The V8 Owners Forum -

i used some comma 15/40 in the end,
and same as what im running it on now,
i do have some lucas 20/50 race fully synth waiting to go in though,

if it is a bedding in prob, will it need new rings again

On an otherwise good condition engine (ie new ish)I always thought oil smoke on over run was inlet valve guides, at high revs but not low was pistons too small for the bores (ie pistons rocking in the bores) and under load non bedded rings.

engine is a brand new 4.6 crate engine,
with 4.0 pistons on 4.6 rods to bring the comp ratio right up,
pistons did not rock in the bores as we checked that part on the build mate.

JP. wrote:

kiwicar wrote: I still think though the cam run in period should have bedded in the rings.

I was always learned whatever happend, make shure the engine runs inmidiatly 2500rpm for 20 minuts after its first startup. It is even stated in the manuals thats suplied with rebuild or carte engines.

So I think you have a ring bed-in failure.

never did that will the 3.9 and that ran sweet as a nut

Hi Tony
"if it is a bedding in prob, will it need new rings again"
There are two theories on this
1/ new rings, and either a very light hone (though I have used a the rough face of a pan scourer dipped in 30 weight oil to good effect on a 1500 midget engine re ring, it sounds a bodge but I know several others who used the same technique on minis and motorcycle engines to good effect, you follow the existing honing marks, don't rub too hard in one spot. Keep the top face of the block below the crank centre line and clean it with ATF fluid on workshop towel after)
2/ my mate Derek at school dribbled brasso down the spark plug hole on his honda 50 when the rings wouldnt bed in, ran it for about a mile, flushed it out with 1/2 gallon of parrafin (again down the spark plug hole with the sump bung out) then ran flushing oil in the sump for about 20 miles, then back onto normal oil, it certainly bedded in the rings and ran for a good few months after.
Personally I would re ring, (Derek was an animal when it came to things mechanical) and since you have run in the rest of the engine, wring it's neck from the off so this time the rings don't have the option of not bedding in (use 30 weight single viscosity oil if you can get it).
Best regards
Mike

Depends what your bores are like T whether you will need new rings or not. They might have glazed which means you will need a quick hone and new rings. Your EFI might have been throwing in too much fuel when it wasn't right leading to bore wash which could possibly have caused some damage. Its all hypothetical at the mo tho. You need to do a comp/leakdown test and see what's going on in there. Could be a simple valve guide or seal giving problems. While your doing the comp test check the plugs as they come out. That will probably give you an idea of what pot is giving you probs specially if its just a bad seal or guide.

cheers for the replys guys,

managed to get a comp test done today, (cold engine)

cyl 1: 180ps1 plug lightbrown/white
cyl 2: 190psi plug as cyl1,
cyl 3: 180psi plug as cyl1,
cyl 4: 180psi plug dark black smells burnt oil,
cyl 5: 180psi plug as cyl1,
cyl 6: 185psi plug as cyl1,
cyl 7: 185psi plug as cyl1,
cyl 8: 190psi plug same as cyl4,

looks like i have a prob on cylinders 4 and 8.

all stem seals are in place still.

Hi Tony
Your compression is pretty even across all the cylingers.
Which end of the plenum is the pipe from the breather system?
Mike

Hmmmm with these readouts it made me wonder about valve guides and/or seals.
Might trie and borrow an endoscope and have look inside your heads.
Wonder how the intake valves of cil 4 & 8 look like on both sides ( intake runner side & combustionchamber side).

Might be hopefull & cheaper & less hassle to correct.

kiwicar wrote:Hi Tony
Your compression is pretty even across all the cylingers.
Which end of the plenum is the pipe from the breather system?
Mike

front end mike near cylinders 1&2

Oh well, another idea out the window
I still think as JP says the top end is worth further investigation before you strip it all down. The endoscope is worth a try, you can then look down the spark plug hole and see if there is anything obviously wrong with the bores (just before you pour in the brasso )
best regards
Mike

or say f**k it and thrash it within an inch of its life,
if that fails load it up with 500bhp nitrous,

if 500bhp of nitrous doesn't bed the rings in. . . .
Mike

engine angle wrong?just a thought

where can i get an endoscope from?

would agree it doesn't look like bore problems with those readings so I would be looking at top end. There isn't anything odd going on with the rocker shaft causing it to either over oil the head or squirt oil at the valves?

rocker gear and heads are from the old 3.9 setup, which never had this problem before,

which has got us beat