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 Post subject: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Fri Mar 16, 2012 6:23 pm 
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Location: Florida
I am about to do this for the first time ever on my LS5. I picked up a solid lifter, adjustable pushrods, and a 12" micrometer. I think I am going to need them about .100" shorter than stock. Most of the articles I found online show how to do it with roller rockers. Since I am building a Factory/Pure Stock car, I am using stock, stamped steel rocker arms. I have a good general idea as to what I am looking for. But, always open to pictures and suggestions from those who have done it before.

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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Tue Jul 10, 2012 5:51 pm 
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Well, it is back at the machine shop as of 2pm today. Left work early so I could run home and load it up. I am going over Thursday after work to help sort it out. Hoping it doesn't cost me an arm and a leg to fix. Might have to flycut the valve reliefs deeper. :bang

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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Tue Jul 10, 2012 9:35 pm 
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Did you get the info you needed?

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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Wed Jul 11, 2012 6:34 pm 
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Sorta... I spoke with a friend at Crane, he gave me a few ideas. I measured, had PTV interference with stock length push rods. (I kinda figured) Adjusted my length checkers to .100" shorter than stock, still had interference. I checked and rechecked, wrapped it up and walked away. Been doing other things on the car since. Just now have had the time & money to go forward. Hoping I don't have to flycut the pistons, but in the end... it is what it is. I am giving myself a self-imposed deadline of October to have the car running and driving. One way or another, I am going racing this winter to try and dial this pig in for next year. :bang

I am so tired of sitting on the sidelines. I haven't had a consistent/reliable car to race since my 2000 Z28. (sold in May of 2010)

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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Thu Jul 12, 2012 9:26 am 
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Are your issues with intake and exhaust?

Seems like Thats alot to still have interference!

How little lift would it take to get the right clearances?

May have too much duration and/or overlap?

Just thinking out loud!

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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Thu Jul 12, 2012 1:38 pm 
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Yeah, both valves hit. I did one at a time, same result. The cam checks in @ .461"/.479" lift with stock rockers. I have the HP long slot rockers. But, they don't add a ton of lift. 214/218 duration @ .050" lift. It is a Crane blueprint camshaft. I tightened up the LSA, everything else was left alone to comply with the rules. Valve sizes are stock, (2.065I - 1.725E) Stock pistons with two valve reliefs. The block is decked, the heads have been milled, and am running thin steel head shims. (.020" compressed) It just seems with that small of a cam, etc. - I shouldn't have run into this. I had a friend help me degree the cam, it checked in dead nuts on. It is installed straight up. I'll know more tonight when we tear into it.

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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Thu Jul 12, 2012 9:57 pm 
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Dumb question...pistons installed properly? So dome/ notches properly oriented? That small of cam specs really should be ok with that combo. Cam degreed in properly? I suppose it Inever used that piston had a few ls6 based setups that gave me fits but that was with zero deck 550 plus lift 250 plus duration. I had one we faced the valves to gain some extra clearance ..but tat was just for a little extra safety margin.
Ryan


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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Thu Jul 12, 2012 10:58 pm 
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Location: North Salem NY
Are you saying 469 lobe lift?

With 1.7 rockers your close to .800 less lash!

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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Fri Jul 13, 2012 9:13 am 
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Ryan - I am positive on both items, they are correct. Those were my first two thoughts. I didn't get to it last night, got called into work. :bang Oh well, OT.

Ted, the lobe lifts are 271 Intake, 282 Exhaust - per the cam sheet. No way I would put an .800" lift cam in a stock LS5. :nuts

Hoping I will have some news/progress to report later today.

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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Fri Jul 13, 2012 1:10 pm 
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The whole thing doesn't make any sense. I have run L-88 spec cams with domed 11.0 to 1 pistons and never came close to hitting anything. If I recall correctly, I had about .100" clearence. Are the pistons stock or aftermarket?


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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Fri Jul 13, 2012 1:25 pm 
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I forgot all about this, I have a new set of +.60 454 Hypertectic pistons, I think they are Keith Black, that someone gave me a few years ago. The guy had valve to piston interference and bought a new set of pistons rather than mess with these. I don't know what his set-up was but the pistons don't have much of a dome. I am going to check out what they are as they are still in the original box and now I am curious ???


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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Fri Jul 13, 2012 2:04 pm 
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My block is decked quite a bit, I have the minimum .008" piston the deck clearance. My pistons are Sealed Power, flat top - two valve reliefs. Identical to a factory LS5 piston. My heads are milled down to 106cc from 113cc. Not sure how much we cut out of them, not enough to affect the intake seal. It still fits like it should.

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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Fri Jul 13, 2012 11:39 pm 
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Location: North Salem NY
Curious, check valve lift!
Could you have custom ratio rockers?

Or, maybe, thin gaskets, well milled heads, etc!

A cumulative affect can hide itself!

Good luck, its in there somewhere!

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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Wed Jul 18, 2012 10:40 am 
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:? ::sigh:: Where do I begin? I think I must be slipping in my old age. (33) I recall pulling the timing chain off after degreeing the cam, but cannot remember what for. Anyhow, I am a dumbass and lined up the upper cam gear with the keyway on the crankshaft - not dot to dot. I am feeling really stupid and careless right about now. I am no pro engine builder, but I have put enough together to know better. It's truly a rookie mistake. The end result of my memory lapse left the cam advanced enough to create PTV issues. Once lined up properly, all is well again. I can now get back to making forward progress. Hope to be posting a picture of the engine in the car soon.

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 Post subject: Re: Measuring pushrod length for proper valvetrain geometry...
PostPosted: Wed Jul 18, 2012 4:06 pm 
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:winner

Good news!

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