I understand that it’s an odd thing to do from the factory, but many of these engines last for 100k miles without a rebuild. So if the problem really is the lack of tangs, how does a 10thou regrind make such a difference over buying a new crank on a car that won’t be ragged and will be over serviced?
It’s all academic really as the advice leads me to a no repair conclusion, just going to break it.
I have a MX5 NC 2-litre and was advised to go for a rebuild due to knock rod. One rod was bent and there was damage to piston shells due to over heating. The rod was replaced including all seals, piston rings, timing chain, gaskets, crankshaft, oil filter, timing belts, bearings, etc for £2600. Piston Components Glasgow, speak to Mike. They also fitted a 4-1 manifold exhaust which passed its MOT. The car runs like a dream.
I ended up going for a slightly different approach.
I didn’t rebuild the original engine but bought a running and quiet replacement from someone who did a 2.5 conversion (incidentally they said the conversion wasn’t worth the effort for the minimal power increase). The replacement engine was starting to use some oil but otherwise was OK.
I stripped the replacement for inspection. All the bearings, crank etc showed no signs of wear, the engine was really clean inside so probably very well serviced throughout its life. To resolve the oil burning issue I replaced the piston rings, valve stem seals, had the head refaced and replaced the white metal bearings, gaskets, head bolts etc.
Been running the car a few weeks now, no oil consumption, everything seems fine, total cost £516 including the cost of the replacement engine, consumables (oil and filter) and the new clutch I installed while I was there.
No I haven’t done a full engine rebuild but then the engine didn’t need a full rebuild, I did replace all the worn components.
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Re the part where someone said the 2.5 didn’t make much gains……
This is the issue when people do a 2.5 swap on the cheap.
The 2.5 is a ‘stroker’ and only makes the same HP as a 2.0 UNLESS it’s built properly in which case it will make 230bhp and 215ftlb this then makes a massive difference
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