Do Australian built 351C have the same "weaknesses" as US built 351C?

With U.S-made cylinder heads used on Panteras, two-piece welded valves have multiple grooves and matching split keepers. Even cheap aftermarket stainless steel valves may be welded from two pieces. Good, one-piece valves have a single wider groove and matching keepers. Some two-piece multi-groove exhaust valves have magnetic stems but the welded-on heads are not magnetic (or not near as much as the stems). The problem with welded valves is when engine revs exceed maybe 6000 for any reason, the weld between valve head and stem may break and the welded valves become two pieces again. The muligroove keepers also do not hold the stems tight. Breakage of a single valve (or a keeper letting go) normally destroys the entire engine in a heartbeat.

Aussie-cast blocks are reported to have a smaller diameter hole for their smaller OD distributor shaft; this means that U.S-made distributors (stock or after-market) will not drop in place without drilling out the block's hole first. There are other minor detail differences.

Here's how the Australian engine pans out:

Aus. 351 GT/4V – Late model version, XD - XE Falcon (1979 - 1982)
8.81:1 compression ratio
Low port/small port heads; 2.04/1.65 valves
Camshaft spec: same as US 2V camshaft.
0.407/0.407 gross lift | 258°/266° dur. @ 0.006
Carter Thermoquad 4bbl carburetor (spread bore), approx. 600 cfm.
Model TQ-9071S (manual trans) or TQ-9085S (auto trans)
Bosch breakerless distributor and electronic ignition
Output: approximately 214 DIN HP

Replace carburetor with 650 Holley: +65 HP
Raise compression to 10.2:1(replace pistons): +6 HP
Replace camshaft with US Q code camshaft: +30 HP
Total Gain: +101 HP (315 DIN HP)

The late model Australian 351C had a Bosch breakerless distributor with electronic ignition, its a fine ignition that doesn't need upgrading. However, the engines were emissions tuned, so the OEM spread bore Carter Thermoquad carburetors are calibrated very lean. I don't know whether or not De Tomaso replaced the carburetors with a #4777 Holley as they did with the Pantera GTS, if so it would be a good thing … as the engine's output would increase to about 280 DIN HP.

The fact that the Ford valves are a two piece welded design is not the issue …  as far as I know all OEM valves are two piece, its a more economical way to manufacture them. The Ford valves don't crack where they are welded however, they crack below the weld. The valve heads are brittle from an "aluminizing" process. The question is where did Ford of Australia source the valves, from the US or from a domestic supplier. Unfortunately I can't answer that question. I've never heard of valve failure being an issue in the land of OZ (Australia). I can't say it isn't however, it would be nice if somebody tuned into the scene in OZ could speak up and let us know. 

The OZ manufactured Cleveland Ford V8 still needs all the other stuff however, ARP rod nuts, tappet bore bushings, heavy duty main and rod bearings, wider bearing clearances, fully grooved main bearings, wider rod side gap clearances, new damper, proper thermostat, oil pan windage tray, Q code style oil pump pick-up.

Thank you very much for the information! 

I was in contact with a shop specialized in rebuilding Ford v8 engines earlier today. I will probably send the engine to them to check if it has to be rebuild. They know the 351c-engine quite well and have a good reputation in Norway.

If the cylinder heads are in bad condition they recommended me to buy new fully assembled aluminium heads instead of rebuilding the old ones. I've read the CHI heads are great. Is there any big difference between the 2V-190cc C1/C2 assembly, 60cc or 67cc combustion chambers models? I'm focusing on low-end torque. 

The engine is fitted with an Edelbrock 1806S Thunder carb.

Cheers,

Robert

"I want to keep the drive train as original as possible"

"I've read the CHI heads are great."

So much for keeping it original...... LOL its a slippery slope I tell ya.

That's one of the realities living i Norway, it's probably 2x the price compared to the US. The person I spoke to would not recommend restoring the heads if they have to be rebuilt. But I'm going to keep the original one if it comes to this.