Aussie head air flow/performance problem Shazam help !!!
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Junior User
Joined: Nov 2002
Posts: 97
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From: Morristown USA
Aussie head air flow/performance problem Shazam help !!!
I built a 400 with a lot of suggestions from this site. Something is not right,
I have no bottom end. I started with a good 400 block and bought a pair of Aussie heads, added a Performer intake and topped it with a Holley 4150. The cam was specked out by the local machine shop and is:
050 DUR LIFT ADV DUR LOBE
INT/EXH INT/EXH INT/EXH SEP.
212/218 ?/515 283/298 110
They supposedly put the cam at 0 degrees. Now they are looking at the heads and telling me that the problem is there. I've looked back at previous posts and can't find the air flow specs on the aussie heads. Does anyone have this info? Is this a suitable cam? I want a good 4 wheeling horse trailer pulling truck. Too much money sitting in a truck that won't spin the tires on loose gravel.....
I have no bottom end. I started with a good 400 block and bought a pair of Aussie heads, added a Performer intake and topped it with a Holley 4150. The cam was specked out by the local machine shop and is:050 DUR LIFT ADV DUR LOBE
INT/EXH INT/EXH INT/EXH SEP.
212/218 ?/515 283/298 110
They supposedly put the cam at 0 degrees. Now they are looking at the heads and telling me that the problem is there. I've looked back at previous posts and can't find the air flow specs on the aussie heads. Does anyone have this info? Is this a suitable cam? I want a good 4 wheeling horse trailer pulling truck. Too much money sitting in a truck that won't spin the tires on loose gravel.....
Posting Legend
Joined: Sep 2001
Posts: 30,255
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Aussie head air flow/performance problem Shazam help !!!
Way too much cam for low end. You probably have great high end power tho if you have the compression. A classic example of more is not necessarily better, -sorry. Try a 260/270 ADV Duration cam or even 265/275 at the absolute most.
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Lead Driver
Joined: Nov 2000
Posts: 6,624
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From: Albuquerque
Aussie head air flow/performance problem Shazam help !!!
I think you could get by with that cam. Depends on the total package. Do you have auto? I would run a compression and maybe a leak down test. Make sure you got lots of initial advance going for you. Any idea of compression?
Posting Guru
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Aussie head air flow/performance problem Shazam help !!!
Exactly what are they saying the problem is with the heads? Too large? Your cam and intake should provide good low end power. What is the carb's CFM?
The Aussie heads flow similar to the 351C 2V or early 400 with stock valves.
What's your compression? Timing?
The Aussie heads flow similar to the 351C 2V or early 400 with stock valves.
What's your compression? Timing?
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Junior User
Joined: Nov 2002
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From: Morristown USA
Aussie head air flow/performance problem Shazam help !!!
I used the early 70s' pistons that had an 8.0:1 compression ratio, should have given me around 9.6:1 according to what I've read here. I set the timing at 12 degrees advance and plugged the dizzy into the ported vacuum port. I'm running a c-6 tranny and NP-203 transfer case with 33" mudders. Not sure of rear end ratio, but will check on it. The engine shop is thinking that the runners are too big and I'm losing port velocity. I pretty much had the heads cleaned up and left the 2v valves installed. I am still running stock exhaust manifolds with dual exhaust, no mufflers, straight out the back. The chart that was posted a while ago that had the flow characteristics would be nice to see again. The Holley 4150 is a 600 CFM carb, looks like the truck avenger. Granted I only have 50-75 miles on the motor and the piston rings are probably not seated yet, but still...
Thanks in advance for the great advice, from what I've seen and read Ford wrenches are some of the wittiest around. I am slowly sorting through my trucks and getting rid of the C, D, and J brands.
Thanks in advance for the great advice, from what I've seen and read Ford wrenches are some of the wittiest around. I am slowly sorting through my trucks and getting rid of the C, D, and J brands.
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Junior User
Joined: Nov 2002
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From: Morristown USA
Aussie head air flow/performance problem Shazam help !!!
Something that is sticking in the back of my mind is how they set up the cam. Center line of the intake lobe is supposed to be 106 degrees. This what they used as the 0 mark, the notes they made when installing are a bit unclear and they are not sure if it is 100 or 106 that they set it at. Huge difference I'm sure, the truck has great power at 30-60 MPH
Lead Driver
Joined: Nov 2000
Posts: 6,624
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From: Albuquerque
Aussie head air flow/performance problem Shazam help !!!
