Trying to check my PTV on my LQ4. Help would be great.
03-19-2009, 01:27 AM
#1
Trying to check my PTV on my LQ4. Help would be great. Alright, I have my new cam installed. I am really not wanting to remove my heads. I really need to check my PTV even though COMP and a few other tuners have told me it will clear. I was thinking that placing a dial indictator on top of the valve with a checker spring in place would suffice. With piston at TDC, measuring the valve drop. Will this work? I have been reading and reading, and now wondering if my lifter is going to be messing with my measurments. Set up is, Stock bottm end LQ4, Lingenfelter ported 5.3 heads. Guy that used to work at W2W says these heads are 56cc chamber. I know, way small. But COMP and other tuners reccomended a 236/240 .578 .58X. I thought that was to large and ended up going with,
230/236 .573 .578 114LSA 110ICL.
The piston has a dish to it, But I have read 8cc,10cc and 12 cc. I really want to check this PTV, and without pulling my heads. Can some of you shed some light, Im going back tomorrow to swap springs and PR's. Thanks alot for your help, its greatly appreciated.
230/236 .573 .578 114LSA 110ICL.
The piston has a dish to it, But I have read 8cc,10cc and 12 cc. I really want to check this PTV, and without pulling my heads. Can some of you shed some light, Im going back tomorrow to swap springs and PR's. Thanks alot for your help, its greatly appreciated.
03-19-2009, 06:52 AM
#3
I always pull the head and use a solid lifter and adjustable pushrod.
Plus you need to check the PTV clearance at more than TDC, I do a sweep checking multiple spots.
I actually ccd the dish of an LQ4. Ill find my information today and see if I found what GM says.
Plus you need to check the PTV clearance at more than TDC, I do a sweep checking multiple spots.
I actually ccd the dish of an LQ4. Ill find my information today and see if I found what GM says.
03-19-2009, 09:34 AM
#4
Your cam is a 222/238 duration, 581/605 lift, 114+4. Mine is a 230/236 .573.578 114. My heads are milled more but the L92's have a largers intake valve correct? Trying to put things in comparison.
The only way I can check this for a good measurement is to take the head off?????
03-19-2009, 10:21 AM
#5
Alright, thanks for that. Finally a solid answer.
Your cam is a 222/238 duration, 581/605 lift, 114+4. Mine is a 230/236 .573.578 114. My heads are milled more but the L92's have a largers intake valve correct? Trying to put things in comparison.
The only way I can check this for a good measurement is to take the head off?????
Your cam is a 222/238 duration, 581/605 lift, 114+4. Mine is a 230/236 .573.578 114. My heads are milled more but the L92's have a largers intake valve correct? Trying to put things in comparison.
The only way I can check this for a good measurement is to take the head off?????
03-19-2009, 11:59 AM
#10
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If you want a true/accurate measure - you need to pull one head, use a solid lifter, an adjustable push rod, and a checker spring.
I used springs that I found at the autoparts store. They were on the exterior of a flexible hose and just cut them off and used them - low cost and worked great.
The adjustable push rod is used to set the rocker at zero lash with the solid lifter.
I used a dial indicator.
You will have to check the clearance at more than TDC - some before and after. Once you start checking you will see the clearance get closer and then futher away for both the intake and exhaust valves as you rotate the crank.
If you are concerned - do it once and do it right.
Good luck.
I used springs that I found at the autoparts store. They were on the exterior of a flexible hose and just cut them off and used them - low cost and worked great.
The adjustable push rod is used to set the rocker at zero lash with the solid lifter.
I used a dial indicator.
You will have to check the clearance at more than TDC - some before and after. Once you start checking you will see the clearance get closer and then futher away for both the intake and exhaust valves as you rotate the crank.
If you are concerned - do it once and do it right.
Good luck.
03-19-2009, 12:11 PM
#11
I just talked a buddy on another forum. He said they did his car like this,
Checker spring from home depot.
Installed rocker arm's on both intake and exhaust.
Pushed valve all the way down with piston at TDC
Moved rocker arm to top of valve and measured that clearance with dial indicator.
Repeated steps for BTDC and ATDC.
With such a weak checker spring, why would one need to worry about using a solid lifter? The spring in lifter would overcome the checker spring? This method will not produce good measurements?
Checker spring from home depot.
Installed rocker arm's on both intake and exhaust.
Pushed valve all the way down with piston at TDC
Moved rocker arm to top of valve and measured that clearance with dial indicator.
Repeated steps for BTDC and ATDC.
With such a weak checker spring, why would one need to worry about using a solid lifter? The spring in lifter would overcome the checker spring? This method will not produce good measurements?
03-20-2009, 10:31 AM
#12
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with a weak enough checker you don't need a solid lifter. BUt if you want a solid lifter, very easy to make. Take the retaining clip and pushrod cup out of the lifter, stack about 3 #6 washers in there, re-assemble the cup and retaining clip. There will be no slack in the lifter now.
03-20-2009, 07:25 PM
#13
with a weak enough checker you don't need a solid lifter. BUt if you want a solid lifter, very easy to make. Take the retaining clip and pushrod cup out of the lifter, stack about 3 #6 washers in there, re-assemble the cup and retaining clip. There will be no slack in the lifter now.
03-20-2009, 07:40 PM
#14
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I am running a bigger cam and 2.02 intake valves on some non milled 862 heads with no problems. Should be fine the 114* helps you out to I am on a 112
03-20-2009, 07:59 PM
#15
My heads have been milled to 56cc. Not my choice. Bought it like that. But with the other guy running milled L92's that have larger valves then even mine, more exhuast duration, way more lift on exhuast, more intake lift.... I think ill be fine. Im still gonna do my best to check without a degree wheel though. I need different pushrods then the 7.4's I ordered though. 7.3's came out, I highly doubt the 7.4 would work. Sucks! I ordered them today, be here tuesday.
