Hi Rusty, I know exactly what you mean about body repairs. About 10 years ago repair panels etc were very hard to get. I remember cutting out and repairing the wheel tubs, now you can just buy them. Same for footwells, A,B and C pillar bottoms, outer wheel arches etc. Still nobody does a boot floor!!! and bottom tailgates... I know exactly how you feel, I've been there to.

I know you have been trying to avoid it, but I would strongly say do a wet and dry compression test. Is it possible you have a couple of sticky piston rings that just by coincidence are on pistons 3 & 4? Did you do a leak down test? What did it show?

I still wonder about your cam timing at 106 deg. Really should be 108 deg. I agree about the fuel pump, get it swapped out and check fuel pressure. Interesting what you say about the connector - I had a similar experience. I ordered a new pump and it came with the later type plug but an adapter was included so it is feasible. Your other option if necessary would be cut the old connector off and splice on to new pump. Don't forget to check the connection under the floor on the near side, make sure connection is clean and plug is tightly together. I have also found that with the new pump and adapter plug set up, I had to manipulate the plug to sit in a certain position to get it to work (go figure!) but it does what it is supposed to so I leave alone!

Hope that helps ya, come back and let me know how you get on.
Cheers.

Hi Kev,
I agree. I cursed somewhat when all those panels became available after I’d taken so long to repair it all.. still, if I get it going and keep the car ( I’m that fed up with it) it will make it easier next time around after all it WILL rust away again especially as It does get wet and muddy.

I haven’t done the leakdown test yet purely because it’s been either snow or rain for the last two weekends so I haven’t been able to drag the compressor out on the driveway, hopefully I’ll get to do it on Sunday.

I did consider making up an adapter for the fuel pump but by that time I’d managed to break the suction bit off the bottom of it anyhow and conceded defeat!.
New Bearmach one here waiting to go, hopefully it will last longer than the blue box one.

I’m no expert with the cam timing on these old motors so I don’t know how fickle they are but before I took the engine apart for rebuild no.2 I did check the cam timing and I know where I had set it but the chain had slackened from new enough that it had moved to 110/111 deg atdc.

I’m not going to get stuck in to any mechanical tearing apart until I am treble sure there is no faults with fuel/ sparks/ ecu etc as you well know what a fiddly job doing a can swap with the engine is can be but the more I scrabble to find the problem and the car seems to fight back with more new problems like the fuel pressure that’s been fine til last week the more the gnawing thought that it must somehow be either the cam or something weird wrong with the heads bugs me..
It’s been built twice in 800 miles with new bearings/ rings etc, measured twice and on each occasion the same two pots have ran differently to the rest.

Even pots after first 500 mile running in you can just see the difference in cyl 4 where it was drinking coolant

Have you had a good look around RPi website? They have years of experience with rover V8's Some interesting article there that may be pertinent: cam follower preloading

http://www.v8engines.com/engine-4.htm

Hi Rusty, glad to hear you haven't given up on it just yet! I feel your pain, I've been there too many times over the years I've owned and abused my RRC. I think we share many of the same experiences with rust repairs and mechanical maintenance. Chin up, keep at it.

Anyway, I was interested in the photos of your block. Pot 4 has a noticeably clean patch. Normally I would say indicative of duff head gasket. What you have been saying about the colour of the plugs, I do actually see something similar, one side of the plug appears sooty but the other side is clean. I have always assumed this is something to do with the position of the plug in the head and how the flame front and gas and soot moves inside the combustion chamber but I could be talking nonsense!

Based on various bits in this thread, we know there is fuel and air, there is compression and there is a spark. I wonder, and it is pure speculation here, if using a different heat range plug would make any difference or maybe playing with plug gap? I run NGK BPR6ES. I did use Bosch Super 4's for a long time as well, so maybe something to ponder?

The only other thought I have is inlet manifold. As the block has been decked and heads skimmed, is the inlet manifold sitting flat and true? (vac test says yes??) but is it possible that even if there is no inlet vacuum leak, the gasket is restricting gas flow? Seems a bit unlikely but I can't logically see another potential suspect for the pot specific misfire.

I hesitate to say it but I think you may have to break it down again. It will be something silly.

Let me know how you get on and what results you get from any other tests and checks you carry out.

Cheers.

I was just outside messing about (as you do) and I thought I would pop a vacuum gauge on and check where mine sits at idle with a warm engine. I get 14" Hg too, so that says your engine is OK.

