400 Aussie Head Questions
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Joined: Dec 1999
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From: New Orleans United States
400 Aussie Head Questions
I have a 77F150 4X4 with a 400/C6/NP205 combo.
I have a set of Aussie heads in my garage that are awaiting an influx of cash to get them redone. If i just strap these on the block without any other mods, will the 8:1 pistons cancell out the quench effect of the smaller combustion chamber?
If it does, and I go to flat top pistons, what will the final compression ratio be assuming the block and heads have never been resufaced?
The truck is my first vehicle I ever owned, and is being retired to be a weekend toy, so bucking up for additive for the gas isn't a concern if I am over 93 octane's limit.
I was also thinking about a short fill of hard block to stabilize the bottom of the cylinders. The engine is going to be built more and more nasty as I go and the need for speed increases, so i wanted to do this before i break parts. Do you think it is worth it?
I have a set of Aussie heads in my garage that are awaiting an influx of cash to get them redone. If i just strap these on the block without any other mods, will the 8:1 pistons cancell out the quench effect of the smaller combustion chamber?
If it does, and I go to flat top pistons, what will the final compression ratio be assuming the block and heads have never been resufaced?
The truck is my first vehicle I ever owned, and is being retired to be a weekend toy, so bucking up for additive for the gas isn't a concern if I am over 93 octane's limit.
I was also thinking about a short fill of hard block to stabilize the bottom of the cylinders. The engine is going to be built more and more nasty as I go and the need for speed increases, so i wanted to do this before i break parts. Do you think it is worth it?
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Joined: Jan 2004
Posts: 867
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From: Eastern Pa
The aussies will put you above where you should be compression wise and you won't get quench with the flat top pistons. The ones Tim Meyer has can be made to give you the proper quench and dish. Check this out and play with it a while and you can learn a lot. Keep in mind that you need to be less than .050with your deck clearance to get proper quench.
http://kb-silvolite.com/calc.php?PHP...8a4c4f13feafcd
http://kb-silvolite.com/calc.php?PHP...8a4c4f13feafcd
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Joined: Dec 1999
Posts: 582
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From: New Orleans United States
Its already .060" overbored making it a 414 CI. I managed to find a solid block that could handle that much overbore. It loves to wind up fast (~5200 RPM shift point where power starts to fall off) despite the long stroke. Right now I have the Edelbrock 214/218 cam in it, but i plan go with a 224/230 range cam with a little more lift. I converted it to roller rockers and bigger push rods to help in valvetrain stability. It has a Holley 750, which is a bit much, i need to step down to a 650 to make it launch harder. The bottom end is bone stock except for Total Seal piston rings.
The truck used to have 35" mudders on it, but now I took the 4" lift off, put 31X12.5 street tires on it, and may consider dropping it another 2" or so using different blocks than the factory 4X4 ones and taking some height out of the front coils (over 100MPH and the nose starts to porpoise up and down and gets down right scary).
My final vision is an all wheel drive drag truck with neck snapping acceleration. Like I said, weekend toy, daily drivability not a concern.
The truck used to have 35" mudders on it, but now I took the 4" lift off, put 31X12.5 street tires on it, and may consider dropping it another 2" or so using different blocks than the factory 4X4 ones and taking some height out of the front coils (over 100MPH and the nose starts to porpoise up and down and gets down right scary).
My final vision is an all wheel drive drag truck with neck snapping acceleration. Like I said, weekend toy, daily drivability not a concern.
