R500 Duratec valve spring failure

[KryptonR500]

Hello, I have a 2011 R500 (owner for ~4 years) with zero compression in cylinder 4, from a broken valve spring. I understand this is not uncommon from the various threads, and was planning to remove the head (in car) and start the process of inspection and repair (obviously including all new springs).

 

However, I’m concerned that the instructions I’ve seen reference the tooling bar (and crank pin) to align/time the cam shafts, but my cams have vernier cam chain sprockets, and hence it appears the tooling bar would not fit, due to slightly different angles. Is the vernier installation intended to adjust the timing relative to the crank, or between the two cam shafts (or both) - beginner question, sorry!

 

Now I’m not sure if I should attempt the head removal (and loss of settings), or if I’m better to take the engine out (looks tight/tricky?) and send to an expert; perhaps the guys in CO.

 

Feedback gratefully received; perhaps the verniers are standard for the R500 and I’m over thinking it?

 

I’m based in Charlotte NC, so any local experts, or other recommendation/guidance would be ace.

 

Thank you!

[JohnCh]

The tooling bar sets cam timing to stock Ford specifications which differs from aftermarket cam timing, including those used in the R500. You will need a dial indicator to set it correctly. Personally, I would remove the engine. It's not that much harder than removing the head and it is much easier to reassemble and set cam timing with the engine out of the car.

 

To get a sense of what's involved when installing the head and setting cam timing, check out the Cosworth CSR260 Build manual here. Note: their cam timing instructions are very specific to their cams and associated timing. This site shows a more generic approach: http://www.dubaipetrolheads.com/biggles/cams.html

 

-John

[ashyers]

I agree with John, pull the engine. Unfortunately I suspect you're going to find some ugliness once you dig in and it will be much easier to deal with it when the engine is on the bench. Have you checked the cylinder with a borescope?

[coffee break]

+1 on pulling the engine. It gives you a chance to look at other items that may need attention such as clutch, motor mounts etc.

[KryptonR500]

Thank you all, appreciate the feedback and advice... engine is now out!! I don’t have a bore scope, so don’t know what mess lies within.

 

Time to check clutch and gearbox and motor mounts too; great idea!

 

If I don’t want to do the work myself, does anyone know who works on these engines; the few names recommended didn’t know much about the Duratec, and I think the specification is quite specific?

 

[JohnCh]

You don't waste any time! I know Beachman Racing (Caterham dealer in WA) partners with a shop that does high-end Duratec builds, and Birkin USA has a shop local to them in CO that does the same. Might be worth a call if you can't find anyone local who gives you confidence and you're willing to ship the engine cross country.

 

Are you looking to refresh the engine, or just have the valve spring replaced? If the latter, I'd pull the head now to check the condition of the bores and ensure there is no need to tear apart the short block. If everything else looks fine, then I'd get recommendations for a good local shop that does heads (your local Miata Club chapter might be a good resource given those cars have used the Duratec since 2005) have them give it a once over and replace the springs. Installing the head and timing the cams requires a few specialized tools, but it's not that hard with the engine out.

 

-John

[Brightonuk]

Road and Race West Palm Florida took care of my rebuild

They specialize in race engines

[KryptonR500]

Hi guys, thanks for the recommendations; I have been able to find a relatively local company called Focus Power in Belmont just west of Charlotte, who do a lot of Duratec tuning and some engine building. Seemed familiar with Caterham’s on the phone, and suggested fitting a 2.3 head on my 2.0 for improved performance and to enable ~7,500 rpm. I believe the R500 has the 2.3 head already (found in the original receipts), and is allegedly good for 8,500 rpm, which made me wonder if there is a generic R500D engine spec anywhere that I could share with the engine builder to ensure we are on the same page; i.e. what cams, valves, springs, pistons, etc etc.

 

Thanks again.

[JohnCh]

The person with whom you spoke clearly isn't familiar with the R500. The engine makes peak power at 8500rpm, so recommending you swap to a 2.3L head to achieve 7500rpm is, um...bollocks. The heads have a casting number above the exhaust ports that can be used to identify which version you have, however, I'm pretty sure Caterham fitted a CNC-ported variant to the R500. Is the plan to do a full rebuild?

