Hydro-idi
Full Access Member
Absolutely not. Ask me how I know all this already. Your valves will mushroom if they are recessed too much & not within factory specs.
Been there done that.
Valve train questions/issues
- Thread starter laserjock
- Start date
Absolutely not. Ask me how I know all this already. Your valves will mushroom if they are recessed too much & not within factory specs.
Been there done that.
I know I keep bringing it up but type four is working on a new cam that is supposed to eliminate these issues, I personally would wait until it comes out, but if you've got your engine apart now it's a different story
Over recessing valves messes up rocker to valve stem contact and can cause greater issues w guide wear and poor contact.
Only way to deal w that might be machine stems down...shim the slrings...oh how the issues compuond quickly.
Perhaps a better idea is to machine a few thou off pistons or create a valve recess on the piston crown.
The decomp HG require longer pushrods...so there is an expense.
These engines are über tight tolerances and stack quickly...
Do not mess with them if you are uncertain as to what it does down the chain of events.
Only way to deal w that might be machine stems down...shim the slrings...oh how the issues compuond quickly.
Perhaps a better idea is to machine a few thou off pistons or create a valve recess on the piston crown.
The decomp HG require longer pushrods...so there is an expense.
These engines are über tight tolerances and stack quickly...
Do not mess with them if you are uncertain as to what it does down the chain of events.
IDIBRONCO
IDIBRONCO
I didn't really mean to hijack this thread, but it is about valvetrain issues. I just sent Russ a pm and I'm going to go with his recommendation, even if it means leaving the stock cam in it for now. Yes I had wondered about the effects of extra deep recessing on the valves. It would make them "taller" and the rocker arms would make contact with them sooner. I'm not going to have my pistons milled at this time. I just wanted to fix some oil leaks, have the heads redone after I ported them, and get the engine back in with a turbo on (FINALLY!). The reasoning for the extra head work, I bought it with about 100,000 miles on a rebuild and have no idea as to what was done. I have all new valves and am going to have bronze guides installed. I will discuss the valve recession when I drop off the heads and won't pick them up until it's right. I'll bring my Starrett depth mic and check them all right there. The bigger cam would be nice, but reliability is more important. I can always install a cam later.
IDIBRONCO
IDIBRONCO
I just heard back from Russ. He told me to run the recession toward the deep end and check the clearances. Then to let him know what I find and he'll work with me.
Macrobb
Full Access Member
It's not hard to, say, put a .030" shim under the rockers.
Do it right and your rocker to valve stem ratio should be the same(valves recessed the same amount as the rockers are lifted), though the pushrods will be a hair too short.
However, from personal experience, the lifters can easily add a good .060", so they'll just pump up a bit more and everything will be fine. Obviously, you'd have to check your setup and how much lifter travel you have, but it would have worked fine on the motor I tested with.
True you could SHIM rocker stands some however I dissagree w the pushrod issue...however WITHOUT comparing collapsed vs fully pumped lifter its difficult to say and really it iant the lifters job to make up that change...it too is designed to work within certain parameters and I doubt that this falls into that catagory.
Just sayin....
Race engine builders dont rely on something like...the lifter can make up the differemce...
So why should we w ours
Macrobb
Full Access Member
Because it's cheaper than replacing pushrods with something a hair longer.
Like I said; personal experience on the shimming rockers - I just kept shimming until I found the lifter wasn't taking up the slack, and it was pretty obvious when that happened(engine sounds a lot different, with more noise and, well, less thump... like the valve isn't opening far enough. Strange, that.
)It was easily .060" on the engine I was messing with(so the lifter was taking up more than that due to the rocker ratio).
In any case, I think I'd prefer to have the lifters pumped (almost) as far as it can for a performance build, so that you don't run into any 'pump up' issues at high RPMs.
I've noticed weird stuff happen with lifters when they get old and gummed up, and I'd just prefer to err on the side of caution vs have a lifter hold it just a hair too much and end up with valve-piston contact or a burned valve.
bbjordan
Snow Monkey
Ok if that works for you thats kool.
Think I myself will pass on this teqnique ...however it could be a very usefull tool to determin shorter pushrod length....so win there..
Maybe i am just too damn finicky eh
Think I myself will pass on this teqnique ...however it could be a very usefull tool to determin shorter pushrod length....so win there..
Maybe i am just too damn finicky eh
Macrobb
Full Access Member
It should be longer pushrod length?
I always figure you could try it, figure out what you need and go from there.