Hey Kev,
Thank you I really appreciate that! Knowing our vacuum readings are the same does give me hope that at least it’s not a vacuum leak issue although originally I was sure from the idle symptoms that a vacuum leak was the culprit.
I temporarily botched the valley gasket the other week with some hylomar around all the inlet ports purely because I pretty much knew I would have to have it all apart again very soon, didn’t want to waste another new gasket and I just wanted to check if adding sealant improved the vacuum reading or eliminated any leaks but I guess not.
I was worried about the inlet manifold not fitting squarely after all the machining as I had read it can be an issue but there’s no straightforward guide to what works and what doesn’t.. the heads/ block have had a total of 0.6mm off them but then it would have used tin gaskets before and it’s now on composite head & valley gasket so I doubt there’s much difference in it. The inlet manifold does sit a tiny bit further down after the block was decked but that helped as the bolts were a pig to get in before and now the bolt holes line up perfectly and looking down the inlets everything seems to line up pretty well. I checked how square the manifold fits to the used valley gasket/ heads by putting strips of plastiguage around all the ports and torqueing it down. On removal it all seemed to have squashed to an identical width so I assumed the fit was pretty good.
I also made a home made smoke testing thing and pumped the plenum full of smoke. (Used a cigarette previously but I gave up last August..) I was really hoping some would come out of something easy to fix and cure the issue but the only leaks were a tiny gap on the rubber elbow to plenum and the rubber seal in the back of the throttle spindle (now fixed)

I think my car has nearly always had the odd colours on the plugs too even when it was running happily with tan colour plugs many years ago and I too had put it down to rubbish head design it’s just that it’s more noticeable now as the plugs are so starkly black and white.

The pic of the even pots was taken before the top hats were fitted, well spotted as no.4 had a big crack in the block behind the sleeve. Mr Turner even took a photo of it to show me as he was so impressed with it..
there was no other way to fix it as it was filling the sump with coolant and pressurised the cooling circuit enough to consecutively blow 3 hoses then the rad.
the general colour of the piston crowns then seemed far too carbon black to me for 500 miles and looking down the plug holes they seem to be the same again now.
I’ve only ever used bpr6es plugs in the car and other than usually having to change them every couple of years as they get fouled I’ve never thought to differ. you may be right that it needs a different heat range but I know bugger all about how to gauge what an engine needs. 4.2 pistons are mega rare so I don’t want to melt them! Hehe
Even all the race motors I used to build only ever ran stock plugs. I have got some bp6es to try just to see if the lack of resistor makes any difference but I don’t think i’m near worrying about such minor tweaks at the moment.

I have tomorrow off work so I’m planning to be head down and tear into the pump repair and testing, hopefully I’ll find at least something wrong!
Cheers

My mind as you can imagine has been doing all too much pondering on this fault while I’ve not been able to get the tools out and fiddle with the car. I wondered if the cam lobes on the iffy pots had either been damaged/ prematurely worn or were ground badly or out of time and those pots weren’t getting as bigger gulp of air as the others hence running richer but still building compression during a six crank compression test? Thing is I’m absolutely sure the cam looked ok when it went back in.
I can see me rebuilding the standard heads to replace the fancy ones and fitting an h180 cam. When I can afford it that is.

Mmmmmm....... could it be that in reality you're chasing perfection and these beasts don't do perfect? I also wonder if after the top hat liners were done, were the pistons changed? Could it be the case that pots 3 & 4 need oversize rings? or maybe 3 & 4 are good and it's the others that need checking? It is a conundrum for sure. Would head tilting be worth looking for - assuming your heads have 3 rows of bolts? Personally, I've not experienced this so don't know what symptoms it produces. The counter to that is of course your compression and vacuum figures do not point to head gaskets or valve problems but I still think you should have a go on wet and dry compression testing.

The good news is 4.2 pistons are identical to 3.9 pistons. There is no reference to any differences, rings, clearances and standard oversizes are the same. AFAIK the increased capacity was achieved by changing the stroke. The only other difference I know about is the camshaft. The bores and top end are the same, the distributor for a 4.2 is the same as the dizzzy on a non-cat 3.9 - they run the same advance curves.

Keep at it!

I haven’t got as far as I’d like yet today, bloody freezing and snowing here again today..
I whipped out the fuel pump and par for course with this bloody car the big rubber seal has died! It’s expanded by at least an inch and there is absolutely no way I can make it fit back in in the new pump and reuse it! I guess it’s the ethanol content in new fuel has killed it. I’ve dangerously fitted the new pump without clamping it down just to see what happens. Results-
Key on- fuel pressure rises to 30psi
At idle- 30psi
At idle with vac to regulator removed- 30psi
Key on with return fuel hose clamped shut-41psi
From everything I’ve read the fuel pressure should be 35psi both at key on and with vac removed at idle and only drop to 30 all connected at idle so it seems I either have two duff regulators, a leaky injector or a bad fuel pressure testing guage.

I can’t feel my fingers now as I’m so cold but i’m going to try and do leakdown tests and whatever else I can manage.

