aussie answer. attn bill, brian, bubba, dan. dsmith.
Thread Starter
|
New User
Joined: Dec 2003
Posts: 3
Likes: 0
aussie answer. attn bill, brian, bubba, dan. dsmith.
i know that there are alot of novice engine builders here who would like a definate answer. i have looked here for days and still feel confused after reading about pontiac rods and badger pistons. with a stock fresh rebuilt 400, can i slap on aussie closed chamber heads and use this cam and run on 93 octane without tremendous pinging.
CAM- DEH265
ABDC- 58 degrees.
lift- .510/.526.
duration- 265/275.
thanks a ton and know that your input is muchly appreciated.
CAM- DEH265
ABDC- 58 degrees.
lift- .510/.526.
duration- 265/275.
thanks a ton and know that your input is muchly appreciated.
Posting Guru
Joined: Aug 2000
Posts: 2,416
Likes: 4
From: PacNW
I think you're going to have detonation problems even with the stock pistons but I could be wrong. I know there's been a lot of discussion about it in previous threads because of the fact that even with the better quench properties of the closed chamber heads the 400 piston still sits too far down in the bore to allow for any quench effect.
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
You can not use 58cc heads with that cam without quench on a stock 400.
You could use 62.8cc 4V Cleveland heads with 93 Octane.
You could use flattop pistons and stock heads. You could do a lot of porting work on the exhaust side to improve the flow.
You could use 62.8cc 4V Cleveland heads with 93 Octane.
You could use flattop pistons and stock heads. You could do a lot of porting work on the exhaust side to improve the flow.
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
The DEH275 cam has 60 degrees of overlap. Overlap will reduce vacuum and gas mileage.
The DEH265 has 50 degrees of overlap. You could use a DEH265 with 58cc heads, if you use a retarded timng set. A stock 400 or better, a dual roller set to 4 degrees retarded. I would do some work on the combustion chambers to unshroud the valves and add a couple of cc's.
This will produce 451 ft-lbs torque @2500 RPM and 338 HP@ 4500 RPM.
The DEH265 has 50 degrees of overlap. You could use a DEH265 with 58cc heads, if you use a retarded timng set. A stock 400 or better, a dual roller set to 4 degrees retarded. I would do some work on the combustion chambers to unshroud the valves and add a couple of cc's.
This will produce 451 ft-lbs torque @2500 RPM and 338 HP@ 4500 RPM.
Freshman User
Joined: Jul 2002
Posts: 44
Likes: 0
From: Canada
aussie heads
Hello guys,
me too i have been reading alot here about aussie heads.
I got myself a pair of those ''rare australian 302C heads''
and now i am looking to put those on my 351M, not a 400.
but reading things and specs here, looks like 351M piston sits .016 in the bore, add to this gasket thickness which should be around .050 , which is way too much. Been looking around for thinner head gasket without any luck. looks like .035 to .040 is the target for proper quench. So i ask this: is there any success story to hear from user with 351M matched with those australian
302C heads without any detonation ? if i mill the block to 0 deck clearance, this means i will have to mill the intake acordingly + get some special lenght pushrods, but still, will this work , i dunno.
for now my aussie heads are boat anchor. maybe i will end up selling them.
werk.
me too i have been reading alot here about aussie heads.
I got myself a pair of those ''rare australian 302C heads''
and now i am looking to put those on my 351M, not a 400.
but reading things and specs here, looks like 351M piston sits .016 in the bore, add to this gasket thickness which should be around .050 , which is way too much. Been looking around for thinner head gasket without any luck. looks like .035 to .040 is the target for proper quench. So i ask this: is there any success story to hear from user with 351M matched with those australian
302C heads without any detonation ? if i mill the block to 0 deck clearance, this means i will have to mill the intake acordingly + get some special lenght pushrods, but still, will this work , i dunno.
for now my aussie heads are boat anchor. maybe i will end up selling them.
werk.
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Fel-Pro 1013 gaskets are 0.040. Decking the block 0.016 will get you zero deck on a 351M.
There is no need for quench on a 351M if you have a cam with 58 degrees ABDC IVC or later, like the DEH265.
There is no need for quench on a 351M if you have a cam with 58 degrees ABDC IVC or later, like the DEH265.
