XL unleaded head.

[Colin Cooper]

At the monent I run an XF on 4 star. This works ok locally as Sainsbury's sell the replacement stuff, but it pinks badly on enleaded + additive. Has anyone any experience on changing to an unleaded head?

The engine is a tuned Roger King item. is he still about?

 

 

C.J.Cooper

[Irrelevant]

He is still about and works for either Quaife or Pace IIRC . . . always get them two muddled up (due to customer service similarities).

 

Anyhow, if your motor's been highly ported, you're unlikely to be able get UL valve seats as there's not enough meat left around the valves to machine out. IIRC the heads he used for the RK 170+ spec motors won't take UL valve seats.

If you have one of these or better, you'd have to source a less flowed head and get UL seats fitted to it. If your motor's currently running a highly flowed head with big valves and high compression, and everything's optimised for this, it MIGHT be a real pain getting it running sweetly again. And even when you do, you'll have less power.

However, if you don't have such a highly tuned motor, fitting UL valve seats and getting a tune should get it running well.

Best bet is to try and contact Roger as he still has the notes on his motors(or he did anyhow) so should be able to tell you whether UL valve seats will take or not.

 

 

[Dickie Normuss]

Roger King is still alive but I think stopped doing general engine work a couple of years back. Quite a few have had the conversion done, I don't think it's mega expensive.

 

VX HPC - Loud and proud here

Watch out, whatever hits the fan will not be distributed evenly

[I.Mupferit]

The problem with big valve X/Flow heads is that you will often get cracks appearing between valve seats. I think Michael Calvert had this happen twice on his engine.

 

One way round this problem is to buy the aluminium head which has been designed with increased valve spacing. They aren't cheap but if you are determined to stay with the X/Flow, they will resolve the problem and have the hardened valve seat inserts to allow the use of unleaded.

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

[Colin Cooper]

Yes, I have a 170bhp motor, and yes the valves almost touch, so it doesn't look promising.

Does anyone have a current addresss for Roger King?

Thanks lads,

Col

 

C.J.Cooper

[rgrigsby]

No address or phone number but I think if you call Pace and ask nicely he'll be around, alternatively have a chat with Chris up at the 7's Workshop (01992 470480) as I'll think you may find he knows a man (Angelo) that can help out with this. It won't be cheap for a u/l 170bhp xflow head but it is possible

 

 

Cheers

 

Rob G

www.SpeedySeven.com

[Midnight]

You could always try Steve Parker who still advertises in Low flying. He's very good with X-flows and he did an unleaded conversion on mine about six years ago. Still going strong now, including a faultless run across America in 2005. and on that trip we couldn't always get good petrol in some of the more out of the way places.

[Irrelevant]

Colin Cooper: If it pinks badly on unleaded/additive, then there's something wrong IMO. The 170+ motor should run fine on SUL/additive if setup correctly. I'd get the timing and maybe carbs checked, fix the problem, and continue to use SUL myself.

 

Have you had anything done recently that may have effected the combustion? A head skim for example, a fiddle with the timing?

How long have you have you had the engine? Are you sure it's still stock RK spec with twin 45s? Does it have a VRxxxx engine number?

 

Sweet Crossflow BTW , no midrange torque but revs lovely between 4500 and 7500rpm - nice with a close ratio gearbox.

 

 

[Colin Cooper]

Adam,

As far as I am aware the engine is as original, with 45's. I've had it for 18 months with no problems.

Can't check the engine number as I work away all week.

You are probrobly right in that it just needs a tune up.

I might give Steve Parke a ring though, Windbag.

Col

 

C.J.Cooper

[ian.hoper]

Colin

Had my XF big valve head done by Cylinder Head engineering Broadcut Wallington Fareham ,good job about £350 quids Contact detais I can find but tyhey are on the web.

good luck

[Crudders]

My crossflow is in a somewhat lower state of tune than yours Colin, but I've never had any trouble with pinking, using decent Super Unleaded and Castrol Valvemaster lead replacement additive without hardened vave seat inserts. My Leon Turbo daily driver is pretty intolerant of poor fuel and it doesn't like Sainsbury juice at all, so maybe that's part of your problem.

 

Stick to Shell V-Power or Tesco SUL, both of which are 99 Octane, and you're already 2 Octane points higher than the 'super' unleaded that all other stations sell. Certainly worth a try.

 

Crudders