Adam,
I certainly didn't mean to avoid your initial question. I faced a very similar issue with a couple of destroyed cylinders in my 4.7 engine also.
I can't vouch for this company, but it may be worth a look considering the time and money involved in all your listed options.
Their website claims to ship engines from their depot in the USA to several AUS cities for..... $450.00 USD.
Is this possibly true??
http://www.usatoaus.com/login.aspx

 

Thanks, but I have had discussions with this company. It costs a about $300 US to get the engine to their depot and that was from the same state in the US. Then they do not class Hobart in Tasmania as an international port, this is news to me and everyone else who lives here, so they will only deliver into Melbourne!! To get from Melbourne to me would be another $500 AUD odd, with $ conversion you are at $1500 +/-

Australia is a great place to live but getting/ buying stuff here can be expensive!!

 

Daniel, what did you end up doing?

 

I have had a bit of a 180 over the weekend and am now going away from the one piston idea, and looking at a full rebuild.
It is a Porsche 928, it is a pretty special car, it is my dream car. I intend to have it for a very long time and it would be best if the engine was made to be good now instead of having to go through any ordeal again.
Heads need to be done anyway, I will measure crank and see what it needs there, makes no sense to just do one piston. A used block is still a very unlikely option.....

Interesting I was having a look over things on the weekend and found some differences in the combustion chambers from the left to right heads..... (also noticed 2 different exhaust valves, someone had just done 2 lots of valves previously - yes one of the failed ones.....!)

Left Head



Right Head has a small square relief in it (and is a slightly different shape?)? Is this normal?



Thanks

Adam

 

The right head looks identical to a US low compression head. You can tell from the relief in the exhaust valve (only the small 43mm got that, the larger 45 has the small indentation).

Plus the relief in the head is to lower compression. It looks like someone replaced one of the heads with one from a 4.5 at some point in time.

It will lower the CR about 0.5 of a point so the engine will still run okay, but not perfectly.

 

Thanks Blake,

To confuse matters further, the left head has two exhaust valves as pictured above and two the same as on the right head......

 

Odd, they probably just bought what was available and had no idea the valves were different sizes.

I also doubt they changed the valve seats to accept the larger valves. I had to do that when I stuck 944 turbo exhaust valves in my 4.5 heads. They're 45mm sodium filled valves.

 

I will get the heads CC'd after new valves are in and make them both the same volume (maybe remove aluminium as needed) and then get new pistons with increased compression ratio to compensate.....

 

Probably just me being spoiled with access to used parts, but I'd start with two matching heads that have the same combustion chambers, the same valves, and the same ports.

 

All the intake ports are the same (based upon the gap/ or lack of around the gaskets and a visual inspection) on both heads, as are the valves in size. The left head has what looks like steel inserts into the exhaust port?! This left head appears to be date stamped 85, meaning that it is not original (my car is an 82 build for an 83 year model), the right head is date stamped 7/82 which fits.

This whole thing just gets more confusing.....

Unfortunately euro 2V heads are not that common....

 

That is one of the main reasons I had to turn my 81's heads into Euro heads, well, ones machined just for a 100mm bore.

Any competent machinist can can do the heads if they have done a set of 350 chevy heads before. So long as they follow the Porsche spec you shouldn't have any issues.

I would look into getting a set of matching heads and going from there as Greg suggests above just to make sure everything matches.

P.S. All 944s used 928S sized valves (they have the same P#) so getting a used set is pretty easy and inexpensive compared to tracking down 928S heads or valves

 

https://rennlist.com/forums/928-forum/822187-1978-1986-us-versus-row-cylinder-heads-valve-port-and-combustion-chamber-sizes.html

https://rennlist.com/forums/928-forum/929600-16v-head-and-runner-porting.html

My 1985 928S 4.7L 16v LH-Jetronic non-cat car had the pressed in exhaust port steel sleeves. I removed the sleeves when I did the porting job. I wonder why they were there, must be for heat insulation. Anyhow the ported exhaust ports are flowing very well. The steel sleeves cannot be found in the Porsche spare part catalog (PET).
I also have a pair of 3R heads, think they are from a 1982 engine. The design of combustion chamber is different having the small square relief. All heads have the larger 45/40mm valves. All 4,7L engines have the larger valves. These heads do not have the pressed in exhaust steel sleeves.
Åke

 

Thanks. That confirms what I thought, that I do have euro heads and all the valves are 40mm/45mm. It appears that they must have changed the combustion chamber slightly in 85, I do know that Aus got a slightly lower compression model for that year - it may be they changed the heads slightly as well? also my part numbers are 928.104.348 3R

I will get mine fully checked out and measured and I think it will be fine.

Cheers

 

That makes some sense, as Sweden and Australia did get differences from the R.O.W. cars some of the time....

 

Do ask Greg "Slate Blue" in Australia if he has any heads for sale. He has a lot of stuff.
https://rennlist.com/forums/928-foru...er-thread.html