Ok, results of today’s freeze fest-
Somehow and luckily the swollen pump seal seemed to dry out and shrink back to its usual size after a couple of hours in the boot so I got that back together.
Started car for one minute and it was still missing and a few of the plugs looked wet when I pulled them.
Results of leakdown test in cylinder number order followed by dry comp test figures
1- 20%. (160)
8- 25%. (175)
4- 24%. (180)
3- 26%. (180)
6- 26%. (175)
5- 18% (180)
7- 23%. (180)
2- 15%. (165)
All the escaping air during the leakdown test seemed to be passing the rings and none past valves into inlet or exhaust. Figures seem high to me as I’d read that 5/10% was good for a freshly built engine but the guage says 20%ish is mid way through a good reading.

I didn’t get much else done as it’s so cold that I couldn’t work very fast.. I fitted the spare dissy that I’ve pulled apart and checked plus those new bp6es plugs but didn’t want to foul them by starting the car yet!
The fuel pressure gauge that I’ve left attached to the fuel line for now says that while I have more pressure available from the pump the fuel system still isn’t holding pressure, it dropped from 30 down to 18 over a few hours and before the fuel pressure went all wrong last week it was holding at 26psi for over 24 hours with no drop at all. I’ve double checked fuel lines and they seem dry so it must be regulator or injector leak. I’ll try to clamp the return hose again with the system up to pressure and see if that proves where the pressure is going.

Compression looks suspiciously down on 1 & 2 and compared to the highest readings, there is more than 10% variation but importantly, the same variation is seen between adjacent pots (3&4) but to add to the confusion, the pots you're not happy with (3&4) show very healthy compression. I think you could be right about possible leaking injectors. I know I have said it before, but sticky piston rings are still a possibility or maybe, after top hat liners, oversize rings are needed?

It may be the case that you may need to put it all back together and running as best possible then give it an "Italian tune up"; go and drive the nuts off it, manual shifting and holding high revs as much as possible. I know it isn't very dignified but you might be surprised. After giving it a good thrashing, run vacuum and compression tests again and see how they compare, vacuum should be the same but compression may see some changes with a hot engine. Don't forget, extra care is needed to work on a hot engine. Good luck.

I’m all up for an Italian tune up!
I kind of already did that a couple of weeks ago and it goes pretty dam well (right round to 5.5k without hesitation and plenty of noise) and well enough to worry me if I would get the thing to stop again! a group of objecting walkers rambling up my deserted lane while I passed them at 70 seemed to think it was too fast hehe
For now (at least until this fuel issue appeared) I’d say there’s very little wrong with it once it’s above idle but the cars problems continue to bug me..

I’ve decided that I need to be 110% sure of all fuel/ spark tests before I pull the thing apart again.
The fuel pressure needed sorting as it was not showing correct pressures and losing all pressure overnight when it had previously not dropped below 20psi even if left for days. I pulled the fuel rail and the vac pipe to the regulator had fuel in it so I bit the bullet and found a bargain half price genuine one at a place a mile from where I’m working and fitted that tonight. Even more annoying was when i pulled the rail out today I noticed that two of the injector nozzles were wet with fuel so I’m guessing they were leaking.. entirely my fault for fitting an untested used set last week in the hope it might help so I put the injectors back in that I have flow/ dribble tested a couple of weeks ago but I still have duff fuel pressure...
With the fuel line clamped shut the new pump can provide 41 psi but with ignition on, pump running to prime I’m only getting 26psi instead of the 35ish it’s supposed to.
I’ve left it to see if it holds pressure overnight to see if there’s stilll a leak somewhere. Bloody car..

I also went back through my notes and while I know the figures vary way more than are good the compression figures do mostly follow the same variation that they had before on rebuild no.1 before the tops hats were fitted but are all about 15% higher.
I do need to still do a wet compression test but I’m wondering how to make sure the oil I chuck in actually gets around the rings and not just sit in the piston crown as the pistons are very dished with a raised edge.
Also the vacuum gauge read 12 hg back then on build no.1 and plugs were all lean with the exception of the same two iffy pots which then had perfect colour plugs.

Further minor update with no fixed it news as yet.
I decided my year old fuel pressure tester might be giving erroneous readings so ordered another. Seems to have been a good call. Having left the old guage attached for a few weeks while doing these tests it seems to have killed it so a word of warning to take heed of instructions on fuel gauges that say not for permanent fitting..

