knackered cams and fudged head

Antony

Antony

Ex. Club Member
GRRR

the raceworx head and advanti cams are no more....

after realising that the "chees string" timing chain i baught was exactly the same length as an origonal, and then trying to turn the cams..... i found thatthe inlet cam was very very tight..... compared to the exhaust cam that is...

so we tok the cams out and found scoring around the end cap bearing faces on the chain side of the inlet cam and on the head too.... plus the cam has a groove in it now and is totaly fudged beyond repair... :down: :down:

so im now gonna fit the standard head back on with the standard cams and just run the janspeed and de-cat......

im so dissapointed as i was looking forward to having an N/A screamer.

i may put it back together... get it running and flog it...... i think ive had just about enough.... ive had the head off three times now... and its getting expensive.


any ideas guys?..... bearing in mind i am totaly skint and i need my car for work.. (plus ive put about £4k into this car so far...) fwn :down: :down: :down: :down: :down: :down:
 
Oh dear. I guess you didnt check for freeness of movment on the cams? You need to find out why this happened.
 
the reason for this happening is beyond me at the moment, but my dad recons that there was moveent in the cam (so they were dodgy when i baught them) and that the oil wasnt getting to it properly, now i actualy disputed this and run some compressed air backwords through this gallery (with the head off) and its free from all particulates...... its a mystery...

also, the tops of the pistons did come in contact with the valves, but only enough to make marks in the "dusty grit" that was on top of them... bit of WD40 and a rag got rid of that.

the tollerences on the cams were fine when installed... they where smooth and free running...... but they soon deteriarated and the inlet cam just stopped..


i dont think its worth having them re-welded and re-ground to be honest.
it would be much more worth my while to get some piper cams fitted to a ported head from matt humphries, (and i know theyre £700...) or just buy a new car and bin this one..
 
definately.......

they cost me £240 i think....... the exhaust cam is perfect and the inlet cam needs a bit of work to the bearing surface next to the cam gear end......(probs just a bit of wet and dry to be honest as it looks to just have polished the "gun metal" coloured suraface)

£100...ono.....
 
you would indeed, slightly anyway, although i have all the shims from the knakered head.... wich were matched up to the cams anyway... not sure how that would work with your head but you would have 32 shims..lol
 
ive got a super S car..lol

£80 + postage matey and theyre yours.... you could even have the head if you think you can fix it....
 
antony

post is going to be all to pot for a bit, sooner meet at m1 (example) and pay cash+a bit more?

frank
 
hehe, hold on, its my cams..lol, i cannot drive my car..... so cannot meet you...lol

i can still post them though..
 
right, sorry frank, been up to my eyeballs chaning heads over..

the new head is on, new head gasket, etc etc, started up first time, just like it used to....

chain was silent and tight (not like the other one at all)

but... and heres the big one...

after two or three minutes at idle... the cams become very very noisy... then if you rev it the engine picks up and the rattle stops, for a few seconds... then its back...

it seems to be that the oil pressure is very low. this is probebly what cased the seizure of the cams in the other head. allthough untill i get a pressure guage on it i wont know.


im not driving it at the mo, but it is movable, (cos my dad was moaning he couldnt get his bike out!!)

what could be the problem??... as soon as the engine is cranked over the oil light goes off, and there is plenty in the top of the engine...... just not enough at idle to stop the top tensioner (a brand new nissan one at £70 might i add) from going slack..

SOME ONE PLEASE HELP ME... I MIGHT NEED A NEW ENGINE AFTER ALL.....
 
antony

no probs, if the oil pressure was low the warning light would flicker, on tickover when hot!
i would try the old tentioner, the preload ratchet is possibly sticking on the new one
i would guess your previous problem was shaft bearing clearence, those cam journals need 2 to 3 thou of clearence for the oil to get in, any less than 1 thou, and they start to "pick up" the ally bore then drag out more and more, you end up with ally congealed on the cam journal and big score marks! (we get the same problem with our kart engine big ends)

frank
 
long shot here but has the head gasket or any gasket for that matter blocked an oil gallery in the head?
 
Frank.... thanks matey... yeah exactly what happened... the cam gouged a piece slowly out of the head untill it jumped off the chain and spun 2 teeth...

the tensioner is a nissan new one, i have a mickey mouse cheapo one, two nissan standard new ones and my old one (with huuuge groves in it..lol) i may try the other nissan one..


Fordy... all the gaskets were new, and there has been no sign of any blockages, i even wire brushed the entire head to the point where you could see your face in the combustion chambers and on the front of the head... then it was flushed with clean cool water...... flushed again with de-natured alcohol, left to dry, polished..... and checked over again for any particles..... sprayed with a slight mist of WD40 and then fitted to the cleaned block... with new head gasket..


i use only the best Mobil 1 0-w40 fully synthetic oil. and it is brand new oil.... plenty in it..... i may have just got a dicky tensioner ...again..lol
 
i think, looking at everything elso on the engine, that it is the very guts of the engine...

the Crank bearing clearances are too big and are loosing pressure.

so the engine is toast, unless anyone wants to have a project to change crank bearings...lol
 

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