PTV clearance
Thread Starter
Teching In
Joined: Feb 2023
Posts: 25
Likes: 0
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?
Joined: Apr 2006
Posts: 3,890
Likes: 1,137
From: Grand Rapids, Michigan
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.
Thread Starter
Teching In
Joined: Feb 2023
Posts: 25
Likes: 0
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.
Launching!
Joined: Oct 2022
Posts: 206
Likes: 74
From: FL
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.
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,616
From: Central Cal.