Trending Topics
Posting Guru
Joined: Sep 2003
Posts: 2,259
Likes: 0
From: Florida Hill Country
Re: aussie heads
Originally posted by werkdatool
Hello guys,
me too i have been reading alot here about aussie heads.
I got myself a pair of those ''rare australian 302C heads''
and now i am looking to put those on my 351M, not a 400.
but reading things and specs here, looks like 351M piston sits .016 in the bore, add to this gasket thickness which should be around .050 , which is way too much. Been looking around for thinner head gasket without any luck. looks like .035 to .040 is the target for proper quench. So i ask this: is there any success story to hear from user with 351M matched with those australian
302C heads without any detonation ? if i mill the block to 0 deck clearance, this means i will have to mill the intake acordingly + get some special lenght pushrods, but still, will this work , i dunno.
for now my aussie heads are boat anchor. maybe i will end up selling them.
werk.
Hello guys,
me too i have been reading alot here about aussie heads.
I got myself a pair of those ''rare australian 302C heads''
and now i am looking to put those on my 351M, not a 400.
but reading things and specs here, looks like 351M piston sits .016 in the bore, add to this gasket thickness which should be around .050 , which is way too much. Been looking around for thinner head gasket without any luck. looks like .035 to .040 is the target for proper quench. So i ask this: is there any success story to hear from user with 351M matched with those australian
302C heads without any detonation ? if i mill the block to 0 deck clearance, this means i will have to mill the intake acordingly + get some special lenght pushrods, but still, will this work , i dunno.
for now my aussie heads are boat anchor. maybe i will end up selling them.
werk.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
Elder User
Joined: Apr 2003
Posts: 821
Likes: 0
From: Normal, IL
I have seen flow data on the 2V heads and 4V heads, and the exhaust side(2V) flows much better and with higher port velocity than 4V heads. The reason for this is that the 4V heads were only used on intermediate car applications, causing the port shape to be very very bad. All the 4V has is big, slow, lazy ports. If anything, port the intake on a set of 2V heads, put 4V valves in them, cut them down by .060, and voila, decent compression, good flow, and high port velocity.
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
My data says that the intake side of the 2V heads flow better than the 4V heads from 0.100 lift to 0.400 lift. Above 0.400 lift the 4V heads flow better than the 2V heads. On the exhaust side the 4V heads flow better than the 2V heads across the board, possibly due to the larger exhaust valve.
I think that it is the exhaust side of the 2V (and 4V) heads that needs to be ported.
0.1 0.2 0.3 0.4 0.5 0.6
351C 2bbl Intake 68.5 142.2 189 199.5 196.5 198
Exhaust 57.2 89.7 120.2 143.5 159.6 162.7
351C 4bbl Intake 64.3 115.8 163.5 210 246 273.6
Exhaust 66.7 103.7 133.8 154.4 169 178.4
I think that it is the exhaust side of the 2V (and 4V) heads that needs to be ported.
0.1 0.2 0.3 0.4 0.5 0.6
351C 2bbl Intake 68.5 142.2 189 199.5 196.5 198
Exhaust 57.2 89.7 120.2 143.5 159.6 162.7
351C 4bbl Intake 64.3 115.8 163.5 210 246 273.6
Exhaust 66.7 103.7 133.8 154.4 169 178.4
Posting Guru
Joined: Jun 2002
Posts: 1,099
Likes: 0
Chamber sizes & Flow numbers
I could write a book on the variations. On my chamber Collage, #4,5 & 6 are all 302C heads. The chambers measured 55cc, est. 58-63cc & 70cc. #2 is a mystery chamber, but my guess is a Aussie 351C.
Every little item can change the chamber size. Casting variations, machined surfaces, valve shape, valve depth, and valve diameter will all change the numbers. Something similar should be said for the pistons and blocks. Most parts are second hand, 20-30 years old, so the only advice I can give is to measure everything. There are many ways to increase or decrease the chamber volume.
I don't recommend 302C heads for 351M or 400 engines. Many people pay too much for them, don't understand how to set them up properly, don't realize how quickly compression gets out of hand or how poorly the engine will run with a bad combo, even on 93 octane. They are much easier to set up on a 351C or 351M but you have to do your homework, it's hard to eyeball this stuff.
Every little item can change the chamber size. Casting variations, machined surfaces, valve shape, valve depth, and valve diameter will all change the numbers. Something similar should be said for the pistons and blocks. Most parts are second hand, 20-30 years old, so the only advice I can give is to measure everything. There are many ways to increase or decrease the chamber volume.
