PTV Clearance-screwed
Thread Starter
Launching!
Joined: Jan 2008
Posts: 245
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From: Allen,TX.
PTV Clearance-screwed I picked up a L76 G8 motor (LS@ short block with L92 heads) for my Datsun 240Z and wanted to do a cam only build. I picked up a cam 230/242-600/605 on a 112 plus 1, double valve springs and push rods (7.425) plus DOD kit.
Well, I pulled the motor apart and clayed the pistons, made solid roller lifters out of my old lifters, re-used head gaskets and checked the PTV clearance...I am screwed, the exhaust valves are ok (.100 but the intake side are a joke, maybe .020 at best.
Looks like fly cutting pistons in the block which suck or pull the whole thing apart. Sure would have been nice to know this ahead of time, since I stated I didn't want to go this route.
Does anyone know the cost for fly cutting pistons these days, I had some JE's cut outside of the motor but that has been 10 yrs. Sorry for the rant, just venting frustration!
Well, I pulled the motor apart and clayed the pistons, made solid roller lifters out of my old lifters, re-used head gaskets and checked the PTV clearance...I am screwed, the exhaust valves are ok (.100 but the intake side are a joke, maybe .020 at best.
Looks like fly cutting pistons in the block which suck or pull the whole thing apart. Sure would have been nice to know this ahead of time, since I stated I didn't want to go this route.
Does anyone know the cost for fly cutting pistons these days, I had some JE's cut outside of the motor but that has been 10 yrs. Sorry for the rant, just venting frustration!
I don't find it hard to believe. That cam is well above what is generally accepted to not cause ptv issues with the ls3 heads.
I've never fly cut in the block, I've either pulled it apart and done it in an end mill or just bought pistons with valve reliefs.
You can rent the tools from Lindy to do it, although, I'm not sure if they have one for the 2.165 intake valve.
I've never fly cut in the block, I've either pulled it apart and done it in an end mill or just bought pistons with valve reliefs.
You can rent the tools from Lindy to do it, although, I'm not sure if they have one for the 2.165 intake valve.
Thread Starter
Launching!
Joined: Jan 2008
Posts: 245
Likes: 0
From: Allen,TX.
You would think as many motors, sbf or first gen sbc that I have built or assembled that this would not happen, God getting old sucks!Thanks
Mike
FYI the 6.0 motors with the larger cams are notorious for ptv clearance issues. that intake valve is a little to large for that bore. I know its a little late now but id recommend some nice cathedrals instead for what you've got.
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Bingo, major brain fart!!! I set them at engine assembly torque specs forgetting I was assembling a solid lifter thus needing lash set. I doubt it will make a huge difference, maybe .020-.040, not enough overall to get the required .080 clearance needed.
You would think as many motors, sbf or first gen sbc that I have built or assembled that this would not happen, God getting old sucks!
Thanks
Mike
You would think as many motors, sbf or first gen sbc that I have built or assembled that this would not happen, God getting old sucks!Thanks
Mike
As posted above be sure to use light springs, and set the lash right at zero. Don't run them down as you would for operation. I did the same thing the first time, after years of working with solid rollers in small and big blocks I did'nt stop and think about the lifter adjusting. I just ran the rocker bolt down as if it were to run, and then had little to no clearence.
I would guess that in operation you will have nearly .100
I would guess that in operation you will have nearly .100