 

The R500 uses the Kent DTEC35 cams. Rumor has it these are made to specifications developed by Raceline who then supplies them to Caterham. The valve springs should be the Kent VSK31. Pete at Raceline is a really good, helpful guy. If you can't get definitive answers from others, you could give him a call at the workshop number to discuss. They might also supply Caterham with the other engine internals and could get you what you need. https://www.raceline.co.uk/

 

-John

[Croc]

I think two people on this forum with Caterhams used that company you talked to in Charlotte. Let me PM them to see if they are willing to offer their input to this thread.

[KryptonR500]

Thanks guys, my plan is to take the engine to them; I’m sure they will have a clearer picture of the spec when they have it apart. In fairness it was a quick telephone call after 5pm on a Friday

 

Thanks for the info on the cams & springs John; not sure what work I’ll have done, I’ll be lead by the engine builder.

 

Croc, thanks for following up, always good to get other opinions.

[Shortshift]

If it helps, in the UK there have been several failures of valve springs (usually with fairly catastrophic consequences) in 'early' R500D engines. These seem to have been the single parallel Kent springs - they were fine at the very start of R500 builds but later became unreliable.

 

As a consequence, Caterham Cars moved to a Cosworth conical spring and standard cap set-up (around 2010/11, so it sounds as though your engine might be one of the last pre-Cosworth spring ones), and this remains the current build spec for all of Caterham's performance engines - so 420 and up, including all 620s (which, whilst lower revving, are subject to a hard duty cycle).

 

The recommendation from Mic Attree (well known as Caterham's main man when it comes to the build of these engines) is to replace the Kent springs with Cosworth conical springs and standard caps. He is not aware of any failures with the Cosworth springs.

 

Sorry that I don't have part numbers to hand!

 

James

[JohnCh]

I wish I had heard of this issue prior to my rebuild. Neither Raceline nor Kent mentioned it and Kent does sell double spring kits for their cams more extreme than the DTEC35. Were the failures on track day cars that spent a lot of time north of 8000rpm, or did the issue also affect street cars that just saw brief forays to high revs in the lower gears?

 

Thanks,

John

[Shortshift]

John - I'm not an expert on this but valve spring failures on early R500D's are pretty well known, at least here in the UK. From what I know there is a mix of usage cases, ranging from people who do very little track-time through to others where trackdays are a common occurrence.

 

I think there have also been issues with the double spring arrangements, too - though disaster can be prevented in the event of the main spring failing by the second spring that saves the day. But then you have to realise that something is amiss as the surviving second spring can mask the primary failure. I will look out what I can, but I think the flaw in the two-spring set-up is due to interference between the two springs. I can vouch for this being an issue as I have personally witnessed the strip-down of an engine where a second spring had failed (this followed an earlier failure of a single spring, requiring a major rebuild that included fitment of the double springs - doohhh).

 

If you search BlatChat (likely in TechTalk) and/or the main Facebook Groups you will pick up this stuff quite easily.

 

James

[Croc]

The recommendation from Mic Attree (well known as Caterham's main man when it comes to the build of these engines) is to replace the Kent springs with Cosworth conical springs and standard caps. He is not aware of any failures with the Cosworth springs.

 

Hi James - Did Mic write anything up on the topic so as to read more? Would be interested to study in more depth. Thanks Mike

[Shortshift]

Mike - I was carrying out my own research into this and, as part of that, I reached out to Mic. He replied with some background and a touch more detail and I have published (above) as much of what he told me as I think is right to reproduce in a private forum without his express permission. But I've no problem in sharing his note on a private basis so I'll send that to you as a pm (actually, it really adds very little to what I've said).

 

James

[Croc]

Thank you James!

[JohnCh]

James, would you mind sharing with me too, please? I just completed a long, somewhat painful, 2.0L build using Kent DTEC20 cams which are halfway between the DTEC10 in the R400/420 and the DTEC35 in the R500. Based on other input, I reused the Kent single coil springs from my prior build (Kent DTEC10), which are apparently the old R500 springs prone to failure, so I'm, um...concerned.

 

Thanks,

John

[Shortshift]

John - no worries. PM sent.

 

James

[Kitcat]

Krtypton: The Belmont NC tuner is a member of this forum and goes by 1TurboFocus here. He is known as TurboTom on the Focus Forums. He is a long time Zetec builder and tuner and is also very involved in Duratecs. Since your engine is so rare, I doubt that he knows of it or its spec.