Valve covers are easy to remove on an idi, easier if you've modded the filter head with rubber hoses sp you can move it without disconnection.
AcIdBuRn02ZTS
Full Access Member
If I were in your shoes... the builder that I paid a substantial chunk of change would be standing behind their work... building me another set of heads and replacing pistons if there has been damage done.
I'm sure they warranty their work... don't they?
If so.. it's their problem. Sucks to have to pull it back apart.. but better to make it right now then have it scatter later.
I'd also go down there and check the specs on the heads yourself or have them leave them off the block and you can put them on yourself.. that way you can check everything over. Sadly in most cases, the guy putting your junk together making $12-15/hr doesn't care about the $3k+ you just spent. Always double check the machine shop's work.
I'm sure they warranty their work... don't they?
If so.. it's their problem. Sucks to have to pull it back apart.. but better to make it right now then have it scatter later.
I'd also go down there and check the specs on the heads yourself or have them leave them off the block and you can put them on yourself.. that way you can check everything over. Sadly in most cases, the guy putting your junk together making $12-15/hr doesn't care about the $3k+ you just spent. Always double check the machine shop's work.
77f250diesel
Full Access Member
You have to keep in mind the interference problem is on the exhaust stroke.
As the piston goes up on the exhaust stroke the exhaust valve is open and as the piston approaches tdc the intake valve starts opening to scavenge the cylinder and help pack in more charge.
The TYP4 cam has higher lift but the base circle is smaller, meaning you have less preload on the lifters resulting in loose pushrods.
So just shimming the rocker just ain't gonna get it.
riotwarrior is right, it's not the way it should be done.
I speak from my own experience.
As the piston goes up on the exhaust stroke the exhaust valve is open and as the piston approaches tdc the intake valve starts opening to scavenge the cylinder and help pack in more charge.
The TYP4 cam has higher lift but the base circle is smaller, meaning you have less preload on the lifters resulting in loose pushrods.
So just shimming the rocker just ain't gonna get it.
riotwarrior is right, it's not the way it should be done.
I speak from my own experience.
bbjordan
Snow Monkey
This isn't just a problem on the exhaust side.
I agree shimming the rockers isn't going to fix this problem.
But I don't think the problem is with less preload either. If there was not enough preload, the valve train would sound more clattery. And having less preload wouldn't force the valves into the pistons. It would have the opposite effect.
I think the problem is that the valve spring is not strong enough or not shimmed up enough to have sufficient pressure to have the lifter follow the cam profile. Well, actually the lifter does follow the cam because of the extra little bit of oil pressure from the lifter. Unfortunately, this causes the lifter to pump up...
What are the valve spring pressure #s for valve closed and valve @ max. lift for the TYP4 cam?
I agree shimming the rockers isn't going to fix this problem.
But I don't think the problem is with less preload either. If there was not enough preload, the valve train would sound more clattery. And having less preload wouldn't force the valves into the pistons. It would have the opposite effect.
I think the problem is that the valve spring is not strong enough or not shimmed up enough to have sufficient pressure to have the lifter follow the cam profile. Well, actually the lifter does follow the cam because of the extra little bit of oil pressure from the lifter. Unfortunately, this causes the lifter to pump up...
What are the valve spring pressure #s for valve closed and valve @ max. lift for the TYP4 cam?
77f250diesel
Full Access Member
There's at least three of us on this thread that have had problems installing the TYP4 cam and I can tell you mine had nothing to do with valve float.
I pulled my motor down a second time because I suspected a problem and found dents in all of my pistons.
Using the clay method to check clearance the piston stopped near tdc on the exhaust stroke, it was against the valves.
We checked all the clearances and found that the valve was nearly .025 into the piston.
The only way I was going to gain the clearance I needed was to shave the pistons,lowering the compression ratio more than I was comfortable with.
Not everyone has this problem installing the typ4 cam but the one's that do is well documented both here and over at FTE.
This is the fault of the installer which in my case is me, live and learn.
I pulled my motor down a second time because I suspected a problem and found dents in all of my pistons.
Using the clay method to check clearance the piston stopped near tdc on the exhaust stroke, it was against the valves.
We checked all the clearances and found that the valve was nearly .025 into the piston.
The only way I was going to gain the clearance I needed was to shave the pistons,lowering the compression ratio more than I was comfortable with.
Not everyone has this problem installing the typ4 cam but the one's that do is well documented both here and over at FTE.
This is the fault of the installer which in my case is me, live and learn.
