the timing on the motor (about 1d/1000' above sea level). I'll read it over, the only time I'd go below 4500' would be for Utah trips, may have to up the octane if I go that low.
Thank
Chad
Thank
Chad
