#421  
Old 06-10-2024, 12:52 PM
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Srmmm - That dash really looks great. I'm glad to hear it wasn't too puffy and only needed a little trimming. Thanks!

Dennis

  #422  
Old 06-17-2024, 07:57 PM
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Default RAIII Rebuild Update

Dan tore down the YZ RAIII engine today and found it to be very clean inside from excellent care the past 54 years and that it had never been opened up before. It had factory intake manifold gaskets, valley cover gasket with the factory sealer in the corners with engine paint on them, and the original 9790910 head gaskets (.038”). The block decks have the piston size/selection letter stamps at each of the cylinders. The 068 cam and factory lifters look great and may be reinstalled after a thorough vetting. The pistons were pretty heavily carboned, and the intake valve O-rings were petrified rubber and was pulling some oil down the stems, but it never burned blue anytime (and no broken rings). It appears #8 cylinder may be the cause of the knock, but the rod bearings (and mains) all looked really good still, but #8 has a little more wear, but not by much. We think we caught any problem early enough to not cause any damage. #8 also had the lowest cylinder pressure at 160 psi, the other cylinders ranged from 175 to 185. The block, heads and crank are going to the machine shop for cleaning and magnafluxing.

Dennis
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  #423  
Old 06-17-2024, 09:44 PM
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Don't like the thrust bearing or valves. Are you sure you weren't hearing detonation?

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  #424  
Old 06-18-2024, 07:00 AM
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With the valve guides leaking oil, it would also make it detonate easier,also.



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  #425  
Old 06-18-2024, 07:59 AM
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Mike & John, Nope, no audible detonation and nothing on the plugs (molten aluminum). Now, I did drive it gently the only trip it went on (to the 2021 TA Nats...maybe 700 miles round trip). The soft hammering sound was heard at idle after we returned home.

We left the original heavy factory advance springs in the distributor specifically for the reason to control possible detonation. When we checked, total came in at 4600 rpm at only 32 degrees when set at 9 degrees initial per the tune-up label.

I never opened the secondaries of the Q-jet since it's been drivable. Dan will be doing a more thorough examination this week to see what else may be going on. I'm glad it's getting rebuilt!

Dennis


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  #426  
Old 06-18-2024, 10:09 AM
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Crusty broken valve stem seals are not preferred but they do let more oil pass reducing wear some.

BTW. stock pistons last about a miniute under detonation or preignition, i busted 2 engines that way knocked the ring lands out before i knew better 45 years ago, i could of reused all the bearings the stock cast pistons go fast before bearings take a hit, forged pistons are different tho

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  #427  
Old 06-18-2024, 01:16 PM
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The tops of the pistons look fine, just carboned up a bit. All the ring lands are whole, nothing broken to the naked eye...so far. I don't think that it experienced much, if any, detonation since there was nothing broken before we obtained the car.

The plan is to go to forged Icon pistons (off-the-shelf 2618 alloy +.030 over with the 1/16", 1/16", 3/16" ring pack) and Eagle H-beam forged rods bushed for full floating pins. The block decks will be trued taking the minimal amount off. The pistons could be down the hole .005" to .015" and that will determine which head gasket we use to get to .035" to .040" quench.

The heads will get proper bronze guides, valve seals, 1-pc. Ferrea stainless steel valves, valve springs (not selected yet) and proper retainers & locks.

Dennis
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  #428  
Old 06-18-2024, 02:15 PM
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Dennis, generally what do you feel is a safe overbore on these blocks

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Old 06-18-2024, 05:01 PM
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Quote:
Originally Posted by Norwood View Post
Dennis, generally what do you feel is a safe overbore on these blocks
Hey Craig! We've taken many 400 blocks to .030 and .040 over without problems...maybe a block or 2 to .060 over without issue either. These were all earlier pre-557 block castings. If you need to go .060 over, I would sonic test for cylinder thickness.

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  #430  
Old 06-18-2024, 06:07 PM
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I did a 'square' 455 once, .060 over, got considerable hard/abusive miles out of it, would have to check my notes, but sure it went over 50k miles.

