john_p_b
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| posted on 21/6/10 at 03:00 PM |
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cosworth cylinder head - to skim or not to skim
it's looking more and more likely that i'm going to need to take the head back off my saph as i've done over 700 miles now sinse
rebuild and the tappets are still noisy as hell.
it's only 1 maybe 2 of them but it's driving me insane now and i cant help but feel it's more than likely a blocked oilway going on
what i've seen come out of another head that was ported by the same place that did mine it taps from cold but then shuts up once driven for a
few miles but then as soon as you come to a standstill and leave at idle for a minute it starts again.
so my dilema is this.......it's bad enough i'm going to have to take it off and strip it down after spending over a grand on headwork plus
new MLS gasket and headbolts but am i going to need to get it skimmed again? done just over 700 miles sinse it was last skimmed, had the block face
skimmed too and used a MLS headgasket. i'm undecided as part of me is in pain at taking more thickness off the head but then the other part of
me thinks i'd be a fool to not get it done incase there is a slight leak when i put it all back together.
your thoughts please peeps.
cheers
john
built a car, built a home, had a family. lost the family, lost the home, still got the car.
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mookaloid
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| posted on 21/6/10 at 03:15 PM |
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I wouldn't have thought you needed to get it skimmed again if the only reason that you are removing it is to investigate noisy tappets.
"That thing you're thinking - it wont be that."
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stevec
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| posted on 21/6/10 at 03:20 PM |
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Cant you get the cams out without removing the head?
Steve.
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MikeRJ
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| posted on 21/6/10 at 03:21 PM |
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No, you only need to skim a head if it's not flat (or to remove pitting from corrosion etc). Don't do it just because you are fitting a
new head gasket.
[Edited on 21/6/10 by MikeRJ]
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john_p_b
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| posted on 21/6/10 at 03:26 PM |
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thanks guys, just i was always taught to air on the side of caution and get them skimmed no matter what but with the price of a cosworth head and the
limited amount of material that can come off them i really didn't want to go down that route unless it was completely required.
stevec, yes the cams come straight out the top but i've already done that and replaced the tappets thus my theory about a blocked oil way. it
was suggested i just take the tappets out and blow down the oil ways with compressed air but then if there is swarf in there it's only going to
go 1 place and thats back through the oil pump which i really don't want.
built a car, built a home, had a family. lost the family, lost the home, still got the car.
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britishtrident
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| posted on 21/6/10 at 04:23 PM |
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What grade of oil are you running ?
I have never been able to understand the urban myth of skimming alloys heads. if ia head shows definite signs of warping or corrosion pitting you skim
otherwise leave well alone.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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mcerd1
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| posted on 21/6/10 at 05:10 PM |
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doesn't sound like your there yet...
but if you do ever get to the point where you can't skim it anymore I'm still looking for a good head for a NA cossie (so I can skim a bit
more than you could)
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perksy
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| posted on 21/6/10 at 08:13 PM |
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As above, Definetly don't skim it unless absolutely neccessary
Good Cossie heads are getting harder to find as alot seem to have been skimmed to death 
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garyo
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| posted on 21/6/10 at 08:37 PM |
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Have you had the followers in pieces to check that all's well on the insides? If you slap them down hard onto hard surface their centres will
overcome the circlip and you can strip/rebuild them.
ETA: Ignore me - I see you've fitted new tappets.
How about, cranking the engine over with the plugs and tappets out, but cams in place, and see whether all the buckets are getting equal oil? It
could be very messy though!
Gary
[Edited on 21/6/10 by garyo]
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Strontium Dog
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| posted on 21/6/10 at 10:04 PM |
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You could make up some splash guards and check how the oil is being pumped round the head. I'd be doing a lot of investigations before taking
the head off.
On another point, who built the engine up? It is, and no offence meant here, the responsibility of the engine builder to insure the galleries are
clean and that all machining is done correctly and to tolerance! One of the most important things in building an engine is the cleanliness of the
work. Measure, measure again and then measure it. Then clean it again!
