Aussie's heads

[Manu Mach1]

Hello,

I found a pair of Aussie's head, I guess there are closed chamber, regarding to this:

http://home.comcast.net/~jelerath/mustang/Specs/heads-fr.html

My engine is a 351C with 2V's heads. My vin number tells me it's a Q code, so or the engine has been swapped by a H code or only the heads have been changed.

Is anyone already done this kind of upgrade, from 2V's heads to Australian ones?

About what I read I can keep my intake manifold, which is single plane with a Holley 4 barrels 650 cfm, and keep as well the exaust manifold, Hooker comp. That's true that's I don't need to add additive in the gas with Aussie's heads?

Thanks for any advice.

 

[MechEng]

What would determine if you need to run additive in the gas is irrespective of what intake and exhaust manifolds you're running (mostly, I'm sure they play into it a little) but what you really need to watch is compression ratio, as anything over 10:1 tends to start requiring that you use additives depending on the octane rating of gas in your area (92 vs 96)

Those aussie heads according to that website have a much smaller chamber sizing of 62.8cc vs the 2v heads of 74cc-77cc. That's a pretty big drop (could be nearly 15cc!) which is going to bump your compression up. Is your engine otherwise stock everywhere else? Before you just swap heads you should know the numbers you're working with inside your engine, as to bore, stroke, and deck height as these are all going to effect your compression ratio. If you don't know these things about your engine, you really should before you go doing something like swapping a head out.

Just my $0.02!

 

[TommyK]

Hello,

I found a pair of Aussie's head, I guess there are closed chamber, regarding to this:

http://home.comcast.net/~jelerath/mustang/Specs/heads-fr.html

My engine is a 351C with 2V's heads. My vin number tells me it's a Q code, so or the engine has been swapped by a H code or only the heads have been changed.

Is anyone already done this kind of upgrade, from 2V's heads to Australian ones?

About what I read I can keep my intake manifold, which is single plane with a Holley 4 barrels 650 cfm, and keep as well the exaust manifold, Hooker comp. That's true that's I don't need to add additive in the gas with Aussie's heads?

Thanks for any advice.

Depends on your pistons. If you have flat tops the resulting compression ratio (11:1?) would be too high for pump gas in the US. Not sure what fuel is available in France. Dished pistons and you should be OK. Your other parts should work with the new heads.

 

[will e]

What's the typical comp ration on 4v cc heads with flat tops?

 

[Manu Mach1]

Here in France we use 95 and 98 unleaded.

So first I need to remove the actual heads, to inspect what kind of pistons I have, bore, stroke, bla bla bla.

It's not primordial to me to do this swap. But as the vendor told me, the valve seats on those Aussie's heads are reinforced, so this can avoid me to add additive and gain compression.

What is dished pistons?

I use additive because only unleaded is available, not a question of octane.

 

[MechEng]

Here in France we use 95 and 98 unleaded.

So first I need to remove the actual heads, to inspect what kind of pistons I have, bore, stroke, bla bla bla.

It's not primordial to me to do this swap. But as the vendor told me, the valve seats on those Aussie's heads are reinforced, so this can avoid me to add additive and gain compression.

What is dished pistons?

I use additive because only unleaded is available, not a question of octane.

If the Aussie head has hardened valve seats then the need for additive in the gas (lead) is not required. There are some that will argue that even if they don't have hardened valve seats that you don't need to run the lead additive either.

Dished pistons means that the top of the piston is concave, or has some type of relief cut into it, this increases the volume of the combustion chamber at top Dead Center and therefore decreases your compression ration.

A quick note on Fuel Octane Rating. Here in the USofA we rate our octane based on an Average of the two methods used for determining octane rating so our numbers are DIFFERENT from the rest of the world. There is the Research Octane Method and the Motor Octane Method (If you look at most US pumps near the Octane number you'll see (R+M)/2 to show the average) so the US number is usually 4 to 5 points LOWER than comparable fuel elsewhere in the world. So his 95 and 98 are more like 90 and 93.

 

[TommyK]

What's the typical comp ration on 4v cc heads with flat tops?

An 71 M code cleveland had an advertised comp ratio of 10.7:1 but was probably closer to 10:1 as measured. The slightly smaller chamber of the 2V closed chamber head gets the comp ratio back closer to 10.7:1 which IMHO is too high for a street car on pump gas with iron heads, although I know some people get away with it.

 

[Duncan Mach72]

There's a guy in the UK (mach1mike) runs Aussie heads on a 351C with flat top pistons on our 95 octane with no problem. He's on the MOCGB forum.

 

[MeZapU]

I have them on my Mach 1. I'm running flat top forged TRW pistons. Runs fine off of 91 octane fuel. I had hardened exhaust seats installed. They are ok with the initial valve job for unleaded fuels, but only being induction hardened the actual hardening of the seat is only on the surface. If they are cut or ground for any subsequent valve job, the hardened surface is removed exposing a regular cast iron surface.

 

[Luke]

Hi Manu

plenty of cranky 11:1 street driven 2v clevos here in Aus, most run on BP 98 octane fuel. just to throw a spanner in the works have you done a price comparison of say new TFS heads vs import possible machining and reconditioning of Aussie heads. May be worth looking at. Aussie heads here in Aus are a very cheap option, in France ?? maybe do a few quick sums

Cheers

Luke

 

[Manu Mach1]

thanks all, so first if I buy those heads (very rare over here), I need to check the pistons.

Now "playing" with the heater core, very nice game I would let to my best enemy.