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Valves opening while tightening rocker arms? 318 magnum #1404446 03/18/13 03:32 PM 03/18/13 03:32 PM
Joined: Mar 2005 Posts: 1,630 North Central Florida E eightlitermopar OP top fuel
eightlitermopar OP top fuel E Joined: Mar 2005 Posts: 1,630 North Central Florida	I have a question about putting this motor together regarding the pushrods and valves opening. This is also posted on my original magnum headed 318 post here https://board.moparts.org/ubbthreads/show...e=0#Post7077141 Ok, so I finally measured very carefully and I am installing pushrods today. I ended up using a thin head gasket, so my �zero lash� length for my pushrods was 7.543. According to Comps website, I could calculate .020 - .070 preload with my hydraulic lifters. (The lifters and pushrods are both Comp) I ended up going with an even number at 7.600 for pushrod length. However, when I tighten down the rocker arms, I can see the valve opening. This happens on the valves that are supposed to be closed (the cam lobe is on the �closed� side) These cam and lifters are used previously (together) and so I am wondering if I just need the lifters to �bleed down� ? What am I missing here? I hate to button this up and have problems when I first fire it up. Please help Eightlitermopar Mopar or no car

Re: Valves opening while tightening rocker arms? 318 magnum [Re: eightlitermopar] #1404447 03/18/13 03:47 PM 03/18/13 03:47 PM
Joined: Mar 2005 Posts: 1,630 North Central Florida E eightlitermopar OP top fuel
eightlitermopar OP top fuel E Joined: Mar 2005 Posts: 1,630 North Central Florida	I should also add... I let the motor sit for 30-45 minutes (in case the lifters did need to "bleed down"). I turned the motor slowly over with a breaker bar and no pistons were contacting any valves for the full 720 degrees... eightliter Mopar or no car

Re: Valves opening while tightening rocker arms? 318 magnum [Re: eightlitermopar] #1404448 03/18/13 03:49 PM 03/18/13 03:49 PM
Joined: Mar 2008 Posts: 5,746 Ontario, Canada Dodgem master
Dodgem master Joined: Mar 2008 Posts: 5,746 Ontario, Canada	I thought you wanted 7.5" even if you had 7.543 a 7.6 is .057 longer and will push the valve open about .085 more at rest in theory. about .030 to .040 is all you want for preload you just added .057 to the existing pre load and the thin head gaskets (if thinner than stock) and any deck or head milling add to that since stock pre load is about .070 you may be way to the high side of pre load.

Re: Valves opening while tightening rocker arms? 318 magnum [Re: eightlitermopar] #1404449 03/18/13 03:53 PM 03/18/13 03:53 PM
Joined: Mar 2008 Posts: 5,746 Ontario, Canada Dodgem master
Dodgem master Joined: Mar 2008 Posts: 5,746 Ontario, Canada	At mancini's they offer 7.5 and 7.55 so 7.6 is likely the wrong direction http://chucker54.stores.yahoo.net/compcams5.html

Re: Valves opening while tightening rocker arms? 318 magnum [Re: eightlitermopar] #1404450 03/18/13 05:08 PM 03/18/13 05:08 PM
Joined: Jan 2003 Posts: 75,125 A Banana Republic near you. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,125 A Banana Republic near you.	The lifters might bleed down when the engine is not running but they will pump up to a certain degree when the the engine is running . You went the wrong way on pushrod length if you ask me .

Re: Valves opening while tightening rocker arms? 318 magnum [Re: JohnRR] #1404451 03/18/13 05:38 PM 03/18/13 05:38 PM
Joined: Mar 2005 Posts: 1,630 North Central Florida E eightlitermopar OP top fuel
eightlitermopar OP top fuel E Joined: Mar 2005 Posts: 1,630 North Central Florida	Hmm�.I�ll have to do some more research on this� This is a LA 318 motor with the later style magnum heads. These are not stock 1969 heads. The mopar performance pushrods designed to work with the magnum headed, LA small blocks was 7.625 inches long. This was part number P5007477 and has been discontinued. Some have even run 7.650 inches on their engine combos. The common complaint I see is that the pushrods for this conversion might have been too SHORT. If anything, the pushrods I have now would be even shorter�..which would give me no preload at all. This info was gathered based on information I got offline http://www.dippy.org/forum2/index.php?topic=295.0 and http://www.moparmusclemagazine.com/techarticles/mopp_0409_318_engine_build/viewall.html just to name a few�. This really has me confused� Eightlitermopar Mopar or no car

Re: Valves opening while tightening rocker arms? 318 magnum [Re: eightlitermopar] #1404452 03/18/13 09:18 PM 03/18/13 09:18 PM
Joined: Aug 2005 Posts: 11,543 chicagoland,usa B buildanother I Live Here
buildanother I Live Here B Joined: Aug 2005 Posts: 11,543 chicagoland,usa	They will bleed down. Take a look at it in the morning.

Re: Valves opening while tightening rocker arms? 318 magnum [Re: buildanother] #1404453 03/19/13 01:05 AM 03/19/13 01:05 AM
Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska	Quote: They will bleed down. Take a look at it in the morning. yeah see what your preload is in the morning on the base circle live every 24 hour block of time like it's your last day on earth

Re: Valves opening while tightening rocker arms? 318 magnum [Re: RapidRobert] #1404454 03/19/13 10:14 AM 03/19/13 10:14 AM
Joined: Jan 2003 Posts: 75,125 A Banana Republic near you. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,125 A Banana Republic near you.	Quote: Quote: They will bleed down. Take a look at it in the morning. yeah see what your preload is in the morning on the base circle What happens when the engine is started up and the lifters are filled with pressurized oil ?? How much have the heads been cut vs. stock ?

