The V8 Owners Forum -

This am broken rings...

Only silly ickle pics coz it was 5 years ago (cripes)

Dents look v. similar, but all over coz of larger chunk size.

Dave yr only 40 miles from Sarratt, if stuck for the headers why not take them to Motorvation, unless they say they can't do 'em but they did mine OK.

Spot of idle surfing, found this http://www.sacskyranch.com/deton.htm which mentions carbon cleaning in detonation. Wouldn't you normally expect a bit of carbon the squish area, yours look like they've been cleaned. Not sure of the Rover but the few motors I've opened have been carbon'd up pretty much everywhere.

the bits travel up into the inlet and back down so the fact its all over isnt unusual. I would find it unusual for detonation to be all over. Stevie I know what your saying and detonation causes huge damage but personally I have never seen it in every pot. There are pics posted over on the old forum of a dead chevy somewhere.

Those that say plug damage...

Well, surely this will be blatantly obvious after seeing bits of plug missing ?

Those that say piston ring damage....again, if the engine is in bits, surely you will clearly see evidence of the rings having passed the top of the piston, in order to get out and cause the damage.

Hence I say detonation.


So, what do the plugs look like ? So what do the tops of the pistons look like ?

Do they show evidence of broken parts ?

Latest update.

All 8 pistons removed. All A1, no damage to rings or bores. All big end shells in good condition.

An extra inspection showed that #7 has cuts all over the top of the piston, the others only have it in the squish area.

Removed all 16 valves, all valves and seats A1 even good condition rubber seals on the inlets.

A good look shows small cuts in many of the ports, just as the valve stem exits down from the guide.

It looks to me that somthing brittle has dropped into the carb and gone into pot 7. Then transferred around the engine. The marks are very sharp cuts so I guess this puts Detonation on the back burner.

I guess that I need a skim, so how much can I take off so when I use a composite gasket I get the same compression, please.
Dave

you need to make your measurements in the pic below match the second set. This should give you standard compression on comp gaskets.

Thanks Marki
Dave

Marki help

I have measured the dimensions and have 63.43mm and 23.8mm.

If I assume the comp gasket is 0.5mm would this mean I can remove 63.43 - 63.5 + 0.5 = 0.43mm

or if i use the 23.8 then
23.8 - 23.9 + 0.5 = 0.4mm

Dave

I cant work out how your doing that lol

Anyway:

63.43 - 62.56 = 0.87 you can remove 0.87mm.

What the pic shows is the difference between the original tin gasket heads and the early comp gasket heads. These heads were original castings basically skimmed 1mm to cope with the extra thickness of the comp gasket. They later adjusted the casting on the 4.6 heads.

Does it make sense now? Basically your heads have only had a light skim in the past but they haven't been skimmed level which is why the measurements off.

LMAO too.

Yep, easy when your sober.

Ta

Alley Kat
Do you have any details on motorvation, I can't find any?
Regards
Dave

This post reminds me of my problem at the start of the year - I never found out the cause, but a bit of metal was found embedded in a piston. Only affected 4 cylinders though - but I scrapped the engine rather than rebuild it.

See:

http://www.v-8.org.uk/forum/viewtopic.php?t=524

Pete

Could be worse....you could have 8 broken pistons

No records but pulled this out of Google, www.motorvation.cc, 01923 268 555, WD3 6HH. Don't know who they subbed it to unfortunately, that would've saved a markup no doubt but they did a fine job that none of the local engineers could do (apart from running them over a sander or similar)