56cc Lingenfelter CNC'd heads. What cam?
This is a discussion on 56cc Lingenfelter CNC'd heads. What cam? within the Internal Engine forums, part of the LSx Technical Help Section category; This is a direct quote from LS1howto's website on how to check your PTV. Now, make sure the radiator cap ...
03-19-2009, 10:05 AM #81
This is a direct quote from LS1howto's website on how to check your PTV.
Now, make sure the radiator cap is removed and the coil pack main wiring harnesses are disconnected (one big white connector on each side). Get in the car. Insert the key, pray, and turn the motor over for 4 seconds...it won't start as long as you've disconnected the coil pack wires. If you heard a god awful noise, you screwed something up. Chances are the cam is either too big or the cam was not lined up right with the timing marks on the crank! THIS IS BAD, however, I know you followed my instructions so this didn't happen to you
If the car turned over fine, connect the 2 coil pack harnesses. Now, PREPARE YOURSELF.
Are you serious? Pray?
03-19-2009, 02:16 PM #82
Without a degree wheel you could use the balancer,,,but on LS motors I don't think they have a top dead center mark ("0" degrees) or even timing marks at all so it makes things tricky. In this case a degree wheel is your best friend.
In any event, you install the piston stop, rotate the motor until it hits. Make a note of the crank position via degree wheel or balancer, scribe a mark if you have to. Then rotate the motor the other direction until it hits the piston stop again. Make a note of the balancer position again. (degree wheel or scribe a mark.) Then what you do is remove the piston stop and rotate the motor to EXACTLY the middle of the 2 spots you have noted.
If you use a degree wheel you take the 2 numbers you have, add them together and divide by 2. Then rotate the motor to that number on the degree wheel.
There you have it,,,,top dead center.
Now as far as checking piston to valve clearance it's also easy to do with the heads on the car. Use the set of valves where you just brought the piston up to top dead center. (Valves should be closed)
You will need a dial indicator, with a magnetic base to mount over the rocker arm tip or valve spring retainer,,,anywhere you can get a good reading. From here you will need a valve spring pry bar tool of some sort (they make various styles) to slowly move the valve down until you feel it touch the piston. Take a reading from the dial indicator. Do the same procedure on both valves. You want to take these readings and subtract roughly .080" on the intake valve and .100" on the exhaust for a safety margine. (This varies on types of engines so check what is safe)
After that it's as simple as reading the cam card and making sure your camshaft falls within these specs.
PS. Most places carry a balancer install tool that makes swapping the LS balancer a piece of cake while it's in the car, and you don't have to risk stripping the crank,,,,that's not a good thing.
Once you have one it's universal and can be used on any metric or standard thread car, it's a must have.
Last edited by Firebirdjones; 03-19-2009 at 02:19 PM.
03-19-2009, 03:32 PM #83
Has anyone used the method of keeping the vavles from falling by using the piston at TDC? Say, with the dot staight up, piston 1 and 6 will be at TDC, so they wont fall. Then turn 90 degress and do another two cylinders? Anyone used this/try this?
Also, if I use the air compressor method, do I have to regulate the pressure somehow? Or can I just hook the compressor to the hose going to the spark plug hole and let it fly? That doesnt sound right to me. Anyone try the the piston at TDC method before? GFetting that tooling in the spark plug hole is a royal PITA.
03-19-2009, 03:36 PM #84
03-19-2009, 04:07 PM #85
03-19-2009, 06:13 PM #86
Alright, I feel I made a time consuming mistake. I re-installed my oil pump BEFORE aligning dot to dot. I really dont want to take that bolt out/on again. Is it absolutly necessary to have that off?
Also, With the pump on, I am having a hard time turning engine over. Like its binding up. I didnt try to much, fearing something was binding. I dont know what could be binding. Theres no rockers or PR on at the moment. Anyone with an answer on my mistake? Im working on it right now and want to keep going.
03-19-2009, 06:18 PM #87
Also, all spark plugs are out of engine. It should be turning over easily in my mind, correct?
Any help ASAP would be great.
03-19-2009, 06:26 PM #88
- Join Date
- Jan 2006
- The great red state of MD.
- 2001 Trans Am (sold)
Can't help you much on the binding but I know my friend did his using top dead center method. Can you not get some wooden dowels to use as substitute lifter bars? Everyone on Tech uses them.