Re: Valves opening while tightening rocker arms? 318 magnum [Re: JohnRR] #1404455 03/19/13 10:38 AM 03/19/13 10:38 AM
Joined: Jan 2003 Posts: 25,200 Upper Midwest M MoparforLife Too Many Posts
MoparforLife Too Many Posts M Joined: Jan 2003 Posts: 25,200 Upper Midwest	Make sure that you are checking your preload with the lifter on the base circle of the cam, and from the point that the push rod, rocker arm, and valve tip all make very first contact with 0 clearance. THEN adjust the preload from that point. Make sure that you are not adjusting the preload from the point of when you have the lifter plunger pushed all the way to the bottom of the lifter bore. doing this WILL force the valve open and not shut leaking most of if not all the compression.

Re: Valves opening while tightening rocker arms? 318 magnum [Re: eightlitermopar] #1404456 03/19/13 11:42 AM 03/19/13 11:42 AM
Joined: Mar 2008 Posts: 5,746 Ontario, Canada Dodgem master
Dodgem master Joined: Mar 2008 Posts: 5,746 Ontario, Canada	I have to check more. Thought the rockers where adjustable like a chev but says they are not! Oh well Last edited by Dodgem; 03/19/13 11:53 AM.

Re: Valves opening while tightening rocker arms? 318 magnum [Re: Dodgem] #1404457 03/19/13 11:47 AM 03/19/13 11:47 AM
Joined: Jan 2003 Posts: 16,123 Grand Haven, MI patrick I Live Here
patrick I Live Here Joined: Jan 2003 Posts: 16,123 Grand Haven, MI	what rockers are you using again? stock magnum pedestal mount? 1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod SOLD!* 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)

Re: Valves opening while tightening rocker arms? 318 magnum [Re: buildanother] #1404458 03/19/13 11:59 AM 03/19/13 11:59 AM
Joined: Mar 2008 Posts: 5,746 Ontario, Canada Dodgem master
Dodgem master Joined: Mar 2008 Posts: 5,746 Ontario, Canada	You may want to buy one of these and take your time to mock up exact length you need intake and exhaust making sure you are on the true bottom of the cam base circle! http://chucker54.stores.yahoo.net/hitepuch.html or maybe one of these if mancini does not have the ball ball! http://www.summitracing.com/parts/cca-7702-1/overview/ Last edited by Dodgem; 03/19/13 12:04 PM.

Re: Valves opening while tightening rocker arms? 318 magnum [Re: eightlitermopar] #1404459 03/19/13 12:16 PM 03/19/13 12:16 PM
Joined: Mar 2008 Posts: 5,746 Ontario, Canada Dodgem master
Dodgem master Joined: Mar 2008 Posts: 5,746 Ontario, Canada	What cam shaft?? does the roller hydraulic not use a much shorter pushrod?? Well reading your other post sounds like you stayed with your original LA cam and lifters so it should not be a problem. did you measure the comp pushrod lenghs to see you got the correct ones? maybe you are not on the back of the cam??? Last edited by Dodgem; 03/19/13 12:26 PM.

Re: Valves opening while tightening rocker arms? 318 magnum [Re: eightlitermopar] #1404460 03/19/13 03:01 PM 03/19/13 03:01 PM
Joined: Jan 2003 Posts: 75,125 A Banana Republic near you. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,125 A Banana Republic near you.	Quote: I have a question about putting this motor together regarding the pushrods and valves opening. This is also posted on my original magnum headed 318 post here https://board.moparts.org/ubbthreads/show...e=0#Post7077141 Ok, so I finally measured very carefully and I am installing pushrods today. I ended up using a thin head gasket, so my �zero lash� length for my pushrods was 7.543. According to Comps website, I could calculate .020 - .070 preload with my hydraulic lifters. (The lifters and pushrods are both Comp) I ended up going with an even number at 7.600 for pushrod length. However, when I tighten down the rocker arms, I can see the valve opening. This happens on the valves that are supposed to be closed (the cam lobe is on the �closed� side) These cam and lifters are used previously (together) and so I am wondering if I just need the lifters to �bleed down� ? What am I missing here? I hate to button this up and have problems when I first fire it up. Please help Eightlitermopar according to a post in that thread you link at least one person says he is using 7.625 pushrods so if that is the case then you are fine BUT he doesn't say what he has done to the heads or block , decking , what cam he has , stock or reground , flat tappet or roller , and what head gasket . when you determined the length were you 1000000% sure the lifter was on the absolute base of the CAM LOBE ? The base is 180* from the nose of the lobe , anywhere else and you are starting to get lift. also note that AMC lifters are not the same as Mopar lifter in the location of the pushrod seat. I personally think your pushrods are too long, you should have went fro the .020 extra length instead of closer to .060. You need to reconfirm your measurements.

Re: Valves opening while tightening rocker arms? 318 magnum [Re: JohnRR] #1404461 03/19/13 05:45 PM 03/19/13 05:45 PM
Joined: Jan 2003 Posts: 25,200 Upper Midwest M MoparforLife Too Many Posts
MoparforLife Too Many Posts M Joined: Jan 2003 Posts: 25,200 Upper Midwest	Don't understand why you are using longer pushrods that the standard when you were already having a problem./????? For some reason rereading this again it seems almost like you are taking 0 lash at the bottom of the lifter plunger travel rather than at the top before it starts to move down the lifter bore like it should be done.

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