I’ve heard that the 202 pistons are prone to cracking as they are thinner than the earlier red engines
Also the block crack more often in the 202

Is the 202 a lesser quality engine than the 186? Or have I got it wrong

As Byron said a 202 is a stroked 186. The 186 is more revy, due to the shorter stroke, which is why many like them over the 202.

Personally I would go a blue 202 to mild or factory spec, they make great torque, due to the longer stroke, have good breathing, mechanical secondary carby (spend time getting the auto choke right) stronger rod bolts etc.

What about block thicknesses and quality of metal used in the block, did that change?was there a high nickel block ?
The blue and black pistons were lighter (weaker) ?

I have seen a few red 202s throw number 5 out the side, but not on a blue.

As for lighter pistons prone to break, I remember the ecotec when it came out, thinner rings etc, would not last, they have great longevity.

I guess it depends on what you are using it for, I would choose a blue 3.3 because I would be using it as a cruiser and I found that it was smoother and more economical in my HZ than the red 202. Admittedly I had auto air and steer on it, and it still went very well, for what I wanted.

The 202 block has the mains caps wider apart from the rest and I think that this adds to the block splitting if they make a lot of power, I have seen 186 split as well but looks like much more power to do so.

Apart from that the blocks are much the same, but for the 202 that has the ribbed blocks are better, the ribs can be seen behind where the oil filter goes on and this casting strengthens the block as in twisting I believe, so as power increase the block try's to twist from the passenger side front to the driver side rear and the ribs help strengthen this also the engine mounts are yanking on the passenger side of the block and Holden 6 has the camshaft on the wrong side of the block as it would be better to have this on the passenger side to strengthen that side.

I believe that the mains bolts being wider apart adds to the pressure adding to the passenger side of the block so she can split that part but it takes over 200hp to do this.

As for block casting metal being used I think that this changes as the years go by and it has been said that many a blue head had valves sinking issues to do with soft castings.

But as for a harder casting metal I think that the last of the 202 XU-1 may of had this high nickel content, some say that you can tell by the feel of the surface of them is some what shaper feel, I am not sure it's true but maybe HK1837 could look into that with all the Chevy info he has.

As for Blue 202 pistons I remember that Holden was boasting that the Blue pistons were stronger than the Red, not to mention that the Blue is making much more power and that the main reason for cracked pistons has to do with fools driving flat out from cold and as for numbers there were a lot more 202 made and a lot of idiots are out their abusing their cars, so I would think that would be the main problem, I don't think that the pistons were a problem at all, but more to do with idiots and out of tune engines and driving around with them pinging.

I had one bloke claiming that if you drive you car easy you will not blow head gaskets, I said bull shit you can drive a engine as hard as you like and that will not affect the head gaskets at all, only think is that it's all about fools that destroy engines because they do not understand what is going on, so some fool could drive around easy but the engine is pinging and bingo you are asking for troubles and the list goes on.

173 from a certain time used the same caps as 202 as well. I don’t think you are going to break any Holden 6 unless it is pumping out huge power and revved to stupid numbers. Or abused. Dave McLean (Alan Grice’s XU1 engine builder) reckons that later XU1 blocks are different material, like the F5000 Holden V8 blocks. He says you can feel it when you are boring them.

My VS went quite well. Gutless but smooth and no issues. It was a August 2000 or thereabouts manual so whatever engine they had. I sold it when it was 2 years old and replaced with a VY SS Ute.

There's nothing particularly special about a Repco F5000 block casting. They were purchased as a raw casting from Holden by Repco Engine company and specially machined, useless protuberances lopped off, oil galleries opened up in places, bored, line bored etc etc.
Ditto the crankshaft, which was a production item offset ground to get below the 5 litre formula limit.
The rods were special Repco forgings, as were the pistons.

I was under the impression the F5000 and the L34 blocks were special cast material by GMH. They introduced the stronger block casting that appeared in normal production with HJ 253 and 308. The F5000 engines had slightly smaller (undersize) bores to stay under the 5litre limit hence the special pistons. The F5000 blocks were cast around early 1973 from memory and lots have a big X in the casting, a few have appeared in L34 which often also have an X across the 308 cast mark.

Edited by user Thursday, 19 September 2019 11:40:59 AM(UTC)  | Reason: Not specified

I do not see why the 173 would be like the 179 casting was especially in the HQ up to the time that they got the 202 mains, then they could be the same block but I don't thinks so.
The EH to HD 179 was most likely a safety measure and then they went ahead with the bore to a big 186 because it was all fine.

I don't know of the 149 bore wall thickness but you can not bore them out to 161 or never heard of one being done so a 149 + 0.060 = 155 and 0.120 would make a 161.
But then again a 161 can go out to a 167 at 0.060 and 0.120 would be 173.
But a 173 + 0.060 = 179 and 0.120 = 186 but could you stretch it out to a 192 ? well when the 186 is taken out to 192 they come into problems of running to hot as do the 202 at 208.

If I bored a high performance 202 out I would not want to go 0.060 I think 0.040 is max that I would go.
I am sure that given the right block if it's a exceptional good casting you could make a HQ 173 go out to a 186 but I would keep it a stock powered engine for a grand mother.

But it would be great if the late 173 was just as the 202 block is as you can just drop a 202 crank in it and go 208, but at best I think the 173 could become a 195 if a piston was made but at best a 173 into a 202.

It should be easy to spot if a late 173 bore is the same as a 202 by just popping a welch plugs out, as 0.120 should be able to be seen maybe straight up.