Is This an Indicator of Detonation?

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JGC403

JGC403

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New rebuild 383, for some reason the intermediate shaft bushing got eatten and I can't get the bushing out with the engine in the vehicle, that's another story. Anyways I got the passenger side head off last night, and besides noticing that its running rich. I noticed a light band in the cylinder walls right under where the rings stop at the top of the bore. Then the rest of the bore is a darker color. Its like that in every cylinder on the passenger side. Didn't get the driverside head off yet. Is this a sign of detonation? I couldn't hear any pinging over the exhaust, its on the loud side. Compression ratio is right around 9.8:1. DCR should be around 7.33:1. Iron 906 heads. The smallest MP solid lifter cam.
383 bore #4.jpg



Also the valve tips. Every intake valve and 2 of the exhaust valves have this kind of pattern on the tip where the roller contacted the valve tip on the passenger side. I am trying to remember it was about 10 years ago, but a machine shop told me that this pattern on the valve stem tip was a sign of detonation. Anyone else hear of this or experience??
383 intake valve tip.jpg
 
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Any indication of detonation might be seen on piston tops not in the areas you show. All looks normal so far.
 
All looks semi ok, rich and some oil pass, but ok. How many miles? What was the break in procedure? The valves are not rotating on a few it seems. Those stem marks are not good. In the first pic the piston has some build up. My guess is the heads are not in good shape based on the few pics shown!
 
Couple of comments.

It might be just the light, but contact on the valve tip looks heavier on one side. If so, most likely caused by misalignment within the rocker.

What sort of int shaft bushing, bronze or alum? Also, is the int shaft original factory or aftermarket?
 
Detonation shows up as pock marks on the crown of the piston......show us the top of a piston
 
The carbon that is on the combustion chambers, piston and along the top of the bore was dry, not oily. Some antifreeze got in the bore when I pulled the head, I cleaned out the water with a rag then soaked the bores in PB blaster so the bores don't rust. Then I took a picture, that is why the carbon is so wet looking in the picture. The runners of the intake ports are clean no evidence of oil. I'll post picture of a piston tomorrow.

There is a MP solid lifter cam in the 383, I used Comp Cams Pro Magnum Roller Rockers.
 
The top mark is top ring. 2nd mark is the 2nd ring, which is an oil scraper do the witness Mark will be different.
That’s a lot of oil for a fresh engine. Pattern on the valve tips is not detonation but does show issues with the geometry.
Bushing should be able to be removed - if you have to take off the oil pump and go up the drive hole...
 
moper said:
The top mark is top ring. 2nd mark is the 2nd ring, which is an oil scraper do the witness Mark will be different.
That’s a lot of oil for a fresh engine. Pattern on the valve tips is not detonation but does show issues with the geometry.
Bushing should be able to be removed - if you have to take off the oil pump and go up the drive hole...
Click to expand...

I don't think its oil, the carbon in the chamber is dry. The carbon in the picture I posted is wet because I soaked the bore in PB blaster so it wouldn't rust.

How do I fix the valvetrain geometry if there is a problem?

I tried getting the bushing out from the bottom, but the bushing got so chewed up that there wasn't enough material left for a punch or a bolt the same size to grab.
 
If the chamber is black it’s burning oil. Simple as that.
Geometry on a Mopar shaft system is the valve job. You can correct for it but I’d suggest giving Mike at B3 a call and he can walk you through getting what he needs to fix it.
That busing is oilite bronze. Shatter it into pieces and push it out the bottom. I have a puller I made and it just grabs the bottom lip, and if it breaks, it grabs the bottom edge that’s left. But even having to break it up shouldn’t be more than an hour with a long punch or piece of steel rod.
 
Looks to me like the valve is just slightly spinning back and forth. Makes a butterfly pattern. Don't know how good or bad this is.
 
Got the driverside head off tonight, I don't think any coolant got into the bore when I pulled the head off. Cylinders 1 and 3 had some build up on the tops of the piston compared to the others that had an even amount of carbon on the pistons.

There is less than 40 miles of actual driving on the motor. I broke in the cam bringing the RPM up to 2500 for 20 minutes and varying the RPM during those 20 min a few times. Cam looks fine.

I don't think oil is getting by the guides. Intake runners are clean and I don't see any oil on the stems in the port. I have an oil separator on the PCV. There was a little oil on there.

Could the Rings not be broken in yet? They were Childs & Albert Moly coated 1/16" top ring, 1/16" Ductile iron 2nd ring and a 3/16" Standard tension oil ring. I don't remember seeing any silver smoke out the exhaust.

383 intake runners 906.jpg
383 combustion chamber 906.jpg

383 #3 piston.jpg
 
If oil deposit seem to be similar on all piston tops I feel it's a very good chance at the rings haven't seated yet, there may be more going on hopefully not. I wouldn't sweat the coolant in the bore to much just get it dried out and maybe wipe it down with some oil it happens.
 
If you are not sure if the rings are seated, put it back together, take it out and stand on it as hard as you can. Rings seat due to pressure, not just going up and down in the cylinder; take the car out and put a load on the engine
 
I see Oil burning on piston tops.

Check the spring installed height and psi on a butterfly pattern vs the 2 that are different or stable and center. You might find you are light on pressure, seat pressure. The numbers shouldn't vary from one another more than 8psi. You can have them close to insufficient already and then let a few slide 5 psi lighter and bam...you have issues.
In performance land...we want the valve tip pattern to be a horizontal line, as in ..no valve spin. Spinning ain't winning 'in more ways than one'. Spin is for stock 85psi seat & 200 open psi crap that lifts .390-.410...
The hone job may be too rough for the rings...hence taking "long time" *add in asian voice* and oil on piston tops.

Disclaimer
Never forget ...we love seeing pics of teardowns and will gladly have you ripping back to square one, so dig carefully and have plenty of money. Lol
 
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