McBreadhead

I tested mine recently and got 125, 125, 125 and 90. Time to take the head off and voila - a valve about to let go. As in previous posts the value per se is not so important, it's the consistency of readings that counts. Anything deviating more than 10% I would investigate further.

Peter, Thanks for looking at pics - they probably don't tell such a sorry tale as when viewed in the flesh as they were minutes away from disintegration. The car runs an A6 cam and has a steel rocker assy, ratios unknown I'm afraid. How would I find out that info - is there a ref No. or do I measure sthg? Nick

Anyone have experience of fitting 195 x 14" to rears only, assuming I can get hold of them?

Peter, Yes, you're bang on, the valve is a fusion welded item and it looks like it's detaching around the weld. I plan to have sb like Burton refurb the head so I'd hope they will fix the springs in place as part of the package no? The engine will rev to 7,250 but I tend to restrict to 6k in regular driving. I'll send a pic in a mo. Sorry to have missed you yesterday at Goodwood btw. Nick

Brian, My sympathies to you on this. Funny thing oil consumption as my old xflow 1700 hardly drank a drop, maybe 1 litre in 3,000 miles. Now I have a 1760 with Stage 4 race head it drinks up to 2 litres every 400 miles which has had me on tenterhooks for a while. Discovered this early on which had me checking it regularly and now the head's off I have discovered a cracked valve which may or may not be related. But if yours never really consumed that much and you communicated that to the buyer then if I were him I wouldn't be too worried at checking over that kind of distance. It seems odd that it suddenly let go the oil in that short time so has sthg failed? Do you know if the idiot light come on at all?

Looks like I'll need to overhaul my Stage 4 race head as it's done circa 15k miles and I just caught a valve before it let go 😶‍🌫️ I've so far contacted Burtons who will refurbish head for £325 which includes new valves all round (new valves cost £120 alone). New set of head bolts are £60 plus Comitec head gasket £100. I would hope they would also check valve guides and tappets etc for wear but what else should I look to replace at this point? Is it worth taking out cam also? Burtons seem to be acknowledged experts as even the man from Minister said they get there bits from them; however there may be other avenues I'm unaware of? Car based in Winchester so if anyone can lend a sightful pair of eyes I would be grateful esp wrt pistons/bores as I was hoping not to touch them. In particular I'm flapping about how the valve came to be in its current state so any wisdom imparted would be good. I need to measure cylinder bores to order correct gasket - can I do this with vernier caliper or is more precise reading required? Thanks for any assistance.

Sorry, double valve springs and the valves have 3 channels at top under collets. When we tried to get the offending valve out it fouled the guide and we had to file the shaft around the channels to remove burrs that had built up. Wonder what it could it be? If you're around Goodwood tmrw I can show you the item. I'll email my phone number in case.

Peter It's believed to be built for hill climb spec, 1760cc, 160bhp, 7250rpm limit. Bronze guides, no valve stem oil seals. Steel rocker assembly. Stage 4 race head (totally flat, no combustion chambers). Forged pistons (again completely flat), con rods unknown. A6 cam. Valves are 34.9mm exhaust (haven't measured inlet) with reduced dia shaft before valve flange, no numbering visible. Engine believed to have done circa 15,000m. No further info as it was built in 1993 by another at Paul Matty and I bought it last year assuming it had plenty of life left. Perhaps I should adjust my expectations 😶‍🌫️

Peter, Thanks for the offer but I'll pass as talking to a few engine builders at Donnington today the perceived wisdom is to replace all 8 valves and possibly overhaul the head. What would be the recommended mileage between rebuilds for a 1760 xflow with forged pistons and stage 4 race head, not thrashed but the occasional visit to its 7,250rpm limit? Is there a difference between needing to service just the top end at say 10,000 and the whole engine at say 30,000? Cheers, Nick

I fancy a full Prince Albert with mine....

Haven't got my vernier to hand but roughly 35mm. The man from Burton he say 34.9mm for a Stage 4 head so it must be that. Do your items taper down between shaft and valve itself? Interestingly it runs in valve guides with no valve stem oil seals. Apparently this is a feature of such race heads as the guides need some lube.

Bought the engine with approx 11,000 on clock and I've added another 1,500m or so. As I've never been happy with engine set up I've restricted enjoyment to about 6,000 rpm but had RR all way up to 7,250rpm last summer quoting 160bhp. If it's metal fatigue that's a worry; if it's setting related that's sthg I have more control over.

Need to get a replacement exhaust valve for my 1760 cc xflow but have no idea what sort it is as was built for sb else back in 1993. What's the best way of ensuring a correct spec replacement and can I get away with just one or must I do all 8 now? Do they need to be balanced like pistons? It's running an A6 cam in a stage 4 race head, flat head and forged pistons ie no chambers.

Dave, see my next post......

Just had the head off my xflow as had low compression in No 3 cylinder and found an exhaust valve about to let go. Cracked circumferentially about 60% the way round where it tapers from the back of valve itself to the stem, with daylight showing through the crack! 😳 Cylinders and bores seem ok on first inspection so hopefully just a head job. Any ideas what may have caused such failure?

Yes, I've just had head off and the gasket is real work of copper art so won't be skimping on quality there. Thanks, I had a feeling Burtons might supply these items. However this has now unearthed a load more issues so prepare for a barrage of further questions.......

Running a 1760 xflow with forged pistons, Stage 4 head and A6 cam. Does this take a standard Ford 1600 xflow head gasket or is it a special? Will CC supply this item and is it any good? Reason I ask is the exhaust gaskets they sell are considered inferior to the copper ones that can be obtained elsewhere so same may follow suit for head gasket. If it's a general part, any ideas for supply for my car currently based in Winchester?

Oily thanks for that Guess I'll have to plod on as far as I can in the garage but ultimately another RR session beckons I fear. That'll be No 3 then..........

The plate must be worth the same as the car

Which road did you roll on?

Following on from earlier post re the car having difficulty starting, I am confused over which amount of advance to set on the dizzie. For ref I'm running a 1760cc with early 3D Emerald ECU which I assume is a mapped system which can adjust advance. Caterham's std 1700xflow setting is 14 deg using std ignition system, but no ECU. Emerald say to set static timing on the dizzie at 20 deg then lock it at that as the ECU will then make allowance for reducing amount of advance when starting. Seems as if timing is currently locked at 20 deg as directed yet starting is a real pig. However some dizzies are fixed while others seem to rotate. Is this correct? Can't recall which I have so will look but what's the body of thinking out there re best starting point for this?

The plot thickens.......... I forgot to mention that the car has an early Emerald 3D ECU which stipulates the static timing is locked at 20 deg. Upon examination last night this is what it is set to and I am currently loathe to reset to 14 deg as suggested in the belief that the 3D map will compensate for advance at low revs/load. 14 deg is what my 1996 edition Caterham manual suggests a std 1700 xflow is set to but (which I guess) doesn't allow for an ECU or upgraded engine to 1760cc, A6 cam, race head etc. Am I right to trust the priority of the ECU in this respect?

That would mean new wheels which I must avoid. What would such a move do to the handling?

Looking good Dave but I must put me captain sensible hat on. Would make a smashing car for someone, just not me this year. Good luck

I would try checking your timing isn't too advanced first. Oilyhands has some good words on this in topic marked "xflow spitting back through carbs" Good luck