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john_p_b
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| posted on 21/6/10 at 10:23 PM |
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quote:
Originally posted by Strontium Dog
On another point, who built the engine up? It is, and no offence meant here, the responsibility of the engine builder to insure the galleries are
clean and that all machining is done correctly and to tolerance! One of the most important things in building an engine is the cleanliness of the
work. Measure, measure again and then measure it. Then clean it again!
it takes a fair bit to offend me 
i built the engine, bottom end i fully built up myself so cleaned everything several times before putting it back together. the head i sent away
complete and got it back complete in the words of the guy i trusted to do the job "fit and forget" which for £1100 of headwork and cams i
expected nothing less than a excellent job and really taking the head apart to check and clean things didn't even cross my mind!
built a car, built a home, had a family. lost the family, lost the home, still got the car.
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Strontium Dog
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| posted on 22/6/10 at 07:36 AM |
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As you paid for the head to be built up and be ready to fit I'd do the checks for oil supply etc. as mentioned above. If there seems to be a
problem I'd be on the door step of the chap who did the head work. As you say £1100 is enough of anyone's money to expect a decent job. In
fact, I think I'd be asking the head work guy to diagnose the problem before taking it off especially as it was a "fit and forget".
This implies that the valve clearances have been adjusted by them and if you have tappet noise they can hardly say they have done there job properly.
It is normal of course to expect the clearances to settle in initial use and they normally go slightly tighter by a tiny margin. Less than you are
likely to see with feeler gauges and not by enough to cause a problem though as the clearances should have been set to the middle to loose end of the
tolerance on a road engine. Race engines should be built to the tight end of tolerance for maximum lift.
It's worth checking the cam bearing caps are torqued correctly too.
Might be worth checking your oil pressure at idle as well.
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john_p_b
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| posted on 22/6/10 at 08:24 AM |
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oil pressure is good on my stack gauge, 80psi idle, 30psi at idle after a damn good thrashing and runs constantly between 65-70psi in normal running
at around 3000 rpm.
i've heard varying reports of how long it takes the hydraulic tappets to settle in these engines after a rebuild some ppl say they are quiet
straight away but others are saying it's taken up to 2000 miles for them to settle but imo nothing should take that long to settle in!
built a car, built a home, had a family. lost the family, lost the home, still got the car.
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britishtrident
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| posted on 22/6/10 at 06:20 PM |
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Engine Oil grade ?
Hydraulic tappets are sensitive as hell to oil grade --- they don't work with thick oil.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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john_p_b
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| posted on 22/6/10 at 06:30 PM |
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ran it for 300 miles on a cheapo 10/40 for running in but it was mega tappy and had quite average oil pressure. now running on a 10/50 fully synthetic
which is what i always ran before with no problems.
built a car, built a home, had a family. lost the family, lost the home, still got the car.
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britishtrident
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| posted on 22/6/10 at 07:11 PM |
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Change to 5w/40 or 0w/40 or 5w/30 or 0w/30 and dump a bottle of Wynns Hydraulic lifter treatment in.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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DRC INDY 7
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| posted on 22/6/10 at 07:35 PM |
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5w30 was the grade recomended by ford
forget the wynns its not needed
if the hydralic tappets are new then carry out a engine flush before changing the oil
use a good quality oil
of topic im using 5w50 fully synthetic oil in my rebuilt 2037 pinto engine
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Puddle Dodgers Club
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mcerd1
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| posted on 22/6/10 at 07:48 PM |
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quote:
Originally posted by DRC INDY 7
of topic im using 5w50 fully synthetic oil in my rebuilt 2037 pinto engine
that's a bit OTT isn't it ?
the pinto can run on just about any old mineral oil and like it
my donor one did 120k+ on cheap oil made for diesel tractors and apparently was none the worse for it 
[Edited on 22/6/2010 by mcerd1]
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DRC INDY 7
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| posted on 22/6/10 at 08:32 PM |
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quote:
Originally posted by mcerd1
quote:
Originally posted by DRC INDY 7
of topic im using 5w50 fully synthetic oil in my rebuilt 2037 pinto engine
that's a bit OTT isn't it ?
the pinto can run on just about any old mineral oil and like it
my donor one did 120k+ on cheap oil made for diesel tractors and apparently was none the worse for it
Any engine can run on just about any oil grade does not make it right
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Puddle Dodgers Club
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