2000 TC: does mine need a rebore?

J

johnsimister

Active Member
The engine has done 66,000 miles. Before I took it to bits it blew no blue smoke and used practically no oil. But performance was very sluggish, especially on hills, despite all being correct in the ignition and carburation departments. Compressions varied between 152 and 160psi, some way off the 190psi this 10:1 compression engine should have.

I'm currently refurbishing the head: new valves (slight pitting on some seating faces beyond fixing by simply grinding-in the valves), and new guides (exhaust ones very worn). That should improve compression a bit. Getting the valve timing right should improve it quite a bit more; it was about 8 degrees retarded, which I have learned could reduce compression pressure by as much as 25psi. I'll be replacing the timing chains and tensioners – there was a chain rattle at idle, and the timing discrepancy suggests the chains might be worn – and also the main and big-end shells although oil pressure was good.

So, the bores. There's a wear ridge near the top of all of them, slight but undeniable. Given the foregoing re compression pressures, lack of smoke and oil usage etc, is it viable to leave the pistons and bores alone and still expect performance to be as it should be once the engine is back together? Or do I go the whole way, extract the engine, get it rebored and spend a worrying amount on new pistons? Obviously I would rather do the former, but not if the engine ends up still underperforming.

If a rebore is the only way ahead, is it OK to bore a 2000 block out to take 2200 pistons? I see the 2200 pistons don't have cut-outs for the valves – do they work OK with the flat-face 2000 TC head? Will I end up with the usual 2200 9:1 compression ratio (probably a good thing with today's fuels), or does a 2200 head have shallow combustion chambers so the valves don't protrude as far into the cylinder?

All advice gratefully received.

Thanks, John
 
Personally I'd pop the pistons out (if you haven't done so already) inspect them and then if all looks OK hone the bores and as you're so far in already, fit a new set of rings, but I've done plenty of sets of ends and mains without replacing the rings, and plenty of head overhauls likewise.

2000 blocks can be overbored to take 2200 pistins and there aren't any problems using 2000 heads on 2200 blocks, unlike doing it the other way around.
 
harveyp6 said:
2000 blocks can be overbored to take 2200 pistins and there aren't any problems using 2000 heads on 2200 blocks, unlike doing it the other way around
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I’ve done just that, the lower compression helps with lower quality petrol here in the States. I would say go to the twin HIF6s too if you do go down that route. To be honest, after all the work I’d just bore out to 20 thou plus and stay 2000. The higher compression with less ethanol in UK fuel would be easier.

As for your car in present state, one thing to consider when doing a compression test is how strong the battery and starter motor are. Low starter speed can give low compression readings. If you have access to a leak down tester use that instead. It’ll give you more info on engine condition and what’s leaking. With the steps I’d say a reborn is likely, but if you can borrow bore gauge it might be worth a check.
 
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johnsimister said:
Excellent food for thought, thank you. Can I use the 2000 con-rods with the 2200 pistons without modification?
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The conrods need a small mod if you reuse the 2000 rods. I think that a small amount of the bottom needs to be ground back.
 
sdibbers said:
If the head is already off check the top of the cylinders for a small step, that would indicate wear.
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Steven, thanks for your thoughts. It does indeed have a small step for a cylinder, but my concern is that it could be a giant leap for the engine. I'm wondering how big the step needs to be before it's a problem. Oh, the angst.
 
Do you have a bore gauge to measure the ridge? If it is only a few thou then you should be fine to re ring only.
Is your motor in the car or out of the car?
If it is in your car and you have no easy way to take it out then I would suggest removing the ridge with a ridge reamer, and then remove the pistons and install new rings. You can damage the pistons if you do not take out the ridge first. You can get a ring set for about $80. I can check the part number if you need it. While you are at it put new bearing shells in as well.

If the motor is ready out and you have plenty of cash to spend then by all means re bore it. But I doubt that it is necessary. You can get 9:1 CR pistons to go in a 2000 motor. That is another option instead of going for 2200 pistons, but 2200 pistons may work out less expensive.
 
When i acquired my series 1 2000 TC back in 2006 as a rolling project, the engine felt somewhat tired, was more noisy than a sorted Rover 4 cyl engine, it did use some oil, and also smoked a little under acceleration. Also as i found out later, it had the wrong distributor and some broken piston rings. Despite all that, it could still hit the ton, and cruise at an indicated 90.
I am not sure how you define sluggish, but performance wise your car sounds worse, even if your bores/pistons appear to be considerably better.

I have replaced this engine with a freshly rebuilt one (not by me though) and after some 110 K miles, almost all of them covered between 2007 and 2015, the engine is still reasonably quiet, it hardly uses any oil, and performance is not bad at all for what it is, keeping in mind that it now pulls through a significantly taller V8 diff.

