Help From Those That Have Done the Aussie Head Conversion

H

Hawkco

New member
I own a '77 Maverick with a 250 ci. The previous owner built the engine with .040 flat top pistons, Comp Cams 252H cam, head from a 170, and header. I just acquired an Aussie head that has been rebuilt with 1.70/1.43 valves, 289 springs, and was professionally ported and polished. It came with the 2-bbl intake and a Holley 2-bbl adapter. I also got the Clay Smith 264/274-12 cam, lifters, and a set of adjustable rocker arms. I traded a mild 340 HP 302 and a Grabber hood for all those goodies. I only need to buy push rods and gaskets.

I am very new to the world of the inline six and I got questions.

1. Is there an adapter made for the intake to use a Holley 5200 or Weber 32/36 carb? The casting number on the intake is 72DA-9425-AA. I will ultimately go to a 4-bbl carb.

2. There is a nipple cast onto the manifold by the carb mount that blows through a brass elbow cross-cornered from the cast nipple. I assume that this is some kind of water passage. What is it?

3. There is a threaded hole on top that I assume is for vacuum. Is there a place for EGR? There is also about a 7/8" plug underneath the carb mount, facing toward the engine, requires a huge allen wrench for removal. What is this.

4. Is there any kind of diagram that shows what hooks to where on this intake or simple instructions that I can follow?

Any advice on getting these new goodies installed will be greatly appreciated. I am new to six cylinders, but not to engine building, etc. I've built more than my fair share of 289/302 engines.
 
Who sold you the parts? Just curious.

The water jacket is to regulate intake temps. Australia does not get very cold; it is a mistake to consider this a carb heater. What it does, is stabilise the operating temperature of your carb/manifold best as possible.

The big Allen headed plug is simply to fill a core hole from the casting. It's never needed to remove it unless the jacket is corroded solid.

There's no EGR provision on these; we didn't get that for several years afterwards. Your manifold is 1972 (hence the 72DA prefix). The 1/8 NPT threaded hole on the #5 runner top is for a vacuum tree that takes a brake booster and trans kickdown. Normally the two raised bosses nearby are unthreaded, but a few people have drilled and tapped for various throttle or kickdown setups.

To run a Holley/Weber, is it possible to slot the carb holes? They will be pretty close from what I remember. Personally, I don't recommend the 4V conversion. It may not produce a motor that is overall more tractable and efficient. We've had heated discussions on general testing methodology lately and I subscribe to the view that some results are being unduly held as gospel. If you really feel you must go this way, make every effort to retain that water jacket.

Cheers, Adam.


p.s. Consider a new, hardened distributor driven gear.
 
Hawkco":2qrjea90 said:
1. Is there an adapter made for the intake to use a Holley 5200 or Weber 32/36 carb? The casting number on the intake is 72DA-9425-AA. I will ultimately go to a 4-bbl carb.
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I have the adapters in stock
http://classicinlines.com/proddetail.as ... D250%2DHCA

2. There is a nipple cast onto the manifold by the carb mount that blows through a brass elbow cross-cornered from the cast nipple. I assume that this is some kind of water passage. What is it?
Click to expand...
Correct, its for manifold heat. Hot water is supplied by one of the hoses going to the heater core.

3. There is a threaded hole on top that I assume is for vacuum. Is there a place for EGR?
Click to expand...
Correct, its a port for manifold vac.

4. There is also about a 7/8" plug underneath the carb mount, facing toward the engine, requires a huge allen wrench for removal. What is this.
Click to expand...
It's just a clean out plug. Plug it and forget it.
 
addo":vypa084m said:
Who sold you the parts? Just curious.
Click to expand...

I got the parts from Mark Lee of Warm Springs, GA. I have no idea where he got them, but I do who did the work on them.,

addo":vypa084m said:
There's no EGR provision on these; we didn't get that for several years afterwards. Your manifold is 1972 (hence the 72DA prefix). The 1/8 NPT threaded hole on the #5 runner top is for a vacuum tree that takes a brake booster and trans kickdown. Normally the two raised bosses nearby are unthreaded, but a few people have drilled and tapped for various throttle or kickdown setups.
Click to expand...

Should I bother to rig one up or just put a filter on my valve cover? This is going a '77 and I don't have to pass any emissions test with it.

addo":vypa084m said:
To run a Holley/Weber, is it possible to slot the carb holes? They will be pretty close from what I remember. Personally, I don't recommend the 4V conversion. It may not produce a motor that is overall more tractable and efficient. We've had heated discussions on general testing methodology lately and I subscribe to the view that some results are being unduly held as gospel. If you really feel you must go this way, make every effort to retain that water jacket.
Click to expand...

I'll make an adpater before I cut on the intake. I've been a hotrodder for 35 years. I think a 390 CFM 4-bbl is more efficient than a 350 CFM 2-bbl. Based on cam choice and cubic inches, I need somethin in the 370 CFM for 5,000 RPM. Since 85% of the driving will be at 4,000 RPM or less, I can get by 280 CFM. Thus, my first choice is the Weber 32/36. When I go 4-bbl, it will be with an adapter at first (no modifying the intake) and then a 4-bbl intake.

Thanks for the info.
 
