PRHeads
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You’d think if there was an oil contamination problem it would have been spotted when the heads came off.
Pinging 505 help
- Thread starter PeteyDaMan
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You’d think if there was an oil contamination problem it would have been spotted when the heads came off.
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Like this?
Forgive my novice input on this but wouldn't you think that an over-rich condition would be dull and the shiny areas would indicate oil burning?
Here's a couple picks of the pistons and heads when I pulled the heads a few months ago.
Heads have since been checked, cleaned and valves reseated.
Heads have since been checked, cleaned and valves reseated.
PRHeads
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What’s the puddle?
yep, when I took the heads off the coolant wasn't completely drained so it dripped into the cylinder.
lewtot184
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Correct me if I'm wrong but don't you have closed chamber heads? I do prefer your choice in head gaskets.
PRHeads
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Splangj
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Any updates? It’s been almost a month.
I dropped it off at Danbury Competition Engines in Danbury, CT 3 weeks ago. I called yesterday and they are just getting around to taking a look (busy shop). They're going to tear it down to check my assembly as well as cc-ing the heads and pistons, compression height, etc.
Once I hear more I'll be sure to let you all know.
m79ded
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Here's what I've seen on a few sets of Mahle pistons. They wobble in the BORE, They have no skirts and on 2 engines I've worked on it sounded like a combination of piston slap and ping, Called Mahle and answer was. "It's the nature of the beast" Last time got Mahle, Went to Ross never looked back, because they have a full skirt and much more stable in bore
Geoff 2
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How much slop the piston has in the bore at assembly time [ room temp ] has NOTHING to do with the gap at operating temp. A piston made from 2032 alum & 0.004" bore clearance will be noisier in operation than a 2618 piston with 0.004" clearance, all else being equal. That is because 2032 has a lower expansion rate. All else being equal......the piston shape, the thickness of the alum & the cam ground into the piston affect the clearance at operating temp.
m79ded
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There was enough slap to make it noisy, If you look at Mahle pistons there is absolutely no skirt, and I've seen it with my own eyes and called Mahle on it, No matter how tight it will wobble some. Enough to make noise. BTW Same engine just went to Ross and everything was good, perfect engine customer was happy. Running 10+ years later.
m79ded
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Geoff we had checked all that because we were as much surprised as well. Clearances were spot on perfect. It was just that the piston had no stability in the bore, and I mean nothing.
post #2 shows the measurements for the bores and pistons on my 505. The top chart is the bore variance from 4.350 at different bore depths and orientation. Below that is the piston size. Each marked with a letter to designate which piston went in which bore.
That being said, the skirts on the Mahle pistons are pretty short.
That being said, the skirts on the Mahle pistons are pretty short.
m79ded
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EXACTLY what I was trying to say, it may not be that I hope the OP finds out what issue is.
Meep-Meep
дворянин
Are you running an extended tip plug? If so you need to run a recessed tip. If the plugs are long reach try Autolite R3935. The main reason is the short ground electrode will dissipate heat much faster than that long electrode found on long reach plugs. In my case, running an iron head BB with 9.5:1 and 185 PSI, it pings on a hot day. I put Autolite 303s and the problem seems to have gone away. At least at the last MoPar race at Sac Raceway where I did not have to spike my car with 110.
Geoff 2
Well-Known Member
The heat range of the plug is controlled at the design stage. A projected nose tip plug will have the insulator size adjusted to maintain the nominated heat range. Projected nose tip plugs are better at self cleaning & preventing misfires. You would only switch to a non-projected tip plug if you added a power adder such as nitrous, blower; even then it can be a backwards move.
m79ded
Well-Known Member
So you prefer the Autolite plug for the Iron head? In terms of pinging it was better than NGK or Champion? This is interesting because at around 9.5 Static, 8.2 Dynamic with Iron heads and Manifolds it starts rattling. I'm sure many have that issue with Manifolds especially, Thanks for the info Meep much appreciated
Meep-Meep
дворянин
Over the years I have mostly run Autolites. Champion on occasion and Nippondenso too. Even tried the Bosch platinum when they came out in the late 80s. Never had good luck with NGK even on my dirt bikes. Maybe it was me not knowing much back then but ND always worked in the bikes.
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