The new tester shows 60psi with fuel pump priming with fuel return hose clamped off (good head of pressure?)
36psi with clamp removed and pump priming (also good)
I couldn’t try it engine running with or without vac pipe removed properly as the fuel rail is not yet back in but I did replicate a 14hg vacuum onto the vac pipe/ regulator and pressure drops to 26 psi with vacuum applied.
So in general the fuel pressures now seem pretty good. The only error in the tests is that it’s not holding full pressure from either end when the pump stops priming. From the regulator end it very slowly loses a psi or two over ten mins but there’s is not a single drop from injectors so it must be the regulator letting a very small amount past.
From the feed end when the pump stops running the pressure immediately drops from 36 to 30 then slowly drops to 20 psi where it holds so I can only assume the one way valve in the new pump isn’t great, I’ll take a decision on whether to get it replaced once I’ve double checked the pressures with the engine running soon.

Further minor update with no fixed it news as yet.
I decided my year old fuel pressure tester might be giving erroneous readings so ordered another. Seems to have been a good call. Having left the old guage attached for a few weeks while doing these tests it seems to have killed it so a word of warning to take heed of instructions on fuel gauges that say not for permanent fitting..

The new tester shows 60psi with fuel pump priming with fuel return hose clamped off (good head of pressure?)
36psi with clamp removed and pump priming (also good)
I couldn’t try it engine running with or without vac pipe removed properly as the fuel rail is not yet back in but I did replicate a 14hg vacuum onto the vac pipe/ regulator and pressure drops to 26 psi with vacuum applied.
So in general the fuel pressures now seem pretty good. The only error in the tests is that it’s not holding full pressure from either end when the pump stops priming. From the regulator end it very slowly loses a psi or two over ten mins but there’s is not a single drop from injectors so it must be the regulator letting a very small amount past.
From the feed end when the pump stops running the pressure immediately drops from 36 to 30 then slowly drops to 20 psi where it holds so I can only assume the one way valve in the new pump isn’t great, I’ll take a decision on whether to get it replaced once I’ve double checked the pressures with the engine running soon.

Sounds like, sort of, good news...ish maybe?
60psi priming is good. I'm not sure that with the engine running you would see the fuel pressure drop because the pump runs continuously when the engine runs so I wouldn't worry about it. If it was a fuel starvation issue I'm pretty sure you would know.

Keep at it, I'm sure the answer is close by.

That was my thinking too Kev. There are no external leaks anywhere as I replaced the fuel lines a few years ago so as long as it holds correct pressure while running it won’t bother me.
It’s going to be a while before I try to fire the car up again yet as I want to whip inlet off to have a detailed check on the cam and hopefully (cam allowing) fit the adjustable pushrods to at least eliminate any uncertainty there..

Two months later..
Still no good news.
Adjustable pushrods fitted, no difference.
All ecu multi meter checks done again and all fine.
Went through ignition system again and except for it having 12v between coil -ve and battery + (has always been like that..) all good.
Plugged in rover guage and all seems to be doing what it’s supposed to.
Swapped tune resistor to non cat to keep things simple for diagnosis and it runs exactly the same. Proper misfire from cold start, quietens down after 1 min or so but remains a partial miss, stinks of unburnt fuel and whisps black carbon smoke out the big fat tailpipe.
I drained the 300 mile old running in oil and while it was spotlessly clean it stank like old high miler oil..
I’ve spoken to real steel about the cam and they only said check lifter preload.
The guy who did the big valves said it’s probably over fuelling and to fit megasquirt as the 14cux is an antique..
I spoke to v8 developments who also said it’s probably over fuelling but the local to me rolling road they suggested weren’t interested in my old dinosaur.
Going with the over fuelling idea I tried a cold start with the cts unplugged to fool the ecu into thinking the coolant was 30 degrees and it made no difference. Trying to allow a little extra air in via the inlet vac stub also made it run worse so I don’t know if it’s overfuelling?.
I’ve never been beaten by a machine before but other than blindly pulling it apart and swapping cam and heads in the hope it solves it I’m out of ideas..
I can’t seem to find anyone local who knows the old v8’s or wants to work on it either so I’m going to ponder for a while at what to do with my driveway ornament.

Hi Rusty, glad you're still at it.
I can't remember if you checked it but the misfiring you describe sounds really similar to a problem I had a while back. It was an iffy inlet manifold gasket. Do you have a steady vacuum at idle?

If it was an overfuelling issue Rovergauge should show it up in the fuel trims. Is the airflow meter good? What is the CO trim set at (voltage)? I agree the 14CUX is an antique but it can easily cope with your engine.The other good thing about it is it is a relatively simple system and trouble shooting is rather less complicated than for more modern systems that control fuelling and ignition together.

I'm sure you'll get it licked, good luck!

have you done the obvious and checked compression to see if the valves are closing fully?
extra air via the vac or anywhere else will be unmetered so that will push the fuel off, what are your fuel trims saying?
+1 on the airflow meter
have you checked for a leaky injector?
have you tried unplugging sensors one to see if any make a difference?