CAM CAP HELP

[YungTlon]

Hi guys, I was just wondering when is a cam cap considered “bad”. I know obviously you don’t want your cam cap to look mangled. But my cam caps look like they have normal wear.. I can hear my finger nail scraping against if I scratch it fast enough. But they feel smooth when you run your finger along them in the proper way .. I was going to install cams and I assume all the cam caps are fine but just wanted to know when they should be replaced/honed at the machine shop.

You must be logged in to view this image or video.

 

[FIBA M - EC17PSE]

show us the pics of the caps themselfs

 

[YungTlon]

Here you go, thanks!

 

[ThunderChild]

A couple of those look pretty bad...namely caps #2 for exh. and int.

 

[jakelandry]

edit: that last picture would make me feel uncomfortable using them.


I’ve seen some pretty bad caps in my day but I really can’t recall ever even hearing of a head failing from them and I’ve both frequented the forums daily for 10 years and built several motors.

Without attempting to spread misinformation, I believe the cam may not even touch the bottom section. It’s pretty rare you see damage in the bottom half and logically, most all cam forces should go into the top half. Unlike bottom end bearings that we are used to thinking of, the cams force/bearing area is significantly less and more consistently loaded. Even if they see contamination the aluminum doesn’t spall like steel and it cant spin from the forces. Also, cams have to be “broken in” so it can’t be that critical imo. I’ve always felt pretty safe just lightly hitting them with some Emory and calling it a day.

 

[FIBA M - EC17PSE]

Some of those caps do look a little funky. Can you confirm these are the right cap for the head and not mixed from another head?

A few caps look like its wearing on one side vs the other which tells me the cap might not of been on right. With the cams in the head and caps torqued up to spec can you move the cam by hand (do this without rockers installed) if you can thats a decent sign but if not..... Then you got issues

 

[motomattx]

Its a no from me dawg, I would have those cleaned up somehow, that cam area was starved of oil pressure at some point.

 

[YungTlon]

So this is probably a big cringe for a lot of you but I figured hey if they’re trashed mine as well try it anyway(; so this was all done BY HAND no electric tools or anything just my whole 110 pounds of pure muscle (; . I decided to take a scotch bright pad and clean them up a little and they actually cleaned up really nice . And yes it was starved of oil the bottom end blew up and it ran for maybe 4 Seconds after.. first time blowing a motor I didn’t know what the hell happened . Here’s how they look . Cam cap on the bottom right I haven’t cleaned yet it’s still dirty that’s why it looks like that

 

[YungTlon]

Some of those caps do look a little funky. Can you confirm these are the right cap for the head and not mixed from another head?

A few caps look like its wearing on one side vs the other which tells me the cap might not of been on right. With the cams in the head and caps torqued up to spec can you move the cam by hand (do this without rockers installed) if you can thats a decent sign but if not..... Then you got issues

I can defintley confirm the motor ran in its current state for two years. And all the numbers on the caps lined up .. I’m pretty sure they were all in the right spot and something happened probably when the bottom end blew...

 

[YungTlon]

While I was at it I took some head measurements following this link. https://www.dsmtuners.com/threads/how-to-measure-a-4g63-for-cylinder-head-for-thickness.413757/

 

[motomattx]

They cleaned up pretty good, as long as the caps or journals in the head wont catch a fingernail you might pull it off, you should plastigauge it as a final check, also one single strand of that scotchbright anywhere in that head or cap will do damage, clean it then clean it again, then clean it two more times and then blow it all out with an air gun.

 

[YungTlon]

They cleaned up pretty good, as long as the caps or journals in the head wont catch a fingernail you might pull it off, you should plastigauge it as a final check, also one single strand of that scotchbright anywhere in that head or cap will do damage, clean it then clean it again, then clean it two more times and then blow it all out with an air gun.

yeah everything cleaned up good enough for me to feel comfortable running it , head still needs a deck though. With that being said when the machinist calls me and tells me my block is done I will take him this head and tell him to check over the cam caps and see if they’re within spec and all that fun jaz.. I’ve seen people do worse and I don’t feel too bad about this one . Kind of happy it cleaned up as well as it did

 

[Goldenugget]

They look fine. Like said before just check with plastigauge.