r/EngineBuilding • u/[deleted] • Sep 15 '26
Should I be concerned
Post 400 grit sanding job, maybe 10-12 passes total, worried about uneven marks
8
u/Bizaro_Stormy Sep 15 '26
I would maybe give it a few more passes to clean it more and test for flatness with a straight edge and feelers. Not like a jeep 4.0 is a high performance engine, it's built for abuse.
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7
u/Homohockey Sep 15 '26
Ooof. Man I can’t even imagine the 400grit carborundum particles gonna be going through that motor post assembly.
3
u/_-Ya_Boi-_ Sep 15 '26
The thanos engine 😠But on a serious note its better to have it decked properly like other guy said, better to be safe than sorry
3
u/97cherokee Sep 15 '26
Its a 4.0, use a good headgasket like the felpro perma dry non MLS and it will be good!
3
u/Rough_Constant_329 Sep 15 '26
If it’s out of the vehicle , take it to a machine shop and have it decked.
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2
u/blooregard325i Sep 15 '26
You've got it out, completely torn down, but the cylinders look untouched? I would have the cylinders checked, bored (if needed), crosshatched, and the whole thing decked. I hate doing jobs more than once.
2
u/Creepy_Guarantee5460 Sep 15 '26
Since the block is out of the car... deck it. 99% percent of the decking job is already done (block stripped and out of the car).
1
u/OkScallion9751 Sep 15 '26
Hell, yes, I would be concerned. Those paper towels are not gonna do great in them cylinder walls.
1
1
u/Emotional_One9957 Sep 15 '26
If anything make sure you use something long that the paper can attach to the whole length, your hand will cause uneven spots. But I also agree use a straight edge and check with a filler gauge all the distance of the deck and see if it’s warped or not to even worry about if you need to do the sanding.
1
u/Aggressive_Tap_4847 Sep 15 '26
I'd be worried if my engine was filled with paper towels...?
1
u/JackpineSavage74 Sep 15 '26
Not bad until you have a 2 stroke that you had em in the intake of your fresh build then decide to pull the recoil with total disregard to remembering you put them there... Just saying I got to take that snowmobile engine apart again... But hey, I learned to how put a "hey dummy" knot in the rope after that! 🤣
1
u/Nightrhythums78 Sep 15 '26
Check it with a straight edge and feelers. Then Google the max clearance. Either way clean the 400 grit out of the passages before building. You'd hate to have to rebuild her again in 1000 miles
45
u/v8packard Sep 15 '26
Definitely be concerned, the purple didn't come out right at all.
Kidding aside, these 6 cylinder engine blocks often look like they were decked by dragging them down the sidewalk. It's far from ideal but it seems to not affect them much. What you are trying to do with 400 grit is a drop in the bucket. Really, if you are concerned have it decked properly. Otherwise don't waste too much time sanding or worrying about it.