Is this enough PTV clearance?
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Not the best picture but that bright spot in the clay is the piston. Came out like that twice.
I used a hydraulic lifter. I am going to make a solid lifter to check it but I thought that it would be even worse with that.
I used a hydraulic lifter. I am going to make a solid lifter to check it but I thought that it would be even worse with that.
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That's what I thought - I must have screwed something up, but I've checked it four times now. Even threw the stock heads on to see what they would do. They cleared but not by enough...
You might want to contact TSP, but I'd be willing to bet they do a "clean up" mill to make sure the surface is true. If you don't have the stock valves in, then that probably put you over the top.
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From: Texas and Qatar
Those PRC heads should have similiar intake clearance to your stock heads, and slightly better on the exhaust side. The standard "clean up" milling is less than .003" which has no adverse affect on PtoV when starting out in the "safe" PtoV areas...
I'm not a fan of clay, but what procedure are you using to check PtoV? Test springs + adj. rockers or pushrod?
I use a set of solid lifters (stock lifters with shims internally), set of test springs, dial indicator and adjustable length pushrods to set 0 lash on the cam base circle. You can get within +/- .001" accuracy that way.
In my experience, camshafts that large on 110lsa's are tight on both intake and exhaust, but I've never seen that particular camshaft firsthand.
I'm not a fan of clay, but what procedure are you using to check PtoV? Test springs + adj. rockers or pushrod?
I use a set of solid lifters (stock lifters with shims internally), set of test springs, dial indicator and adjustable length pushrods to set 0 lash on the cam base circle. You can get within +/- .001" accuracy that way.
In my experience, camshafts that large on 110lsa's are tight on both intake and exhaust, but I've never seen that particular camshaft firsthand.
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From: BFE
Originally Posted by chuckyt1
PRC LS6, unmilled for now. The used MLS head gasket and a 243/249 613/620 110 Trex.
Gonna try again and make sure I didn't screw something up....
Gonna try again and make sure I didn't screw something up....
Truth of the matter is none of these big shafts with tight LSAs have enough PTV with safety in mind, certainly not "street" safe anyways.
Flycut a little and call it a day.
If you used a hydraulic lifter and a checker spring and torqued your rockers down to 22 ft lbs, then theres a good chance youre measurements are off. The checker spring isnt strong enough to preload the lifter. The way around this is to hang tighten the rockers until all teh play is gone, but dont torque all teh way down. You may find youve got much more room this way.
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Thanks guys, I really appreciate the help. I wanted to do a quick check just to make sure. I knew it would be tight and even TR told me - "If it clears, it clears" and to be carefull. Think I,m going to put a checker spring on it and us a dial indicator to get a real measurement. If I need to cut, then the heads are going to get milled and .040 Cometices are going in... Hehehe
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Okay - So I put in checker springs, used a hyd. lifter and stock pushrod. Then put the rockers on without torquing them down, just went to zero lash, and used a dial indicator. Still came out with ptv CONTACT, even have a small valve scar on the piston. I did measure my intake valves and they are the 2.02's.
New question - How much can you safely fly cut? Since I have to flycut, I might as well get the heads milled and run an .040 gasket. But I don't want to hog too much out of the piston.
Thanks Again Guy's
New question - How much can you safely fly cut? Since I have to flycut, I might as well get the heads milled and run an .040 gasket. But I don't want to hog too much out of the piston.
Thanks Again Guy's
What are the cam specs? I just cant imagine you actually making contact unless youve got a HUGE cam and the heads have been severely milled. Is it possible the cam is off by a tooth on the timing gear?
Originally Posted by GuitsBoy
What are the cam specs? I just cant imagine you actually making contact unless youve got a HUGE cam and the heads have been severely milled. Is it possible the cam is off by a tooth on the timing gear?
You should flycut, I think you can squeeze .100