I have a mildly built 401 C.I. FE engine in my pickup (.060 over 390). When I went to rebuild the heads in my auto. tech class at college, I was blending the bowls and the block of wood underneath the head slipped and my carbide bit gouged a seat. We didn't have a pilot to fit the guides (heads had been redone previously with .015 bigger stemed valves. I didn't want to knurl the guides that bad anyway so I took them to Billings (MT) and had a machinists put the thickwall bronze silicone guide sleeves in them, bought new Speed-Pro stock (2.03/ 1.55) valves with chrome hardened stems and tips I believe. When I took them back down to college in Miles City, we did a three angle valve job. Heads are C8AE-H and D2TEA-A. Well after I got done doing that, we put .030 shims under the new Edelbrock Sure-Seat springs. Some of my valves were .028 taller than others and some were .030 taller. There were some other variations but can't remember all of them. I bought new adjustable rockers and shafts. I don't know exactly why but would not having my geometry right cause the valvetrain to wear quicker? What are the issues with not having all the valves the same height. The engine encounters valve float at about 5000 RPM, which is probably fine with the Edelbrock Performer-Plus cam (which I think sucks). I just ordered a cam from LazerCams that has the following specs
Duration @.050 225 intake / 230 exhaust
Lift (with 1.76 adj rockers) .566 intake / .552 exhaust
108 Lobe Seperation and 104 intake centerline
I also bought their recommended springs, retainers and locks. With as much lift as this cam has I was thinking that it would be important to get my geometry corrected which I am guessing may involve new valve seats and/ or grinding the valve-stem tips. I don't really want to put much money into these heads as I would rather have some better flowing ones but we can discuss that later. I think the springs are single coil type with an inner damper spring. I was thinking of going from umbrella seals to some kind of positive seal type which with this cam would probably involve have the guides machined down. Sorry for writing a novel but I just need some answers.

JC

 

.002 worth of play would be taken up by the lifters if you run hydro. So i really would not see any wearing problems, possibly a little bit, but with ajd. rockers and a hydro setup you would be fine.

 

My titanium valves are .080 shorter on the exhaust than the intake (I think they were built for a Chevy). I found lash caps from a 4 cyl Ford that fit perfectly to line them back up. If it bugs you, fix it. I think you would be ok with it the way it is.

-Scouder

 

That kind of valve stem height variance is exactly the kind of thing the adjustable system is built for. Adjust 'em right and it'll be fine. I'd just run the umbrella seals, they'll be fine. I'm running 'em in my 390.

 

Allright, but what I didn't like about that was the fact that some of my valves being taller than .030 would mean that even with a .030 shim that my spring pressures wouldn't all be the same. Same goes for some of the valves that may have only needed a .015 shim, (if that) having to much pressure. Don't know if it was enough to worry about but, I know a guy that used double valvesprings on a Performer-Plus cam years ago (it says in the directions not to use double valve springs, maybe it didn't back then) and ate 2 cams because of it. I doubt that with even the shorter valves being a little taller than they were before grinding the seats that a .030 shim would increase pressure enough to eat lobes, but still makes me wonder. Do you guys think that with that much lift that I will need to get some positive type seals installed? Even though the cam swap probably won't come till late spring/early summer, I just want to know everything that I can. I think I will probably send the cam and springs back untill I get closer to doing it and just keep the locks and retainers. I would like to see how it runs with my heads and if I am not impressed, upgrade to better flowing heads (which I still haven't decided on when and if the time comes).

 

Also, other than maybe preparing for normal wear, why do magazines (when they build engines make such a deal out of having proper rockerarm geometry? Maybe they just get it close and don't tell us that some were taller than others...??? How much play can hyd. lifter take up?

 

I think the magazines make such a big fuss only 'cause they CAN. Sure it would be nice to have everything perfect but the gains are extremely minimal so why get **** about it. As long as your geometry doesn't exceed the ability of the valvetrain to absorb said discrepancies you will be alright. The thought is that by having it all "balanced" there is less mechanical strain and thus less wasted HP to overcome the unbalanced strains. Guess it helps them to sell more magazines and makes them seem better or smarter then they really are. Just my .02, though it is a push to value it that high, lol.

 

Annihilator, with SS valves (TRW), adjustable rockers with roller tips your valve guide side pressure wear will be minimum like over 200,000 miles. Do have the the valve stem heigth matched as well as having the cam manufactures springs or match their valve open and closed pressures. Use aluminum spacers between rockers, not springs between them. Positive control results in positive results. After the valve stems have been ground and set, polish the grind marks until like a mirror. Details, details, make a great motor vs just another motor.

Carl....=o&o>....

 

I wouldnt worry too much about the height difference, especially with the adjustable rockers. With that much lift you will have to carefully check the valve seal clearance, you likley wont have room for the stock umbrella seals. I prefer teflon seals myself, although they require machining, they are superior in oil control, allow more valve lift, and never get brittle...just one more thing not to wory about....

 

That's what I was thinking.