Based on the aforementioned experience, i would tend to leave alone the bores, especially if your intended use will be light. However, since the head is already out, it would be a shame not to pull the pistons, just in case there are any broken rings.

I also understand that the valve timing and tappet clearances have a major effect in the performance of these engines.
 
Demetris, yes, I think my car goes less well than yours did even when tired.

I have decided to make it a 2200 and have ordered the pistons, Hepolite ones on eBay at a pleasingly low price. There is now the matter of whether or not to use the larger 2200 exhaust valves. If I have my existing cylinder head fitted with larger exhaust-valve seats to suit, is there enough metal thickness in the ports to allow for opening-up behind the seats and blending for good gasflow? Are the 2000 and 2200 castings the same?

And, in the end, is it worth fitting the larger valves or will the difference be small? I notice that the 2200 piston gives a very different shape of combustion chamber from the 2000 one, wider and flatter with more space around the valves. Was that for emissions reasons, I wonder?

What might have been fixable with a correction to the valve timing – it was retarded by half the width of the camshaft locking key – has turned into a fairly comprehensive engine rebuild. As tends to be the way with classic cars, but we still love them.
 
John, i think that you will be happy with the result. At least those that have done it in the past report a significant improvement.
I myself have retained the block of the original engine, and have already a set of std 2200 pistons to move into this direction. However, at the moment i cannot justify it, the current engine is fine.
I am afraid that the shape of the 2200 piston is simply down to the cost, being much simpler as a design compared with the original 2000 piston. I also suspect that the 2000 piston should be more efficient, designed specifically for the flat head, and not being just a generic design like the 2200 piston is. However, i cannot offer any hard evidence for the above. What i know for sure is that the 2200 piston is rather lighter than the 2000 one, which is something that probably contributes to the 2200 engine being smoother than the 2000.
Regarding the cylinder heads, 2200 ones are different castings from the 2000 ones, so i personally wouldn't be tempted to fit the larger exhaust valve in the 2000 head.
 
What I know about the 2000 engine you could write on the head of a pin. What I do know however is that if you lap a valve in and get a nice thin grey ring, any area of valve seat that is left inside that ring is restricting flow. So opening up the seat to the size of the lapped ring can gain good results, and can be a 'free' uplift instead of going to a larger valve, this combined with a good 3 angle job.
If you are determined to go bigger valves sometimes slightly larger valves can be installed in existing seats by re cutting the seats.
 
The problem with this certain engine is that the exhaust valve is the Achillea's heel. Even on otherwise standard heads the valves tended to burn and the seats to drop. Any modification that reduces the width of the heat path from the valve to the head is a risk IMHO with this engine.
 
johnsimister said:
Steven, thanks for your thoughts. It does indeed have a small step for a cylinder, but my concern is that it could be a giant leap for the engine. I'm wondering how big the step needs to be before it's a problem. Oh, the angst.
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IIRC anything you can catch a fingernail on is a pretty worn cylinder wall (0.003" - 0.005"). Personally I have found the cylinder walls can glaze pretty badly too, making wear happen faster and reduce ring sealing into the bargain. If the engine was together I'd say test for blow by from the hose on the top of the valve cover. Because of the position of the timing chain you get a false positive for blow by at the oil filler cap. Best reliable indicator of course is a leak down test. The issues with just replacing rings on an engine with that step are:
1) Rings still not sealing due to ovalled or oversized bore
2) Breaking the top ring as it hits the step at the top of it's stroke.

johnsimister said:
Can you elaborate on the conrod mod?
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I've racking my brains to remember the exact mod for the conrods (I was lucky enough to find some 2200TC rods instead of making the mods myself). I seem to remember it was at the small end, hopefully someone can confirm that?

On the conversion to from 2000 to 2200 I would say power isn't greater, (in fact numbers on BHP drop a little). But mid range and bottom end torque are better (I think that's more due to HIF6s over the HS8s fitted). Chris York has made the point that the 2000 pistons have much more elegantly designed combustion chambers in the crowns than the rather simplistic 2200 pistons. I wouldn't say I regret making the conversion on my car, but I feel that the gains would mostly be explained with the conversion to HIF6 carbs.
 
The ridge is certainly big enough to catch a fingernail, so a rebore is necessary. Latest snag is that there is erosion of the aluminium next to number 3 exhaust valve seat, exposing a small part of the outside of the seat. The fear is that this is the precursor to the seat dropping out. Ideally the seat needs to be removed and the damage repaired by welding. However, I have a lead on a complete 2200 TC engine, probably in need of similar overhaul work to my engine but I could use the head and the conrods on/in my soon-to-be overbored 2000 block. The cost of all this is getting a bit out of control but it will be worth it in the end.
 
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