What size bolts or studs are needed to mount the intake to the head and what size to mount the headers?
 
I can't remember the bolts for the intake manifold as mine had them.

For the headers, I just went out and boought standard 289/302 header studs and they worked great.
 
Okie dokie. I may have messed here by assuming. I just assumed that the threads would be metric since it is not an American head. My intake only has two studs.
 
Threads are imperial; from memory 5/16 UNC. There's a mix of studs and bolts for the intake, the exhaust is all bolts with locking tab washers.
 
I used studs with locking nuts for my exhaust headers. Only had one tight fight and that was the #6 header tube...but that was the older Pacemaker headers, not sure if there is any issue with the newer ones CI has.

I like to use studs as much as possible...IMO, it makes getting the headers on the head much easier. However removing the headers after you have an exhaust system welded up...it makes it tough...trust me on that one...

Slade
 
Took the old head off last Saturday and learned a lot. The pistons are dished, not flat top. I will measure them this weekend. The previous owner said he used the "tightest" pistons he could get and they were Sealed Power. It appears that they may be the 6.5cc dished pistons that were advertised as 9.2 compression ratio.

I also had the new Aussie head measured and the chambers range from 54cc to 55cc in all six cylinders. I will get the flow numbers later. With .040 over, 6.5 cc dish pistons, .120 deck height, and these combustion chambers, I'm looking at CR of a hair better than 8.5 to 1. I do know that when the head was rebuilt before I purchased it, it was decked .015. Based on the chamber size, I'm guessing it had been shaved previously as well.

I'd like to get a little more CR, but still be able to use 87 octane gas. The easiest thing to do is to take another .010 off the head. The best thing is to deck the block. Of course, that means pulling it out of the car. I suppose my chances of walking on water are greater than getting a head gasket of less than .050. Suggestions?

I also have adjustable rockers for this set up. What am I looking at needing to do for push rods?


You guys have been a great help.
 
sorry i cant be of any help, but congrats on throwing a bad ass 250 together for a maverick 8)


so whats your plans for that comp cam after you replace it with the clay smith one?

*wink wink* ;)
 
Someone here may have a steel shim type head gasket available. I don't know if they ever came stock on a 250, but the 200 part number will work and it should measure in at .025" or so.
 
For the intake and exhaust, you can use 3/8-16 bolts and/or studs. For the header you need 11 bolts or studs 1" long. For the intake, 4 bolts or studs 1" long and 4 bolts 1 1/4" long with nuts. Plus 18 washers.

For the adjustable rockers you need standard ball and cup pushrods for the 250ci.
 
AzCoupe":2lz4ypo0 said:
For the adjustable rockers you need standard ball and cup pushrods for the 250ci.
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You know better than me, so I'm just making sure. These rods will not be too long for the head with about .040 to .050 (total) shaved off the head?
 
hawko:

i am a believer of getting the quench distance correct ( 0.040)and then sorting out the head CC - wether its a log/2v/mikes Alu or whatever head .

imo its no use to get your comp ratio up by skimming the head if you still have an appreciable quench distance.

min quench will allow best use of low octane petrol and minmise pinging on a higher comp ratio

i guess the problem is that the 250's are built with such a large deck height ( down the block)- the ford performance handbook lists other pistons ( Ford 2.3 HSC?) that come with a higher compresion height( +0.050 thou) so you dont have to skim the block as much but taking out 120 though will give you 10.6 or so comp ratio which has to be bought back down again - bigger dish pistons ?




i have skimmed my 200 block to give about 37 thou squish - but not back together yet !

but again over to you- no matter how you put it together it will give sterling service with more oomph from the 2v head

have alook at these post ( by falcon60) where he has got the quench is 40 - 35 thou by decking the 200 block so the pistons stick out the top of the block by 5 - 10 thou ( and his experience of driving the reworked engine )


http://fordsix.com/forum/viewtopic.php? ... highlight=


brett
melbourne
 
Getting the quench right will have to be on the next engine.

I did measure the pistons tonight and I do have the 6.5cc dish pistons. Hopefully, I can find a thin, metal gasket. If not, I'm giving what I got a try. I'm getting 8.57 to 1 as the CR with the best calculators and my own math.
 
I used the stock 200 push rods with my adjustable rockers.
on the intake, i was tempted to go with studs. I ended up using stainless bolts. they shine up nicely. 8)
 
In a hot climate, I understand that the "coolant" cools the carb mounting plate, preventing too much heat from radiating up to the carb and causing boiling in the float bowl. You may not want to overlook the carb mounting plate serving as a heat-sink. Some, I hear, use a shroud to deflect heat away from the carb. This may not be as much of a problem in your ride as in the old Econolines (like mine) where the doghouse accumulates a lot of heat, but I know how hot it gets in Georgia, and Aussie summers get up there too. A water-cooled carb plate may be a good idea for you.

I'm a newbie with Falcon sixes, but I hope the advice helps you in your decision.

Good luck, Corey

addo":1ntqtvnu said:
The water jacket is to regulate intake temps. Australia does not get very cold; it is a mistake to consider this a carb heater. What it does, is stabilise the operating temperature of your carb/manifold best as possible.
Click to expand...
 
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