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PTV clearance

Old May 5, 2023 | 09:45 AM
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Default PTV clearance

When I checked in with solid lifter and test spring I had .090 clearance. Probably a dumb question but I thought I’d check it with the head torqued down, with the pushrods and lifters I’m running. Will the valve just hit the piston because there is not enough valve spring pressure to push pushrod into lifter plunger?
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Old May 6, 2023 | 08:56 AM
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So you made solid lifters and ran them with test springs and used the correct length pushrod on your first check, correct? Was this with a compressed or non-compressed head gasket? Always best to save an old compressed gasket for this purpose. If that is what you did, rechecking with your normal lifters won't help you any. However, how did you make your solid lifters? I always disassemble the lifter and fill the body with washers to take up ALL the clearance inside the lifter. Reason I ask this, is that your question doesn't quite make sense. Under running conditions, nearly all of the slack in the lifter is taken up by the oil that gets pumped into the lifter. So, if you do a check with "normal" lifters and the plunger gets compressed, you'll actually end up with MORE PTV clearance than is actually there. I just want to make sure you didn't make your solid lifters simply by removing the spring inside and letting them be fully collapsed - You'll end up with a lot of bent valves on startup if so. But to answer your question, if you just use your regular lifters and pushrods along with checker springs, your PTV shouldn't change any except for if the plunger gets depressed slightly. And it would increase PTV if so. The big variable is whether you checked with a new or used head gasket and if it was torqued down or not.
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Old May 6, 2023 | 05:26 PM
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Originally Posted by LS1Formulation
So you made solid lifters and ran them with test springs and used the correct length pushrod on your first check, correct? Was this with a compressed or non-compressed head gasket? Always best to save an old compressed gasket for this purpose. If that is what you did, rechecking with your normal lifters won't help you any. However, how did you make your solid lifters? I always disassemble the lifter and fill the body with washers to take up ALL the clearance inside the lifter. Reason I ask this, is that your question doesn't quite make sense. Under running conditions, nearly all of the slack in the lifter is taken up by the oil that gets pumped into the lifter. So, if you do a check with "normal" lifters and the plunger gets compressed, you'll actually end up with MORE PTV clearance than is actually there. I just want to make sure you didn't make your solid lifters simply by removing the spring inside and letting them be fully collapsed - You'll end up with a lot of bent valves on startup if so. But to answer your question, if you just use your regular lifters and pushrods along with checker springs, your PTV shouldn't change any except for if the plunger gets depressed slightly. And it would increase PTV if so. The big variable is whether you checked with a new or used head gasket and if it was torqued down or not.
I originally checked with the length checker rod, old head gasket and old lifter I tack welded. I’m sure I did it right was just wondering if there was a way I could double check with the heads torqued on
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Old May 6, 2023 | 07:27 PM
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Originally Posted by Lq4c10
I originally checked with the length checker rod, old head gasket and old lifter I tack welded. I’m sure I did it right was just wondering if there was a way I could double check with the heads torqued on
Make a lifter set at the preload you plan to run.
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Old May 6, 2023 | 09:31 PM
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Originally Posted by Lq4c10
I originally checked with the length checker rod, old head gasket and old lifter I tack welded. I’m sure I did it right was just wondering if there was a way I could double check with the heads torqued on
No need in doing that. You checked ptv during mock up, and it doesn’t lie if done correctly, which it sounds like you did. I do it a similar way, only I use .030 valve spring shims between the head and block during the process. It’s a known number, so I simply add the remainder of the headgasket I’m using for that build…example here would be if my intake ptv is .100 and I’m planning on using a .040 headgasket….030 valve spring shim is in place, so add .010 for COMPRESSED thickness of .040 gasket, to my .100 ptv. So my actual ptv will be .110…
If I’m building a hydraulic engine, I’ll use shims/washers under the lifter cup, to make the lifter that I’m using into a solid lifter, and check ptv with that in place. You want to do this (which you did) to see what your MINIMUM ptv will be. Doing that ensures the lifter cup can’t raise up anymore due to cold oil starts, or hot oil pressure spikes, which will decrease ptv. Bottom line here is your fine. Don’t overthink this. Send it.
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Old May 8, 2023 | 08:30 AM
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Where do you get the checker springs? I might need to check PTV clearance soon.
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Old May 8, 2023 | 09:42 AM
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Originally Posted by Utinator
Where do you get the checker springs? I might need to check PTV clearance soon.
Any light compression spring that will fit between the retainer and head with enough force to hold the valve closed,
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