hey,

 

just wondering, apparently after putting a cam in my 5k, i have to run adjustable rocker gear? ( even though keeping hydro lifters )

 

just wondering if this is a " have to do " or can i get away without doing it?

I can't see you having to run one?

Youd be better off calling crow cams or tighe etc who make the cam your after, and ask what's needed.

 

If it's a large lift cam they'll tell you that you may need heavier duty valve springs etc so it's really best to ask the manufacturer.

Have the cam people told you to keep the hydro lifters? I think you'd either run the hydro setup or adjustable, I can't think of a reason to mix it unless you're trying to do something particularly funky.

It sounds to me like you have been given a solid cam grind, not a hydro one.

 

Also, in future, can you please think about continuing on with your previous threads rather than a complete new thread for every question? You currently have 5 very similarly themed topics on page one of general mechanical.

Why would he keep the hydro lifters though?

Yeh good point. None of this makes sense.

 

Can you please elaborate mate, who told you this is so, and why?

sorry about that..

 

and the whole story,

 

i took my stock cam to tighe yesterday, and told them that i wanted the thighe 104 gring? and i want to keep hydro lifters.. so I'm getting the hydro grind..

 

but he was saying something along the line's of, needing to get adjustable rockers, due to grinding the cam, the lifters / pushrod / rockers wont be sitting properly? but yet i havnt come across anyone with this problem before?

hmmm... When they grind the cam they take material off the heel, which is where you set the tappets. So the hydraulic follower will sit lower than stock, and the difference must be taken up by the piston moving further up the cylinder.

 

Maybe he figures the hydraulic cylinders can't move that much before they bind.

Edited December 17, 201114 yr by altezzaclub

also as you shave the head. measure lifter preload. and use appropriate valve springs

 

i don't see a problem?

There is a reasonable amount of movement in the lifter though, you wouldn't be taking more off the base circle of the cam than that the lifter can take up surely? (I've never done it, so I don't know that for sure).

 

Either way it sounds a bit concerning to me! You'd hope they're telling you the right thing!

With my reground 5k cam, the standard rockers did the job. From memory it was a Wade 169 grind.

Well I'll double check with them when I pick it up, and see what they say, and what will happen if I don't change it..

 

If I can get away with it, I will.. Due to having a short-ish budget.. But if I have to.. Oh well

I saw the difference in height between the stock and the 104 cams not too long ago. It is quite substantial. As in, almost half of the adjustment available.

Also you'd have a bitch of a time find the correct pustrod length to use. The hydro rods have balls on both ends.

 

This whole thing is why we use the holden/datsun combo.

will i not be able to use datsun a12 pushrods?

Before you worry about a fix, determine if you actually have a problem.

 

First step for you, google "hydraulic lifter preload" and read up. There may be some info on this on rollaclub, but limited. I think I wrote about it once before. Regardless, there is ample info on the net.

 

Once you understand it, you need to measure up to work out if you have a problem. Generally you should aim for 1.5mm preload. When you read up you wil learn how to measure it. Be advised this is a very finicky process, not difficult but you need to take care on a k motor to fleet accurate values.

 

It is possible that you won't have enough preload, the solution to this is to shorten your rocker posts commensurate with the difference in preload. For example if you only have 1mm preload, you would shorten the post .5mm to get the 1.5mm desired.

 

Any machine shop will easily be able to shorten the posts for you.

 

This is the simplest solution, you might have a lot of trouble finding the exact Length pushrod to suit.

 

Snot35 makes an interesting point about takeup of the lifter but it's not that straightforward. Lifter preload is the key. Read up you must young padawan.

 

A12 lifters are for solid conversions. Forget them, you have a hydro cam not a solid one.