Head Skimming

[jimmi 0 1 Cars]

I know this is one of those ' How long is a piece of string' queries.... but Generally if a gti 'D6B' head in good condition is sent to a reputable machine shop just to be 'faced' only ...how many 'thou' would they skim-off ? The Head has already had 65 thou skimmed-off during initial build process by PRP Lincoln back in the late 90's which left 26.6cc chambers in the head ...

[welshpug 1,661]

however much it needs to make it flat or remove any pitting from corrosion.

[dcc 855]

i had a head skimmed recently, asked for the face to be cleaned up with minimal amounts removed. it had a tag when returned which said '0.15mm removed', hope that helps

[jimmi 0 1 Cars]

Thanks dcc......Unfortunately, my machine shop did not disclose how much they skimmed-off the head. which was re-attached to engine in a hurry in order to compete on a rally the next day. Thus I did'nt have time to do a 'cc' check of the head chambers.....

Also for info: I contacted PAYEN today... I rebuilt engine using their complete engine gasket set GL650 ... My query being how thick their headgasket is in that set (GL650) .. For Forum members info..Payen Headgaskets are 1.20mm thick

[welshpug 1,661]

I'm sure there is a 1.4mm repair gasket available if the compression is too high.

[jimmi 0 1 Cars]

Thanks for that Welshpug .. worst case scenario I will have to re-do headgasket with thicker gasket. Currently, The engine is mildly 'pinging' on partial/mid load since head gasket was renewed... hoping the 're-map' on RR I've booked for next week sorts it ...my car runs an Emerald M3D / PTS 4078 cam / on 'standard' injection with the larger yellow injectors (762's) ... Looking forward to seeing BHP/Torgue figures on the Rolling-road...

[dcc 855]

what spark plugs?

[jimmi 0 1 Cars]

what spark plugs?

dcc ... Currently running on NGK BCPR7ES ..... I have ordered a set of BCPR8ES ...will try those (colder) plugs before going to RR. What plugs should I be running with compression ratio being over 11.1 ? FYI: car running on Super Unleaded with Millers CVL additive

[dcc 855]

You've done well to get bcpr8es (they stopped making them in 2010 iirc) - but I assume you mean BCR8ES. I picked some up from GMF for less than £2 a plug, and they had them on the shelf.

[dcc 855]

I don't use any additive and have shell v power, roughly 12.0;1 cr

[allanallen 528 2 Cars]

Dan, .15mm is a decent sized skim, a light refacing skim to us is around .002"/0.05mm

[dcc 855]

Cheers Al, I asked him to take off whatever was needed in order to make it good.

[jimmi 0 1 Cars]

You've done well to get bcpr8es (they stopped making them in 2010 iirc) - but I assume you mean BCR8ES. I picked some up from GMF for less than £2 a plug, and they had them on the shelf.

Dan.... What plugs you running and are you on TB's, Carbs, or modified stock fuel injection ? Any idea whats dif between BCPR8ES and BCR8ES ... I assume R means they have a resistor ,,, What does P represent ?

[welshpug 1,661]

dta s40 on jenvey 45's.

 

r is resistor, p is protruding insulator.

[jimmi 0 1 Cars]

Would NGK BCR8ES be suitable given that the insulator on those does not protrude ?

[Henry Yorke 269 3 Cars]

I'm sure there is a 1.4mm repair gasket available if the compression is too high.

I was looking recently and there are two Payen head gaskets dependent on how much has been skimmed in the past, so I have held off picking up a headset until I know if the head has been skimmed before. Spesso also used to do a higher compression one too as I had the thickest one fitted to my CTI just to keep the compression low.

[jimmi 0 1 Cars]

You've done well to get bcpr8es (they stopped making them in 2010 iirc) - but I assume you mean BCR8ES. I picked some up from GMF for less than £2 a plug, and they had them on the shelf.

dcc .... BCR8ES are what motor factors have sourced... so I got 12 of each ( 7's +8's )... just to have them. I was interested to read you do not use fuel additive... must try mapping on Super Unleaded only ...wud save me £8 cost of bottle of Millers CVL for every 20litres of fuel I use !

[dcc 855]

Yes no additive. Go on advice of your engine builder or mapper. Shell v power was the best way to go for me. Has some minor additives anyway. I run my car on the road, covered many miles without issue. Changed plugs 1 week ago, should have done it sooner after seeing the plugs. Maybe every 6months

 

There are iridium equivalents for bcpr8es, but at £55 a set, I'll stick to what's working at the moment.

[Alan77 78 1 Cars]

Peugeot still do the 1.5mm repair head gasket for the XU9 D6B. Just looked on SB and the part no. is 0209L3 but I can't get to the order page to check the price for some reason...

[mrfirepro 127 1 Cars]

£50.92+VAT for 0209L3

[jimmi 0 1 Cars]

By way of an update.... I discovered that the pistons had been fitted( by a previous owner) the wrong way round ( ie: Arrows pointing towards distributor and not towards cam wheel ). No wonder engine was not burning fuel properly( hydro-carbons emmisions were off the scale !). Also noted that the inlet valves had been lightly kissing the pistons - this was most likely cause of the metallic 'pinging' noise audible under revs/load. I clamped the liners ( which did not appear to be polished/ovalled) and re-moved the pistons..turned them 180' and refitted with new big-end bearings. New Cambelt /adjuster/ water pump..Also noted all volumetric values .. engine now running 11.4:1 comp ratio. Have engine running ( after re-calibrating the TPS ). All running ... grand.... no more 'pinging' ...and no oil leaks whatsoever - that must be a first !!

 

All set now for a RR session to remap the Emerald ECU.... got booked in with a reputable Emerald mapper to release more horses /torque.....

[Kane 34]

Did you replace the valves or at least have them checked? I just mention this because if, as you say, there was contact with the pistons then you a likely looking at some bent valves.

[jimmi 0 1 Cars]

All valves were seating/sealing properly,,, checked them when measuring 'cc' of head chambers ( filled with kero).