The factory crank broke, and yes, it was fully checked at time of machine work. I believe it was due to an OE type balancer (new at time of build), which looked like it had walked a little after the 'incident', but I still to this day won't run an OE crank.

It had heavy TRWs, fully prepped OE rods, aftermarket caps on center 3 with studs, internally balanced.

It broke right in front of the #2 main cap, at edge of rod journal and throw.

New cranks are plentiful and are not much more than doing the machine work on an OE crank, so I've never gone back.

Pretty sure I posted pics of its demise here.


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  #431  
Old 06-18-2024, 07:34 PM
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The ‘piston-codes’ stamped into the deck surface of the block driver side front to back are S-P-P-P, the passenger side front to back are M-L-M-M. Does anyone know the size difference of the letter designations?

Dennis
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  #432  
Old 06-18-2024, 07:36 PM
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Quote:
Originally Posted by Held for Ransom View Post
Don't like the thrust bearing or valves. Are you sure you weren't hearing detonation?
Mike, the thrust bearing looks fine after closer inspection...not sure what you are seeing?

Dennis

  #433  
Old 06-18-2024, 08:12 PM
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Quote:
Originally Posted by SD455DJ View Post
Mike, the thrust bearing looks fine after closer inspection...not sure what you are seeing?

Dennis

Second look. Shop light glare (my story and sticking to it), rest of them look fine too. Maybe piston skirt slap. How out of round were the cylinders?

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  #434  
Old 06-18-2024, 08:32 PM
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Mike, we haven't checked the cylinders yet for roundness, but that's a great idea to measure them. The cylinder pressure was pretty good for a 54 year old engine at 175 - 185 psi, with one outlier at 160 (#8). I think the previous owner(s) drove it like a grandma as evidenced by the excessive carbon build-up in the pistons and chambers.

Dennis

  #435  
Old 06-19-2024, 09:20 PM
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Well, it could just be a bad piston pin.

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  #436  
Old 06-20-2024, 12:50 PM
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Quote:
Originally Posted by Held for Ransom View Post
Well, it could just be a bad piston pin.
That's possible...we'll look at them too.

Dennis

  #437  
Old 06-20-2024, 08:38 PM
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Quote:
Originally Posted by SD455DJ View Post
The ‘piston-codes’ stamped into the deck surface of the block driver side front to back are S-P-P-P, the passenger side front to back are M-L-M-M. Does anyone know the size difference of the letter designations?

Dennis
It's pretty interesting that I am reading this today (I just happen to be catching up on this thread right now) because today I picked up a block of mine from a machinist, and I knew it was standard bore - but before it was baked and blasted for magnafluxing, I didn't actually see the stamped piston codes:

the stamped piston codes for 1-3-5-7 are: P-T-P-P
the stamped codes for 2-4-6-8 are: M-P-S-S

I had previously read of these piston codes, but before today, I don't recall ever seeing them!!
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  #438  
Old 06-20-2024, 09:26 PM
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Oops, never answered that...
400 STD.
L.....4.1200-4.1204
M....4.1204-4.1208
P.....4.1208-4.1212
S.....4.1212-4.1216
T.....4.1216-4.1220
U.....4.1220-4.1224

OS will have 2 characters.

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  #439  
Old 06-21-2024, 08:01 AM
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Thanks Mike! What is your source for the information?

Dennis

  #440  
Old 06-21-2024, 08:04 AM
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Quote:
Originally Posted by unruhjonny View Post
It's pretty interesting that I am reading this today (I just happen to be catching up on this thread right now) because today I picked up a block of mine from a machinist, and I knew it was standard bore - but before it was baked and blasted for magnafluxing, I didn't actually see the stamped piston codes:

the stamped piston codes for 1-3-5-7 are: P-T-P-P
the stamped codes for 2-4-6-8 are: M-P-S-S

I had previously read of these piston codes, but before today, I don't recall ever seeing them!!
Jonny, Interesting to see another uncut block with the stamps. I wanted to document the factory stampings before they get obliterated when the decks get cut. I'm sure some to the deeper stamps will still be visible after the milling, but the shallower stamps will be gone.

Dennis

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