What to do with this TV175 engine?

[Warkton Tornado No.1]

If you assess the port timings you have, it’s likely you can easily tolerate an increase in transfer & exhaust ports, which is one benefit of deleting the head gasket. If any gasket is likely to weep, it will be the head gasket IME. Personally, I’ve not used them on any engine for the best part of 50 years.

Metal base gaskets are extremely reliable & have the advantage of being re-useable & serve as a brilliant means of matching the barrel & case transfers…..

[Storkfoot]

These were done in a bit of a rush so will need rechecking.

With 2mm packer:

Exhaust 153
Transfers 118
Inlet 144

With 3mm (2mm packer and a couple of 0.5mm paper gaskets):

Exhaust 159
Transfers 124
Inlet 140

To my limited knowledge eye, the 3mm packer option seems to offer a very rideable engine but lacking power because of the relatively low exhaust timing. I knew that would be the case when I made the conscious decision to not have the barrel tuned.

Thoughts please?

[Warkton Tornado No.1]

The 175 S III engine is quite a rarity by comparison with the other capacities, but in my experience very smooth.

I have only ever tuned one & that was already fitted with an Indian alloy finned barrel. I would never do one again unless there was a ton of money upfront to cover the time involved. However, it turned out extremely well.The poor quality, mismatched transfers & chilled - extremely hard - cast iron ports required many hours of work & almost dictated the extent of tune just to get things tidy.

I realise that none of that helps you, but if I can track down my notes of port timings, I will let you know. The tune was not wild but the exhaust was some aftermarket un-named expansion chamber that worked well.

[Storkfoot]

The 175 S III engine is quite a rarity by comparison with the other capacities, but in my experience very smooth.

I have only ever tuned one & that was already fitted with an Indian alloy finned barrel. I would never do one again unless there was a ton of money upfront to cover the time involved. However, it turned out extremely well.The poor quality, mismatched transfers & chilled - extremely hard - cast iron ports required many hours of work & almost dictated the extent of tune just to get things tidy.

I realise that none of that helps you, but if I can track down my notes of port timings, I will let you know. The tune was not wild but the exhaust was some aftermarket un-named expansion chamber that worked well.

Thanks again for the reply. I think I am just going through a phase where I crave reliability and the chance of being able to easily strip a top end on the road, if needed. Cast iron barrels, Piston port, Japanese piston with a gudgeon pin that slides in easily, not tuned to the max, that sort of thing.

I checked the timings and, other than getting an inlet timing of 141, as opposed to 140, they were the same. On that basis, I have ordered a 3mm packer.

I had another look at the layshaft. The pitting isn’t too bad and I am sure in years gone by, I’d have just stick it back in. But, there is a ridge where first gear sits. You can see it in this photo and you can catch your nail on it.



Let’s see if I can set up one of the new layshafts when they come back from the machine shop. If not, I may well just put this one back in. The threads and splines are spot on.