Safe max lift on X heads that retainer hits seal @ .550??

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swinger340

swinger340

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Kinda a branch stemming from another thread, but I have some fresh X heads hardened seats, 5 angle valve job w stainless valves. They have been cleaned up w port work and now flow 245 @ .500 Im thinking hard about using these on my most resent 340 but what is the max lift I can safely go w/o worrying about retainer damaging the valve seal? When flowing the heads the retainer was touching the valve seal @ .550 lift. Is a voodoo .513/.533 to close for comfort, or does anyone know if this cam really grosses .533 or less lift on the exhaust side?
 
inertia said:
couldn't you trim down the top of the guide a few thou,, thus lowering the seal ?
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@ the time of the valve job and other work the guides were milled and cut down to accept Viton seals. I don't want to swap to longer valves now. Will just make the most out of what I have. Originally was going to go w a MP .509 so this was not an issue. The exhaust #s are a little low so a duel ramp/duration would be a better choice.
 
swinger340 said:
@ the time of the valve job and other work the guides were milled and cut down to accept Viton seals. I don't want to swap to longer valves now. Will just make the most out of what I have. Originally was going to go w a MP .509 so this was not an issue. The exhaust #s are a little low so a duel ramp/duration would be a better choice.
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Do you have viton seals on the exhaust side too? I always ran basic umbrella's on the exhaust side. Those guides get a lot hotter then the intakes so they actually like a little oil, plus there's no vacuum there.
 
OldmanRick said:
Do you have viton seals on the exhaust side too? I always ran basic umbrella's on the exhaust side. Those guides get a lot hotter then the intakes so they actually like a little oil, plus there's no vacuum there.
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Yes. Got Viton seals on both intake and exhaust
 
You will be fine. Your not going to get the full .533 lift anyway due to the wonderful SBM pushrod angle.
 
Mike, what do you think about the Viton's on the exhaust? Been a while for me, just wondering if the thinking has changed over the years.
 
hi, usually rule is , .060 min clearance retainer to seal. .500 lift is about max.
at RPM, things hit each other. just food for thought.
 
MRL Performance said:
You will be fine. Your not going to get the full .533 lift anyway due to the wonderful SBM pushrod angle.
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Perfacar "hi, usually rule is , .060 min clearance retainer to seal. .500 lift is about max.
at RPM, things hit each other. just food for thought."



He beat me to it. The loss is somewhere around .020 or so, maybe a little less because it's not a hydraulic roller. IMO I'd limit lift to .500 advertised because it's still a little too close for my comfort. I like at least .060 as Perf mentions, especailly given the capabilities of the cam.
 
I use the metal clad blue viton seals. They seem to last pretty good. The stock type black one do end up getting hard, then they break up and end up in the oil pickup screen.

Your end lift result depends on the rocker, shaft position(if its been shimmed or not), how far from shaft center line the adjuster is where it meets the pushrod, how long the pushrod is and the angle of the pushrod. You can get it as perfect as you can, but you will still lose lift on a 59* block no matter what. Most of the time, to get the real theoretical lift, you have to use a 1.6 rocker.
 
I mocked up my 340 w an XE282S .520/.540 advertised lift. With the lash set @ .016/.018 and PRW 1.5 rockers witch fall shy of an actual 1.5. More like 1.45. Put a dial indicator on the valves and am only getting .483/.502 actual lift. Thats ALOT of lift lost. I may just use this cam after my curiosity surprised the hell out of me.
 
OldmanRick said:
Do you have viton seals on the exhaust side too? I always ran basic umbrella's on the exhaust side. Those guides get a lot hotter then the intakes so they actually like a little oil, plus there's no vacuum there.
Click to expand...

I have done this in the past too....it was explained to me that the guides lived longer by getting a little more oil.
This was on a series of big Fords and I never had any trouble taking the guides out.......but I don't know if using a P.C. type seal on the exhaust would have made a difference there or not.
I was told that it was more critical with a heavier valve.
It worked on paper. :D
 
On big blocks I've seen guys run the .513/.533 lift lunati without the valve guides being cut down
 
swinger340 said:
When flowing the heads the retainer was touching the valve seal @ .550 lift. Is a voodoo .513/.533 to close for comfort, or does anyone know if this cam really grosses .533 or less lift on the exhaust side?
Click to expand...
. The stock rocker arms are actually a little less than a true 1.5 ratio and I'd say you have just enough room for the .533 to clear if it wasn't hitting it until the lift reached .550. With proper valve springs I'd say you're good to go
 
I have a question regarding lift myself, my heads can handle .700 lift but I'm running stock type Pistons in a 400 with no valve reliefs Pistons are .100 down the hole which in a way could act as somewhat of a valve relief. Would I be ok with a cam in the .545-.557 range?
 
My head guy has set up some for me that can take up to .600"

You can machine them to get a little more lift (or a little extra padding for mid .500" lifts)...
 
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