Replacing valve guide stem seals

Are you saying your engine was rebuilt and the stock teflon style seals were used and you want to install the positive rubber seals? The replacement guides I buy have a different detail on the top that the new style seals "grip" . .. if you want I can see what the new style seals feel like on the old style guide?

Sean

edit: the front head would be no fun trying to do this ... . I know it's a horrible thought having to pull the motor but once you've done it a few times it's really not that bad (I tell myself)

 

Yes, it can be done especiall on the GT4 with better access. But, it is not going to be fun at all and your vocabulary of four letter words will be much more prolific when you are done.

 

I'm sure the compressed air will work . . .keep in mind what I said about the detail on top of the guides being different for the other seals.

Did you put your heads together? The reason I'm asking is you have to put the valve keepers in with tweezers and it's not that easy . .. there's an adapter I put on the end of the valve spring compressor (standard thing for overhead cam engines/bucket setup) . .. acutally just thinking a little more about it you could probably make a tool that would go in the cam journals after pulling the cams and maybe just lever off of that to get the retainers/keepers out.

Good luck,

Sean

 

I can take one it's nothing special .. . just a sleeve with openings cut in the side for you to get tweezers/tiny fingers thru to insert keepers . .. check Norwood's site or most engine rebuild tool places and search for "overhead cam valve spring compressor adapter" or something like that.

Like I said in other post . . making something custom that would lever off the cam journals will save a lot of grief . . thinking about it a little more the adapter for the spring compressor is kinda useless for what you're doing . . . I'll let this one bounce around in the gray matter and look at a head today while I'm fiddling and see if something is obvious . . .I have an assembled 2V head on my bench so I'll be able to see if there's something simple to make.

Sean

 

Don't know . . just got them from my typical parts supplier .. I'll take a pic .. they look identical to those used on new Porsches only different stem diameter . . I'm sure they're something standard . . they're green with a spring etc. . . someone that works on import heads all the time will recognize 'em.

 

something came to mind which might work as a tool for this . .

machine a piece of round stock to fit in the cam journals . . . leave a section large over the retainer to grind by hand with a grinder to the shape of a cam that will push the retainer down as you rotate it . .. you'd have to machine away the material in between the 2 "lobes" where the valve stem and keepers are . . . .

someone else might comment on this . .. there's always a lot of "stiction" between the keepers/retainers/valve stem . . . rebuilding domestic V8's as a kid we use to take 'em apart with a hammer and socket . . the socket would sit on the retainer with clearance for the keepers and when you hit it usually the keepers would just fly out . . didn't need a valve spring compressor for disassembly (not the right way to do things but it was not an F1 environment by any stretch ).

you might need to do something like this just to "break" the stiction on the keepers . . just seems like the valve is going to have a tendency to push open . . . are you supposed to do this at TDC so the valve doesn't drop in?

 

something easier to make . . round bar machined to cam journal diameters . . drill & tap 2 holes to line up with the retainer . . screw in bolts to push down retainer . . . sounds easy but?

 

First, how much smoke, beacuse these engines like oil and if I remember right these engines like 0.1 oil litre on a 100km ride, so they smoke sometimes.

 

need a pic to see how that thing works . . . probably a good start though . . looks like the handle screws down and pushes 2 of the tabs . . .but where do the other legs go?

 

He mentioned his engine is fresh . . my engine is fresh and I run the hell out of it . . no smoke whatsoever . . . uses 1 qt every 20 hrs . .. my original motor used 1 qt every gas tank and when I tore 'er down she really didn't have that much wear . . . I think it was all valve seals and gunk in the oil ring . . . what was weird is that engine didn't seem to smoke but there'd be black soot on the rear and it would smell almost like a 2 stroke . .. but I never noticed it smoking at idle or just revving stationary . . . could've been dumping plumes at full throttle but none of the guys I went on drives ever with mentioned anything about that . . comments were just "man you're hard on that car" .

 

I don't know but think that ebay tool wont get onto your springs.
Certainly wont on a 2 valve head, judging by Pizzaman Chris's pics.
This is such a pain of a job, think I'd want to get my mixture right and measure the oil consumption etc before taking it on.
I'm not experienced with these engines so take it for what its worth, but it sounds like the smoke isn't at the time I'd expect it to be with leaking guides/stem seals.
It'd be a buga up numba 1 to go through the job and still have the same problem.

 

Pics of the 308 valve buttress in the following thread.
http://ferrarichat.com/forum/showthread.php?t=196565&highlight=308+heads

 

don't think there's room to get those legs on the spring . . . the o.d. of the springs sometimes rubs on the inside of the buckets . . that's how tight it is in there . . . unless you have aftermarket springs . .. . making what I described with the two threads/bolts and locate in the cam journals should do it.

 

Maurice,

Maybe it's not the valve seals, the new OEM seals should be OK, otherwise every 308 would have similar symptoms. You mentioned the engine has had a recent rebuild, maybe the rings haven't seated properly in the bore - what kind of oil are you running and what oil did you use to run it in ?

Also, I have that valve tool, and it will not fit a 308 2v head (great for Holden V8's though !). The air hold works surprisingly well in keeping the valve in place, but for the Ferrari you will need to fab a tool that allows you to push the valves down ( and hold them there ) sufficiently long enough to get the collets out / in.

Regards

Michael

 

I'll get you some numbers if no one else pipes in.