If you are only getting 12 degrees advance at idle it may not be enough. I'd try straight vacuum for advance with about 15 initial and hopefully 6 more on the vacuum advance. Say about 20 while at idle.
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Elder User
Joined: Feb 2001
Posts: 829
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From: Porterfield
Aussie head air flow/performance problem Shazam help !!!
Ya the timing sounds pretty weak to me . I have my timing set at 38 Degree total, It's now welded at that but I use to run it open and wanted it to be totally in by 3000 Rpm's.
Set-up your timing light and have someone rev and hold the motor at 3000 Rpm's and set the timing at 34 Degrees, all of your centifacal advance will be in at 3000 Rpm's or it should be, Your idle timing will be around 18 to 20 Degrees with vacume attached.
You'll see your motor come to life totally differant with the timing set to this .. If it start hard when it's up to temp. then back the timing off just a little to help in starting but not to much. Clevelands Like alot of timing and the 400 is a Cleveland.
Set-up your timing light and have someone rev and hold the motor at 3000 Rpm's and set the timing at 34 Degrees, all of your centifacal advance will be in at 3000 Rpm's or it should be, Your idle timing will be around 18 to 20 Degrees with vacume attached.
You'll see your motor come to life totally differant with the timing set to this .. If it start hard when it's up to temp. then back the timing off just a little to help in starting but not to much. Clevelands Like alot of timing and the 400 is a Cleveland.
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Posting Guru
Joined: Jun 2002
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Aussie head air flow/performance problem Shazam help !!!
Double check your compression again. If the early piston is the flat top used in '71 the compression should be 9:1. Using AU 302C heads (62cc) would make it more like 10.5:1.
The runner size is almost the same on the heads. The manifold runners are smaller than stock. The engine shop is making poor guesses.
I thought your LSA was 110?
Are you using a stock crank timing gear? Possibly retarded up to 8 deg.
Do a compression test if possible.
The runner size is almost the same on the heads. The manifold runners are smaller than stock. The engine shop is making poor guesses.
I thought your LSA was 110?
Are you using a stock crank timing gear? Possibly retarded up to 8 deg.
Do a compression test if possible.
Posting Guru
Joined: Aug 2000
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From: PacNW
Aussie head air flow/performance problem Shazam help !!!
>The chart that was posted a while ago that had
>the flow characteristics would be nice to see again.
[link:www.waldens.com/waldens/351heads.htm|351 Head Flow Table]
>the flow characteristics would be nice to see again.
[link:www.waldens.com/waldens/351heads.htm|351 Head Flow Table]
Posting Legend
Joined: Sep 2001
Posts: 30,255
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Aussie head air flow/performance problem Shazam help !!!
His pistons are probably the stock 8.0:1 dished pistons used from 73 onwards listed as replacements in the parts books for everything, even 71's.
The problem is his cam choice, the machine shop messed that one up. His motor is acting exactly like a cam of that size would. Gutless bottom end but with great high end power.
I would "assume" the machine shop used an aftermarket timing set rather than a OEM stocker type so they could set the cam at 0. It would be worth checking out, since a retarded cam would make the problem worse.
Thanks for using FTE!
[font color=red]As a Moderator I do not "Subscribe" to most topics,
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The problem is his cam choice, the machine shop messed that one up. His motor is acting exactly like a cam of that size would. Gutless bottom end but with great high end power.
I would "assume" the machine shop used an aftermarket timing set rather than a OEM stocker type so they could set the cam at 0. It would be worth checking out, since a retarded cam would make the problem worse.
Thanks for using FTE!
[font color=red]As a Moderator I do not "Subscribe" to most topics,
please send email/pm if you need a reply -Thanks![/font]
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Elder User
Joined: Sep 2001
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From: Jax FL
Aussie head air flow/performance problem Shazam help !!!
I forget where i read it, but the aussie head chamber size is about 58cc in size. most often unshrounding the intake valve will increace this to 62-65cc. this info was posted in anothr forum awhile back. he stated that you really have to do this to get proper air flow. you might also look into back cutting the valve for more flow.
Freshman User
Joined: Nov 2002
Posts: 47
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From: Florida
Aussie head air flow/performance problem Shazam help !!!
Too much cam,put a stick in wtih around 485in lift 512ex 272in duration 280ex with a 112 deg lobe sep.Something in this area cam wise will give you the torque you need to get it moving.Some 4.11s or 4.56s with a high stall converter [if you have a auto] would complement the package.
