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Weber selection and initial jet tuning


blodi

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Hmm...looks like I have stock retainers from those pics. 

So...last night I reassembled everything. Then reset the lash to .008 and .010 on all the valves. I double and triple checked that #4 intake valve.  I then pulled the fuel pump fuse and coil wire and cranked it over probably 100 times and watched that valve closely....no odd movement at all...looked to be operating smoothly at cranking speed at least.  I installed the valve cover and fired it up.  After a few minutes...the tapping sound came back....so I immediately stopped the engine and pulled the valve cover.  I looked over everything and it all looked fine.  I checked the lash again on #4 intake....it was fine....nothing seemed out of place at all.  Reinstalled valve cover...fired it up and after a little bit the tapping sound came back .  I also could see plenty of oil flowing from the cam while I was cranking it with the cover off...so it seems lubrication is not an issue. 

I then decided to pull out my bore scope and stick it into the #4 intake.  Only thing of note that i saw was this pit on the side of the port just above the top of the valve.  Not sure if that is anything of concern or not.  So at this point...still stumped. Could the valve or guide be damaged and when it heats up the valve becomes a bit sticky and is floating? No obvious issue with the valve springs that I can see.   I could get it up to temp again and pull the cover and crank to see if I notice anything different with the movement of the valve when it's hot.  Anyways...that's where I'm at....man, this thread got off topic :(

40530475382_e7c15f01a2_b.jpgIMG_4509 by blodi, on Flickr

 

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blodi if this motor was a spare race engine as stated, do you mean spare never run or used but pulled as a back up engine.

This motor may have been run very hard previously. If so I might think about pulling head to have it checked out.

I know thats a lot of work but as long as it still Winter time.....

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You need taller retainers to keep those lash pads in place.  Isky retainers from carid.com are reasonable. (Thanks Steve Bonk)

You can also use 426 hemi keepers (thanks Steve Bonk again!) which put the valve tip lower in the retainer if you're stuck with stock retainers.

Riley at Lynchburg Nissan has lots of lash pads at just over $6 each.  http://datnissparts.com/search.php?search_query=lash&Search=

Don't be afraid of getting fatter ones and belt sanding them down to spec as you check each wipe pattern like a good little engine builder.

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I would agree that those lash pads do seem too tall for those retainers.

Really do not see why the head was built with that spring/retainer combination. 

Part of cam kit or mix and match set up? Who,s springs are those I wonder.

If mine I would remove and replace all with Schneider spring and retainer kit. My builder prefers those over Isky for the street.

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Ok...here are a couple dumb questions:

-Do I have to remove the head to replace the retainers/springs? Seems the valves would just drop if not right? 

-Would the same lash pad thicknesses apply to aftermarket retainers? I guess so since the pad still sits on top of the valve directly. 

The springs I have in the car are a dual spring setup....is the stock setup dual? 

Yeah, it seems like for as massive of a cam as this is....it should have some good springs/retainers to keep up. 

Still...I wonder why this issue would come up only after 3K+ miles on this engine....and only on the #4 intake valve.....maybe those particular springs are just getting weak? 

 

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6 hours ago, blodi said:

Ok...here are a couple dumb questions:

-Do I have to remove the head to replace the retainers/springs? Seems the valves would just drop if not right? 

-Would the same lash pad thicknesses apply to aftermarket retainers? I guess so since the pad still sits on top of the valve directly. 

The springs I have in the car are a dual spring setup....is the stock setup dual? 

Yeah, it seems like for as massive of a cam as this is....it should have some good springs/retainers to keep up. 

Still...I wonder why this issue would come up only after 3K+ miles on this engine....and only on the #4 intake valve.....maybe those particular springs are just getting weak? 

 

1. Not if you use the right tools

2. Probably

3. Yes

I've run up to .230" lash pads in stock retainers and currently run .190-.200" without issue. A valve guide issue is plausible and can be checked if you pull your springs/retainers out and wiggle the valves.

Edited by LeonV
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  • 2 weeks later...
On 3/2/2018 at 11:01 PM, Lumens said:

I would agree that those lash pads do seem too tall for those retainers.

Really do not see why the head was built with that spring/retainer combination. 

Part of cam kit or mix and match set up? Who,s springs are those I wonder.

If mine I would remove and replace all with Schneider spring and retainer kit. My builder prefers those over Isky for the street.

Where can I get the springs/retainers? I am not sure what part number I need from Schnieder's site. 

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