03-19-2009, 06:47 PM #89
I think when Im trying to turn engine over with pump back on im fighting the pump.
03-19-2009, 07:02 PM #90
Well dang, no one is on right now and Mark must be driving his damn semi. Bastard. I guess I will go take the effing pump back off and double my chances of screwing up the pick up seal. Getting that bolt back in is such a PITA. Damnit!!!!!!!!!
03-19-2009, 07:36 PM #91
- Join Date
- Jan 2006
- The great red state of MD.
- 2001 Trans Am (sold)
03-19-2009, 07:46 PM #92
I figured out my problems. I am a dumbass on both accounts.
1. transmission was in 4th gear. I got excited and stopped thinking.
2. I already had removed oil pump, again. I pinched that seal to all hell. That means my night is over. Im pretty upset. Wanted to pull an all nighter and get it finished. I hope GM dealerships carry these in stock. At least I found out before starting the engine up. Im trying to look at the bright side.
Will go at it again. Tomorrow is a busy day for me. GF is already mad at me for working on car all day today and yesterday, and the week before that. But yet she bugs me about finishing everything cause she wants to ride again. Women.
03-19-2009, 07:48 PM #93
03-19-2009, 07:50 PM #94
03-19-2009, 08:28 PM #95
Even if you wing it and get by with it this time,,,I would still put a degree wheel and piston stop in your arsenal of tools for the next time.
Sorry it's probably not what you want to hear, just hate to see all that work go down the tubes
I forgot to add,,,,,use the air pressure method to change your springs. Works great. No need to regulate the pressure. If you have a compressor that pumps up around 125 psi just let it go. It won't hurt anything and just leaks past the rings, valves etc...or where ever the most wear is,,,,much like a leak down test.
Last edited by Firebirdjones; 03-19-2009 at 08:32 PM.
03-19-2009, 08:33 PM #96
Dial indicator on end of valve stem or rocker arm. Running Piston up till it hits valve anf watch DI. Zero gauge out and mark crank. Would that not give me my TDC? I mean, with a really weak checker spring, I will be having my valve touching my piston at one point correct? Could I not just watch the DI and wait for it to stop reading positive and start going back to zero? For some reason this makes sense in my head. Tell me what you think FirebirdJones.
03-19-2009, 08:46 PM #97
I've never done it this way but I guess you could compress the spring completely and hold it there,,,,then rotate the motor by hand until it contacts the valve and let it push the valve up slowly while reading the dial indicator,,,just as you explained. Once you feel the piston has reached top dead center then zero the dial indicator and see how much piston valve clearance you have.
Sounds like this operation may take an extra set of hands though. If you have to make do this way,,,,give it a shot.
Last edited by Firebirdjones; 03-19-2009 at 08:49 PM.
03-19-2009, 09:02 PM #98
After you wrote it back to me it seemed alot harder to do. I would have to hold valve down, then wait for piston to touch then "I" would have to let the valve up as I turn the crank. Or I could just have someone put light pressure on it while I slowly turn the crank and wait for negative reading.
So that might work, who knows. But when and if I do find true TDC. I push the valve all the way down on the checker spring until it hits the top of piston correct? and THAT number should be say... .080 for exhaust for example? hat Im asking is if the only reading I am trying for is piston at TDC and how far valve travels before it hits. Sounds right in my head, just want to hear you or someone else say "yes".
03-20-2009, 07:48 AM #99
A piston stop for an LS engine is a good question, not sure on that one, but they have to be out there somewhere. One of these LS suppliers should have stuff like that for the do-it-yourselfers out there.
Ya you have the right idea,,,and your method is definately going to take an extra set of hands.
If the piston is at top dead center and you compress your spring until the valve touches. Take a reading on the dial indicator.
Lets say you have .650" From there you subtract a safe margin for clearance of .080" So from there you can safely install a camshaft with .570" without issues. Make sense????
03-20-2009, 02:02 PM #100
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By cz28mdn in forum Internal EngineReplies: 2Last Post: 10-14-2008, 08:00 PM
By Ed Blown Vert in forum Almost Anything GoesReplies: 7Last Post: 07-09-2008, 03:59 PM
By a338566 in forum Internal EngineReplies: 31Last Post: 07-29-2007, 11:06 AM
By NightRiderZ in forum General HelpReplies: 0Last Post: 07-11-2007, 05:46 PM