6G Celicas Forums

i upgraded my cams yesterday to 272 duration and 9.3 lift for both intake and exhaust. i noticed that my engine became so noisy. it's like someone's working on a typewriter.

my mechanic said that it's natural because i used stock valve springs. my tappets, according to him, is also within specs so i don't need to worry.

after driving so long, i also noticed that my oil pressure is almost zero. my sensor connection is okay and when i rev the engine, the reading goes up also. again, according to my mechanic, it is natural for the oil pressure to go lower than usual when you upgrade cams and the reason why i am probably getting a very low reading is that my gauge may not be very accurate. btw, the brand of my gauge is autogage and my cams is Jun.

please enlighten me on this. i plan to go to the dyno shop on monday and i'm not sure if this already okay.

thanks guys.

your mechanic is dead WRONG! installing cams has nothing to do with oil pressure. as for the noise. i would double check his work, especially after making a statement like that. This is a DOHC now an old school V8.

that's what i'm thinking also cause i really don't know the connection of the cams with the oil pressure. although the oil pressure symbol on the dashboard does not light, i'm not sure if there something might get damaged in using the car.

btw, i don't get what you mean by "This is a DOHC now an old school V8". are old school V8s souding like typewriters?

thanks for your reply

DOHC = Dual over head cams. old school V8's have a single cam in the middle of the engine, its run by a small chain usually and then lifter rods push up on pivoting rockers that push down on the cams. alot of these older engine the cam also has a gear on it to drive the oil pump and sometimes the fuel pump.

that now was supposed to be a not. Not an old school V8

thanks for explaining it further.

my dilemna now whether it's safe to use the car or not cause i'm planning to have it dyno tuned on monday.

sounds like you need a valve shim adjustment, and your mechanic is either too lazy, or dont know how to do it.

if it has something to do with valve shim adjustment then i think it is safe to drive the car. do i have the right assumption?

thanks.

I'd get it fixed asap

from the 3S-GE repair manual

reference: page 36 or book ref page ENG - 22
your valve clearance (cold)
Intake:
0.15mm - 0.25mm (0.006in. - 0.010in.)
exhaust:
0.28mm - 0.38mm (0.011in. - 0.015in.)

also from page 40 or book ref page ENG - 26
has info (charts and formula) regarding replacing shims (sizes)




whats the idle like otherwise with the cams?

This post has been edited by Rusty: Sep 12, 2010 - 1:35 AM

thanks for the reference and advise.

as for the idle, it's actually smooth after adjusting the camgears.

below are the camgear settings done and results:
1) intake = 0, exhaust = +3: idle is good when cold but engine stalls when engine is hot
2) intake = -3, exhaust = +3: idle is good during cold but engine almost stalls when engine is hot
3) intake = -4, exhaust = +4: idle is good whether engine is hot or cold

btw, in addition, what would happen if valve clearance is either big or little?

thanks.

increased wear, and diminished valve opening/closing function.

what about the effect of not having the valve shim adjusted? would it only be the noise?

thanks.

valve shims = valve clearance.
same answer as above.

if the valves are too loose, that would cause the noise. if they are too tight then the valves will not close fully and they will burn. tight valves will also cause lower compression

so putting your answers together, then valves that are too loose would be noisy and will increase valve wear and will diminish valve openning/closing function?

please let me know if i have the right understanding.

thanks again guys for your replies.

loose valves wont really demininsh closing, but it can wear out the valve and the seat in the head. the best thing to do is just take the valve cover off and check your clearances.

okay, thanks. i'll do that.

btw, do i have to remove the cams and the camgears to adjust the lifters/tappets and shims?

thanks.

a whole lot of stuff, best to check the repair manual in the NA sticky thread, to see what you need to do.

any chance of going back to the person who installed the cams and get them to fix it, or taking it somewhere else??

i'm probably taking it to the same guy who did the swap. i asked him how it's going to be done and he told me that the process is just like when he installed the cams. that is, taking out the cams and camgear before adjusting or replacing the shims. although he told me, and i saw it during the install, that the tappets are still within specs so adjustment is really not necessary.

i'm also thinking of bringing it to my tuner and have him check it and if it's okay then i'll have him dyno tune it.

This post has been edited by fgvillegas: Sep 15, 2010 - 8:46 AM