Fairly Basic Engine question maybe?

[scooby_doo_do]

I'll probably be laughed at for asking this, but I was taking my rocker cover's off to change the gaskets, and realised i don't actually know what the bit's do underneath.. The only time i've seen under a rocker cover was when i changed the gaskets on my other car's and they had cam's under them..

So i was a little confused when i saw this:

http://tripkings.co.uk/ultima/large/0084.jpg
http://tripkings.co.uk/ultima/large/0087.jpg
http://tripkings.co.uk/ultima/large/0086.jpg

I'm just wondering if someone could tell me what they are and what they do?
After taking both sides off, i realised only two from one side looked lower than the rest.. I'm guessing that they move up and down depending on the cam? but i'm sure someone will be able to explain to me :-)

Sorry for the daft question..

Craig.

[ezakimak]

simplified description
the cam in the SBC is hiden down in the block between the two banks.
pushrods are actuated by the cam, the ends of these can be seen pushing on the rockers at the point near the air filter.
the rocker the pivots on the central part/bolt to push the valve and spring down. when it is required to open in the engine cycle.

[738 driver]

No such thing as a daft question......what you can see is the upper valve gear on your pushrod engine.
The valve and spring assemblies,which are much the same as your previous overhead cam experiences, the rocker arms, which transfer movement from the pushrods (the steel straws that disappear down inside the engine) via a rocking motion (just like a lever). The small running clearances between the rocker tip and top of the valve (middle of the spring) are commonly know as valve clearance or in the Uk "tappet settings". Dont be tempted to turn the nuts on the rockers, it may well upset your existing settings and dont worry if you cannot feel any clearance....the engine has to be turned to particular position for each individual clearance.
Also it goes without saying really....dont drop anything into the engine..small washers bolts..screwdriver bits etc...when you are inside the rocker boxes its a bit like open heart surgery!

Edited by 738 driver on Saturday 24th January 10:52

[scooby_doo_do]

Ok, thanks guys.. The reason i changed them was because i didn't like all the orange sealent someone had stuck aroud them previously..

As you said, i was very carefull at removing all the sealent from inside...

http://tripkings.co.uk/ultima/large/0080.jpg

I also removed the exhaust manifold as i was having trouble turning the quick release bolt from the cover (Until i realised i could just pull the handle off). - But i found this to be a good thing as it looked like the exhaust gasket had been leaking underneath. - Ordered up some replacments.

Exhaust wrap is horrible stuff, when you get that on your hands.. I'm guessing it's like fibre glass...

[Gulf -LS7]

good to see you learning, see if you can get hold of a haynes manual or similiar that will help.

[suntiger1965]

scooby_doo_do said:

I'll probably be laughed at for asking this, but I was taking my rocker cover's off to change the gaskets, and realised i don't actually know what the bit's do underneath.. The only time i've seen under a rocker cover was when i changed the gaskets on my other car's and they had cam's under them..

So i was a little confused when i saw this:

http://tripkings.co.uk/ultima/large/0084.jpg
http://tripkings.co.uk/ultima/large/0087.jpg
http://tripkings.co.uk/ultima/large/0086.jpg

I'm just wondering if someone could tell me what they are and what they do?
After taking both sides off, i realised only two from one side looked lower than the rest.. I'm guessing that they move up and down depending on the cam? but i'm sure someone will be able to explain to me :-)

Sorry for the daft question..

Craig.

hope this helps you Craig

the rockers are uprated roller rockers but the same principle.
the gear in the front is bolted to the camshaft which is driven by crankshaft....How it works is already answered

Dont be worried about any questions... Its better to ask than think you know it all...I like to learn something new everyday




dom

Edited by suntiger1965 on Saturday 24th January 13:21

[scooby_doo_do]

Thanks for all the explanations :-) much appreiciated.

So i take it, if you adjust the nuts - your actually adjusting when valve's and the combustion cycle? - Is there a way to check these are all ok and in the correct position?

Thanks

Craig.

[suntiger1965]

scooby_doo_do said:

Thanks for all the explanations :-) much appreiciated.

So i take it, if you adjust the nuts - your actually adjusting when valve's and the combustion cycle? - Is there a way to check these are all ok and in the correct position?

Thanks

Craig.

adjusting valves

if solid lifters... adjusting the nut alters the valve clearance(a measurement between valve head and rocker)as you need some clearance as metal expands when it gets hot. The clearance is measured at a certain temperature(some engines static at cold, some engines hot and running)

if you have hydraulic lifters adjusting the nut is for preloading the lifter(as it is filled with oil)

you need to know if you have hydraulic or solid lifters. Race engines used to be solid lifters and quite noisy and easy to tell but tend to have roller cams nowadays which are a bit quieter.

Seeing as the start of this thred was asking what the parts were and what they do i suggest you get someone who is mechanically sound(dont take that the wrong way ....please...) to check them for you while the covers are off if you really want to know, otherwise you might well damage your engine...

putting a clearance on a hydraulic lifter setup will make the engine sound like a tractor and wear out parts quickly or preloading a solid lifter will smash a piston into a valve as soon as you turn the engine over.....be careful

Dom

Edited by suntiger1965 on Saturday 24th January 18:17

Edited by suntiger1965 on Saturday 24th January 18:20

[738 driver]

X 2 !

V8 tappets on a modified engine are probably not the best starting point to learn without experienced guidance by your side.

Just for any new engine enthusiast....Haynes do a good, working,clear plastic model engine in which you can see all the internals doing their thing in the correct fashion. Its a four cylinder OHC but if you search there was also a V8 some years ago. I got one for Xmas when I was about 10 or 11...really excellent as a first engine build for a young guy and still very interesting for the older guys too!

Gals too of course!

Edited by 738 driver on Saturday 24th January 19:25

[scooby_doo_do]

:-) I won't be touching any of them, so not too worry just yet :-)

I'm taking it to a garage when the weather is a little better, for a nice tune up and check over. Would be cool to go to a meet when it's all running properly.

Craig.

[eliot]

Disable the igntion system and the crank the engine over, you can then watch them in all their glory.

[shithotfast]

eliot said:

Disable the igntion system and the crank the engine over, you can then watch them in all their glory.

Actually, for old farts like me, that's all I have ever seen with rocker covers off. All this new fangled stuff like overhead camshafts - it will never catch on. This is great 100 year old technology and it works! great stuff.

Last summer at the FOS at goodwood you could see a lots of old engines which ran without rocker covers at all - and all the valve stems bouncing up and down.... Fantastic stuff.

[V8 DOM]

scooby_doo_do said:

:-) I won't be touching any of them, so not too worry just yet :-)

I'm taking it to a garage when the weather is a little better, for a nice tune up and check over. Would be cool to go to a meet when it's all running properly.

Craig.

good call, but watch the genius do his stuff, dont walk away..... just because you did not do it this time doesnt mean you cant next...... Dom