I don't recommend 302C heads for 351M or 400 engines. Many people pay too much for them, don't understand how to set them up properly, don't realize how quickly compression gets out of hand or how poorly the engine will run with a bad combo, even on 93 octane. They are much easier to set up on a 351C or 351M but you have to do your homework, it's hard to eyeball this stuff.
Elder User
Joined: Apr 2003
Posts: 821
Likes: 0
From: Normal, IL
You're right, you can't eyeball it. But when you want an increase in compression, and higher flow rates, go with the Aussie heads. With just placing a set of Aussie heads with .020 milled off(54 cc) on a basically stock 400, with the piston .025 below deck, will put compression a hair over 12:1. Raising compression 3.5 points over stock should be worth an easy 90 hp, if not more. The Aussies are good for more power, and if you can find a chamber shaped dished piston, would be the hot ticket for the street. Of course, this only works if the piston is .040 from the combustion face, but you knew that already.
Posting Guru
Joined: Jun 2002
Posts: 1,099
Likes: 0
I was hoping readers got a little more out of what I said
-than you can't eyeball it. High compression does not make that much power but it does require late valve timing, very late to run on pump fuel with iron heads and 12:1. In the 1st Engine Masters Challenge, Dave Storlien's CHI 3V headed Windsor produce the highest peak power, 605HP/532TQ with only 10:1 compression. All the engines are required to run on 92 octane pump fuel provided.
There's no good reason why an Aussie head should out flow a 351M/400. The starting flow numbers for the Aussie's, provided by www.PowerHeads.com are not impressive. Remember they sell these.
Flow Numbers
Intake* Lift .100" .200" .300" .350" .400" .450" .500" .550"
Stock AU 2-V 58.9 112.2 155.8 169.2 178.0 184.0 186.9 188.4
The port size and shape are virtually identical to the 2V 351C & 351M/400 and the valves are much more shrouded in the chamber.
There's no good reason why an Aussie head should out flow a 351M/400. The starting flow numbers for the Aussie's, provided by www.PowerHeads.com are not impressive. Remember they sell these.
Flow Numbers
Intake* Lift .100" .200" .300" .350" .400" .450" .500" .550"
Stock AU 2-V 58.9 112.2 155.8 169.2 178.0 184.0 186.9 188.4
The port size and shape are virtually identical to the 2V 351C & 351M/400 and the valves are much more shrouded in the chamber.
Elder User
Joined: Apr 2003
Posts: 821
Likes: 0
From: Normal, IL
I can't remember where, I'll look for it, but I read and have seen proof that a one point compression increase is worth over 30 hp, not to mention increased throttle response, which, lets face it, M blocks need it. Did I mention that the engine these heads will go on will see nothing but 114 octane leaded race fuel? Also that light shrouding of the intake valve(and only the intake valve) helps swirl, which helps power, the last time I checked. Plus, when the machinist puts the larger valves in, the shrouding is gone. For both of our benifit, I will look for that article on the compression increase=hp.
Posting Guru
Joined: Jun 2002
Posts: 1,099
Likes: 0
I could find a lot of examples where a 1 point increase in compression was worth 30 or more hp but it depends what method they used to raise the compression. You can't multiply the power increase by the number of points. It dosn't work that way. Power increase through compression increase alone diminishes. 8-9 is worth 2.0%, 9-10 is 1.7%, 10-11 is 1.3, 11-12 is 1.0. All that adds up to 6%, about 25HP. You get 15-20HP from proper quench design without increasing compression at all.
M blocks need a little more compression. Some ping with only 8.5:1 The thread starter was asking about 93 octane, so I missed the part about the 114 octane race fuel. Intake shrouding is not the same as swirl. Swirl, shear and tumble are a whole other discussion. Installing larger valves increases shrouding, the machinist should releave the chamber to compensate, even though it does reduce compression slightly.
M blocks need a little more compression. Some ping with only 8.5:1 The thread starter was asking about 93 octane, so I missed the part about the 114 octane race fuel. Intake shrouding is not the same as swirl. Swirl, shear and tumble are a whole other discussion. Installing larger valves increases shrouding, the machinist should releave the chamber to compensate, even though it does reduce compression slightly.